CN212588095U - Power compensation power transformation system applied to power transmission - Google Patents
Power compensation power transformation system applied to power transmission Download PDFInfo
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- CN212588095U CN212588095U CN202020988902.1U CN202020988902U CN212588095U CN 212588095 U CN212588095 U CN 212588095U CN 202020988902 U CN202020988902 U CN 202020988902U CN 212588095 U CN212588095 U CN 212588095U
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/50—Arrangements for eliminating or reducing asymmetry in polyphase networks
Abstract
The utility model discloses a be applied to power transmission's electric power compensation transformer system, this system include electric current accuse voltage source subsystem, electric current accuse current source subsystem, power supply transform subsystem and public direct current bus four bibliographic categories. The current control voltage source subsystem is connected in series in the power transmission line, the output voltage of the current control voltage source subsystem is controlled by the line current, and the current control voltage source subsystem has the functions of voltage boosting, impedance compensation and the like; the current control current source subsystem is connected in parallel in the power transmission line, and can perform cooperative impedance compensation with the current control voltage source subsystem on one hand to improve power transmission efficiency except for realizing basic functions such as dynamic reactive compensation and the like; on the other hand, through the interaction with the energy storage device, the double work of charging and discharging is carried out, the balance and the adjustment of the energy of the power grid are realized, and the problem of peak-valley balance of the power grid is effectively solved.
Description
Technical Field
The utility model relates to an alternating current transmission line or alternating current distribution network's electric power compensation electric power transformation system belongs to the circuit arrangement or the technical field of system of power supply or distribution.
Background
The problems that power grid companies face all the world are that power grid construction in load-dispersed areas is poor in economic benefit and low in input-output ratio. South Africa Eskom electric power company and Australian Country Energy electric power company research shows that the traditional power generation and distribution system is only suitable for residential areas with higher population density and lower user density (lower than 70 users/km)2) In the rural areas, the problems of low power supply voltage at the tail end of the line and unqualified power quality are easy to occur due to the large power supply radius. In addition, as the load of the users increases and the load of a single point increases, the power supply quality of the users at the tail of the line is more affected. In areas with low population density, the load is dispersed, the load rate is low, the cost of a power distribution network is high, the input-output ratio is low, and the problems of low utilization efficiency of the power grid, high operation and maintenance cost and the like are faced after the power grid is built.
For countries with prominent climatic characteristics, regional centralized power supply is realized mainly by fully utilizing climatic advantages and vigorously developing new energy for power generation. However, the climate conditions of China are complex, the power supply problem of remote areas cannot be solved singly by relying on distributed new energy power generation, and various energy sources are comprehensively considered to form a complementary system. Like inland high-altitude areas such as Qinghai province, the construction and maintenance process of the power grid is abnormal and hard due to higher altitude of the area and severe weather conditions, and the investment and operation and maintenance cost is far higher than that of developed areas in the east. The load is dispersed, and the power supply radius of transformer substation is limited, often needs longer medium voltage circuit and the power supply of dispersed transformer substation ability realization whole region, and the utilization ratio of dispersed transformer substation owner transformer is low, and a most power loss has been at the in-process of line transmission, and mainly because of the loss that active current flowed through longer transmission line and caused, can't improve terminal voltage characteristic through parallelly connected reactive compensation equipment simply. In order to ensure the electricity quality of the end users and reduce the line loss, the traditional scheme is to newly build a substation close to the load point. Although the scheme ensures that the voltage of the user side is qualified, the high investment and construction cost and the low transformer substation resource utilization rate seriously violate the economic, reliable, safe and efficient operation requirements of the smart grid and are not beneficial to the construction and development of the smart grid. Therefore, a low-cost and high-reliability comprehensive compensation scheme is urgently needed, which can still adjust the impedance characteristic of the power transmission line under the condition of load fluctuation and realize impedance compensation, thereby improving the power transmission efficiency, stabilizing the terminal voltage, eliminating harmonic current, realizing peak-valley balance in the peak and valley of power utilization, optimizing energy conservation, and really realizing safe, economic and efficient operation of a power grid.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to provide a be applied to power transmission's power compensation transformer system, this system includes current accuse voltage source subsystem, current accuse current source subsystem, power supply transform subsystem and public direct current bus portion. The current control voltage source subsystem is connected in series in the power transmission line, the output voltage of the current control voltage source subsystem is controlled by the line current, and the current control voltage source subsystem has the functions of voltage boosting, impedance compensation and the like; the current control current source subsystem is connected in parallel in the power transmission line, and can perform cooperative impedance compensation with the current control voltage source subsystem to cooperatively change the equivalent impedance of the power transmission line and improve the power transmission efficiency on the one hand besides realizing basic functions such as dynamic reactive compensation and the like; on the other hand, through interaction with energy storage equipment comprising a battery, double work of charging and discharging is carried out, so that the balance and adjustment of the energy of the power grid are realized, and the problem of peak-valley balance of the power grid is effectively solved.
In order to achieve the above purpose, the utility model adopts the following technical scheme:
a power compensation power transformation system applied to power transmission adopts a power compensation power transformation working mode to carry out signal control; the power compensation power transformation system applied to power transmission comprises a current control voltage source subsystem, a current control current source subsystem, a power supply conversion subsystem and a common direct current bus;
the current control voltage source subsystem is connected in series in the electric power transmission line, the input end of the current control voltage source subsystem is a three-phase line terminal of a power supply end, and the output end of the current control voltage source subsystem is a three-phase line terminal of a power receiving end; the amplitude and the phase of the voltage generated by the current-controlled voltage source subsystem are controlled according to the current of the power line, and the current-controlled voltage source subsystem is used for realizing the functions of voltage compensation, impedance compensation and the like of the power transmission line;
the current control current source subsystem is connected in parallel in the power transmission line, namely connected between the three-phase line terminal and the neutral line terminal; the current control current source subsystem is used for realizing the current compensation, impedance compensation and power balance functions of the electric transmission line;
the specific connection relation between the current control voltage source subsystem and the current control current source subsystem comprises two topologies; wherein the content of the first and second substances,
the first topology is that the current control current source subsystem is close to a three-phase terminal at a power supply end, and the current control voltage source subsystem is close to a three-phase terminal at a power receiving end, namely the current control current source subsystem is connected with the three-phase terminal at the power receiving end after passing through the current control voltage source subsystem;
the second topology is that the current control voltage source subsystem is close to a three-phase terminal at a power supply end, and the current control current source subsystem is close to a three-phase terminal at a power receiving end, namely the current control current source subsystem is directly connected with the three-phase terminal at the power receiving end;
the power supply conversion subsystem, the current-controlled voltage source subsystem and the current-controlled current source subsystem are connected in parallel and are connected to a common direct current bus together; the power supply conversion subsystem replaces respective independent power supplies in the current-controlled voltage source subsystem and the current-controlled current source subsystem to supply power to the two subsystems when a new energy and energy storage equipment access mode is selected;
and the common direct current bus is connected with the current-controlled voltage source subsystem, the current-controlled current source subsystem and the power supply conversion subsystem and is used for realizing energy transfer in the system.
Preferably, the power compensation power transformation system applied to power transmission is mainly controlled by an upper computer through signals of a power compensation power transformation working mode of power transmission, centralized control is performed by external equipment of the system, equipment management and maintenance are facilitated, and the accident rate is reduced.
Preferably, the current controlled voltage source subsystem comprises: the voltage source independent power supply rectifies alternating current of a power grid through an isolation transformer to obtain direct current, and outputs the direct current to the voltage source power converter for providing an independent energy source for the voltage source independent power supply; the voltage source power converter adopts an inverter topology, the direct current side of the voltage source power converter is connected with the direct current output end of the voltage source independent power supply, a common direct current bus access terminal is led out from the connection position of the voltage source power converter and is used for being connected with a common direct current bus, and the alternating current side of the voltage source power converter is connected with a primary side winding of a transformer and is used for generating corresponding compensation voltage according to a control signal of the voltage source controller; the primary side winding of the transformer is connected with the alternating current side of the voltage source power converter, and the secondary side winding of the transformer is connected in series in the power transmission line and used for compensating the compensation voltage generated by the voltage source power converter into the power transmission line so as to realize the function of voltage compensation or impedance compensation; the voltage source controller adopts a voltage-giving set PWM controller, takes a current signal of a power transmission line as a phase reference given value, calculates and solves voltage given values under different working modes, and accordingly outputs a corresponding control instruction to the voltage source power converter for the controller to generate compensation voltage required under different working modes.
Preferably, the current control current source subsystem comprises a current source independent power supply, a current source power converter, a current source controller and a reactor; the current source independent power supply rectifies alternating current of a power grid through an isolation transformer to obtain direct current, and outputs the direct current to the current source power converter for providing an independent energy source for the current source power converter; the current source power converter adopts an inverter topology, the direct current side of the current source power converter is connected with the direct current output end of the current source independent power supply, a common direct current bus access terminal is led out from the connection position of the current source power converter and is used for being connected with a common direct current bus, the output port of the neutral point on the alternating current side of the current source power converter is connected with the neutral line of the power transmission line, and the three-phase output port is connected with the reactor and is used for realizing electric energy conversion under different working modes according to the control signal of the current source controller and; one side of the reactor is connected with the three-phase output end of the current source power converter, and the other side of the reactor is connected with the three-phase line of the power transmission line and used for injecting compensation current into the power grid or receiving feedback current of the power grid; the current source controller adopts current to give the design PWM controller, gives with the current signal of electric power transmission line as the phase reference, produces different PWM control commands to the current source power converter according to different mode of operation, is used for controlling its work in rectification or contravariant state to make it produce required compensating current or convert the feedback current of receiving the electric wire netting into direct current and transmit to the energy storage device that the power supply transform subsystem inserts through public direct current bus and carry out the electric energy storage.
Preferably, the power supply conversion subsystem comprises an energy storage battery converter, a wind energy access converter, a photovoltaic access converter and a power supply conversion controller; the energy storage battery converter adopts a direct current chopper circuit topology, one side of a direct current end of the energy storage battery converter is connected with an external energy storage battery access port, and the other side of the direct current end of the energy storage battery converter is connected to a common direct current bus and is used for realizing the charge and discharge functions of the energy storage battery; the wind energy access converter adopts a rectifying circuit topology, the AC side of the wind energy access converter is connected with an external wind turbine access port, and the DC side of the wind energy access converter is connected to a common DC bus and is used for accessing electric energy generated by wind power generation; the photovoltaic access converter adopts a direct current chopper circuit topology, one side of a direct current end of the photovoltaic access converter is connected with an external photovoltaic panel access port, and the other side of the direct current end of the photovoltaic access converter is connected to a common direct current bus and used for accessing electric energy generated by photovoltaic power generation; and the power supply conversion controller is respectively connected with the three converters and is used for controlling the direct current output ends of the three converters to generate direct current with the same voltage amplitude as the common direct current bus.
In some embodiments of the present invention, the working mode of the novel power compensation transformation system includes: the compensation method comprises a current control voltage source independent compensation mode, a current control current source independent compensation mode and a cooperative compensation mode.
The utility model discloses an in some concrete examples, novel electric power compensation electric power transformation system's mode of operation, its characterized in that, the independent compensation mode of electric current accuse voltage source includes: the system comprises a voltage boosting mode and an impedance compensation mode, wherein the voltage boosting mode is used for boosting the transmission voltage of the power line, ensuring the tail end voltage to be qualified and reducing the line loss; the impedance compensation mode is used for changing the equivalent impedance of the electric power transmission line and improving the power transmission efficiency.
The utility model discloses an in some concrete examples, novel electric power compensation electric power transformation system's mode of operation, its characterized in that, the independent compensation mode of electric current accuse current source includes: the power transmission system comprises an impedance compensation mode, a current compensation mode and an energy storage mode, wherein the impedance compensation mode is used for changing the equivalent impedance of the power transmission line and improving the power transmission efficiency; the current compensation mode is used for providing reactive compensation and harmonic compensation and improving the power factor of the line; the power balance mode is used for receiving electric energy fed back by the power grid, is matched with the energy storage equipment, realizes the balance control of the power grid-load, realizes the power balance and solves the problem of peak-valley balance.
The utility model discloses an in some concrete examples, novel electric power compensation electric power transformation system's mode, the mode of compensation in coordination includes following several kinds:
cooperative impedance compensation mode: the current-controlled voltage source subsystem and the current-controlled current source subsystem work in an impedance compensation mode and coordinate and control uniformly, and the total equivalent impedance of the whole system is adjusted and controlled, so that the equivalent impedance of the power transmission line is changed, and the power transmission efficiency is improved.
Impedance-current compensation mode: the current control voltage source subsystem works in an impedance compensation mode, and the current control current source subsystem works in a current compensation mode and is uniformly coordinated and controlled.
Impedance-power balance mode: the current control voltage source subsystem works in an impedance compensation mode, and the current control current source subsystem works in a power balance mode and is uniformly coordinated and controlled.
Voltage-current compensation mode: the current control voltage source subsystem works in a voltage boosting mode, and the current control current source subsystem works in a current compensation mode and is in unified coordination control.
Compared with the prior art, the utility model discloses following profitable technological effect has:
(1) the utility model discloses be applied to electric power transmission's electric power compensation transformer system and have impedance compensation, multiple functions such as voltage compensation and power balance; the current control current source subsystem and the current control voltage source subsystem can work independently to realize compensation of corresponding different modes, can also run cooperatively, and can switch the working mode of the whole power transformation system according to the actual transmission condition of the power line so as to achieve the optimal power line transmission effect;
(2) the utility model discloses be applied to the energy resource extensive in the power supply transform subsystem among the electric power compensation transformer system of power transmission, including new forms of energy such as energy memory, electric wire netting and photovoltaic, wind-powered electricity generation for the energy configuration of system is nimble, does not rely on single energy source, and multiple energy has formed complementary system jointly; in addition, the energy storage module is added, and the energy storage module is matched with the current control current source subsystem for use, so that the problem that the energy demand amount is suddenly changed and the energy source is unstable due to load fluctuation, climate fluctuation and day and night change factors, which cannot be compensated, can be effectively solved;
(3) the utility model discloses a be applied to electric power transmission's electric current accuse voltage source module in electric power compensation transformer system, because PWM rectifier inverter has the characteristic of energy bidirectional flow, consequently can be according to the trend condition of circuit, switch over two kinds of mode of working of energy storage and discharge; when the demand of electric energy is large, and the module works in a discharge mode, current can be injected into a circuit for compensation, so that the problems of harmonic waves, three-phase imbalance and the like can be effectively eliminated; when the load is in the low valley, the module works in an energy storage mode, rectifies the energy of the power grid and feeds the rectified energy back to the energy storage device, and the peak-valley load balance problem can be solved without forced management on the power demand side, so that the optimization and energy conservation are realized.
Drawings
Fig. 1 is a schematic diagram of a specific implementation structure of the novel power compensation power transformation system of the present invention, which adopts a first topology.
Fig. 2 is a schematic structural diagram of the current control voltage source subsystem of the present invention.
Fig. 3 is a schematic diagram of the operation mode of the current-controlled voltage source subsystem according to the present invention.
Fig. 4 is a schematic structural diagram of the current-controlled current source subsystem of the present invention.
Fig. 5 is a schematic diagram of the operation mode of the current-controlled current source subsystem according to the present invention.
Fig. 6 is a schematic structural diagram of the power supply conversion subsystem of the present invention.
Fig. 7 is a schematic diagram of a specific implementation structure of the novel power compensation power transformation system of the present invention, which adopts a second topology.
Detailed Description
In order to better explain the present invention and to facilitate understanding of the technical solutions of the present invention, the present invention will be further described in detail with reference to the accompanying drawings and specific embodiments. It should be understood that the following examples are illustrative only and do not represent or limit the scope of the present invention, which is to be controlled by the appended claims.
The first embodiment is as follows:
in the present embodiment, referring to fig. 1 and 7, a power compensation transformation system applied to power transmission performs signal control by using a power compensation transformation operation mode of power transmission; the power compensation power transformation system applied to power transmission comprises a current control voltage source subsystem 1, a current control current source subsystem 2, a power supply conversion subsystem 3 and a common direct current bus 4;
the current control voltage source subsystem 1 is connected in series in the electric power transmission line, the input end of the current control voltage source subsystem is a three-phase line terminal of a power supply end, and the output end of the current control voltage source subsystem is a three-phase line terminal of a power receiving end; the amplitude and the phase of the voltage generated by the current-controlled voltage source subsystem are controlled according to the current of the power line, and the current-controlled voltage source subsystem is used for realizing the functions of voltage compensation, impedance compensation and the like of the power transmission line;
the current control current source subsystem 2 is connected in parallel in the power transmission line, namely connected between a three-phase line terminal and a neutral line terminal; the current control current source subsystem is used for realizing the functions of current compensation, impedance compensation, power balance and the like of the power transmission line;
the specific connection relation between the current-controlled voltage source subsystem 1 and the current-controlled current source subsystem 2 comprises two topologies; wherein the content of the first and second substances,
the first topology is that the current-controlled current source subsystem 2 is close to a three-phase terminal at a power supply end, and the current-controlled voltage source subsystem 1 is close to a three-phase terminal at a power receiving end, namely the current-controlled current source subsystem 2 is connected with the three-phase terminal at the power receiving end after passing through the current-controlled voltage source subsystem 1;
the second topology is that the current-controlled voltage source subsystem 1 is close to a three-phase terminal at a power supply end, and the current-controlled current source subsystem 2 is close to a three-phase terminal at a power receiving end, namely the current-controlled current source subsystem 2 is directly connected with the three-phase terminal at the power receiving end;
the power supply conversion subsystem 3, the current-controlled voltage source subsystem 1 and the current-controlled current source subsystem 2 are connected in parallel and are commonly connected to a common direct current bus 4; the power supply conversion subsystem replaces respective independent power supplies in the current-controlled voltage source subsystem and the current-controlled current source subsystem to supply power to the two subsystems when a new energy and energy storage equipment access mode is selected;
and the common direct current bus 4 is connected with the current-controlled voltage source subsystem 1, the current-controlled current source subsystem 2 and the power supply conversion subsystem 3 and is used for realizing energy transfer in the system.
In the embodiment, the current-controlled voltage source subsystem is connected in series in the power transmission line, and the output voltage of the current-controlled voltage source subsystem is controlled by the line current and has the functions of voltage boosting, impedance compensation and the like; the current control current source subsystem is connected in parallel in the power transmission line, and can perform cooperative impedance compensation with the current control voltage source subsystem on one hand to improve power transmission efficiency except for realizing basic functions such as dynamic reactive compensation and the like; on the other hand, through interaction with energy storage equipment, the double work of charging and discharging is carried out, so that the balance and adjustment of the energy of the power grid are realized, and the problem of peak-valley balance of the power grid is effectively solved.
Example two:
this embodiment is substantially the same as the first embodiment, and is characterized in that:
in this embodiment, referring to fig. 1 to 7, the current-controlled voltage source subsystem 1 includes a voltage source independent power supply 11, a voltage source power converter 12, a voltage source controller 13, and a transformer 14, where the voltage source independent power supply 11 rectifies an ac power of a power grid through an isolation transformer to obtain a dc power, and outputs the dc power to the voltage source power converter 12; the voltage source power converter 12 adopts an inverter topology, the direct current side of the inverter topology is connected with the direct current output end of the voltage source independent power supply 11, a common direct current bus access terminal is led out from the connection position of the inverter topology, and the alternating current side of the inverter topology is connected with a primary side winding of the transformer 14; the primary winding of the transformer 14 is connected to the ac side of the voltage source power converter 12; the voltage source controller 13 employs a voltage to give the type PWM controller.
In the present embodiment, the current-controlled current source subsystem 2 includes a current source independent power supply 21, a current source power converter 22, a current source controller 23 and a reactor 24; the current source independent power supply 21 rectifies alternating current of a power grid through an isolation transformer to obtain direct current, and the direct current is output to the current source power converter 22; the current source power converter 22 adopts an inverter topology, the direct current side of the current source power converter is connected with the direct current output end of the current source independent power supply 21, a common direct current bus access terminal is led out from the connection position of the current source power converter and is used for being connected with the common direct current bus 4, the output port of the neutral point on the alternating current side of the current source power converter is connected with the neutral line of the power transmission line, and the three-phase output port of the current source power converter is connected with; one side of the reactor 24 is connected with the three-phase output end of the current source power converter 22, and the other side is connected with the three-phase line of the power transmission line; the current source controller 23 employs a current-giving type PWM controller.
In the embodiment, the power supply conversion subsystem comprises an energy storage battery converter 31, a wind energy access converter 32, a photovoltaic access converter 33 and a power supply conversion controller 34; the energy storage battery converter adopts a direct current chopper circuit topology, one side of a direct current end of the energy storage battery converter is connected with an external energy storage battery access port, and the other side of the direct current end of the energy storage battery converter is connected to a common direct current bus 4; the wind energy access converter adopts a rectifying circuit topology, the AC side of the wind energy access converter is connected with an external wind turbine access port, and the DC side of the wind energy access converter is connected to a common DC bus 4; the photovoltaic access converter adopts a direct current chopper circuit topology, one side of a direct current end of the photovoltaic access converter is connected with an external photovoltaic panel access port, and the other side of the direct current end of the photovoltaic access converter is connected to a common direct current bus 4; the power supply source conversion controller 34 is connected to the three converters, respectively.
Example three:
this embodiment is substantially the same as the previous embodiment, and is characterized in that:
in this embodiment, the current-controlled voltage source subsystem is shown in fig. 2, and includes a voltage source independent power supply, a voltage source power converter, a voltage source controller, and a transformer. Wherein: the voltage source independent power supply rectifies alternating current of a power grid through an isolation transformer to obtain direct current, and outputs the direct current to the voltage source power converter to provide an independent energy source for the voltage source power converter; the voltage source power converter adopts an inverter topology, the direct current side of the inverter topology is connected with the direct current output end of the voltage source independent power supply, a common direct current bus access terminal is led out from the connection position of the inverter topology and connected with a common direct current bus, the alternating current side of the inverter topology is connected with a primary side winding of a transformer, and corresponding compensation voltage can be generated according to a control signal of the voltage source controller. The primary side winding of the transformer is connected with the alternating current side of the voltage source power converter, the secondary side winding of the transformer is connected in series in the power transmission line, and compensation voltage generated by the voltage source power converter is compensated into the power transmission line so as to realize the function of voltage compensation or impedance compensation. The voltage source controller adopts a voltage-giving set PWM controller, takes a current signal of a power transmission line as a phase reference given value, calculates and solves voltage given values under different working modes, and accordingly outputs a corresponding control instruction to the voltage source power converter for the controller to generate compensation voltage required under different working modes. The specific operation principle analysis is as follows:
suppose that: for three-phase line voltage at supply terminal
For indicating the voltage of the three-phase line at the receiving end
For indicating the compensation voltage generated by the current-controlled voltage source subsystem
It is shown that, based on kirchhoff node voltage theorem:
amplitude and phase of compensation voltage generated by current control voltage source subsystem are controlled by current in power transmission and distribution line
Controlling, i.e. compensating voltage generated and current in line
The phase difference and the amplitude proportion are adjustable, so the generated compensation voltage can be expressed by the following formula:
is shown as ZsIs a transfer resistance parameter of the current-controlled voltage source, which reflects the compensation voltage generated by the current-controlled voltage source subsystem
And line current
The specific relationship of (a). A current-controlled voltage source subsystem is connected in series in a power supply line, and viewed from a power supply end or a power receiving end according to the voltage and current characteristics at two ends of the subsystem, the subsystem can be equivalently regarded as impedance connected in series in a power transmission line, the voltage of the subsystem is in direct proportion to the line current, and the impedance value is Zs. By adjusting ZsCan change the compensation voltage of the series connection power transmission line
Thereby changing the voltage of the power receiving end of the line
And voltage boosting is realized. In addition, due to the generated compensation voltage
And line current
Can be at any angle, so ZsCan be regarded as composite impedance composed of capacitor, resistor and inductor, and is realized by changing ZsThe load compensation method can adjust in real time according to the load fluctuation condition to realize impedance compensation, thereby improving the power transmission efficiency.
As shown in fig. 3, the voltage setting control signals generated by the voltage source controller in the two working modes are different, although both the line current signals are used as phase reference setting, the setting of the given compensation voltage amplitude phase in the voltage boosting working mode is mainly based on the fact that the voltage at the receiving end conforms to the voltage amplitude range of the power system to obtain the corresponding compensation voltage setting signal for control, and the setting of the given compensation voltage amplitude phase in the impedance compensation working mode is mainly based on the impedance characteristics of the line to enable the equivalent impedance Z of the current-controlled voltage source subsystem to be equivalentsThe primary impedance Z to the transmission linelThe matching is carried out according to the obtained corresponding compensation voltage given signal (including the integral equivalent impedance of the load impedance at the moment).
In this embodiment, as shown in fig. 4, the current-controlled current source subsystem includes: the power supply comprises a current source independent power supply source, a current source power converter, a current source controller and a reactor. Wherein: the current source independent power supply rectifies alternating current of a power grid through an isolation transformer to obtain direct current, and outputs the direct current to the current source power converter to provide an independent energy source for the current source power converter; the current source power converter adopts an inverter topology, the direct current side of the current source power converter is connected with the direct current output end of the current source independent power supply, a public direct current bus access terminal is led out from the connection position of the current source power converter and connected with a public direct current bus, the output port of the neutral point of the alternating current side of the current source power converter is connected with the neutral line of the power transmission line, and the three-phase output port is connected with the reactor and used for realizing electric energy conversion under different working modes according to the control signal of the current source controller and carrying out rectification; one side of the reactor is connected with the three-phase output end of the current source power converter, and the other side of the reactor is connected with the three-phase line of the power transmission line and used for injecting compensation current into the power grid or receiving feedback current of the power grid; the current source controller adopts a current giving and setting PWM controller, takes a current signal of a power transmission line as a phase reference giving, generates different PWM control instructions to the current source power converter according to different working modes, and is used for controlling the current source power converter to work in a rectification or inversion state, so that the current source power converter generates required compensation current or converts feedback current of a received power grid into direct current and transmits the direct current to the energy storage device through a common direct current bus for electric energy storage. The specific operation principle analysis is as follows:
suppose that: for three-phase line current at supply terminal
For indicating, receiving, three-phase line current
Indicating the use of current flowing through a current-controlled voltage source subsystem
And (3) indicating that the current is known based on the kirchhoff node current theorem:
under different working modes, the current flows in different directions, the current source power converters have different working states and different control targets, and the specific analysis is as follows:
in this embodiment, as shown in fig. 5, when the current-controlled current source operates in the impedance compensation mode, the current flowing through the current-controlled voltage source subsystem
The flow direction of the current is that the current is injected into the power grid by the current control current source subsystem, and the current is injected into the power grid
Amplitude and phase of the current received by the line
Control of so
kiIs the current amplification factor of the current-controlled current source, which reflects the compensation current generated by the current-controlled current source subsystem
Current of original line
In particular, the current source power converter operates in an inverter state. The current given control signal generated by the current source controller is mainly used as a control target according to the impedance characteristic matching of the power transmission line, so that the adjustment and matching of the impedance characteristic of the line are realized. When the current-controlled current source works in the current compensation mode, the current flowing through the current-controlled voltage source subsystem
The current is injected into or absorbed from the power grid by the system, and the current source power converter circuit absorbs or sends reactive current meeting the requirements under the mode based on the active compensation principle, so that the aims of dynamic reactive compensation and dynamic voltage control are fulfilled, harmonic waves and three-phase imbalance phenomena can be eliminated, and the power factor of the line is improved. When the current-controlled current source works in a function balance mode, the current flowing through the current-controlled voltage source subsystem
The flow direction of (a) is that of the current-controlled current source subsystem injected by the grid, in which mode,the current source power converter works in a rectification state, and under the condition that the power transmitted by a power grid power supply end is greater than the power received by a power receiving end, the part of power is transmitted to an energy storage battery of a power supply conversion subsystem through a public direct current bus after power conversion in a load valley period to be stored, so that the recovery of the energy of a power grid is realized. When the power transmitted by the power supply end of the power grid is smaller than the power received by the power receiving end, the power is injected into the power grid again in a current compensation mode, so that the balance and adjustment of the line energy are effectively realized, and the problem of peak-valley balance is solved.
In this embodiment, as shown in fig. 6, the power supply conversion subsystem includes: the system comprises an energy storage battery converter, a wind energy access converter, a photovoltaic access converter and a power supply conversion controller. The energy storage battery converter adopts a direct current chopper circuit topology (DC/DC), one side of a direct current end of the energy storage battery converter is connected with an external energy storage battery access port, and the other side of the direct current end of the energy storage battery converter is connected to a common direct current bus and used for realizing the charge and discharge functions of an energy storage battery; the wind energy access converter adopts a rectifying circuit topology (AC/DC), the AC side of the converter is connected with an external wind turbine access port, and the DC side of the converter is connected to a common DC bus and used for accessing electric energy generated by wind power generation; the photovoltaic access converter adopts a direct current chopper circuit topology (DC/DC), one side of a direct current end of the photovoltaic access converter is connected with an external photovoltaic panel access port, and the other side of the direct current end of the photovoltaic access converter is connected to a common direct current bus and used for accessing electric energy generated by photovoltaic power generation; and the power supply conversion controller is respectively connected with the three converters and is used for controlling the direct current output ends of the three converters to generate direct current with the same voltage amplitude as the common direct current bus. It can be seen from this that: for the power supply conversion subsystem, the energy sources mainly include two types: one is that the current control current source subsystem is matched with an energy storage device comprising a battery, the power of a power grid is absorbed during load wave trough, the power-load balance of the power grid is realized, and the other is that a new energy source is accessed into a port comprising wind power and photovoltaic ports to form a multi-energy fusion system.
In this embodiment, the operation modes of the power compensation transformation system include: the power transformation system can switch a proper working mode according to the power flow state of a power line. Particularly, when the system adopts cooperative work, as shown in table one, the following working modes are specifically included:
in the present embodiment, in cooperation with the impedance compensation mode: the current-controlled voltage source subsystem and the current-controlled current source subsystem work in an impedance compensation mode and are uniformly coordinated and controlled to control and change the total equivalent impedance of the whole system, so that the equivalent impedance of the power transmission line is changed, impedance compensation is carried out, and the transmission efficiency is improved. In this embodiment, the equivalent impedance of the power transmission line after the power transformation system is added is, as viewed from the load side:
wherein: zlineThe equivalent impedance of the original line viewed from the load end; z'lineThe equivalent impedance of the transmission line is seen from the load end after compensation; k is a radical ofiThe current amplification coefficient of the current control current source subsystem specifically reflects the relationship between compensation current generated by the current control current source subsystem and line current; zsThe impedance is transferred for the current-controlled voltage source subsystem, and the relation between compensation voltage generated by the current-controlled voltage source subsystem and line current is reflected specifically.
Impedance-current compensation mode: the current control voltage source subsystem works in an impedance compensation mode, and the current control current source subsystem works in a current compensation mode and is uniformly coordinated and controlled. In this embodiment, in this mode, the power line first changes the equivalent impedance of the line through dynamic reactive compensation, eliminating the harmonic current, and then through the current-controlled voltage source subsystem.
Impedance-power balance mode: the current control voltage source subsystem works in an impedance compensation mode, and the current control current source subsystem works in a power balance mode and is uniformly coordinated and controlled. In this embodiment, in this mode, the current-controlled current source subsystem absorbs the grid current to store energy, and this operation also changes the impedance characteristic of the line, so that the influence thereof can be eliminated by the impedance compensation of the current-controlled voltage source subsystem, and the impedance characteristic of the power transmission system is stabilized.
Voltage-current compensation mode: the current control voltage source subsystem works in a voltage boosting mode, and the current control current source subsystem works in a current compensation mode and is uniformly coordinated and controlled, so that the overall improvement of the quality of electric energy is realized.
Example four:
in the present embodiment, as shown in fig. 7, the present embodiment is substantially the same as the first embodiment, and the features are:
the specific connection relationship between the current control voltage source subsystem and the current control current source subsystem is as follows: the current control voltage source subsystem is close to a three-phase line terminal at a power supply end, and the current control current source subsystem is close to a three-phase line terminal at a power receiving end, namely the current control current source subsystem is directly connected with the three-phase line at the power receiving end;
in this case, since the equivalent characteristic impedance of the power transmission line changes when the cooperative impedance compensation mode is performed, the control signal obtained when the corresponding compensation is performed also changes. In this embodiment, the characteristic impedance of the power transmission line after the power transformation system is added is, as seen from the load side:
wherein: zlineThe equivalent impedance of the original line viewed from the load end; z'lineThe equivalent impedance of the transmission line is seen from the load end after compensation; k is a radical ofiThe current amplification coefficient of the current control current source subsystem specifically reflects the relationship between compensation current generated by the current control current source subsystem and line current; zsThe impedance is transferred for the current-controlled voltage source subsystem, and the relation between compensation voltage generated by the current-controlled voltage source subsystem and line current is reflected specifically.
It should be noted that the above-mentioned cooperative compensation mode is not simply equal to the addition of two independent compensation modes. When a power transformation system generates corresponding compensation signals, the outputs of the two subsystems are uniformly coordinated, so that the power transmission characteristics of the power transmission line are optimized, and the table 1 is referred to.
TABLE 1. the system of the present invention cooperates with the mode table
To sum up, the utility model discloses be applied to power transmission's power compensation electric power transformation system, this system includes four bibliographic categories such as electric current accuse voltage source subsystem, electric current accuse current source subsystem, power supply transform subsystem and public direct current generating line. The current control voltage source subsystem is connected in series in the power transmission line, the output voltage of the current control voltage source subsystem is controlled by the line current, and the current control voltage source subsystem has the functions of voltage boosting, impedance compensation and the like; the current control current source subsystem is connected in parallel in the power transmission line, and can perform cooperative impedance compensation with the current control voltage source subsystem on one hand to improve power transmission efficiency except for realizing basic functions such as dynamic reactive compensation and the like; on the other hand, through the interaction with the energy storage device, the double work of charging and discharging is carried out, the balance and the adjustment of the energy of the power grid are realized, and the problem of peak-valley balance of the power grid is effectively solved.
Therefore, the purpose of the utility model is completely and effectively realized. The functional and structural principles of the present invention have been shown and described in the embodiments, and the embodiments may be modified without departing from the principles. The present invention includes all modifications based on the spirit and scope of the claims.
Claims (4)
1. A power compensation power transformation system applied to power transmission adopts a power compensation power transformation working mode of power transmission to carry out signal control, and is characterized in that the power compensation power transformation system applied to power transmission comprises a current control voltage source subsystem (1), a current control current source subsystem (2), a power supply conversion subsystem (3) and a common direct current bus (4);
the current control voltage source subsystem (1) is connected in series in the power transmission line, the input end of the current control voltage source subsystem is a three-phase line terminal of a power supply end, and the output end of the current control voltage source subsystem is a three-phase line terminal of a power receiving end;
the current control current source subsystem (2) is connected in parallel in the power transmission line, namely connected between a phase line terminal and a neutral line terminal of the three phases;
the specific connection relation between the current-controlled voltage source subsystem (1) and the current-controlled current source subsystem (2) comprises two topologies; wherein the content of the first and second substances,
the first topology is that the current-controlled current source subsystem (2) is close to the three-phase terminal of the power supply end, and the current-controlled voltage source subsystem (1) is close to the three-phase terminal of the power receiving end, namely, the current-controlled current source subsystem (2) is connected with the three-phase terminal of the power receiving end after passing through the current-controlled voltage source subsystem (1);
the second topology is that the current-controlled voltage source subsystem (1) is close to the three-phase terminal of the power supply end, and the current-controlled current source subsystem (2) is close to the three-phase terminal of the power receiving end, namely, the current-controlled current source subsystem (2) is directly connected with the three-phase terminal of the power receiving end;
the power supply conversion subsystem (3), the current-controlled voltage source subsystem (1) and the current-controlled current source subsystem (2) are connected in parallel and are commonly connected to a common direct current bus (4);
and the common direct current bus (4) is connected with the current-controlled voltage source subsystem (1), the current-controlled current source subsystem (2) and the power supply conversion subsystem (3).
2. The power compensation power transformation system applied to power transmission of claim 1, wherein: the current control voltage source subsystem (1) comprises a voltage source independent power supply (11), a voltage source power converter (12), a voltage source controller (13) and a transformer (14), wherein the voltage source independent power supply (11) rectifies alternating current of a power grid through an isolation transformer to obtain direct current, and the direct current is output to the voltage source power converter (12); the voltage source power converter (12) adopts an inverter topology, the direct current side of the inverter topology is connected with the direct current output end of the voltage source independent power supply (11), a common direct current bus access terminal is led out from the connection position of the inverter topology, and the alternating current side of the inverter topology is connected with a primary side winding of the transformer (14); the primary side winding of the transformer (14) is connected with the alternating current side of the voltage source power converter (12); and the voltage source controller (13) adopts voltage to give a fixed PWM controller.
3. The power compensation power transformation system applied to power transmission of claim 1, wherein: the current control current source subsystem (2) comprises a current source independent power supply (21), a current source power converter (22), a current source controller (23) and a reactor (24); the current source independent power supply (21) rectifies alternating current of a power grid through an isolation transformer to obtain direct current, and the direct current is output to the current source power converter (22); the current source power converter (22) adopts an inverter topology, the direct current side of the current source power converter is connected with the direct current output end of the current source independent power supply (21), a common direct current bus access terminal is led out from the connection position of the current source power converter and is used for being connected with the common direct current bus (4), the alternating current side neutral point output port of the common direct current bus is connected with the neutral line of the power transmission line, and the three-phase output port of the common direct current bus access terminal is connected with the reactor (24); one side of the reactor (24) is connected with the three-phase output end of the current source power converter (22), and the other side of the reactor is connected with the three-phase line of the power transmission line; the current source controller (23) adopts current to give the fixed PWM controller.
4. The power compensation power transformation system applied to power transmission of claim 1, wherein: the power supply conversion subsystem comprises an energy storage battery converter (31), a wind energy access converter (32), a photovoltaic access converter (33) and a power supply conversion controller (34); the energy storage battery converter (31) adopts a direct current chopper circuit topology, one side of a direct current end of the energy storage battery converter is connected with an external energy storage battery access port, and the other side of the direct current end of the energy storage battery converter is connected to the common direct current bus (4); the wind energy access converter (32) adopts a rectifying circuit topology, the alternating current side of the wind energy access converter is connected with an external wind turbine generator access port, and the direct current side of the wind energy access converter is connected to the common direct current bus (4); the photovoltaic access converter (33) adopts a direct current chopper circuit topology, one side of a direct current end of the photovoltaic access converter is connected with an external photovoltaic panel access port, and the other side of the direct current end of the photovoltaic access converter is connected to the common direct current bus (4); and the power supply conversion controller (34) is respectively connected with the three converters.
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