CN112671032A - Grid-connected steady-state starting method and device for photovoltaic power generation system - Google Patents
Grid-connected steady-state starting method and device for photovoltaic power generation system Download PDFInfo
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Abstract
The invention discloses a grid-connected steady-state starting method and a grid-connected steady-state starting device for a photovoltaic power generation system, wherein the method comprises the following steps: the method comprises the steps that a photovoltaic power generation system is equivalent to a grid-connected series circuit formed by a filter inductor and an equivalent voltage source, and grid-connected working voltage of the equivalent voltage source is determined; based on the fact that the photovoltaic power generation system allows normal grid connection, determining the initial value of each PI controller in the photovoltaic power generation system through reverse estimation; and controlling the equivalent voltage source and the photovoltaic power generation system to perform steady-state starting and switching grid connection based on the set switching time. The embodiment of the invention can reduce overshoot and adjusting time for grid connection of the photovoltaic power generation system, thereby ensuring grid connection starting of the photovoltaic power generation system and smoothly achieving a stable state.
Description
Technical Field
The invention relates to the technical field of photovoltaic grid connection, in particular to a grid-connected steady-state starting method and device of a photovoltaic power generation system.
Background
With the rapid development of global economy, the demand of people for energy is increasing, and the traditional fossil energy mainly comprising petroleum, coal and the like has the defects of non-regenerability, environmental pollution and the like, so that the energy shortage and the environmental pollution become problems to be solved urgently in social development. Therefore, people pay more attention to the development and utilization of new energy, solar energy is one of the main forms of new energy utilization due to the advantages of richness, cleanness, reproducibility and the like, and meanwhile, the starting, control and protection of a photovoltaic power generation system are the key points of research of various national scholars.
The prior photovoltaic power generation system has the following technical problems in the grid-connected starting process: firstly, the filter inductor at the alternating current side and the voltage stabilizing capacitor at the direct current side need to be charged and discharged, so that a longer transient process and longer adjusting time exist; secondly, the initial state of the control system during starting is zero, the difference between the initial state and the stable value is large, and a large overshoot exists in the adjusting process, so that the system is easy to be unstable; thirdly, when determining the parameters of the PI controller in the control system, the overshoot and the adjusting time need to be considered comprehensively, so that the parameter design is difficult and the adjusting capability is limited. Therefore, how to optimize the grid-connected mode of the photovoltaic power generation system becomes a problem to be solved by the invention.
Disclosure of Invention
The invention aims to overcome the defects of the prior art, and provides a grid-connected steady-state starting method and device of a photovoltaic power generation system, which can reduce overshoot and adjusting time for grid connection of the photovoltaic power generation system, thereby ensuring grid-connected starting of the photovoltaic power generation system and smoothly achieving a stable state.
In order to solve the above problems, the invention provides a grid-connected steady-state starting method for a photovoltaic power generation system, which comprises the following steps:
the method comprises the steps that a photovoltaic power generation system is equivalent to a grid-connected series circuit formed by a filter inductor and an equivalent voltage source, and grid-connected working voltage of the equivalent voltage source is determined;
based on the fact that the photovoltaic power generation system allows normal grid connection, determining the initial value of each PI controller in the photovoltaic power generation system through reverse estimation;
and controlling the equivalent voltage source and the photovoltaic power generation system to perform steady-state starting and switching grid connection based on the set switching time.
Optionally, the determining the grid-connected operating voltage of the equivalent voltage source includes:
constructing a circuit phasor diagram of the grid-connected series circuit by taking the grid-connected point voltage as a reference phasor;
and calculating the voltage value and the voltage phase of the equivalent voltage source according to the circuit phasor diagram.
Optionally, the voltage value of the equivalent voltage source is:
the voltage phase of the equivalent voltage source is as follows:
wherein e is the voltage component of the grid-connected point voltage, P is the active power injected into the grid, Q is the reactive power injected into the grid, R is the resistance value, X is the reactance value, theta0Is the initial phase of the grid-connected point voltage.
Optionally, the determining, by inverse extrapolation, an initial value of each PI controller in the photovoltaic power generation system includes:
determining an instantaneous power value of an inverter injected into a power grid in the photovoltaic power generation system based on a voltage outer loop control principle, and calculating an input current initial value of an outer loop PI controller in the photovoltaic power generation system based on the instantaneous power value;
based on the current inner loop control principle, the initial value of the input voltage of the inner loop PI controller in the photovoltaic power generation system is calculated by utilizing a Park inverter algorithm.
Optionally, the instantaneous power value injected into the power grid by the inverter is as follows:
the initial value of the input current of the outer ring PI controller is as follows:
the initial value of the input voltage of the inner loop PI controller is as follows:
wherein, P1Injecting instantaneous active power, Q, of the grid into the inverter1Injecting instantaneous reactive power of the grid into the inverter, edFor projection of the grid-connected point voltage onto the d-axis voltage component, i, in the dq-rotation coordinate systemdD-axis current component, i, projected to dq rotation coordinate system for three-phase voltageqProjecting the three-phase voltage to the q-axis current component, i, of the dq rotating coordinate systemdrefFor the component of the input current of the outer-loop PI controller on the d-axis, iqrefFor the component of the input current of the outer loop PI controller on the q-axis, udrefFor the component of the input voltage of the inner-loop PI controller on the d-axis, uqrefAnd inputting the component of the voltage at the q axis for the inner loop PI controller.
Optionally, the controlling the equivalent voltage source and the photovoltaic power generation system to perform steady-state startup and switching grid connection based on the set switching time includes:
before the switching moment comes, controlling the equivalent voltage source to operate in a grid-connected mode;
and switching and controlling the grid-connected operation of the photovoltaic power generation system after the switching moment comes and comes.
In addition, the embodiment of the invention also provides a grid-connected steady-state starting device of the photovoltaic power generation system, and the device comprises:
the equivalent circuit analysis module is used for enabling the photovoltaic power generation system to be equivalent to a grid-connected series circuit formed by a filter inductor and an equivalent voltage source and determining grid-connected working voltage of the equivalent voltage source;
the control strategy reverse-pushing module is used for determining the initial value of each PI controller in the photovoltaic power generation system through reverse pushing based on the fact that the photovoltaic power generation system allows normal grid connection;
and the grid-connected operation control module is used for controlling the equivalent voltage source and the photovoltaic power generation system to perform steady-state starting and switching grid connection based on set switching time.
Optionally, the equivalent circuit analysis module is configured to construct a circuit phasor diagram of the grid-connected series circuit by using the grid-connected point voltage as a reference phasor; and calculating the voltage value and the voltage phase of the equivalent voltage source according to the circuit phasor diagram.
Optionally, the control strategy back-stepping module is configured to determine an instantaneous power value of an inverter injected into a power grid in the photovoltaic power generation system based on a voltage outer-loop control principle, and calculate an initial input current value of an outer-loop PI controller in the photovoltaic power generation system based on the instantaneous power value; and calculating an initial value of the input voltage of an inner ring PI controller in the photovoltaic power generation system by using a Park inverter algorithm based on a current inner ring control principle.
Optionally, the grid-connected operation control module is configured to control the equivalent voltage source to perform grid-connected operation before the switching time comes; and switching and controlling the grid-connected operation of the photovoltaic power generation system after the switching moment comes and is later than the switching moment.
In the embodiment of the invention, the equivalent voltage source is utilized to charge and discharge the filter inductor in the early stage of grid connection, so that the transient process time of the filter inductor can be reduced for the subsequent grid connection of the photovoltaic power generation system; the initial value of the PI controller in the photovoltaic power generation system is controlled to be the calculated steady state value in the later period of grid connection, so that the overshoot and the adjusting time in the grid connection starting process of the photovoltaic power generation system can be reduced, and the grid connection starting of the photovoltaic power generation system is ensured and the stable state is smoothly reached.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic flow chart of a grid-connected steady-state starting method of a photovoltaic power generation system in an embodiment of the invention;
FIG. 2 is a schematic diagram of an equivalent circuit of a photovoltaic power generation system in an embodiment of the present invention;
FIG. 3 is a detailed schematic diagram of an equivalent circuit phasor diagram in an embodiment of the present invention;
FIG. 4 is a schematic diagram of a photovoltaic power generation system control circuit in an embodiment of the present invention;
FIG. 5 is a schematic diagram of the PI control principle of the photovoltaic power generation system in the embodiment of the invention;
FIG. 6 is a schematic diagram of parameter testing during grid-connected startup of a photovoltaic power generation system in the embodiment of the invention;
fig. 7 is a schematic structural composition diagram of a grid-connected steady-state starting device of a photovoltaic power generation system in the embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Examples
Referring to fig. 1, fig. 1 shows a schematic flow chart of a grid-connected steady-state starting method of a photovoltaic power generation system in an embodiment of the present invention.
As shown in fig. 1, a grid-connected steady-state starting method for a photovoltaic power generation system includes the following steps:
s101, enabling a photovoltaic power generation system to be equivalent to a grid-connected series circuit formed by a filter inductor and an equivalent voltage source, and determining grid-connected working voltage of the equivalent voltage source;
the implementation process of the invention comprises the following steps:
(1) a photovoltaic power generation system is equivalent to a grid-connected series circuit formed by a filter inductor and an equivalent voltage source, as shown in fig. 2, wherein u is the voltage of the equivalent voltage source, L is the filter inductor, R is the equivalent resistor, i is the current injected into the power grid, e is the voltage of a grid-connected point, P is the active power injected into the power grid, Q is the reactive power injected into the power grid, L, R are all known circuit parameters, and e, P and Q can be obtained through load flow calculation;
(2) using the voltage e of the grid-connected point as the reference phasor (i.e. let e equal to e ═ theta-0Degree), constructing a circuit phasor diagram of the grid-connected series circuit, as shown in fig. 3, where Δ u is the longitudinal component of the voltage drop (in phase with e) and δ u is the transverse component of the voltage drop (90 ° different from e), and then obtaining a relation of the circuit phasor diagram:
du＝u-e＝Δu+jδu
according to the equivalent circuit diagram shown in fig. 2, the voltage of the equivalent voltage source can be obtained as follows:
by combining the above two equations, we can see that:
(3) determining the voltage value of the equivalent voltage source as follows:
and the voltage phase of the equivalent voltage source is:
where e is a voltage component of the grid-connected point voltage, X is a reactance value (X ═ ω L), and θ0Is the initial phase of the grid-connected point voltage.
S102, determining initial values of all PI controllers in the photovoltaic power generation system through reverse estimation based on the fact that the photovoltaic power generation system allows normal grid connection;
the implementation process of the invention comprises the following steps:
(1) according to the schematic diagram of the control circuit of the photovoltaic power generation system shown in fig. 4, the relationship between the three-phase instantaneous voltage generated by the inverter and the grid-connected point three-phase voltage can be obtained as follows:
the above relation is subjected to Park transformation to obtain:
further calculating the initial power injected into the power grid by the inverter according to an instantaneous power theory as follows:
wherein u isaFor instantaneous voltage of phase A, u, output by the inverterbB-phase instantaneous voltage, u, output by invertercInstantaneous voltage of C phase output from inverter, eaFor the grid-connected point A phase voltage, ebFor the grid-connected point B phase voltage, ecFor grid-connected point C phase voltage, iaFor injection into the A-phase current of the grid, ibFor injection into the B-phase current of the grid, icFor injection into the C-phase current of the grid, udFor the d-axis voltage component, u, of the three-phase instantaneous voltage projection onto the dq rotation coordinate systemqFor the q-axis voltage component of the three-phase instantaneous voltage projection onto the dq rotating coordinate system, edFor projection of the grid-connected point voltage onto the d-axis voltage component in the dq-rotation coordinate system, eqProjecting the grid-connected point voltage to a q-axis voltage component under a dq rotating coordinate system, wherein omega is the angular frequency of a power grid, idD-axis current component, i, projected to dq rotation coordinate system for three-phase voltageqFor the q-axis current component, P, of the three-phase voltage projected onto the dq-rotation coordinate system0For initial active power injection into the grid, Q0Is the initial reactive power injected into the grid;
at this time, the inverter PI control system shown in fig. 5 may be designed according to the above relational expression, and it operates in a double closed loop control manner of a voltage outer loop and a current inner loop, in which the relevant parameters are all converted into a dq coordinate system for representation;
(2) determining an instantaneous power value of an inverter injected into a power grid in the photovoltaic power generation system based on a voltage outer loop control principle, and calculating an input current initial value of an outer loop PI controller in the photovoltaic power generation system based on the instantaneous power value;
specifically, a grid voltage directional control mode (i.e. command e) is utilizedq＝0，ed＝epk) And determining the instantaneous power value injected into the power grid by the inverter as follows:
the d axis is controlled by constant DC voltage, when the DC voltage reaches the maximum power point voltage (namely P)1＝Pmax) And obtaining the component of the input current of the outer ring PI controller on the d axis as follows:
the q axis adopts constant reactive power control, and the component of the input current of the outer loop PI controller on the q axis can be obtained as follows:
in the formula: p1Injecting instantaneous active power, Q, of the grid into the inverter1Injecting instantaneous reactive power of the grid into the inverter, epkIs the peak value of the grid-connected point voltage, PmaxIs the rated maximum power of the photovoltaic cell;
(3) based on the current inner ring control principle, calculating an initial value of input voltage of an inner ring PI controller in the photovoltaic power generation system by using a Park inverter algorithm, wherein the initial value is as follows:
wherein u isdrefFor the component of the input voltage of the inner-loop PI controller on the d-axis, uqrefAnd inputting the component of the voltage at the q axis for the inner loop PI controller.
S103, controlling the equivalent voltage source and the photovoltaic power generation system to perform steady-state starting and switching grid connection based on set switching time.
The implementation process of the invention comprises the following steps: (1) before the switching moment comes, controlling the equivalent voltage source to perform grid-connected operation, wherein the input of the inverter PI control system is zero, and the initial value is the initial value of the input current solved in the step S102(idref、iqref) And an initial value of the input voltage (u)dref、uqref) (ii) a (2) And switching and controlling the grid-connected operation of the photovoltaic power generation system after the switching moment comes and the switching moment, wherein the input of the inverter PI control system is a control quantity, namely a difference value between a direct-current side voltage reference value and a measured value, a difference value between a reactive power reference value and a measured value and a difference value between a dq-axis current reference value and a measured value.
In combination with the grid-connected steady-state starting method of the photovoltaic power generation system described in the steps S101 to S103, a grid-connected topological structure is built for the existing photovoltaic power generation system and a simulation test is executed under an MATLAB simulation environment with reference to fig. 2, wherein the illumination intensity of the photovoltaic unit is set to 870.927w/m2The environmental temperature is 25 ℃, the switching time is 2s, the simulation step length is 10s, and the simulation time is 7 s. At this time, a zero-state starting method (that is, the initial value of the photovoltaic power generation system is in a zero state at 2 s) and a steady-state starting method (that is, the initial value of the photovoltaic power generation system is in a steady state at 2 s) are respectively adopted for simulation comparison, and the corresponding simulation results are shown in fig. 6, so that it can be known that: the steady state starting and the steady state starting are the same, but the starting processes of the zero state starting and the steady state starting have larger difference, namely under the same parameters, the overshoot and the adjusting time of the steady state starting method provided by the embodiment of the invention in the starting process are obviously smaller than those of the zero state starting method.
In the embodiment of the invention, the equivalent voltage source is utilized to charge and discharge the filter inductor in the early stage of grid connection, so that the transient process time of the filter inductor can be reduced for the subsequent grid connection of the photovoltaic power generation system; the initial value of the PI controller in the photovoltaic power generation system is controlled to be the calculated steady state value in the later period of grid connection, so that the overshoot and the adjusting time in the grid connection starting process of the photovoltaic power generation system can be reduced, and the grid connection starting of the photovoltaic power generation system is ensured and the stable state is smoothly reached.
Examples
Referring to fig. 7, fig. 7 is a schematic structural composition diagram of a grid-connected steady-state starting device of a photovoltaic power generation system in the embodiment of the present invention.
As shown in fig. 7, a grid-connected steady-state starting device for a photovoltaic power generation system includes:
the equivalent circuit analysis module 201 is used for enabling the photovoltaic power generation system to be equivalent to a grid-connected series circuit formed by a filter inductor and an equivalent voltage source, and determining grid-connected working voltage of the equivalent voltage source;
the implementation process of the invention comprises the following steps:
(1) a photovoltaic power generation system is equivalent to a grid-connected series circuit formed by a filter inductor and an equivalent voltage source, as shown in fig. 2, wherein u is the voltage of the equivalent voltage source, L is the filter inductor, R is the equivalent resistor, i is the current injected into the power grid, e is the voltage of a grid-connected point, P is the active power injected into the power grid, Q is the reactive power injected into the power grid, L, R are all known circuit parameters, and e, P and Q can be obtained through load flow calculation;
(2) using the voltage e of the grid-connected point as the reference phasor (i.e. let e equal to e ═ theta-0Degree), constructing a circuit phasor diagram of the grid-connected series circuit, as shown in fig. 3, where Δ u is the longitudinal component of the voltage drop (in phase with e) and δ u is the transverse component of the voltage drop (90 ° different from e), and then obtaining a relation of the circuit phasor diagram:
du＝u-e＝Δu+jδu
according to the equivalent circuit diagram shown in fig. 2, the voltage of the equivalent voltage source can be obtained as follows:
by combining the above two equations, we can see that:
(3) determining the voltage value of the equivalent voltage source as follows:
and the voltage phase of the equivalent voltage source is:
where e is a voltage component of the grid-connected point voltage, X is a reactance value (X ═ ω L), and θ0Is the initial phase of the grid-connected point voltage.
The control strategy reverse-pushing module 202 is used for determining the initial value of each PI controller in the photovoltaic power generation system through reverse pushing based on the fact that the photovoltaic power generation system allows normal grid connection;
the implementation process of the invention comprises the following steps:
(1) according to the schematic diagram of the control circuit of the photovoltaic power generation system shown in fig. 4, the relationship between the three-phase instantaneous voltage generated by the inverter and the grid-connected point three-phase voltage can be obtained as follows:
the above relation is subjected to Park transformation to obtain:
further calculating the initial power injected into the power grid by the inverter according to an instantaneous power theory as follows:
wherein u isaFor instantaneous voltage of phase A, u, output by the inverterbB-phase instantaneous voltage, u, output by invertercInstantaneous voltage of C phase output from inverter, eaFor the grid-connected point A phase voltage, ebFor the grid-connected point B phase voltage, ecFor grid-connected point C phase voltage, iaFor injection into the A-phase current of the grid, ibFor injection into the B-phase current of the grid, icFor injection ofPhase C current of the grid, udFor the d-axis voltage component, u, of the three-phase instantaneous voltage projection onto the dq rotation coordinate systemqFor the q-axis voltage component of the three-phase instantaneous voltage projection onto the dq rotating coordinate system, edFor projection of the grid-connected point voltage onto the d-axis voltage component in the dq-rotation coordinate system, eqProjecting the grid-connected point voltage to a q-axis voltage component under a dq rotating coordinate system, wherein omega is the angular frequency of a power grid, idD-axis current component, i, projected to dq rotation coordinate system for three-phase voltageqFor the q-axis current component, P, of the three-phase voltage projected onto the dq-rotation coordinate system0For initial active power injection into the grid, Q0Is the initial reactive power injected into the grid;
at this time, the inverter PI control system shown in fig. 5 may be designed according to the above relational expression, and it operates in a double closed loop control manner of a voltage outer loop and a current inner loop, in which the relevant parameters are all converted into a dq coordinate system for representation;
(2) determining an instantaneous power value of an inverter injected into a power grid in the photovoltaic power generation system based on a voltage outer loop control principle, and calculating an input current initial value of an outer loop PI controller in the photovoltaic power generation system based on the instantaneous power value;
specifically, a grid voltage directional control mode (i.e. command e) is utilizedq＝0，ed＝epk) And determining the instantaneous power value injected into the power grid by the inverter as follows:
the d axis is controlled by constant DC voltage, when the DC voltage reaches the maximum power point voltage (namely P)1＝Pmax) And obtaining the component of the input current of the outer ring PI controller on the d axis as follows:
the q axis adopts constant reactive power control, and the component of the input current of the outer loop PI controller on the q axis can be obtained as follows:
in the formula: p1Injecting instantaneous active power, Q, of the grid into the inverter1Injecting instantaneous reactive power of the grid into the inverter, epkIs the peak value of the grid-connected point voltage, PmaxIs the rated maximum power of the photovoltaic cell;
(3) based on the current inner ring control principle, calculating an initial value of input voltage of an inner ring PI controller in the photovoltaic power generation system by using a Park inverter algorithm, wherein the initial value is as follows:
wherein u isdrefFor the component of the input voltage of the inner-loop PI controller on the d-axis, uqrefAnd inputting the component of the voltage at the q axis for the inner loop PI controller.
And the grid-connected operation control module 203 is used for controlling the equivalent voltage source and the photovoltaic power generation system to perform steady-state starting and switching grid connection based on the set switching time.
The implementation process of the invention comprises the following steps: (1) before the switching moment comes, controlling the equivalent voltage source to carry out grid-connected operation, wherein the input of the inverter PI control system is zero, and the initial value is the initial value (i) of the input current solved in the step S102dref、iqref) And an initial value of the input voltage (u)dref、uqref) (ii) a (2) And switching and controlling the grid-connected operation of the photovoltaic power generation system after the switching moment comes and the switching moment, wherein the input of the inverter PI control system is a control quantity, namely a difference value between a direct-current side voltage reference value and a measured value, a difference value between a reactive power reference value and a measured value and a difference value between a dq-axis current reference value and a measured value.
In the embodiment of the invention, the equivalent voltage source is utilized to charge and discharge the filter inductor in the early stage of grid connection, so that the transient process time of the filter inductor can be reduced for the subsequent grid connection of the photovoltaic power generation system; the initial value of the PI controller in the photovoltaic power generation system is controlled to be the calculated steady state value in the later period of grid connection, so that the overshoot and the adjusting time in the grid connection starting process of the photovoltaic power generation system can be reduced, and the grid connection starting of the photovoltaic power generation system is ensured and the stable state is smoothly reached.
Those skilled in the art will appreciate that all or part of the steps in the methods of the above embodiments may be implemented by hardware related to instructions of a program, which may be stored in a computer-readable storage medium, and the storage medium may include: read Only Memory (ROM), Random Access Memory (RAM), magnetic or optical disks, and the like.
The grid-connected steady-state starting method and device of the photovoltaic power generation system provided by the embodiment of the invention are described in detail, a specific example is adopted in the method to explain the principle and the implementation mode of the invention, and the description of the embodiment is only used for helping to understand the method and the core idea of the invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.
Claims (10)
1. A grid-connected steady-state starting method of a photovoltaic power generation system is characterized by comprising the following steps:
the method comprises the steps that a photovoltaic power generation system is equivalent to a grid-connected series circuit formed by a filter inductor and an equivalent voltage source, and grid-connected working voltage of the equivalent voltage source is determined;
based on the fact that the photovoltaic power generation system allows normal grid connection, determining the initial value of each PI controller in the photovoltaic power generation system through reverse estimation;
and controlling the equivalent voltage source and the photovoltaic power generation system to perform steady-state starting and switching grid connection based on the set switching time.
2. The grid-connected steady-state starting method of the photovoltaic power generation system according to claim 1, wherein the determining the grid-connected working voltage of the equivalent voltage source comprises:
constructing a circuit phasor diagram of the grid-connected series circuit by taking the grid-connected point voltage as a reference phasor;
and calculating the voltage value and the voltage phase of the equivalent voltage source according to the circuit phasor diagram.
3. The grid-connected steady-state starting method of the photovoltaic power generation system according to claim 2, wherein the voltage value of the equivalent voltage source is as follows:
the voltage phase of the equivalent voltage source is as follows:
wherein e is the voltage component of the grid-connected point voltage, P is the active power injected into the grid, Q is the reactive power injected into the grid, R is the resistance value, X is the reactance value, theta0Is the initial phase of the grid-connected point voltage.
4. The grid-connected steady-state starting method of the photovoltaic power generation system according to claim 3, wherein the determining the initial value of each PI controller in the photovoltaic power generation system through the reverse estimation comprises:
determining an instantaneous power value of an inverter injected into a power grid in the photovoltaic power generation system based on a voltage outer loop control principle, and calculating an input current initial value of an outer loop PI controller in the photovoltaic power generation system based on the instantaneous power value;
based on the current inner loop control principle, the initial value of the input voltage of the inner loop PI controller in the photovoltaic power generation system is calculated by utilizing a Park inverter algorithm.
5. The grid-connected steady-state starting method of the photovoltaic power generation system according to claim 4, wherein the instantaneous power value injected into the grid by the inverter is as follows:
the initial value of the input current of the outer ring PI controller is as follows:
the initial value of the input voltage of the inner loop PI controller is as follows:
wherein, P1Injecting instantaneous active power, Q, of the grid into the inverter1Injecting instantaneous reactive power of the grid into the inverter, edFor projection of the grid-connected point voltage onto the d-axis voltage component, i, in the dq-rotation coordinate systemdD-axis current component, i, projected to dq rotation coordinate system for three-phase voltageqProjecting the three-phase voltage to the q-axis current component, i, of the dq rotating coordinate systemdrefFor the component of the input current of the outer-loop PI controller on the d-axis, iqrefFor the component of the input current of the outer loop PI controller on the q-axis, udrefFor the component of the input voltage of the inner-loop PI controller on the d-axis, uqrefAnd inputting the component of the voltage at the q axis for the inner loop PI controller.
6. The grid-connected steady-state starting method of the photovoltaic power generation system according to claim 1, wherein the controlling the equivalent voltage source and the photovoltaic power generation system to perform steady-state starting and switching grid connection based on the set switching time comprises:
before the switching moment comes, controlling the equivalent voltage source to operate in a grid-connected mode;
and switching and controlling the grid-connected operation of the photovoltaic power generation system after the switching moment comes and comes.
7. A grid-connected steady-state starting device of a photovoltaic power generation system is characterized by comprising:
the equivalent circuit analysis module is used for enabling the photovoltaic power generation system to be equivalent to a grid-connected series circuit formed by a filter inductor and an equivalent voltage source and determining grid-connected working voltage of the equivalent voltage source;
the control strategy reverse-pushing module is used for determining the initial value of each PI controller in the photovoltaic power generation system through reverse pushing based on the fact that the photovoltaic power generation system allows normal grid connection;
and the grid-connected operation control module is used for controlling the equivalent voltage source and the photovoltaic power generation system to perform steady-state starting and switching grid connection based on set switching time.
8. The grid-connected steady-state starting device of the photovoltaic power generation system according to claim 7, wherein the equivalent circuit analysis module is configured to construct a circuit phasor diagram of the grid-connected series circuit by using a grid-connected point voltage as a reference phasor; and calculating the voltage value and the voltage phase of the equivalent voltage source according to the circuit phasor diagram.
9. The grid-connected steady-state starting device of the photovoltaic power generation system according to claim 7, wherein the control strategy back-stepping module is configured to determine an instantaneous power value of an inverter injected into a grid in the photovoltaic power generation system based on a voltage outer-loop control principle, and calculate an initial input current value of an outer-loop PI controller in the photovoltaic power generation system based on the instantaneous power value; and calculating an initial value of the input voltage of an inner ring PI controller in the photovoltaic power generation system by using a Park inverter algorithm based on a current inner ring control principle.
10. The grid-connected steady-state starting device of the photovoltaic power generation system according to claim 7, wherein the grid-connected operation control module is used for controlling the equivalent voltage source to perform grid-connected operation before the switching moment comes; and switching and controlling the grid-connected operation of the photovoltaic power generation system after the switching moment comes and is later than the switching moment.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113852116A (en) * | 2021-07-26 | 2021-12-28 | 贵州电网有限责任公司电网规划研究中心 | Steady-state control quantity calculation method of new energy grid-connected system |
Citations (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2013116814A1 (en) * | 2012-02-03 | 2013-08-08 | Massachusetts Institute Of Technology | Systems approach to photovoltaic energy extraction |
| CN103904876A (en) * | 2014-04-22 | 2014-07-02 | 华北电力大学 | Modularized multi-level converter smooth starting method with synchronized grid connection function |
| CN103997067A (en) * | 2014-04-30 | 2014-08-20 | 重庆大学 | Inverter output voltage state stabilizing method based on sliding mode control |
| CN104734191A (en) * | 2015-03-31 | 2015-06-24 | 华南理工大学 | Photovoltaic grid-connected inverter low-voltage ride through method based on reactive current injection |
| CN104810858A (en) * | 2015-05-27 | 2015-07-29 | 广西大学 | Control method for grid-connected power generation system of optical storage microgrid |
| WO2015161679A1 (en) * | 2014-04-22 | 2015-10-29 | 深圳市金宏威技术股份有限公司 | Parallel control system and method for modular photovoltaic grid-connected inverter |
| US20170279376A1 (en) * | 2016-03-28 | 2017-09-28 | The Aerospace Corporation | Grid-tie inverter with active power factor correction |
| CN108110799A (en) * | 2018-01-30 | 2018-06-01 | 国家电网公司 | The grid-connected virtual synchronous control method and device of isolated island double-fed fan motor field high voltage direct current |
| CN108448589A (en) * | 2018-05-09 | 2018-08-24 | 国网上海市电力公司 | A kind of photovoltaic generating system low voltage crossing powerless control method |
| WO2019174331A1 (en) * | 2018-03-12 | 2019-09-19 | 江苏固德威电源科技股份有限公司 | Impact-current-free grid-connected control method for three-phase photovoltaic grid-connected inverter |
| CN110556871A (en) * | 2019-10-17 | 2019-12-10 | 电子科技大学 | large-scale photovoltaic power generation system aggregation equivalence method based on structure keeping method |
-
2020
- 2020-12-14 CN CN202011474869.1A patent/CN112671032A/en active Pending
Patent Citations (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2013116814A1 (en) * | 2012-02-03 | 2013-08-08 | Massachusetts Institute Of Technology | Systems approach to photovoltaic energy extraction |
| CN103904876A (en) * | 2014-04-22 | 2014-07-02 | 华北电力大学 | Modularized multi-level converter smooth starting method with synchronized grid connection function |
| WO2015161679A1 (en) * | 2014-04-22 | 2015-10-29 | 深圳市金宏威技术股份有限公司 | Parallel control system and method for modular photovoltaic grid-connected inverter |
| CN103997067A (en) * | 2014-04-30 | 2014-08-20 | 重庆大学 | Inverter output voltage state stabilizing method based on sliding mode control |
| CN104734191A (en) * | 2015-03-31 | 2015-06-24 | 华南理工大学 | Photovoltaic grid-connected inverter low-voltage ride through method based on reactive current injection |
| CN104810858A (en) * | 2015-05-27 | 2015-07-29 | 广西大学 | Control method for grid-connected power generation system of optical storage microgrid |
| US20170279376A1 (en) * | 2016-03-28 | 2017-09-28 | The Aerospace Corporation | Grid-tie inverter with active power factor correction |
| CN108110799A (en) * | 2018-01-30 | 2018-06-01 | 国家电网公司 | The grid-connected virtual synchronous control method and device of isolated island double-fed fan motor field high voltage direct current |
| WO2019174331A1 (en) * | 2018-03-12 | 2019-09-19 | 江苏固德威电源科技股份有限公司 | Impact-current-free grid-connected control method for three-phase photovoltaic grid-connected inverter |
| CN108448589A (en) * | 2018-05-09 | 2018-08-24 | 国网上海市电力公司 | A kind of photovoltaic generating system low voltage crossing powerless control method |
| CN110556871A (en) * | 2019-10-17 | 2019-12-10 | 电子科技大学 | large-scale photovoltaic power generation system aggregation equivalence method based on structure keeping method |
Non-Patent Citations (3)
| Title |
|---|
| 佟云剑;沈健;刘鸿鹏;王卫: "光伏发电系统运行模式无缝切换控制策略", 电网技术, no. 010 * |
| 王楠楠;刘泽浩;李洋;: "基于滤波电感辨识及延时补偿的并网逆变器模型预测控制", 曲阜师范大学学报(自然科学版), no. 04 * |
| 鞠昌斌;冯伟;王环;王一波;许洪华;: "基于Boost隔离升压拓扑的光伏直流并网变流器的设计与实现", 太阳能学报, no. 03 * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113852116A (en) * | 2021-07-26 | 2021-12-28 | 贵州电网有限责任公司电网规划研究中心 | Steady-state control quantity calculation method of new energy grid-connected system |
| CN113852116B (en) * | 2021-07-26 | 2023-11-10 | 贵州电网有限责任公司电网规划研究中心 | Steady state control amount calculating method of new energy grid-connected system |
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