CN218183021U

CN218183021U - AVQC system with zero-voltage support and steady-state voltage compensation

Info

Publication number: CN218183021U
Application number: CN202222442731.4U
Authority: CN
Inventors: 贾梅梅; 张俊奇; 周大磊; 侯飞; 王森
Original assignee: Suzhou Actionpower Power Supply Technology Co ltd
Current assignee: Suzhou Actionpower Power Supply Technology Co ltd
Priority date: 2022-09-15
Filing date: 2022-09-15
Publication date: 2022-12-30
Anticipated expiration: 2032-09-15

Abstract

The utility model discloses a have zero voltage concurrently and support and stable state voltage compensation's AVQC system, in this AVQC system, combine high-pressure thyristor subassembly V1 and super capacitor assembly U2, realize also can provide qualified stable three-phase voltage for 10kV user when the voltage of temporarily dropping to 0V appears in the 10kV circuit, current does not have discontinuously at whole switching process, guarantee user power consumption quality, through adding high-pressure thyristor subassembly V1, when having guaranteed that grid system takes place voltage transient (temporarily drop), can realize the former high-pressure return circuit of quick disconnection, low pressure bidirectional converter equipment exports compensation immediately, it supplies with the load to rise to 10kV through shunt transformer with compensating voltage, when can realizing that grid voltage drops to 0V, guarantee the power supply stability of load. Meanwhile, when the voltage of the power grid system returns to normal, the equipment seals the LOCK signal, and after the output is stopped, the high-voltage thyristor component V1 is quickly conducted, so that the quick switching between the equipment loop and the original power grid loop is realized, and the reliability of load power utilization is ensured.

Description

AVQC system with zero-voltage support and steady-state voltage compensation

Technical Field

The utility model relates to an electric energy quality administers technical field, concretely relates to have AVQC system that zero voltage supported and steady state voltage compensated concurrently.

Background

The voltage is the main quality index of electric energy, and the voltage has direct influence on the stability of a power grid, the safe operation of power equipment, the line loss, the industrial and agricultural safety production and the electricity utilization of people life. The power consumption of enterprises and residents is rapidly increased along with the development of economy and society, higher requirements are put forward on the quality and reliability of power supply, and the requirements of intelligent electrical equipment adopting digitization and informatization technologies are increased day by day. The problem of low voltage that exists more 10kV distribution network line end at present is especially outstanding, and some industrial enterprises have sensitive load moreover, and the reliability and the stability requirement to voltage quality are extremely high, and current electric wire netting framework can not satisfy user's power consumption demand, needs to improve urgently. The main solutions at present are:

1) Building a new transformer substation;

2) Adjusting a main transformer tap to change the system voltage;

3) The circuit is connected in series with a capacitor;

4) The line is connected in series with an on-load voltage regulator;

5) The line is connected with a DVR in parallel to perform transient compensation;

newly-built transformer substations and main transformer tap adjustment are mainly modified from a power supply side, wherein the newly-built transformer substations can directly solve the problems of low voltage at the tail ends and the like, and have the best effect, but the overall investment is large, the period is long, users at the tail ends of circuits are few, and the overall economy is poor; the adjustment of the tapping point of the main transformer can be improved under certain conditions, but the effect is not good, and the low voltage at the tail end of the existing circuit is mainly caused by the large line loss of the long circuit, and the outlet voltage of the main transformer is qualified, so the scheme can not effectively treat the voltage at the tail end;

three schemes of connecting a capacitor in series on a line, connecting a loaded voltage regulator in series on the line and connecting a DVR in parallel on the line are modified from the line side. The scheme of the series capacitor of the circuit is that the inductive reactance part in the power transmission line is counteracted through the series capacitor, so that the purpose of reducing the circuit is indirectly achieved, the voltage at the tail end is improved, the voltage drop caused by the resistance on the circuit cannot be treated, and the transferred overall compensation effect is limited. The line is connected in series with an on-load voltage regulator to try to realize voltage regulation by changing a tap, but the reliability of the line is poor when the line is frequently operated, the active loss and the reactive loss of the line can increase the line network loss, the fault needs to be maintained by power failure, and when the reactive loss of the line is insufficient, the voltage regulation effect is poorer, the flexibility is poor, and the line is not suitable for distributed installation along with the line. The DVR device connected in parallel with the line can be used for voltage sag control of part of sensitive enterprises, but cannot be used for effectively controlling long-term fluctuation of steady-state voltage.

Through comparing the power supply side and line side transformation schemes, each scheme has large limitation, so that a system capable of solving the power quality problems of various power grids is needed. The AVQC system with zero voltage support and steady state compensation can realize treatment of complex power quality problems, can perform full compensation aiming at voltage drop caused by resistance, capacity and inductance on a circuit, can effectively treat unbalanced three phases, can also treat the problem of voltage sag (voltage drops to 0V) of the circuit, protects rear-stage sensitive equipment from conforming, and ensures the power utilization safety of rear-stage users.

SUMMERY OF THE UTILITY MODEL

The utility model aims at overcoming the not enough of prior art, provide an AVQC system that has zero voltage concurrently and supports and steady state voltage compensation.

In order to achieve the above purpose, the utility model adopts the technical scheme that: an AVQC system with zero voltage support and steady-state voltage compensation comprises a high-voltage loop and a low-voltage loop, wherein the low-voltage loop comprises a main circuit unit and a low-voltage bypass unit U4,

the high-voltage loop comprises a 10kV voltage input end, and the 10kV voltage input end is sequentially connected with an input isolation switch QS1, a high-voltage thyristor assembly V1, an auxiliary side of a step-up transformer T2 and an output isolation switch QS3 in series and then connected with a load; two ends of the high-voltage bypass switch QF2 are respectively connected with a 10kV voltage input end and a load;

the main circuit unit comprises a step-down transformer T1, the primary side of the step-down transformer T1 is connected with the output end of a high-voltage thyristor assembly V1, the secondary side of the step-down transformer T1 is connected with a low-voltage input circuit breaker QF1, the low-voltage input circuit breaker QF1 is connected with a low-voltage bypass unit U4 after being sequentially connected with an AC/DC converter U1, a super capacitor U2 and a DC/AC converter U3, and the low-voltage bypass unit U4 is connected to the primary side of a step-up transformer T2.

As a specific implementation manner, the low-voltage bypass unit U4 includes a low-voltage thyristor assembly, a low-voltage AC contactor, and a zinc oxide assembly, and each two phases of the output end of the DC/AC converter U3 are respectively connected to two ends of the low-voltage thyristor assembly, the low-voltage AC contactor, and the zinc oxide assembly.

As a specific embodiment, the low-voltage input circuit breaker QF1 adopts a low-voltage 400V molded case circuit breaker; the high-voltage bypass switch QF2 adopts a high-voltage 10kV vacuum circuit breaker.

As a specific embodiment, the high-voltage thyristor assembly V1 is a high-voltage 10kV thyristor assembly; and the input isolation switch QS1 and the output isolation switch QS3 both adopt high-voltage 10kV isolation switches.

Because of the application of above-mentioned technical scheme, compared with the prior art, the utility model has the following advantage: the utility model discloses a have zero voltage concurrently and support and stable state voltage compensation's AVQC system, it is in 10kV circuit stable state voltage compensation's active voltage regulation system, combine high-voltage thyristor subassembly V1 and super capacitor subassembly U2, realize also can provide qualified stable three-phase voltage for 10kV user when the voltage of falling temporarily appears in the 10kV circuit falls to 0V, current does not have discontinuously at whole switching process, guarantee user power consumption quality, through adding high-voltage thyristor subassembly V1, when having guaranteed that grid system takes place voltage temporary change (temporarily falls), can realize the former high-voltage circuit of quick disconnection, low pressure bidirectional current transformer equipment exports the compensation immediately, it supplies with the load to rise to 10kV through shunt transformer with the compensating voltage, when can realizing that grid voltage falls to 0V, guarantee the power supply stability of load. Meanwhile, when the voltage of the power grid system is recovered to be normal, the equipment seals the LOCK signal, and after the output is stopped, the high-voltage thyristor component V1 is quickly conducted, so that the quick switching between the equipment loop and the original power grid loop is realized, and the reliability of load power utilization is ensured.

Drawings

Fig. 1 is a system schematic diagram of an AVQC system with zero voltage support and steady-state voltage compensation according to the present invention;

FIG. 2 is a working loop of the AVQC system when the grid voltage is normal;

FIG. 3 is a working loop of the AVQC system when the grid voltage fluctuates;

FIG. 4 is a working loop of the AVQC system during a voltage sag of the power grid;

fig. 5 is a working loop of the AVQC system when a general fault occurs in the grid (converter-related fault);

fig. 6 shows the working circuit of the AVQC system when a grid has a serious fault (low voltage bypass fault or high voltage overcurrent).

Detailed Description

The technical solution of the present invention will be further explained with reference to the accompanying drawings and specific embodiments.

An AVQC system with both zero voltage support and steady-state voltage compensation, as shown in fig. 1, includes a high voltage loop and a low voltage loop, the low voltage loop includes a main circuit unit and a low voltage bypass unit U4,

the high-voltage loop comprises a 10kV voltage input end, and the 10kV voltage input end is sequentially connected with an input isolation switch QS1, a high-voltage thyristor component V1, an auxiliary side of a boosting transformer T2 and an output isolation switch QS3 in series and then connected with a load; two ends of the high-voltage bypass switch QF2 are respectively connected with a 10kV voltage input end and a load;

the main circuit unit comprises a step-down transformer T1, the primary side of the step-down transformer T1 is connected with the output end of a high-voltage thyristor assembly V1, the secondary side of the step-down transformer T1 is connected with a low-voltage input circuit breaker QF1, the low-voltage input circuit breaker QF1 is connected with an AC/DC converter U1, a super capacitor U2 and a DC/AC converter U3 in sequence and then is connected with a low-voltage bypass unit U4, and the low-voltage bypass unit U4 is connected to the primary side of a step-up transformer T2.

The low-voltage bypass unit U4 comprises a low-voltage thyristor assembly, a low-voltage alternating current contactor and a zinc oxide assembly, and each two phases in the output end of the DC/AC converter U3 are respectively connected with two ends of the low-voltage thyristor assembly, the low-voltage alternating current contactor and the zinc oxide assembly.

Here, the zinc oxide component is also connected between any two phases in the output end of the DC/AC converter U3, and is a surge protector. When a system fault (such as a high-voltage short circuit) occurs, the system needs to be switched to operate with high-voltage and low-voltage bypasses, firstly, the low-voltage thyristor assembly needs to be triggered, and the low-voltage alternating current contactor and the high-voltage bypass switch QF2 are closed at the same time, but because the contact attraction between the high-voltage bypass switch QF2 and the low-voltage alternating current takes time (dozens of seconds), in the period of time, if the low-voltage thyristor assembly is partially failed, the low-voltage side of the series transformer is in an open circuit state, and a large voltage is generated on the low-voltage side to damage the converter. At the moment, a zinc oxide component is added, if fault voltage is generated on the low-voltage side, the internal gap of the zinc oxide component is broken down, overvoltage energy is released through arc discharge, and the low-voltage alternating current contactor or the high-voltage bypass switch QF2 is closed, so that the converter part is protected from being damaged. And after the fault disappears, the zinc oxide component restores to the original high-resistance state to continue system protection.

Here, in fig. 1, the low-voltage input circuit breaker QF1 is a low-voltage 400V molded case circuit breaker; the high-voltage bypass switch QF2 adopts a high-voltage 10kV vacuum circuit breaker; the high-voltage thyristor component V1 adopts a high-voltage 10kV thyristor component; the input isolation switch QS1 and the output isolation switch QS3 both adopt high-voltage 10kV isolation switches; the step-down transformer T1 adopts 10kV/0.4kV; the booster transformer T2 adopts 0.4kV/AkV (the value range of A is determined by 10kV compensation range).

The AVQC system has the following working states:

1. normal voltage of 10kV three-phase network

Referring to fig. 2, when the grid voltage is normal, the operation states of the switches are as follows:

the input isolation knife switch QS1, the output isolation knife switch QS3 and the low-voltage input circuit breaker QF1 are closed, the high-voltage bypass switch QF2 is disconnected, the low-voltage bypass unit U4 is closed, the step-down transformer T1 is conducted, the high-voltage thyristor assembly V1 is conducted, the AC/DC converter U1 operates, and the super capacitor U2 is charged.

The working circuit is as follows:

1) A power supply loop of a power grid:

10kV line voltage input → input isolation switch QS1 → high voltage thyristor assembly V1 → step-up transformer T2 → output isolation switch QS3 → 10kV line voltage output.

2) The super capacitor charging loop:

the method comprises the steps of inputting 10kV line voltage → inputting an isolation disconnecting link QS1 → a step-down transformer T1 → a low-voltage input circuit breaker QF1 → an AC/DC converter U1 for rectification operation → a super capacitor U2 for charging.

2. Voltage fluctuation of 10kV three-phase power network

Referring to fig. 3, when the grid voltage fluctuates, the operating states of the switch are as follows:

the input isolation knife switch QS1, the output isolation knife switch QS3 and the low-voltage input circuit breaker QF1 are closed, the high-voltage bypass switch QF2 is disconnected, the low-voltage bypass unit U4 is disconnected, the step-down transformer T1 is conducted, the high-voltage thyristor assembly V1 is conducted, the AC/DC converter U1 and the DC/AC converter U3 operate, and the step-up transformer T2 is conducted.

The working circuit is as follows:

1) A power supply loop of a power grid:

the voltage of the 10kV line is input → the input isolation switch QS1 → the high-voltage thyristor assembly V1 → the step-up transformer T2 → the output isolation switch QS3 → the voltage of the 10kV line is output.

2) A converter compensation loop:

10kV line voltage input → input isolation switch QS1 → step-down transformer T1 → low-voltage input breaker QF1 → AC/DC converter U1 rectifying operation → super capacitor U2 → DC/AC converter U3 voltage source inverter operation → step-up transformer T2 is coupled to the high-voltage side.

3. Voltage sag of 10kV network (minimum to 0V)

Referring to fig. 4, when the grid voltage drops temporarily (to 0V at the lowest), the operation state of the switch is as follows:

the input isolation switch QS1, the output isolation switch QS3 and the low-voltage input circuit breaker QF1 are closed, the high-voltage bypass switch QF2 is disconnected, the high-voltage thyristor component V1 is turned off, the step-down transformer T1 is turned on, the AC/DC converter U1 operates, and the low-voltage bypass unit U4 is closed.

The working circuit is as follows:

1) A converter power supply loop:

discharging the super capacitor U2 → switching the AC/DC converter U1 to the voltage source mode operation → boosting to 10kV through the step-down transformer T1 → the high-voltage side winding of the step-up transformer T2 → the output isolation switch QS3 → 10kV line voltage output.

4. General fault of 10kV power grid voltage (converter related fault)

Referring to fig. 5, when a general fault occurs in the grid voltage, the operating state of the switch is as follows:

the input isolation knife switch QS1, the output isolation knife switch QS3 and the low-voltage input circuit breaker QF1 are closed, the high-voltage bypass switch QF2 is disconnected, the high-voltage thyristor assembly V1 is switched on, the step-down transformer T1 is closed, and the low-voltage bypass unit U4 is closed.

The working circuit is as follows:

1) A power supply loop of a power grid:

5. Serious failure of 10kV power grid voltage (low voltage bypass failure, high voltage overcurrent, etc.)

Referring to fig. 6, when the grid voltage has a serious fault, the operating state of the switch is as follows:

and the input isolation knife switch QS1, the output isolation knife switch QS3 and the low-voltage input breaker QF1 are disconnected, and the high-voltage bypass switch QF2 is closed.

The working circuit is as follows:

1) A power supply loop of a power grid:

10kV line voltage input → high voltage bypass switch QF2 → 10kV line voltage output.

According to the working mode analysis, the system can solve the problems of high and low voltages, unbalanced three phases of the voltage and voltage harmonic waves in a stable state, and can also solve the problems of voltage temporary rise and temporary drop (voltage drops to 0V), and is comprehensive electric energy quality problem treatment equipment. Meanwhile, due to the configuration of the high-voltage bypass and the low-voltage bypass, the back-stage uninterruptible power supply can be ensured in the switching process of the main circuit, the low-voltage bypass and the high-voltage bypass, and the overall stability of a power grid is improved.

The above embodiments are only for illustrating the technical concept and features of the present invention, and the purpose of the embodiments is to enable those skilled in the art to understand the contents of the present invention and implement the present invention, which cannot limit the protection scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered by the protection scope of the present invention.

Claims

1. An AVQC system with zero voltage support and steady-state voltage compensation comprises a high-voltage loop and a low-voltage loop, wherein the low-voltage loop comprises a main circuit unit and a low-voltage bypass unit U4,

the main circuit unit comprises a step-down transformer T1, the primary side of the step-down transformer T1 is connected with the output end of a high-voltage thyristor component V1, the secondary side of the step-down transformer T1 is connected with a low-voltage input circuit breaker QF1, the low-voltage input circuit breaker QF1 is connected with a low-voltage bypass unit U4 after being sequentially connected with an AC/DC converter U1, a super capacitor U2 and a DC/AC converter U3, and the low-voltage bypass unit U4 is connected to the primary side of a step-up transformer T2.

2. The AVQC system according to claim 1, wherein the low-voltage bypass unit U4 comprises a low-voltage thyristor assembly, a low-voltage AC contactor and a zinc oxide assembly, and each two phases of the output of the DC/AC converter U3 are connected to two ends of the low-voltage thyristor assembly, the low-voltage AC contactor and the zinc oxide assembly respectively.

3. The AVQC system with zero voltage support and steady-state voltage compensation according to claim 1, wherein the low-voltage input breaker QF1 is a low-voltage 400V molded case breaker; the high-voltage bypass switch QF2 adopts a high-voltage 10kV vacuum circuit breaker.

4. An AVQC system according to claim 1 having both zero voltage support and steady-state voltage compensation, wherein the high voltage thyristor assembly V1 is a high voltage 10kV thyristor assembly; and the input isolation switch QS1 and the output isolation switch QS3 both adopt high-voltage 10kV isolation switches.