CN102545242A - Intelligent switching device for 10kV reactive power compensation equipment - Google Patents

Abstract

The invention relates to an intelligent switching device for 10kV reactive power compensation equipment, including a composite switch, a controller, and a photoelectric conversion system. The composite switch is connected to one end of the photoelectric conversion system, and the other end of the photoelectric conversion system is connected to the controller; Advantages of the invention: the state of the composite switch is controlled by the controller, and the transient impact is small during switching; the failure rate of the switching switch is low; the impact on the safe operation of the power grid is small; The silicon controlled valve does not require a radiator, thereby reducing the size and cost of the device and improving reliability.

Description

10kV reactive power compensation equipment intelligent switching device

technical field

The invention relates to an intelligent switching device for 10kV reactive power compensation equipment. the

Background technique

In the "Twelfth Five-Year" plan, it is required that during the "Twelfth Five-Year Plan" period, the integration, intelligence and automation of the safety analysis of the power grid operation mode will be realized. And with the continuous increase of power supply supervision, the requirements for power supply quality are getting higher and higher, the wide application of VQC in the power grid, and the continuous increase of fast-changing loads in the power grid, the switching of compensation capacitors in substations is also increasing. Frequent, then, at present, the switching of compensation capacitors in substations adopts ordinary switches, which cannot realize intelligent zero-crossing switching, so capacitor switching has a large transient impact on the system, the capacitor body, and the switching switch Voltage and current cause great harm to the safe operation of power grid equipment, compensation capacitors, and switching switches. Theoretical research, actual test and operating experience show that frequent non-zero switching of capacitors will lead to:

1) The failure rate of the switching switch is greatly improved;

2), the failure rate of the compensation capacitor is greatly improved;

3) The protection of the frequency conversion device trips frequently, which seriously affects the safe production of the user and brings great economic losses to the user. the

Among them, the power grid companies in some areas have made some statistics. Among them, there are currently 90 10kV capacitor switches in a certain area. According to the preliminary statistics of capacitor interval faults from 2007 to 2009, it is found that the main faults are capacitor switch faults, accounting for 48.6%. Local small hydropower and impact loads In coexisting substations, capacitor banks are switched frequently. For example, a 110kV substation has accumulated 560 switching times in January 2008. Such frequent switching will inevitably lead to defects. From the point of view of the nature of defects, those related to the control loop Defects account for a large proportion, mainly including opening and closing coils, burning of closing contactors, loose contact of circuit terminals, damage to auxiliary switches, rectifier silicon and micro switches, etc. the

Frequent capacitor switch interval failures affect the availability of capacitors, increase the work of maintenance personnel to eliminate defects, and are not conducive to the safe operation of the power grid (accidents caused by capacitor switch interval elimination are increasing year by year), resulting in a low pass rate of Class A voltage in rural power grids. Reduced power supply quality of the grid. the

Therefore, it is very necessary to carry out research and development work on the application of "reactive power compensation equipment intelligent switching device" in 10kV medium voltage system. the

In the 1980s, ABB made relevant research in this field and developed corresponding products. Due to the price and technical problems of power electronic products at that time, they used conventional switches plus closing time prediction technology to realize the zero-crossing closing function, so the product had the problem that the zero-crossing closing time was not very accurate, and the transient impact when closing The voltage and current are still relatively large. the

Another technical route is to use TSC (capacitance compensation for thyristor switching). This technology has been applied to some extent in the power grids of countries such as Europe and the United States. This technology uses a thyristor valve instead of a mechanical switch switching capacitor, so it can realize the accurate zero-crossing opening and closing function, thereby minimizing the transient impact voltage and current generated by capacitor switching. However, since the thyristor valve is used as a mechanical switch, it generates a large amount of heat in the closed state, so there are problems of high loss, large volume, and high cost. the

In low-voltage applications (380V), the technical scheme of parallel connection of AC contactor and thyristor is widely used at home and abroad: when closing, first trigger the conduction of the thyristor at zero crossing and then close the AC contactor; once the contactor is closed At the gate position, the thyristor is automatically turned off, which not only achieves the purpose of accurate zero-crossing closing, but also solves the problem of high heat generation of the thyristor. Products based on this technology are called "composite switches" in the market. the

Contents of the invention

The technical problem to be solved by the invention is that the switching compensation of the compensation capacitor in the existing substation has the above problems, thereby providing an intelligent switching device for 10kV reactive power compensation equipment. the

In order to solve the above-mentioned technical problems, the present invention is achieved through the following technical solutions: 10kV reactive power compensation equipment intelligent switching device, comprising a composite switch, a controller, a photoelectric conversion system, the composite switch is connected to one end of the photoelectric conversion system, the The other end of the photoelectric conversion system is connected with the controller. the

Preferably, the composite switch includes a thyristor valve, a trigger plate, a high-frequency current source, and a unipolar AC vacuum contactor, the thyristor valve is connected to the trigger plate, and the trigger plate is connected to the high-frequency current source, The unipolar AC vacuum contactor is connected to the thyristor valve, and the trigger plate connected to the thyristor valve is controlled by the unipolar AC vacuum contactor. The trigger plate can accurately detect the voltage at both ends of the thyristor, so the thyristor valve It can meet the requirements of zero-crossing closing, simple structure, safe use and strong reliability. the

Preferably, the composite switch is provided with an A-phase composite switch and a C-phase composite switch, which reduces the volume of the device and reduces the cost. the

Preferably, the thyristor valve is composed of two anti-parallel thyristor groups in series, and the thyristor valve is provided with a resistance-capacitance absorption circuit, a pressure equalization circuit, a commutation overvoltage protection and a breakdown protection circuit , Fault self-diagnosis system, simple in structure, safe and practical, ensures normal work under various fault states, and improves performance. the

Preferably, the photoelectric conversion system includes a photoelectric converter and an optical fiber, one end of the photoelectric converter is connected to the trigger plate through the optical fiber I, and the other end of the photoelectric converter is connected to the controller through the optical fiber II, and the photoelectric conversion system realizes the controller The electrical signal between the trigger board and the trigger board is converted into a photoelectric signal, and the optical signal is transmitted through the optical fiber. The optical fiber can not only transmit the signal, but also play the role of isolation between the high-voltage device and the low-voltage control system. The signal transmitted through the optical fiber In addition to digital input and output such as each switch state, it also includes state signals such as zero-crossing signals of each thyristor valve. the

In summary, the advantages of the present invention are as follows: the state of the composite switch is controlled by the controller, and the transient impact during switching is small; the failure rate of the switching switch is low; the influence on the safe operation of the power grid is small; Arc extinguishing capability is required, and the thyristor valve does not require a radiator, thereby reducing the size and cost of the device and improving reliability. the

Description of drawings

The present invention will be further described below in conjunction with accompanying drawing:

Fig. 1 is the structural block diagram of 10kV reactive power compensation equipment intelligent switching device of the present invention;

Fig. 2 is the structural representation of composite switch of the present invention;

Fig. 3 is the structural block diagram of photoelectric conversion system of the present invention;

Fig. 4 is a structural schematic diagram of the overall control system of the present invention. the

Detailed ways

As shown in Figure 1, Figure 2, Figure 3, and Figure 4, the intelligent switching device for 10kV reactive power compensation equipment includes a composite switch, a controller 2, and a photoelectric conversion system 3, and the composite switch is connected to one end of the photoelectric conversion system 3 , the other end of the photoelectric conversion system 3 is connected to the controller 2, and the controller 2 includes a CPLD chip, a level converter, and a photoelectric isolation, and its main function is to receive the switching signal of the capacitor bank of the VQC, and detect the thyristor Zero-crossing, to ensure that the thyristor valve 12 and the unipolar AC vacuum contactor 15 are switched on in the normal order, and at the same time detect the voltage at both ends of the thyristor, protect the thyristor valve 12 and return the alarm/protection signal to VQC, so The composite switch includes a thyristor valve 12, a trigger plate 13, a high-frequency current source 14, and a unipolar AC vacuum contactor 15. The thyristor valve 12 is connected to the trigger plate 13, and the trigger plate 13 is connected to the high-frequency current The source 14 is connected, the unipolar AC vacuum contactor 15 is connected with the thyristor valve 12, the trigger plate 13 connected to the thyristor valve 12 is controlled by the unipolar AC vacuum contactor 15, and the trigger plate 13 can accurately detect the controllable The voltage across the silicon, so the thyristor valve 12 can meet the requirements of zero-crossing, simple structure, safe use, and strong reliability. The thyristor valve 12 adopts a redundant design (N+1, based on the original One more layer is added on the top to increase the reliability of the device), the composite switch is provided with an A-phase composite switch 10 and a C-phase composite switch 11, which reduces the volume of the device and reduces the cost. The thyristor valve 12 consists of two Only anti-parallel thyristor groups are connected in series. The thyristor valve 12 is provided with a resistance-capacity absorption circuit, a voltage equalization circuit, a commutation overvoltage protection and breakdown protection circuit, and a fault self-diagnosis system. The structure is simple and safe. Practical, guaranteed to work normally under each failure state, improved performance, described photoelectric conversion system 3 comprises photoelectric converter 31, optical fiber, and one end of described photoelectric converter 31 links to each other with trigger plate 13 by optical fiber 1 32 , the other end of the photoelectric converter 31 is connected to the controller 2 through the optical fiber II33, the photoelectric conversion system 3 realizes the conversion of the electrical signal between the controller 2 and the trigger board 13 for photoelectric signal, and transmits the optical signal through the optical fiber. Not only can it carry out signal transmission, but it can also play an isolation role between the high-voltage device and the low-voltage control system. In addition to the digital input and output of each switch state, the signal transmitted through the optical fiber also includes the zero-crossing signal of each thyristor valve 12, etc. status signal. the

Through the switching of the transfer switch installed on the VQC control cabinet, the intelligent switching device of 10kV reactive power compensation equipment can work in two working modes of "intelligent switching" and "conventional switching". the

(1) Intelligent switching mode

When the device is functioning normally, it is generally in this working mode. the

Closing process: Controller 2 immediately closes the B-phase AC contactor after receiving the VQC closing command, and sends a trigger pulse to the A and C-phase thyristor valves at the voltage zero-crossing point after the B-phase AC contactor is closed signal (the thyristor trigger board 13 can accurately detect the voltage at both ends of the thyristor, so the thyristor valve 12 can meet the requirements of zero-crossing closing), trigger the conduction of the thyristor valve 12, and then close the A , C-phase AC contactor. Once the AC contactors of phase A and C are in the closing position, the voltage at both ends of the thyristor valves of phase A and C is basically 0, then the thyristor valves of phase A and C can be turned off naturally at the point where the current crosses zero. At this time, the capacitor The group puts in normally. the

Opening process: After the control system receives the VQC opening command, it immediately sends a trigger pulse signal to the A and C-phase thyristor valves, and then opens the A and C-phase AC contactors; once the A and C-phase thyristor valves have When the voltage is applied, the thyristor valves of A and C phases are immediately turned on, and when the AC contactors of phases A and C are in the fully open state, the A and C phase thyristor valves trigger pulse signals, and then the phases A and C are controlled. The silicon valve can be turned off naturally at the current zero crossing, and after the A and C-phase thyristor valves 12 are disconnected, the B-phase AC contactor is opened, and the capacitor bank is normally cut off at this time. the

(2) Normal switching mode

When the thyristor valve 12 is damaged on more than one layer or the device control system fails to control the thyristor valve 12 normally, after the device protection trips, in order not to affect the continuous input and removal of the capacitor bank, the transfer switch is turned on at this time. In the remote normal mode, first close the three-phase single-stage AC vacuum contactors A, B, and C, and then VQC continues to control the upper-level circuit breaker to switch on/off the capacitor bank (the closing sequence of the circuit breaker and the AC vacuum contactor, through its auxiliary contacts to interlock). the

The state of the compound switch is controlled by the controller, and the transient impact is small during switching; the failure rate of the switching switch is low; the impact on the safe operation of the power grid is small; the unipolar AC vacuum contactor of the device does not need arc extinguishing ability, and the thyristor valve does not A heat sink is required, thereby reducing the size and cost of the device and increasing reliability. the

Claims (5)

1. The intelligent switching device for 10kV reactive power compensation equipment is characterized in that it includes a composite switch, a controller (2), and a photoelectric conversion system (3), the composite switch is connected to one end of the photoelectric conversion system (3), and the photoelectric The other end of the conversion system (3) is connected with the controller (2). 2. The intelligent switching device for 10kV reactive power compensation equipment according to claim 1, characterized in that: the composite switch includes a thyristor valve (12), a trigger plate (13), a high-frequency current source (14) , unipolar AC vacuum contactor (15), the thyristor valve (12) is connected to the trigger plate (13), the trigger plate (13) is connected to the high-frequency current source (14), and the unipolar AC The vacuum contactor (15) links to each other with the thyristor valve (12). 3. The intelligent switching device for 10kV reactive power compensation equipment according to claim 1 or 2, characterized in that: the composite switch is provided with an A-phase composite switch (10) and a C-phase composite switch (11). 4. The intelligent switching device for 10kV reactive power compensation equipment according to claim 2, characterized in that: the thyristor valve (12) is composed of two anti-parallel thyristor groups connected in series, and the thyristor valve (12) The silicon-controlled valve (12) is provided with a resistance-capacitance absorption circuit, a pressure equalization circuit, a commutation overvoltage protection circuit, a breakdown protection circuit, and a fault self-diagnosis system. 5. According to the 10kV reactive power compensation equipment intelligent switching device according to claims 1 and 2, it is characterized in that: the photoelectric conversion system (3) includes a photoelectric converter (31), an optical fiber, and the photoelectric converter ( 31) One end is connected to the trigger board (13) through the optical fiber I (32), and the other end of the photoelectric converter (31) is connected to the controller (2) through the optical fiber II (33). the

Images