SVG control system and control method with bypass function

Abstract

The present invention discloses an SVG control system and control method with bypass function, including an SVG main control system, a power module, and a three-phase circuit; each phase of the three-phase circuit is provided with 2n power modules, the power modules in the same phase are connected in series, and the series circuit outputs high voltage through a three-phase star connection; each power module is connected to the SVG main control system, and is used to receive instruction information issued by the SVG main control system, and send module working information to the SVG control system. Advantages: The present invention does not require power supply, replaces the traditional complex power supply circuit from the DC side or the AC side, and enhances the reliability of bypass energy supply; the bypass structure of the present invention can realize the online recovery function, and the faulty power module that exits the chain link can be recharged and restored to use, avoiding the problem of repeated power on and off and the switch operation of the incoming circuit breaker, and improving the working efficiency of the system operation; the power module fault bypass and the faulty power module online recovery are controlled by the SVG main control system, and the operation is convenient.

Description

Technical Field

[0001] The invention relates to an SVG control system and a control method with a bypass function, belonging to the technical field of reactive power compensation devices. Background Art

[0002] The chain-type high-voltage static var generator (SVG) uses switchable power electronic devices (such as IGBT) to form a self-commutated bridge circuit, which can be directly connected to the grid to absorb and output reactive power and quickly and dynamically adjust the system reactive power.

[0003] The bypass structure is usually connected in parallel to both sides of the power module. When a power module fails, the bypass structure bypasses the failed power module to ensure that the SVG can continue to operate smoothly. However, the common bypass structure currently has low reliability. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide an SVG control system and a control method with a bypass function, and an easy-to-implement bypass structure of a power module of a chain-type high-voltage static reactive power generator, so that the chain-type high-voltage static reactive power generator can operate smoothly, reduce the tripping frequency, and greatly reduce the operation and maintenance of engineering and technical personnel.

[0005] In order to solve the above technical problems, the present invention provides a power module bypass structure, comprising: a bypass contactor, wherein the bypass contactor is a non-mechanically locked electrical holding contactor;

[0006] The secondary side of the bypass contactor is connected to both ends of the output side of the adjacent power module, and the primary side of the bypass contactor is connected in series with a switch controlled by a control signal and in parallel to the DC side.

[0007] A power module, comprising: a bypass contactor, a module control unit, a discharge circuit, an H-bridge conversion circuit, a module output interface terminal P1, a module output interface terminal P2, a bypass interface terminal P3, and a bypass interface terminal P4;

[0008] The bypass contactor is a non-mechanically locked electrically held contactor.

[0009] The primary side of the bypass contactor is connected in series with the switch controlled by the control signal of the module control unit and is connected in parallel with the DC side. The DC side is also connected in parallel with a discharge circuit and an H-bridge conversion circuit. The H-bridge conversion circuit leads to the module output interface terminal P1 and the module output interface terminal P2, and the secondary side of the bypass contactor leads to the bypass interface terminal P3 and the bypass interface terminal P4.

[0010] An SVG with bypass function, comprising an SVG main control system, a power module as claimed in claim 2, and a three-phase circuit;

[0011] Each phase of the three-phase circuit is provided with 2n of the power modules, the power modules in the same phase are connected in series, and the series circuit outputs high voltage through a three-phase star connection method;

[0012] Each power module is connected to the SVG main control system via a bidirectional optical fiber, and is used to receive instruction information issued by the SVG main control system and send module working information to the SVG main control system.

[0013] Furthermore, the power modules in the same phase are connected in series, including:

[0014] The module output interface terminals P1, P2 and the bypass interface terminals P3, P4 between adjacent power modules are cross-connected, and each power module is then connected end to end through the output interface terminals P1 and P2 to form a series single-phase chain link.

[0015] Furthermore, it also includes:

[0016] The output port P2 of the first power module of each phase is connected to form a three-phase neutral point.

[0017] An SVG control system with a bypass function, comprising:

[0018] The incoming circuit breaker QF1, the transformer T, the parallel circuit, the series reactor L and the SVG are connected in sequence; wherein the parallel circuit is a contactor KM and a charging resistor R connected in parallel.

[0019] A control method of an SVG control system, comprising:

[0020] When a power module fails, the SVG main control system determines whether it can be bypassed. If so, it sends a bypass contactor closing command to the adjacent power module.

[0021] The bypass contactor of the adjacent power module is closed, and the return state of the bypass contactor of the adjacent power module is detected;

[0022] If the bypass contactor of the adjacent power module is determined to be unsuccessful in closing according to the returned status, the SVG main control system stops outputting and issues a command to open the circuit breaker QF1;

[0023] If it is determined according to the return status that the bypass contactor of the adjacent power module is closed successfully, the output side of the faulty power module is bypassed, the DC bus of the faulty power module is discharged, and the SVG main control system detects that the control unit of the faulty power module is powered off, it is determined that the SVG system is in the n-1 level chain operation state.

[0024] A control method of an SVG control system, comprising:

[0025] Obtain an online recovery instruction, and detect whether the online recovery instruction is valid and whether there is a power module bypass;

[0026] After that, the SVG main control system stops pulse output, confirming that the SVG is in hot standby state with bypass;

[0027] The SVG main control system first sends an opening command to the contactor KM, and then sends a bypass contactor opening command to the adjacent power module. The bypass power module bus is charged, and the bypass power module control unit resumes power supply.

[0028] When the SVG main control system detects that the restored power module voltage reaches the charging completion threshold, it sends a closing command to the contactor KM to ensure that the SVG is in a non-bypass hot standby state.

[0029] The beneficial effects achieved by the present invention are:

[0030] 1. The present invention does not require power supply, replacing the traditional complex power supply circuit from the DC side or the AC side, thereby enhancing the reliability of bypass energy supply; 2. The bypass structure of the present invention can realize the online recovery function, and the faulty power module that has exited the chain link can be recharged and restored to use, avoiding the problem of repeated power on and off and the switching operation of the incoming circuit breaker, thereby improving the work efficiency of the system operation; 3. The power module fault bypass and the online recovery of the faulty power module are controlled by the SVG main control system, which is easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is the electrical diagram of SVG control system;

[0032] Figure 2 A schematic diagram of a three-phase power module chain connection (n is an even number);

[0033] Figure 3 The power module structure diagram of the SVG system with bypass function and online recovery;

[0034] Figure 4 It is a flow chart of a power module fault bypass control method;

[0035] Figure 5 The figure is a flow chart of the online recovery control method for a faulty power module. DETAILED DESCRIPTION

[0036] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0037] like Figure 1As shown, it includes an incoming line circuit breaker QF1, a transformer T, a contactor KM, a series reactor L, a charging resistor R and SVG connected in sequence; wherein, both ends of the contactor KM are connected in parallel with the charging resistor R.

[0038] The power-on startup logic is:

[0039] A. Initialize the contactor KM to the open state, close the incoming circuit breaker QF1, and the current flows through the transformer T, the charging resistor R, the series reactor L and the static VAR generator SVG to charge the power module. After the charging is completed, the contactor KM is closed to bypass the charging resistor R, and SVG is in the hot standby state.

[0040] like Figure 2 As shown, the power modules in the same phase are connected in series, and the series circuit realizes high-voltage output through a three-phase star connection, wherein the output interfaces P1, P2 and bypass output interfaces P3, P4 between adjacent power modules are cross-connected, such as A1-P1 connected with A2-P4, A1-P2 connected with A2-P3, A1-P3 connected with A2-P2, A1-P4 connected with A2-P1, and each power module is then connected end to end through output ports P1 and P2 to form a series single-phase chain link, and the P2 output ports of A1, B1, and C1 are connected to form a three-phase neutral point. Each phase power module is connected to the SGV main control system through an optical fiber, and can receive pulse instructions, bypass instructions and other information issued by the SGV main control system, and can also send module status, module voltage and other information to the SGV main control system.

[0041] like Figure 3 As shown, the power module structure with contactor bypass function without power supply circuit includes power module 1, module control unit 2, bypass contactor 3, discharge circuit 4, H-bridge conversion circuit 5, module output interfaces P1, P2 and bypass output interfaces P3, P4. The H-bridge circuit structure is composed of four IGBTs, which is the core circuit of the power module for outputting compensation voltage.

[0042] like Figure 4 , Figure 5 As shown, an SVG system with bypass function and online recovery and a control method thereof include a power module fault bypass control method and a fault power module online recovery control method.

[0043] The power module fault bypass control method mainly includes the following steps:

[0044] 1) Power module fault bypass When a power module (such as A1) fails, the main control system determines whether it can be bypassed. If it can be bypassed, it sends a bypass contactor closing command to the adjacent power module (such as A2);

[0045] 2) The bypass contactor of the adjacent power module (such as A2) is closed, and the bypass contactor of the adjacent power module (such as A2) is detected to return to the state;

[0046] 3) If the bypass contactor of the adjacent power module (such as A2) fails to close, the SVG system stops outputting and issues an opening command for the incoming circuit breaker;

[0047] 4) If the bypass contactor of the adjacent power module (such as A2) is closed successfully, the output side of the faulty power module (such as A1) is bypassed, the DC bus of the faulty power module (such as A1) is discharged, and the system can detect that the control unit of the faulty power module (such as A1) is powered off. The SVG system is in the n-1 level chain operation state.

[0048] The online recovery control method of the faulty power module mainly includes the following steps:

[0049] 1) The system detects whether the online recovery command is valid. If it is valid, the system detects whether there is a power module bypass. If there is a power module bypass, the system stops output and is in a hot standby state with bypass.

[0050] 2) The main control system first sends an opening command to the contactor KM, and then sends a bypass contactor opening command to the adjacent power module (such as A2). The bypass power module (such as A1) bus is charged, and the control unit of the bypass power module (such as A1) resumes power supply.

[0051] 3) When the SVG main control system detects that the voltage of the restored power module (such as A1) reaches the charging completion threshold, it sends a closing command to the contactor KM. The SVG is in the non-bypass hot standby state.

[0052] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A power module, characterized in that: include: Bypass contactor, module control unit, discharge circuit, H-bridge conversion circuit, module output interface terminal P1, module output interface terminal P2 and bypass interface terminal P3, bypass interface terminal P4; The bypass contactor is a non-mechanically locked electrically held contactor. The primary side of the bypass contactor of the power module is connected in series with the switch controlled by the module control unit of the power module to obtain a series structure, and the series structure is connected in parallel to the DC side of the power module. The DC side is also connected in parallel with a discharge circuit and an H-bridge conversion circuit. The H-bridge conversion circuit leads to the module output interface terminal P1 and the module output interface terminal P2, and the secondary side of the bypass contactor leads to the bypass interface terminal P3 and the bypass interface terminal P4.

2. An SVG with bypass function, characterized in that: It comprises an SVG main control system, a power module as claimed in claim 1, and a three-phase circuit; Each phase of the three-phase circuit is provided with 2n of the power modules, the power modules in the same phase are connected in series, and the series circuit outputs high voltage through a three-phase star connection method; Each power module is connected to the SVG main control system via a bidirectional optical fiber, and is used to receive instruction information issued by the SVG main control system and send power module working information to the SVG main control system.

3. The SVG with bypass function according to claim 2, characterized in that: The power modules in the same phase are connected in series, including: The module output interface terminals P1, P2 and the bypass interface terminals P3, P4 between adjacent power modules are cross-connected, and each power module is then connected end to end through the module output interface terminals P1, P2 to form a series single-phase chain link.

4. The SVG with bypass function according to claim 2, characterized in that: Also includes: The module output interface terminal P2 of the first power module of each phase is connected to form a three-phase neutral point.

5. An SVG control system with bypass function according to claim 3, characterized in that: include: The incoming circuit breaker QF1, the transformer T, the parallel circuit, the series reactor L and the SVG are connected in sequence; wherein the parallel circuit is a contactor KM and a charging resistor R connected in parallel.

6. A control method based on the SVG control system according to claim 5, characterized in that: include: When a power module fails, the SVG main control system determines whether it can be bypassed. If so, it sends a bypass contactor closing command to the adjacent power module. The bypass contactor of the adjacent power module is closed, and the return state of the bypass contactor of the adjacent power module is detected; If the bypass contactor of the adjacent power module is determined to be unsuccessful in closing according to the returned status, the SVG main control system stops outputting and issues a command to open the circuit breaker QF1; If it is determined according to the return status that the bypass contactor of the adjacent power module is closed successfully, the output side of the faulty power module is bypassed, the DC bus of the faulty power module is discharged, and the SVG main control system detects that the module control unit of the faulty power module is powered off, it is determined that the SVG system is in the n-1 level chain operation state.

7. A control method based on the SVG control system according to claim 6, characterized in that: include: Obtain an online recovery instruction, and detect whether the online recovery instruction is valid and whether there is a power module bypass; After that, the SVG main control system stops pulse output, confirming that the SVG is in hot standby state with bypass; The SVG main control system first sends an opening command to the contactor KM, and then sends a bypass contactor opening command to the adjacent power module. The bypass power module bus is charged, and the module control unit of the bypass power module resumes power supply. When the SVG main control system detects that the restored power module voltage reaches the charging completion threshold, it sends a closing command to the contactor KM to ensure that the SVG is in a non-bypass hot standby state.

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