Resonance prevention device for power distribution system

Abstract

The utility model provides a resonance prevention device for a power distribution system, and belongs to the technical field of power distribution control. The device is connected to each capacitor bank branch on a compensation device bus of a 10kV power distribution system, and comprises a sampling unit and a control unit, each capacitor bank branch comprises an electric control switch, a current transformer, a series reactor and a parallel capacitor bank which are connected in sequence; the sampling unit is connected between the current transformer and the series reactor, the signal input end of the control unit is connected with the sampling unit, and the output end is connected with the electric control switch; the sampling unit is used for carrying out signal sampling on the series reactor and the parallel capacitor bank and outputting a sampled signal to the control unit; and the control unit carries out processing according to the received sampling signal and outputs a corresponding control instruction to control the electric control switch to execute closing / opening operation. The device can be used for preventively monitoring each capacitor bank branch of the 10kV power distribution system, breaking resonance generation conditions and avoiding resonance generation.

Description

Technical Field

[0001] The utility model belongs to the technical field of distribution control, and particularly relates to a resonance prevention device for a distribution system. Background Art

[0002] In a factory's 110KV main step-down substation 10KV distribution system, high-voltage capacitor banks are usually installed to centrally compensate for the reactive power on the high-voltage side, improve the power factor, reduce line losses, reduce line voltage drop, improve voltage quality, and enhance the system's power supply capacity. At the same time, with the start and stop changes of electrical equipment, the impedance inductance and capacitance in the 10KV system change, and under specific conditions, resonance will occur with the high-voltage capacitors, causing resonance overvoltage and abnormal sounds in the capacitors. At the same time, it will cause voltage fluctuations in the 10KV distribution system, resulting in damage to electrical components in the system or malfunction and tripping of the frequency converter.

[0003] Traditional 10KV bus capacitor compensation devices are not equipped with effective protection measures. When overvoltage, undervoltage faults occur in the system, components fail, or resonance occurs between the system and the capacitor bank branch, the capacitor bank cannot automatically withdraw from operation, posing a great hidden danger to the entire power supply system. Content of the Utility Model

[0004] In view of this, the purpose of the utility model is to provide a resonance prevention device for a distribution system to solve the problem that the capacitor bank cannot automatically withdraw from operation when overvoltage, undervoltage faults occur in the system, components fail, or resonance occurs between the system and the capacitor bank branch.

[0005] The purpose of the utility model can be achieved by the following technical solutions: A resonance prevention device for a distribution system is connected to each capacitor bank branch on the compensation device bus of a 10kV distribution system. It is characterized by including a sampling unit and a control unit; each of the capacitor bank branches includes an electric control switch, a current transformer, a series reactor, and a shunt capacitor bank connected in sequence; the sampling unit is connected between the current transformer and the series reactor, the signal input end of the control unit is connected to the sampling unit, and the output end is connected to the electric control switch; the sampling unit is used to sample signals of the series reactor and the shunt capacitor bank and output the sampled signals to the control unit, and the control unit processes the received sampling signals and outputs corresponding control instructions to control the execution of closing / opening operations of the electric control switch.

[0006] Preferably, the sampling unit is a dedicated discharge coil for impedance characteristic monitoring. The dedicated discharge coil for impedance characteristic monitoring collects analog signals of the A, B, and C phases of the series reactor and the shunt capacitor bank and transmits the analog signals to the control unit through secondary wires.

[0007] Preferably, the control unit is the host of the WRS-CIS series impedance characteristic monitoring system, and the output terminal of the output quantity of the impedance characteristic monitoring system host is connected to the electric control switch. The impedance characteristic monitoring system host adopts existing equipment. By presetting its impedance and then analyzing and judging the received data, if the impedance characteristic undergoes a jump mutation and the jump mutation value exceeds the impedance limit value set in the monitoring system, the host sends a tripping instruction to the electric control switch through the output terminal of the output quantity to disconnect the capacitor bank branch where the impedance value has mutated.

[0008] Preferably, the electric control switch is a vacuum permanent magnet switch.

[0009] Preferably, a lightning arrester is also connected between the series reactor and the shunt capacitor bank of the capacitor bank branch.

[0010] Compared with the prior art, the resonance prevention device of the present distribution system has the following advantages: The impedance characteristic monitoring dedicated discharge coil as the sampling unit samples the series reactor and the shunt capacitor bank in real time, and then the impedance characteristic monitoring system host analyzes the signals for preventive monitoring, monitors the impedance characteristic state of each branch of the capacitor bank in real time, and eliminates the resonance faults occurring in the capacitor in the budding state. Description of the Drawings

[0011] Figure 1 is the circuit schematic diagram of the resonance prevention device of the distribution system of the embodiment.

[0012] In the figure, 1. Compensation device busbar; 2. Electric control switch; 3. Current transformer; 4. Sampling unit; 5. Control unit; 6. Series reactor; 7. Shunt capacitor bank; 8. Lightning arrester. Detailed Embodiment

[0013] The embodiments of the present utility model will be described in detail below. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions from beginning to end. The embodiments described below with reference to the respective drawings are exemplary and are intended to explain the present utility model and should not be construed as limiting the present utility model.

[0014] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present utility model, "a plurality of" means two or more unless otherwise specifically defined.

[0015] In the present utility model, unless otherwise clearly defined and limited, terms such as "installation", "connection", "linkage", "fixation" shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral body; it may be a mechanical connection or an electrical connection; it may be a direct connection or an indirect connection through an intermediate medium, and it may be the internal communication between two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0016] As Figure 1 shown, the present utility model provides a device for preventing resonance in a power distribution system, which includes a sampling unit 4 and a control unit 5. The sampling unit 4 is a dedicated discharge coil for impedance characteristic monitoring, and the control unit 5 is a host of an impedance characteristic monitoring system of the WRS-CIS series. This device is connected to each capacitor bank branch on the compensation device bus 1 of the 10 kV power distribution system. Each capacitor bank branch includes an electric control switch 2, a current transformer 3, a series reactor 6, and a shunt capacitor bank 7 connected in sequence. An arrester 8 is also connected between the series reactor 6 and the shunt capacitor bank 7 of the capacitor bank branch, and the electric control switch 2 uses a vacuum permanent magnet switch.

[0017] The dedicated discharge coil for impedance characteristic monitoring of the present utility model is connected between the current transformer 3 and the series reactor 6, and is used to collect analog signals of the A, B, and C phases of the series reactor 6 and the shunt capacitor bank 7, and transmit the analog signals to the control unit 5 through secondary wires.

[0018] The signal input end of the impedance characteristic monitoring system host is connected to the sampling unit 4, and the output terminal of the opening quantity is connected to the electric control switch 2; by presetting its impedance threshold, and then analyzing and judging the received data, if the impedance characteristic undergoes a jump mutation and the jump mutation value exceeds the impedance limit set in the monitoring system, the host issues a tripping instruction to the electric control switch 2 through the output terminal of the opening quantity to disconnect the capacitor bank branch where the impedance value has mutated.

[0019] The present utility model adds a monitoring system composed of a dedicated discharge coil for impedance characteristic monitoring and a host of an impedance characteristic monitoring system of the WRS-CIS series to each capacitor bank branch, and monitors the impedance change of the shunt capacitor bank 7 in real time, realizing capacitance deviation alarm, capacitor unit element breakdown tripping, reactor turn-to-turn short circuit tripping, impedance characteristic jump tripping, and discharge coil fault tripping. When resonance occurs, the system detects a jump change in the impedance characteristic, exceeding the set value, and the controller issues a tripping instruction to disconnect the corresponding shunt capacitor bank 7, breaking the resonance condition, eliminating the resonance fault in the bud state, not generating subsequent overvoltage, ensuring the stability of the 10 kV power supply voltage, and ensuring the safe operation of the capacitor bank.

[0020] The specific embodiments described herein are merely illustrative of the spirit of the present utility model. Those skilled in the art to which the present utility model pertains can make various modifications or supplements to the described specific embodiments or use similar ways for substitution, but will not deviate from the spirit of the present utility model or exceed the scope defined by the appended claims.

Claims

1. A device for preventing resonance in a power distribution system, connected to each capacitor bank branch on a compensation device busbar (1) of a 10 kV power distribution system, characterized in that: The invention comprises a sampling unit (4) and a control unit (5); each of the capacitor bank branches comprises an electrically controlled switch (2), a current transformer (3), a series reactor (6) and a parallel capacitor bank (7) connected in sequence; the sampling unit (4) is connected between the current transformer (3) and the series reactor (6); the signal input end of the control unit (5) is connected to the sampling unit (4), and the output end is connected to the electrically controlled switch (2); the sampling unit (4) is used to sample the signals of the series reactor (6) and the parallel capacitor bank (7) and output the sampled signals to the control unit (5); the control unit (5) processes the received sampled signals and outputs corresponding control instructions to control the execution of the closing / opening operation of the electrically controlled switch (2).

2. A device for preventing resonance in a power distribution system according to claim 1, characterized in that: The sampling unit (4) is a discharge coil dedicated to monitoring impedance characteristics. The discharge coil dedicated to monitoring impedance characteristics collects analog signals of the three phases A, B, and C of the series reactor (6) and the parallel capacitor group (7), and transmits the analog signals to the control unit (5) via the secondary line.

3. A device for preventing resonance in a power distribution system according to claim 2, characterized in that: The control unit (5) is a WRS-CIS series impedance characteristic monitoring system host, and the output terminal of the impedance characteristic monitoring system host is connected to the electric control switch (2).

4. A device for preventing resonance in a power distribution system according to claim 1, 2 or 3, characterized in that: The electrically controlled switch (2) is a vacuum permanent magnet switch.

5. A device for preventing resonance in a power distribution system according to claim 1, 2 or 3, characterized in that: A lightning arrester (8) is also connected between the series reactor (6) and the parallel capacitor group (7) of the capacitor group branch.

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