Device for capacitor bank protection and state monitoring and method thereof

Abstract

The invention relates to a device and a method for capacitor bank protection and state monitoring. The device consists of a capacitor bank, a breaker, a voltage mutual inductor, a current mutual inductor and a controller, wherein the controller controls the switching on/off of the breaker according to signals of the mutual inductors. The method comprises the following steps: calculating condensance change rate according to the condensance value of a fault phase of the capacitor bank and a rated condensance value, and taking the condensance change rate as a protection setting value; calculating the power-frequency condensance value of each phase of the capacitor bank according to the end voltage and current power-frequency effective value of each phase of the capacitor bank detected in real time; before the switching of the capacitor bank, inputting the original measured value and protection setting value of each phase in a protective device; after the switching of the capacitor bank, calculating real-time condensance change rate according to condensance monitored in real time and an original value; and finally, comparing the real-time condensance change rate and the protection setting value, and switching off the breaker when meeting the conditions so as to switch off a fault capacitor bank. The device is sensitive and reliable and is free from the influences of external factors such as capacitor imbalance, asymmetrical balance of a three-phase power supply, operating characteristic deviation between sensors and harmonic of a power system.

Description

technical field [0001] The invention relates to a parallel capacitor and parallel capacitor group protection and method thereof, in particular to a high-voltage parallel capacitor group protection and state monitoring device and method thereof. Background technique [0002] The backup protection (when the internal or external fuse is used as the main protection) or the main protection (when there is no fuse protection) of the internal failure of the high-voltage shunt capacitor in my country is based on and implemented the current national standard GB50227-95 "Design Specifications for Parallel Capacitor Devices" for a long time Regarding the following provisions in the configuration of the internal fault protection mode of the capacitor: [0003] 6.1.2 The capacitor bank should be equipped with unbalance protection, and should meet the following requirements [0004] 6.1.2.1 The capacitor bank with single star connection can adopt open delta voltage protection. [0005] 6....

AI Technical Summary

Problems solved by technology

[0012] 1. Since the existing unbalance protection device can only choose to cooperate with one of the external fuse, internal fuse and non-fuse protection, if the external fuse or internal fuse protection fails, the unbalance protection will Losing the expected protective effect, causing the internal fault of the capacitor to continue to develop, and even causing serious accidents;

[0013] 2. The existence of the initial unbalanced voltage or initial unbalanced current not only increases the protection setting value, but also may reduce the actual protection action value (when the capacitor fails, the phase gap between the expected protection action value and the initial unbalanced when the angle is between 90° and 270°);

[0014] 3. When a symmetrical fault occurs, the unbalance protection does not work;

[0015] 4. The existing protection device lacks real-time monitoring of the operating state of the capacitor, and lacks the wave recording function of the switching process of the capacitor bank and the fault tripping process, so that the analysis of the operating state of the capacitor device, especially the analysis of the cause of the accident of the capacitor device Research lacks foundational evidence

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