On-line monitoring method and on-line monitoring device for transformer substation parallel connection compensating capacitor group

Abstract

The invention relates to an on-line monitoring method for a transformer substation parallel connection compensating capacitor group. According to the method, a self power supply current measurement unit is additionally arranged and designed at the high-voltage side of each capacitor, the work current of each capacitor is obtained and is sent to a monitoring base station positioned in a transformer substation in a wireless way, an engineering calculation model built by a computer according to the serial and parallel connection capacitance and current change amplitude and direction of the capacitor group is utilized for calculating the capacitance of each capacitor, the calculation results are sent to a monitoring host machine of a remote monitoring center, data of the same capacitor is subjected to historical comparison, data of the same group of capacitor is respectively subjected to transverse and longitudinal comparison, and the fault warning is provided for the capacitors with the variation greater than a certain value after the capacitor parameter variation is integrally estimated.

Description

technical field [0001] The invention belongs to the technical field of on-line monitoring of electric power equipment, and in particular relates to an on-line monitoring method and device for a substation parallel compensation capacitor bank. Background technique [0002] Shunt capacitors are widely used in reactive power compensation of power systems, and are generally installed in substations for centralized compensation. The capacitor bank structure of a 500KV substation is as follows: figure 1 shown. With the increasing scale of the power grid and the increasing load demand, the system adjusts its voltage and reactive power more and more frequently. The safe operation of parallel capacitor banks plays a very important role in the stable and normal power supply of the entire power system. When a capacitor in the frame-type capacitor group is damaged and the entire group of capacitors trips, other capacitors may be damaged due to impact, and in severe cases, the capacitor...

AI Technical Summary

Problems solved by technology

First of all, for substations with a voltage level of 110KV and above, since the distance between different devices is relatively long, the reference voltage signal used for calculation is prone to distortion during long-distance transmission in the complex electromagnetic environment of the substation, thus affecting Measurement accuracy, causing misjudgment of faults

Secondly, long-distance cable laying will also increase the probability of cable ground faults, which will affect the safe and reliable operation of the system

Furthermore, there are many capacitive devices in the substation, so a large number of cables need to be laid, and the site construction is heavy.

In addition, if the main wiring of the primary equipment in the substation changes, the problem of laying or removing the transmission signal cable will occur; (2) For the reactive power compensation capacitor bank in the substation, the measured capacitor is always in a high-voltage live state. Allows the PT secondary side voltage signal to be connected to the capacitive current acquisition unit in a high-voltage state by wire, so this technical solution is not suitable for on-line monitoring of substation compensation capacitor banks

[0006] (2) For the monitoring of substation compensation capacitance, it is required that the measured voltage and current must be sampled at the same location, otherwise it will lead to unstable Fourier calculation results. If the compensation capacitor bank in the substation is installed with a discharge PT and discharge The PT has a secondary output, and the discharge PT can also be used to solve the problem that the measured voltage and the measured current of the compensation capacitor must be fixed at the same position and sampled synchronously. However, if the discharge PT has no secondary output or the secondary output has been used for protection or measurement, When only the working current of the substation compensation capacitor can be obtained, how to realize the monitoring of its capacitance becomes a technical problem that needs to be solved

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