Method for restraining sub-synchronous oscillation of power system based on SSSC (Static Synchronous Series Compensator)

Abstract

The invention discloses a method for restraining sub-synchronous oscillation of a power system based on SSSC (Static Synchronous Series Compensator), comprising the following step of: generating an additional control signal, carrying out superposition on the additional control signal and an amplitude control signal, and then carrying pulse width modulation with a phase control signal to obtain a trigger pulse of a voltage source inverter in a static synchronous series compensator so as to control the output voltage of the static synchronous series compensator. The step of generating the additional control signal comprises the following steps of: collecting and filtering rotation speed difference signals of a generator in a power system to obtain all torsional vibration frequency signals of a generator shaft system, amplifying carrying out phase compensation on all the torsional vibration frequency signals and carrying out superposition to obtain additional control signals. With the method, the SSSC can supply positive electric damping near each torsional vibration mode of a generator unit through the control of the output reference voltage amplitude modulation coefficient ma and phase theta of the static synchronous series compensator of a flexible AC transmission device, thereby achieving the purpose of restraining sub-synchronous oscillation.

Description

technical field [0001] The invention relates to the technical field of power system control, in particular to a method for suppressing subsynchronous oscillation of a power system. Background technique [0002] The use of series compensation capacitors in long-distance transmission lines is an effective method to improve the transmission capacity and transient stability of power systems. It is widely used in the transmission lines of large-capacity power plants in my country, such as Inner Mongolia Tuoketuo Power Plant, Shaanxi Jinjie power plant and Yimin Power Plant in Northeast China, etc. However, the use of series compensation capacitors may cause torsional vibration of the generator shafting, which seriously endangers the safety of the generator. [0003] In order to solve this problem, the electric power academic and engineering circles have done a lot of work to study countermeasures and solutions. Some thyristor-based flexible AC transmission control devices can al...

AI Technical Summary

Problems solved by technology

However, compared with fixed series capacitors, the cost of SSSC is expensive. For cost considerations, SSSC is not used for series compensation alone, and often only part of the fixed series compensation capacitors in the original system are replaced by SSSC.

Therefore, although SSSC can provide greater damping than fixed series compensation, it still cannot prevent the occurrence of subsynchronous resonance

Images