A Fuzzy Control Method for Frequency of DC Sending Island Island System

Abstract

A method for performing fuzzy control on the frequency of a direct-current sending end island system is characterized by comprising the following steps: (1) extracting a real-time frequency value of a direct-current sending end island system and determining a frequency deviation grade parameter; (2) calculating a real-time frequency change rate value of the direct-current sending end island system; (3) using a fuzzy control method to determine an adjusted frequency deviation grade parameter; (4) determining a corrected real-time frequency deviation grade parameter; (5) determining the real-time modulation quantity of direct-current power; and (6) determining a real-time direct-current power value. According to the method, the concept of frequency deviation grade is introduced, frequency fluctuation can be pre-judged by the use of the fuzzy control method based on the change of the frequency change rate, and the method has excellent timeliness and control precision and is valuable in engineering.

Description

technical field [0001] The invention relates to a power system frequency stability control method, in particular to a fuzzy control method for the frequency of an isolated island system at a DC sending end, and belongs to the technical field of power system stability control. Background technique [0002] DC islanding operation is a special form of power system operation, which is formed in the early stage of grid planning or after the splitting of AC and DC parallel transmission systems. The grid structure of the isolated island system at the DC sending end is weak, the ability to maintain frequency stability is weak, and the system frequency changes drastically. If the control measures are not appropriate, large-scale power outages are likely to occur. Since the DC sending-end island system and the main grid are only connected by the DC transmission line, how to effectively regulate and control the DC sending-end island system using the fast controllability of DC transmiss...

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Problems solved by technology

[0004] There are three main problems in this method at this stage: First, it is not easy to determine the upper and lower limits of the frequency. Deterministic, can not guarantee the matching degree of frequency limit and frequency fluctuation; second, the judgment condition of this method is single, and the timeliness of grasping the frequency change of the system is poor, which reduces the efficiency of system frequency stability control and delays The implementation of stabilization control measures has no obvious effect on improving the stability and reliability of the system; third, the control measures of this method are relatively simple, and the frequency control effect cannot be guaranteed in the case of severe frequency fluctuations, and there is a lack of follow-up emergency frequency control measures

Based on the above reasons, this method cannot guarantee the maximum frequency control stability in engineering

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