Inter-harmonics control method in wind power collection station

Abstract

The present invention discloses an inter-harmonics control method in a wind power collection station. The method comprises that an inter-harmonic signal extraction module carries out spectral analysis on a tie line current from the wind power collection station to a main network, calculates frequency fc of a harmonic component with the maximum amplitude, and extracts inter-harmonic signals in a tie line voltage and each wind power farm current; a wind power farm that is allowed to be cut in the collection station is determined according to the tie line inter-harmonic current, the inter-harmonic voltage, and the wind power farm inter-harmonic current; absolute values of difference values between the fc and a set of characteristic frequencies are calculated, and a minimum value dfmin among the absolute values is solved; and a sub-round and level-to-level cutting module cuts each wind power farm that is allowed to be cut in a series of rounds and level by level according to the tie line inter-harmonic current, the dfmin, and the wind power farm inter-harmonic current. According to the method disclosed by the present invention, the tie line between the wind power collection station and the main network, and each wind power farm can be monitored simultaneously, the relatively large inter-harmonic current existing in the power grid can be online monitored in real time, and whether there is an inter-harmonic generation source in the wind power collection station can be online determined in real time.

Description

technical field [0001] The invention relates to the field of electric power control, in particular to a method for controlling harmonics between wind power collection stations. Background technique [0002] With the rapid economic growth and the rapid development of high energy-consuming industries, the demand for renewable new energy is becoming more and more urgent. In recent years, with the increasing maturity of wind power and photovoltaic power generation technologies, the cost of power generation has also gradually decreased, and large-scale commercial operation of wind power and photovoltaic power has become possible. By 2020, the installed capacity ratio of non-fossil energy and fossil energy in China will be about 4:6. , the installed capacity of wind power and solar power generation reached about 300 million kilowatts, with an increase of about 180 million kilowatts; China's large-scale wind and solar energy development areas are generally at the end of the power g...

AI Technical Summary

Problems solved by technology

In recent years, with the increasing maturity of wind power and photovoltaic power generation technologies, the cost of power generation has also gradually decreased, and large-scale commercial operation of wind power and photovoltaic power has become possible. By 2020, the installed capacity ratio of non-fossil energy and fossil energy in China will be about 4:6. , the installed capacity of wind power and solar power generation reached about 300 million kilowatts, with an increase of about 180 million kilowatts; China's large-scale wind and solar energy development areas are generally at the end of the power grid, while most of the grid load is located in the economically developed eastern and central regions. Electric energy can be efficiently and long-distance transported to the load centers in the central and eastern regions. UHV large-capacity transmission technology or EHV / UHV AC transmission with series compensation capacitors are often used. This type of power grid is used in wind turbine inverters, SVC, SVG, Under the action of various factors such as DC transmission and series compensation capacitors, interharmonic currents and voltages whose frequency is not an integer multiple of the power frequency of the power grid may be generated in the power grid, which will lead to subsynchronous oscillation of nearby thermal power units. China has put it into operation at present The thermal power units near the large-scale wind power collection station have experienced multiple synchronous oscillations, seriously affecting the safe and stable operation of the power grid and the safety of thermal power units in the area.

At present, most of the analysis methods for interharmonics are offline analysis based on PMU recorded wave data after the accident, which does not achieve the purpose of online real-time control. When subsynchronous oscillation occurs in thermal power units, the generator can only be cut off by the torsional vibration protection action of the generator , did not cut off the source of interharmonics that caused the subsynchronous oscillation, resulting in the expansion of the accident; or the dispatcher manually ordered to cut off part of the wind farm to calm the oscillation, manual control can lead to overcutting and slow response

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