Subsynchronous oscillation inter-harmonic wave extracting method of online adaptive frequency change

Abstract

The invention discloses a subsynchronous oscillation inter-harmonic wave extracting method of online adaptive frequency change. The method comprises steps of firstly, acquiring original sampling data of phase current and phase voltage of a circuit in real time in an online manner, or through the original sampling data of the phase current and the phase voltage, calculating instantaneous power of the circuit so as to obtain input data to be calculated and extracted; carrying out filtering on the input data through a narrow-band comb-shaped filter group; acquiring real-time output data of each narrow-band filter; comparing output real-time waveform peak values of the narrow-band filters so as to obtain an extreme point of a broadband amplitude value, wherein the central frequency of the filter corresponding to the extreme point is the main oscillation frequency of the oscillation; and carrying out data fitting on the output data of the filters through zero passage comparison, and determining the precise main oscillation frequency. According to the invention, the algorithm can be applied to an online monitoring device of the subsynchronous oscillation monitoring; and online rapid recognition of oscillation signals is achieved.

Description

technical field [0001] The invention belongs to the field of dynamic monitoring of power systems, in particular to a method for online extraction of sub-synchronous and super-synchronous inter-harmonic waves. Background technique [0002] In recent years, with the rapid development of UHV power grids, a large number of new energy sources such as wind power and photovoltaics have been connected to the grid, and the scale of long-distance cross-regional power transmission has continued to grow. The characteristics of grid power electronics have become prominent, and the characteristics of the grid have undergone profound changes. Various power electronic equipment or devices, such as static synchronous compensator (STATCOM) and flexible direct current transmission converter, have been widely used. However, once these new types of power equipment are connected to the grid for operation, it is easy to form a continuous sub-synchronous and / or super-synchronous harmonic injection ...

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Problems solved by technology

However, once these new types of power equipment are connected to the grid for operation, it is easy to form a continuous sub-synchronous and / or super-synchronous harmonic injection system under a specific control mode or operation mode, which will stimulate the shafting torsional vibration of the nearby units and cause the thermal power unit to trip. , DC blocking and other chain reactions, endangering the safe and stable operation of the power grid and affecting the quality of power supply

[0003] With the increasingly prominent problem of broadband stability in power electronic systems, real-time on-line broadband monitoring of the system is very necessary. The monitoring methods currently used on the power grid are mainly for power frequency signals or the entire harmonic of power frequency. , at these frequency points, conventional monitoring methods are very effective

The monitoring and analysis methods for non-integral harmonics and inter-harmonics are relatively incomplete. For the analysis of a signal, it is mainly to analyze the signal characteristics of the two domain spaces of the signal: time domain and frequency domain characteristics, offline Fu When the data window is long enough, Lie transform can effectively identify the signal in the frequency domain. Its frequency resolution is closely related to the selection of the data window. Therefore, in order to obtain more accurate frequency information, a data window of 10s or longer is often used. To analyze, the response time is too long

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