Inter-harmonic impedance-based island detection system and detection method

Abstract

The invention provides an inter-harmonic impedance-based island detection system and a detection method thereof. The system comprises a reference signal generation module used for generating a corresponding inter-harmonic reference signal according to a voltage signal at a common coupling point; a driving module used for carrying out pulse width modulation on the inter-harmonic reference signal and driving an inverter to work by adopting a current signal at the common coupling point; a signal detection module used for detecting the inter-harmonic content of the voltage signal and the current signal in real time, and obtaining the voltage amplitude value and the current amplitude value of a preset inter-harmonic frequency; an impedance monitoring module used for obtaining the inter-harmonicimpedance of the preset inter-harmonic frequency according to the voltage amplitude value and the current amplitude value; and an island judging module used for judging whether the difference value between the inter-harmonic impedance measured in real time and the inter-harmonic impedance in the grid-connected condition is not smaller than a preset value or not. If the difference value between the inter-harmonic impedance measured in real time and the inter-harmonic impedance in the grid-connected condition is not smaller than the preset value, the island effect is judged to occur. Based on the system and the method, the adverse effect of an active method on the power quality of the power grid can be effectively avoided. A small blind area can be guaranteed, and the high measurement accuracy is achieved.

Description

technical field [0001] The invention relates to the technical field of grid stability analysis, in particular to an islanding detection system and detection method based on interharmonic impedance. Background technique [0002] In recent years, the problems of energy shortage and environmental pollution have become increasingly prominent worldwide, and the development of renewable energy has attracted widespread attention. Distributed power generation technology has attracted global attention because of its economical efficiency, cleanliness and environmental protection. However, grid-connected distributed generation (DG for short) also brings challenges to the power system. When the grid power supply is interrupted unexpectedly, the distributed power generation and the local load form an unplanned island. If islanding is not eliminated in a timely manner, serious damage can be caused to electrical equipment and grid personnel. Therefore, it is of great significance to det...

AI Technical Summary

Problems solved by technology

The passive method is relatively simple and does not need to add external hardware, but the detection threshold is difficult to determine, the real-time performance of the detection is poor, and there is a very obvious detection blind area; the active method has a smaller blind area and higher accuracy than the passive method, but the active detection method injects disturbance. Decrease the quality of the grid and have a dilution effect when applied to the detection of multiple inverters

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