A Reactive Phase Angle Deviation Island Detection Method Based on Frequency Positive Feedback

Abstract

The invention discloses a reactive power phase angle deviation island detection method based on frequency positive feedback. The difference between the standard frequency of the microgrid and the actual frequency of the microgrid is used as the input to calculate the reactive power disturbance and the phase angle deviation of the feedback current, and the phase angle deviation of the feedback current is used as the input to calculate the output reactive power of the energy storage. The sum of the reactive power can be output as the input for calculating the reactive power of the load. The reactive power of the load will feed back and affect the frequency of the microgrid, causing the frequency of the microgrid in the island state to gradually deviate until it exceeds the limit. The detection method has the advantages of fast detection speed and small current harmonics.

Description

technical field [0001] The invention relates to the field of micro-grid operation control, in particular to a detection method for micro-grid island operation. Background technique [0002] Microgrid has two states of grid-connected operation and island operation. The occurrence of isolated islands will not only cause damage to power system equipment, but also threaten the life safety of power system maintenance personnel and other serious problems. Therefore, the photovoltaic grid-connected power generation system must have an island detection function to ensure the safe operation of the grid. [0003] The methods for detecting islanding operation can be divided into three categories, which are active detection, passive detection and switch state detection. Active detection methods include: active frequency offset method, synovial membrane frequency offset method, active frequency offset method with positive feedback, automatic phase offset method, etc. These methods brea...

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Problems solved by technology

Passive detection methods include: overvoltage / undervoltage detection method, overfrequency / underfrequency detection method, phase mutation detection method, voltage harmonic detection method, etc. The advantage of this type of method is that it is simple to implement, and the disadvantage is that when an island occurs, the public coupling When the point voltage is in the non-detection area, there is an unrecognizable problem

The switch state detection method uses communication means such as power line carrier communication (PLCC) and data acquisition and monitoring (SCADA) to detect isolated islands. This type of method has a small detection blind spot, but due to high cost and complicated design, it is not used in distributed power generation. widely used in the system

[0004] After searching the existing technical literature, it was found that a new method of island detection based on positive feedback of harmonic distortion rate (Ma Jing, Mi Chao, Wang Zengping. A new method of island detection based on positive feedback of harmonic distortion rate[J].Automation of power systems Acta Sinica, 2012,36(1):1-4) proposed an islanding detection method based on positive feedback of voltage harmonic distortion rate, which can quickly and effectively detect The occurrence of isolated islands, but the occurrence of false islands will affect the detection results

An Improved Active Frequency Shift Islanding Detection Technology (Cai Fenghuang, Wang Wu, Chen Sixiong, Hong Qiaowen. An Improved Active Frequency Shift Islanding Detection Technology[J]. Power System Protection and Control, 2013,41(24):1 -3) Based on the traditional AFD disturbance method, a new improved current disturbance strategy is proposed. This detection method greatly improves the detection efficiency, but it is easy to cause the current distortion rate to increase

A New Method of Low-Frequency Phase Disturbance for Islanding Detection (Chen Zenglu, Meng Xinxin, Wang Xiaojun, Wang Ning, Tian Miaomiao. A New Method of Low-frequency Phase Disturbance for Islanding Detection[J]. Acta of Electric Power System Automation, 2014,38(13):3-5) proposed A new low-frequency disturbance island detection method AFLD is proposed. The outstanding feature of this detection method is that there is no island detection blind zone, but the detection speed is slow

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