A hybrid inverter distributed power island detection method

Abstract

The present invention relates to a hybrid inversion distribution power supply island detection method. The method comprises the steps of: comparing a voltage measurement value VPCC with a voltage rated value VN, a frequency f and a rated value 50Hz thereof in a normal condition on the basis of real-time measurement of the voltage effective value VPCC and the frequency f thereof and an IBDG activepower output PDG at a PCC, determining sizes of a cross correlation coefficient and a setting valve between reactive disturbance and frequency offset, and adaptively regulating the rate of change of disturbance applied on an IBDG rated reactive reference value.

Description

technical field [0001] The invention belongs to the field of power system protection and control. Aiming at the problem of unplanned islands that may occur in inverter-type distributed power sources based on renewable energy, a hybrid island that makes full use of passive detection information to adaptively adjust the size of reactive power disturbances is proposed. Detection method. Background technique [0002] Unplanned island means that after the main grid is tripped and disconnected due to a fault accident or power outage maintenance, the distributed power supply fails to detect that the main grid is in a power outage state in time, and still supplies power to the local load, forming a self-sufficient power supply that cannot operate safely and stably isolated island. Unplanned island operation may bring a series of problems to the safe and stable operation of the power system, such as failure to completely eliminate faults, failure of reclosing, prolongation or even f...

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Problems solved by technology

[0003] Common unplanned islanding detection methods include three categories: communication method, passive method and active method: 1) The communication method uses communication technology to send the opening and closing status of the grid circuit breaker to the distributed power supply to realize the operation mode judgment. There is a detection blind spot, and it does not affect the power quality, but the implementation of this method is more complicated and the economy is poor, and when the communication network fails, the method will also fail; 2) The passive method detects voltage, phase, frequency Whether the basic electrical quantities such as its rate of change and harmonics are within the allowable range is used to determine islanding. This method will not affect the power quality of the system, but there is a large detection blind spot, and it is usually used in conjunction with the active method; 3) Active method Usually, a disturbance signal is injected into the control system of a distributed power supply, and through a positive feedback link, the relevant electrical quantity exceeds the threshold value after the island occurs, so as to determine the island. This method can reduce or even eliminate the detection blind zone, but it also has a negative impact on the power quality. However, most of the existing methods are only effective for a single distributed power source. When it is applied to multiple distributed power sources, the synchronization of the disturbance signals may not be guaranteed, which may cause the disturbances to cancel each other out and be diluted, which greatly reduces the islanding detection. reliability

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