Island detection method for external centralized disturbance impedance measurement applicable to multi-machine cluster

Abstract

The present invention relates to the technical field of power system analysis, in particular to an external centralized disturbance type impedance measurement island detection method suitable for multi-machine clusters. Current signal iInj; monitor the voltage uPCC at the common coupling point of the system, perform intermittent zero-crossing injection control at the system common coupling point, and simultaneously measure and collect the data of the voltage uPCC at the common coupling point of the system and the disturbance current signal iInj during the injection process After data processing, the measured impedance characteristic quantity is calculated; the island state is judged according to the change of the characteristic quantity. The present invention is applicable to distributed power supply systems with multiple inverters, and is also applicable to synchronous generators and other power supplies without inverters, which improves the accuracy of impedance measurement and calculation, reduces the requirements for the DC voltage level of the injection device, and has a wide frequency range The high-frequency reactance calculation amplifies the difference of feature quantities before and after the island, and has higher detection sensitivity and precision.

Description

technical field [0001] The invention relates to the technical field of power system analysis, in particular to an external centralized disturbance impedance measurement island detection method suitable for multi-machine clusters. Background technique [0002] The demand for efficient energy utilization and the development of power electronics technology have prompted a large number of new energy distributed power sources such as photovoltaics and wind power to be connected to the grid to supply power to nearby loads. After the Distributed Generator (DG) is connected to the network, the unplanned island operation of the DG and the nearby load due to the failure of the main network and the malfunction of the switch will endanger the life safety of the maintenance personnel and users of the grid line; affect the equipment in the island system Normal operation and reclosing action. Therefore, the distributed grid-connected power generation system must have the ability to detect...

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Problems solved by technology

However, as the system develops towards multi-inverter and multi-power source type grid connection, the disturbance signal of the active method can be amplified to destroy the system stability and power quality, and can also cancel each other, resulting in the failure of island detection. The effectiveness of its islanding detection faces new challenges, so it is necessary to study the islanding detection technology suitable for multi-type power supplies and multiple grid-connected inverter cluster systems

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