Open-phase protection method and device of 35kV American box-type substation for wind power station

Abstract

The invention relates to an open-phase protection method of a 35kV American box-type substation for a wind power station, belonging to the technical field of power system failure analysis. A current transformer and a zero sequence transformer in a breaker are used to collect required current signals and then the current signals are operated by a central processing unit to obtain current magnitude which is taken as a main criterion, and an auxiliary criterion current magnitude is collected and operated by a system directly; the non electrical quantity and a switching value are subjected to optoelectronic isolation and then collected by the central processing unit so as to judge the open-phase state of the 35kV American box-type substation for the wind power station; and a control output module outputs the judgment result automatically or manually in accordance with conditions. The method and device provided by the invention is suitable for eliminating the open-phase operation failures at a high-voltage side and a low-voltage side of the 35kV American box-type substation for the wind power station; and the device integrates the protection function, the control function, the measurement function, the state monitoring function and the like into a whole, has the open-phase protection function at the high-voltage side and the low-voltage side of the transformer, the overcurrent protection function at the low-voltage side, the overvoltage function, the undervoltage protection function and the overload alarm function, and can prevent a wind driven generator from being influenced by burnout of a fuse at a high-voltage side of a step-up transformer.

Description

Technical field: [0001] The invention relates to a phase loss protection method and device for a 35kV American-style box-type transformer used in a wind farm, and belongs to the technical field of power system failure analysis. Background technique: [0002] A box-type substation (referred to as a box-type substation) generally consists of a high-voltage room, a transformer room and a low-voltage room. According to the different product structure and the different components used, it can be divided into two typical styles: European-style box-type transformer and American-style box-type transformer. The high-voltage side of the American-style box-type transformer is protected by a fuse, while the load switch only performs the function of switching and cutting off the high-voltage load current, and its capacity is small. When a phase fuse blows on the high-voltage side, the voltage on the low-voltage side will drop, and the undervoltage protection or overcurrent protection of...

AI Technical Summary

Problems solved by technology

In this case, it will not cause overvoltage, and generally it will not cause large current (except for non-full-phase operation accompanied by oscillation), but due to longitudinal asymmetry, negative sequence components and zero sequence components will be generated in the system. (except for non-grounded systems), when the negative sequence current flows through the generator, it will endanger the rotor of the generator, causing overheating of the rotor and damage to the insulation, affecting the output of the generator

In wind farms, a circuit breaker is designed on the low-voltage (0.69kV) side of the step-up transformer, and a fuse is installed on the high-voltage side, but there is no phase loss protection function

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