Multifunctional power distribution net flexible grounding device and control method

Abstract

The invention discloses a multifunctional power distribution net flexible grounding device and a control method. The device is arranged on the side of an electricity generator and a power distributionnetwork transformer secondary side or a power distribution network busbar side; the device comprises a three-phase converter and a controllable switch, and the neutral point of the three-phase converter can be grounded through the controllable switch; the device works in the reactive compensation mode under the normal condition, when a single-phase grounding fault of the power distribution net happens, the controllable switch is closed, the device injects zero-frequency / common mode current or zero frequency / common mode voltage into a power distribution network three-phase circuit so as to achieve the purposes of single-phase grounding fault arc extinction and fault positioning, and the reactive compensation, single-phase grounding fault arc extinction and fault positioning functions can be enabled at the same time. The reactive compensation, circuit grounding parameter measurement, arc extinction, fault line selection, positioning and other functions can be integrated into the same device, the reactive compensation function can be normally enabled while the single-phase grounding arc extinction, single-phase grounding line selection, positioning and other functions are achieved, and multiple purposes of the device are truly achieved.

Description

technical field [0001] The invention belongs to the electric power industry, and in particular relates to the fields of reactive power compensation of a distribution network of a three-phase neutral point ungrounded system, online measurement of line-to-ground parameters, single-phase ground fault arc suppression, and line selection and positioning of a single-phase ground point. A multifunctional distribution network flexible grounding device and a control method. Background technique [0002] Most of the domestic medium-voltage distribution network adopts the operation mode of ungrounded neutral point. Due to the development of the city, the urban distribution network continues to expand, the use of power cables continues to increase, and the capacitance of the distribution line to the ground is increasing. When a single-phase ground fault occurs in the network, it is easy to cause serious ground current. The capacitive current of distribution network lines to ground is a...

AI Technical Summary

Problems solved by technology

The signal injection method generally uses a signal injection device to inject a specific current signal into the system through the bus PT. Commonly used AC signal injection has problems such as being limited by the capacity of the PT and the current signal transmitted from the PT to the system is relatively weak and difficult to detect.

[0005] The above-mentioned methods of ground parameter measurement, arc suppression, and line selection and positioning not only have insurmountable shortcomings, but also require specific protection devices for each function, resulting in complicated protection devices for the distribution network system, inconvenient management, and protection and detection devices. Problems such as low utilization rate

On the other hand, flexible grounding devices based on power electronic devices are generally installed at the neutral point of the distribution network, and only work when a single-phase ground fault occurs in the distribution network line, without other additional functions, and the equipment utilization rate is low

Images