Overvoltage protection configuration system of unified power flow controller

Abstract

The invention discloses an overvoltage protection configuration system of a unified power flow controller. The system comprises a direct-current overvoltage protection device, a valve overvoltage protection device and a sub-module overvoltage protection device. The relation of protection action constant values can be expressed by a relational expression that (N*Vov2)>(N*Vov1)>Uov1>...>Uovm>Unom. The cooperative relation of protection action delay can be expressed by a relational expression that Tvo2<Tvo1<Tuo1...<Tuom. Lightning arresters and by-pass switches which are in bridge joint are configured at two ends of the circuit-side winding of a series transformer; grounding lightning arresters are respectively configured at the near bus-bar end and near circuit end of the circuit-side winding of the series transformer; grounding lightning arresters are configured at the alternating-current power grid side and converter side of a parallel transformer; and grounding lightning arresters areconfigured at the alternating current-direct current side and valve bottom of a converter. With the overvoltage protection configuration system of the invention adopted, the converter can act reliably when the system is disturbed or the sub-modules of the converter fail, and therefore, the reliability of the unified power flow controller can be improved.

Description

technical field [0001] The invention relates to an overvoltage protection configuration system of a unified power flow controller, which belongs to the technical field of power electronics in power systems. Background technique [0002] The structure of the unified power flow controller is mainly composed of two or more voltage source converters, and also includes DC capacitors, series transformers, parallel transformers and control systems, which can realize parallel compensation, series compensation, phase shift and Terminal voltage regulation and other basic functions. At present, the main direction of research and application of voltage source converter is modular multilevel converter (MMC). Reduced power consumption, low loss, small harmonics, etc., easy to expand to higher voltage levels. Modular multilevel converters occupy a major part of the investment in UPFCs, and the main components, IGBTs and capacitors, are extremely sensitive to overvoltage compared to trans...

AI Technical Summary

Problems solved by technology

However, when the AC or DC system is operating abnormally, if a large disturbance occurs and the control system cannot effectively control the system voltage, it may cause the voltage to exceed the normal allowable range. This type of overvoltage often has large energy and lasts The time is long, but it is far lower than the operating voltage of the arrester. In this case, it is not suitable to use the arrester to limit the voltage, and the protection system needs to be used to protect the converter.

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