Pilot protection method of VSC-HVDC (Voltage Source Converter-High Voltage Direct Current) power transmission circuit based on shunt capacitance parameter identification

Abstract

The invention provides a pilot protection method of a VSC-HVDC (Voltage Source Converter-High Voltage Direct Current) power transmission circuit based on shunt capacitance parameter identification. According to the pilot protection method, internal and external faults are distinguished by identifying shunt capacitance values at two sides of the VSC-HVDC power transmission circuit by adopting a time domain algorithm. When the direct-current power transmission circuit generates an external fault, the capacitance values at two sides of the circuit can be accurately identified simultaneously; and when the direct-current power transmission circuit generates an external fault, the capacitance values at two ends of the circuit cannot be identified simultaneously. According to the characteristics, pilot protection criteria are constructed. The pilot protection method is simple in principle, easy to implement, not affected by transition resistance, circuit distributed capacitance and control modes and can be used for rapidly and reliably distinguishing the internal and external faults under various working conditions. The pilot protection method can be not only used for supplementing main protection of the traditional VSC-HVDC power transmission circuit, but also used for accelerating backup protection action. The pilot protection method provided by the invention is not only suitable for a two-end VSC-HVDC system, but also suitable for a multi-end VSC-HVDC system.

Description

technical field [0001] The invention relates to a power system protection method, in particular to a VSC-HVDC transmission line longitudinal protection method based on parallel capacitance parameter identification. Background technique [0002] Voltage Source Converter HVDC (Voltage Source Converter HVDC, VSC-HVDC) transmission system adopts fully-controlled switching devices and high-frequency PWM modulation technology, which is a flexible and efficient DC transmission and distribution technology. It has the characteristics of passive inverter, independent control of active and reactive power, no need to change voltage polarity for power flow reversal, no need for a large number of filtering and reactive power compensation devices, etc. Grid interconnection, multi-terminal direct current transmission and other fields have broad application prospects. [0003] DC transmission lines are generally long and have a high failure rate. A sound and reliable relay protection is of ...

AI Technical Summary

Problems solved by technology

[0005] Most of the main protection in the existing VSC-HVDC lines adopts traveling wave protection, which has the problem of high sampling frequency and insensitivity under high transition resistance faults; as the current differential protection for detecting high transition resistance ground faults, it is vulnerable Due to the influence of line distributed capacitance, there is a disadvantage of slow action speed

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