Calculation method of oscillation loop parameters based on improved capacitance model

UHV DC switch is an indispensable primary equipment in UHV DC transmission project. Its operating condition directly affects the safe and reliable operation of HVDC transmission system. Compared with conventional AC circuit breaker, DC circuit breaker increases oscillation and energy absorption. The auxiliary loop, etc., leads to a significant increase in the amount of detection and complexity. The oscillating circuit in the DC switch provides oscillating current for breaking, which is of great significance for its research. In order to accurately obtain the operating state and various parameter indexes of the DC switch in real time, a calculation method of the DC switch oscillation circuit parameters is proposed. The method collects the oscillating current data through the high-frequency sampling signal, strives to collect the peak point data, extracts the positive and negative peak points of the current through the program, and uses the adjacent two positive (negative) peak point data to obtain the oscillation loop parameter RLC value. Taking the MRTB data of ±1100kV Changji Station as an example, compared with the traditional peak point calculation method, the method can reduce the inductance error to 2% and the resistance error to within 5%. The experimental results fully prove the accuracy of the calculation method feasibility.