EVALUATE HVDC PROTECTION AND CONTROL SCHEMES USING HIGH SPEED PROCESS BUS TECHNOLOGY

Abstract

The correct operation and control of an HVDC system greatly depends on the quality of voltage and current measurements. The feasibility and benefits of high-speed measurements (process bus) are analysed from three perspectives: voltage and current sensor technologies, data communication structure, and various HVDC applications. It is found that the recommended sampling frequency of 96 kHz by IEC 61896-9 is adequate for most HVDC protection and valve controls. However, for fault location applications, a higher sampling frequency beyond 200 kHz is preferred. In this paper, a high-speed process bus technique is presented. An HVDC control system testbed is developed using the high-speed process bus technique, featuring 250 kHz Sampled Value (SV) communication, which is more than double the highest sampling rate from the standard. An in-service HVDC control and protection scheme associated with an offshore to onshore wind connection, rated at 900 MW, is investigated on the testbed with a Real Time Digital Simulator (RTDS). HVDC protection and control applications are studied. The results indicate that the high sampling rate allows some protections to act faster, ensuring that expensive primary equipment can be better protected leading to a reduction in size, providing further cost and installation benefits.