Researches on grounding modes of the AC/DC hybrid system with various distributed renewable energy

Abstract

With the considerable demand for distributed renewable energy and the significant increase of generalised DC loads, such as IT equipment, DC air-conditioner, electric vehicle, the traditional AC distribution network is no longer efficient. Driven by the rapid development of power electronics technology, the AC/ DC hybrid system is an effective way for large capacity AC/DC sources and loads efficient integrated. To ensure the stable operation of AC/DC hybrid system, the grounding mode analysis is necessary, which is the precondition for overvoltage analysis, lightning arrester configuration, and protection design. To select grounding mode of AC/DC hybrid system, the detailed system structure scheme is first determined considering the factors such as integrated object, reliability requirement, capacity of sources and loads, and converter type. Then the main connection scheme is selected considering the principle of line insulation, economy, and reliability. Based on the system structure and main connection scheme, a suitable grounding mode is selected for the AC/DC hybrid system with various distributed renewable energy, by weighing various factors such as power supply reliability, protection sensitivity, insulation level, and personal safety.