MICRO PMUS FOR MONITORING AND PROTECTION OF AC MICROGRID

Abstract

In general, Phasor Measurement Units (PMUs) used in transmission system are able to synchronize to GPS time because of which measurements made by PMUs were able make accurate measurements. In distribution system angle difference is very small, due to which they are rarely used in distribution system. The recently developed µPMUs are capable of mill-degree accuracy and micro-second resolution, which is very much higher resolution than the traditional transmission-type PMUs. Therefore, µPMUs could be an extremely useful tool for distribution systems and microgrids. Microgrids are evolving as a next generation of distribution systems integrated with Distributed Energy Resources (DERs), and Energy Storage System (ESS).However, the addition of renewable and a variety of control operations in AC Microgrid introduce new challenges in protection. Lake of proper standards and guidelines for the AC grid make it more complex for control and protection. To protect power electronic converters, fault clearing time also affected, so high-speed Circuit breaker is required. For the protection of the system from fault and isolation of faulty part, different protection scheme has been developed. All methods have certain advantages and disadvantages, so we have to optimize the scheme, which works in all the conditions of AC microgrid (example high resistance fault and grid-connected mode). Availability of distribution generations (DGs) in AC Microgrid activates the bidirectional flow of current, which is not able to detect faulty section by conventional AC system overcurrent relay.