Power system online load shedding in a market environment considering renewable energy generations

Abstract

Significant loss of the generating plant without adequate system response can produce extreme frequency excursions outside the operating range of power plants. Furthermore, large frequency deviations can degrade load performance, overload transmission lines and even lead to a system collapse. As a result, suitable responses are required to maintain power system frequency. Among those, underfrequency load shedding (UFLS) is one of the most important emergency control actions designed to ensure system stability by curtailing system load to match generation supply. An UFLS strategy usually uses power system parameters which are post-indices. In contrast, electricity market operations is to facilitate trading of electricity while ensureing system security. UFLS in a market environment is more complex given that the determination of loads to be shed need to consider system requirement as well as market requirement. Furthermore, power system operation and protection have become more complicated after electric industry deregulation and distributed generations (DGs) interconnection. Therefore, it is difficult to build an accurate mathematical model of power system frequency stability based on the integration of UFLS and electricity market power indices. However, present UFLS schemes do not provide the ability of decentralized optimal curtailment of load shedding, and are lack of considering network constraints and power industry deregulation. This thesis details new methods based on integrating real time simulation with online intelligent technology to improve underfrequency load shedding protection. An online load shedding strategy for electricity market with large DG penetration is proposed through the research and reported in this thesis.