A Real-time Hierarchical and Distributed Control Scheme for Reactive Power Optimization in Multi-area Power Systems

This paper presents a hierarchical and distributed reactive power optimization and control scheme which is characterized by distributed and parallel optimization algorithm. There are 2 levels in the scheme; each contains a set of agents. Level 1 is composed by the local control agents (CA). Level 2 consists of the distributed and parallel optimization agents (OA). The purpose is to propose a real-time system. When constraint violations of reactive power or voltage occur, CA acts first so as to reduce the violations to the minimum. After OA receives data transmitted by CA, optimal reactive power flow computation is conducted at regular intervals. Considering that OA always responses slower to the local variable changes than CA, CA can eliminate or alleviate some bus violations quickly, and OA therefore requires less computation time than usual. To get a further speedup, special control strategies are introduced, in which OA takes all the variables as continuous variables, while CA deals with the discrete variables. The simulation results show the validity of the proposed scheme