A new market-based approach for daily Volt/Var control of distribution systems in the presence of distributed energy resources using Benders decomposition algorithm

摘要

Distributed energy resources (DERs), if properly coordinated with other Volt/Var control (VVC) devices, could be incorporated in daily VVC problem. In this paper, a new 2-stage model is presented for daily VVC of distribution systems including DERs, taking into account environmental and economic aspects. First, in the day-ahead market, an initial environmental-economic dispatch is performed to minimize both the electrical energy costs and the gas emissions pertaining to generation units. The initial scheduling results determined by the market operator are delivered to the second stage, namely the daily optimal dispatches of VVC devices, to examine them from operational viewpoints and to yield the daily optimal dispatches of the VVC devices. The objective function of the second stage consists of the total cost of the following components: active power losses, adjustment of the initially scheduled active powers, and depreciation of switchable devices. In this paper, attention is directed towards 2 important types of DERs to be connected to the network: synchronous machine-based distributed generations and wind turbines. Because the active and reactive powers of DERs are coupled via the capability diagram, in this paper, this issue is addressed by considering the capability diagram of DERs in the proposed model. In particular, the Q-capability diagram of wind turbines should be analyzed taking the hourly wind speed fluctuations into consideration, so that delivery of a uniform reactive power can be ensured over the entire hour of operation. Due to the complexity of solving mixed integer nonlinear programming problems, an algorithm based on Benders decomposition is suggested to solve the proposed VVC model in the second stage. Finally, 2 standard distribution test networks are utilized to validate the effectiveness of the proposed method.