Shinq-Jen Wu, Hoach The Nguyen, and Wei-Che Chien
Cooperative demand response, load adjustment, congestion
When social benefits are reduced for transmission network limitation, congestion brings significant electricity pricing rise and social sources waste. In this study, we propose an optimal cooperative demand adjustment scenario for system congestion. The contribution is on three: solving congestion in power systems through only demand response adjustment, offering the demand side market power in a way of guiding to an optimal co-operative response, and providing an implementable procedure to deal with multi-objective optimal power flow (OPF) optimization (minimizes total generation cost and minimizes load adjustment under no total load shedding). The proposed scenario is able to reach the total demand and achieve the minimal adjustment at each load through three-step optimization. First, the expected free-congestion operating state is obtained through solving an OPF problem without congestion limit constraints (called OPF-1). Based on bided data and the predicted load patterns, this model generates dispatching results with minimal generation cost. Second, a full-constrained OPF model (OPF-2) is used to dispatch generators again to get a feasible solution. By comparing the results between OPF-1 and OPF-2, we get the social benefit loss. Third, we consider an optimization problem with least-squared load adjustment objective (OPF-3), wherein the free-congested dispatch results of OPF-1 are introduced as a constraint, the predicted total load is remained (power-balance onstraints) and the demand for each bus is adjustable. Based on the time-ahead data of single-sided auction markets, the results give an optimal adjustment scenario for the demand side in a real-time electricity market. The proposed method is able to identify the critical buses to be cut down most, and the buses whose load to be increased. The procedure and optimal scenario are tested with an IEEE 30-bus system.
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