Study On Economic Dispatch And Its Multiobjective Optimization In Power Systems

With the rapid economic development in China, energy demand is steadily increasing. Meanwhile, due to huge energy consumption and pollutant discharge, the electric power industry in China is strictly regulated by the Chinese government with respect to energy conservation and emission reduction. As a result, the fact that how to allocate the energy appropriately and take the environmental issue into account becomes a serious problem in power system operation. In order to fully consider different situational applications of power generation scheduling problem, this paper firstly proposes three deterministic models, and then puts forward the corresponding methods to solve these models. Finally, the effectiveness of the proposed methods is verified on some benchmark test systems and compared with the existing methods.Above all, this paper proposes a non-convex static economic dispatch model, in which valve-point effect, prohibited operating zones, transmission loss, ramp rate constraints, and spinning reserve requirement are considered. The integrity of the static model is improved with the above constraints considered, but its complexity increases significantly. In order to solve the non-convex economic dispatch model, this paper presents three methods, including the fast parabola-based lambda iteration method(PBLI), the hybrid linear iteration and compact formulation method(LICF), and two-phase mixed integer programming method(TPMIP). For verification of the efficiency of the proposed methods, they are implemented on four benchmark test systems.Then, two dynamic economic dispatch models are presented in this paper, including the non-convex dynamic economic dispatch model considering valve-point effect and the dynamic economic dispatch model considering the DC transmission losses. Compared with the static economic dispatch model, the ramp rate constraints between the adjacent time intervals are incorporated into the first dynamic model, and hence the scale of this non-convex problem becomes very large. Based on linear approximation and mixed integer encoding technique, this paper proposes two methods, including the two-stage mixed integer linear programming method(TSMILP) and the dynamic economic dispatch method based on linear approximation and mixed integer programming(LAMIP), to tackle this large-scale optimization problem. In order to deal with the second dynamic model, this paper makes use of the relaxation technique for DC transmission losses constraints and penalty factor, and then proposes a penalty-based mixed integer quadratically constrained quadratic programming method(PMIQCQP). To examine the effectiveness of PMIQCQP, it is compared with the DC optimal power flow, AC optimal power flow, and static piecewise linear model method.Finally, this paper presents a weighting-based multi-objective optimization method with two phase mechanism(WTPMOED) to solve the economic and emission dispatch model. The proposed WTPMOED method mainly uses the weighting method to convert the multi-objective optimization problem into a single objective optimization problem. The comparative simulation results on a 40-unit test system verify the applicability of WTPMOED in solving the economic and emission dispatch model.