Multi Objective Optimal Power Flow Considering Wind Power Penetration

Abstract

The study of the optimal power flow (OPF) is an important tool, in modern-day power systems, to enhance the existing system capacities and to plan for new extensions in an efficient manner. The OPF is a large-scale, highly constrained, nonlinear, non-convex optimization problem that includes a mixture of discrete and continuous control variables. The minimization of fuel cost is mostly considered as an objective function of the OPF problem. Moreover, the increasing environmental protection concerns make it important to take emission pollutant minimization as an objective function. Furthermore, the minimization of real power loss is included in the OPF problem because transmission losses are very significant aspect of the power system planning and design. Additionally, due to the mismatch of generation and transmission capacity, the overall system voltage instability leads to disputes of network participants. This factor makes it necessary to consider the voltage magnitude deviations as one of the objectives of the OPF problem. Due to the contradictory nature of objective functions i.e., fuel cost, emission pollutant, real power loss and voltage magnitude deviations, the OPF problem is considered as a multi-objective optimal power flow (MO-OPF) problem. The power generation companies are facing challenges like scarcity of conventional fossil fuels, increasing energy production cost and environmental concerns. The researchers are focusing on combined heat and power (CHP) generation and renewable energy sources (RESs) for clean and efficient energy generation. The CHP generation is relatively economical and environment friendly technology to produce heat and power. The RESs are non-polluting sources to supply electricity to consumers which helps to reduce dependency on conventional fuels. Wind power (WP) is one of the most popular form of RESs having great prospective for the solution of aforementioned problems. However, the integration of WP and CHP units makes the OPF problem more complex. The intent of the thesis is to formulate and solve the OPF problems for thermal generation system, wind-thermal generation system and CHP-thermal-wind generation system. An integrated optimization technique, established with the integration of the invasive weed optimization (IWO) and Powell’s pattern search (PPS) method is proposed for the solution of OPF problem. The IWO algorithm has been undertaken as a global search technique and the PPS method is employed as a local search technique. The effectiveness of the proposed IWO-PPS technique is tested by applying it to the standard IEEE test systems and results are compared with the reported results by the well-established optimization techniques and found promising. A non-interactive approach is applied to search the best non-dominated solution of MO-OPF problem. The results illustrate that the IWO-PPS technique performs better as compared to IWO technique in terms of the quality of solution and convergence characteristics. A hybrid approach integrating the IWO and space transformation search (STS) technique has also been implemented to the OPF problem to authenticate the performance of proposed IWO-PPS technique. Further, the chaotic Tent map is applied with both IWO-PPS and IWO-STS techniques to tune the algorithm parameters that accelerate the convergence speed and helps to avoid local optimal solutions. A t-test is performed to validate the statistical performance of the optimization technique.