Power System Planning With Large-scale Wind Power Based On Value Evaluation

The development and utilization of renewable energy sources such as wind energy in China, this is very helpful not only to optimize energy structure and improve environment, but also to enhance our energy supply diversity and security. So that is a nesessary choice for sustainable development of electric power industry in China. According to the national strategy on wind power development"building large bases, integration into bulk power grid", the wind power base development in China is initiated at present. However, due to inhenrent characteristics of wind power output, that brings great challgenes to powet system planning and operation. Based on this, power planning when large-scale wind power is integrated into the power system is studied in the dissertation.Firstly, the integrated expansion planning approach for transmission network with large-scale wind power is proposed. The impacts of variability for wind power ouput on active power flows and reactive power flows for transmission network are considered in the approach, and the whole optimization of active planning and reactive planning could be realized. To cope with the computing complexity, the heuristic optimization algorithm is presented. At first, the original problem is divided into two sub-problems: investment decisions of power network equipments and the cost evaluation for remedial controls of an alternative. Then comprehensive coordination between the sub-problems is achived by planning objective. Based on this, the characteristics of planning objective and the problem itself are analyzed, and then the optimization strategy is designed. The proposed algorithm is easy to understand and the physical meaning is clear, moreover it could reduce computation burden significantly, and is able to get superior planning alternatives in the acceptable time for engineering practice.Secondly, the framework of evaluation for power system planning with large-scale wind farms is established from the perspective of the total social cost. Aiming at the framework, the improved value evaluation method is proposed. Considering the variability of wind power is considered, daily-ahead (or week-ahead) unit commitment model, steady state and dynamic secutiy constrains based economic dispatch model and remedial control model are included in the simulation process. The raised method implements detailed simulation for system operation process. Hence the hourly fuel, environmental and network loss cost in the year for the given planning alternative could be calculated. These costs are to be combined with generation capacity cost, power network cost and system reliability cost, so that the total social cost of the alternative can be determined. Finally the importance of detailed operation simulation and the effectiveness of the method are verified by means of case studied.Finally, for conventional transmission expansion planning (without wind power), the mathematical model for the short term integrated expansion planning of real and reactive power for transmission network was formulated, and the sum of cost of the lines, reactive power compensation, operation cost and risk cost were considered as an objective function, the probability of contingency and AC power flow constraint were included in the model. The best alternative obtained by solving the planning model could reach the balance between investment and risk. For purpose of achieving the static security risk assessment based on the AC model, the two-stage approach for load curtailments based on active power steady-state security region and voltage sensitivity iteratively was proposed. To deal with the computing complexity of solving the model presented, the two-step optimization algorithm was provided, which not only could reduce the difficulty of the problem, but also some satisfactory solutions could be identified to support planners in decision making.