Research On Coordinated Planning Of Power System With Wind Farms And Vehicles

Under the pressure of the energy crisis and environment protection, the system planning will face new challenges. On generation-side, in order to reduce the carbon emissions, China has promulgated a series of policies to encourage the development of wind power; On load-side, due to the depletion of oil resources and the improvement of electric vehicle technology, electric vehicle which is considered as the pioneer of low-carbon transport, is gaining more and more attention and expected to receive wider popularity. Both integrated wind and electric vehicle will have uncertain impact on power system operation. The intermittent and fluctuations of wind need to be described by appropriate method. Since it is difficult to accommodate the intermittent power at this moment, it is of great significance to select optimal transmission system planning schemes. EV charging load has randomness for time, space, and acts. In consideration of the random effects, the planning of distribution system needs to be coordinated with that of charging station. A number of elements should be taken into account when preliminary selecting the site of charging station. Thus, in the planning of power system containing wind power and electric vehicles, appropriate methods and processes will not only reduce the impact of uncertainty, improve the safety and reliability for the system, but also reduce the cost of investment, so as to achieve the overall economics.Given this background, the research results are obtained as follows:1) Although wind power gained great share, the lack of appropriate transmission channel has led to the poor accommodating, and parts of which is abandoned seriously. Compared with wind power construction, construction of transmission system requires more complex approval and a longer construction period. Considering the uncertainty of wind power integrated, selecting the synthesis optimal one from several candidate schemes is effective means of coordinating the issue. Therefore it is necessary to discuss how to select the optimal transmission system expansion planning with wind power2) A systematic approach is developed to comprehensively select the best one from candidate transmission planning schemes with given sites and sizes of wind generation farms, and this is a multi-objective decision-making problem under uncertainty. To carry out a comprehensive evaluation of the candidate planning schemes, in selecting the evaluation indices not only the reliability, security and economics of each scheme need to be considered, but also the costs of accommodating wind generation by an increased reserve capacity as well as the environment conservation and low-carbon benefits have to be taken into account. Given this background, an interval entropy based method is presented to select the best candidate planning scheme. In this methodological framework, the preferences of various experts can be appropriately described, and both objective and subjective factors comprehensively addressed. In addition, the uncertainties associated with wind power generation are also represented by interval numbers. Finally, a46-bus power system is served for demonstrating the essential feature of the proposed method.3) Rational placement of charging station can ensure the power supply, can also increase the efficiency of operation and the convenience of user. At the initial site selecting, candidates should be evaluated by a variety of factors. This thesis sets out the principle and preliminary site-selection process for candidate sites; The charging demand is multi-perspective analyzed and calculation methods are summed up. Analytic steps are given by taking into account of urban planning, transportation planning, and charging demand. Finally, the impacts of electric vehicles integrated are stated on the load forecasting, the planning of substation and network which points out that the coordinated planning for distribution system and electric vehicle charging stations is important.4) In this thesis, a coordinated planning method for EV charging station power distribution system is studied and validated. An optimization model, which is capable of minimizing the overall annual cost of investment (costs of EV charging station investment and maintenance, costs of line investment and maintenance, costs of substation investment and maintenance)and energy losses, is developed with constraint conditions of the user convenience and adequacy requirements. A genetic algorithm with sectional coding based on elitist strategy is developed to solve this model. Finally, the model is validated through the IEEE123node system data, the result of which shows that the proposed method can be used for coordinated planning for EV charging stations and distribution system expansion planning.Finally, several conclusions are obtained based on the research outcomes, and directions for future research are indicated.