Studies On Planning Method In Rural Power Network Based On Virtual Technology

Distribution network correlates closely to the customers, which can provide a stable long-term supply of electric power to the users. It is important to plan distribution systems scientifically, reasonably and accurately, which can make lower investment and operational costs, and can help to economic development and operation of power system, and can yield remarkable social and economic benefits. Rural distribution system is the important part of the distribution network. The development of rural distribution touches on a wide range of problems such as the development of rural economy, the purpose of raising the level of agricultural production, and the improvement of the peasants’ living standards, and also affects the reliable, economic, reasonable, low-budget and high-quality operation of the rural network. So, it is very important to make an overall plan on the rural distribution system.On the basis of systematically analyzing the the present state of the rural distribution, a new idea of rural power system planning is proposed based on virtual system, and the total planning and the methods are also presented on the same base.The systematic approach is put forward to found virtual system of the rural power network planning. According to the present conditions and its trend of the development in rural system, the elements included power source, capacitor, line, node and load are formed, and the main interface and databases related to the virtual system are completed, and also the relational analysising and computing results of are showed. Virtual system can be established on the main interface, which gets easy to analyze the operation of the rural power system, and easy to achieve the edit and drawing of electric map, and easy to save data, and easy to show the relational results. Combined with the virtual system, the models contained line, capacitor, load and PV node in the power flow of distribution system, and the method of power flow is given based on network topology analysis.Based on the virtual system, the systematic method of reactive power optimization is proposed in the rural power grid. In view of rural reactive power optimization, the load uncertainties are accounted in this paper, and the mathematical models of fuzzy information are determined. The model of rural reactive power optimization is formed. In accordance with operational chariacteristics and the historic data of the rural system, three load levels are given. According to the optimum of power losses at the maximum load to determine the reactive compensation positions, and then reactive power compensation capacity is calculated for the least accounting expenditure cost. On the basis of power flow analysis, the method to determine main line is presented in the rural. The results of reactive power optimization can be showed in the virtual system. And the effects to node voltage, branch power flow and branch power loss are analyzed for different load, and also the sitting and capacity of reactive compensation device can be observed intuitively.Based on the virtual system, the systematic method of distributed generation (DG) is proposed in the rural power network. The type of DG adapted to our rural network is given, and the problem to placing DG is advanced in rural distribution systems. The node priority is employed to describe the DG’s effect of node voltage, power network loss and short-circuit current. According to the annual minimum electric power loss and maximum economic benefit after placing DG, the sitting and sizing of DG is determined under certain node priority. Under the same total capacity, effects of electric power loss and node voltage are calculated and compared by single, double and three sites of DG, which can be showed in the virtual system. In virtue of the optimal results showed in the virtual system, the effects illustrated that the node voltage is greatly improved, the power flow is reformed, and the power loss is significantly reduced, and also the sitting and capacity of DG can be observed intuitively.Optimal approach on renewing framework of upgrading rural power network is proposed in the rural power network. On the basis of the virtual system, and in the light of the principle to satisfied voltage quality, minimum investment, and lowest power loss, the weak part of rural distribution is confirmed, and the renewal schemes of network analyzed is determined. In order to analyze the weak part, the model of adaptabilities is proposed, and the method to confirm paths with bad adaptability is found subsequently. On the basis of satisfied active and reactive power balance, voltage quality, and current limit, and lowest power loss, the renewal model is presented according to the object function of minimum investment and lowest power loss. According to the minimum and maximum load increasing rate respectively, the method is put forward to analyze the adaptabilities of the rural network. The method proposed is applied to a real grid example, and methods are valide by results analysis and comparison.The necessary data can be inputed in the main interface of the virtual system, and the renewal results can be showed in the virtual system.Optimal planning method for distribution network is proposed in the rural power network. The method to partition load area is presented, and the ways to routing optimal problem and analyzing reliability are determined. Under taking account of constraint conditions such as physical conditions, buildings, node voltage, branch current, and so on, and on the basis of the shortest path and minimum load moment algorithm, thn distribution network is optimized and planed, and the approaches are given to determine main line, to connect load node, to select section of the lines and to ordering technology of nodes and branches before and after the lines connected. The methods are given to automatically search the cross point (intermediate nodes) and adjacent join points between two lines, and two adjacent lines can be connected hand in hand. Finally the function of automatic routing is achieved between adjacent lines. In order to ensure nomal operation, the configuration parameters must be modified many times according to the power flow before and after the lines connected. The methods proposed are applied to a real grid example, and methods are valide by results analysis and comparison. Moreover, on the basis of the main interface of the virtual system, the data can be inputed easily, and the autimatic routing and planning results can be showed in the virtual system. In view of the proposed approaches in this paper, corresponding algorithms and programs are made, and those methods are tested on various example grids.The results shows the feasibility of the proposed methods.