Optimization of the grid structure of the hottest

Optimization of rural frame structure

Abstract: compared with urban power, rural topology should be simple and clear, but due to other reasons such as the requirements of load on power reliability, there are generally small power plants, which are usually small capacity units, that is, the system receives regional large power through several 220 kV and 110kV substations, It often includes several power supply points of 110 kV and below and generates power "Now build a house with an area of 100 square meters, so that electricity is not a simple radial unidirectional model. It is necessary to establish a mathematical model to establish the construction of power points and the way of system wiring.

key words: optimization of agricultural frame structure 1 Characteristics of agricultural high-voltage distribution structure compared with urban electricity, the topological structure of agriculture is simple and clear, but due to the requirements of load on power reliability and other reasons, there are generally small power plants And they are usually small capacity units, that is, in addition to receiving regional large power through a number of 220 kV and 110kV substations, the system often includes a number of 110 kV and below power points that generate electricity simultaneously, so that electricity is not a simple radial unidirectional model. It is necessary to establish a mathematical model to establish the construction of power points and the system wiring mode. 2. Selection of optimization method of agricultural frame structure 2.1 general method of frame structure optimization load forecasting is the basis of power system planning. On the basis of load forecasting, load distribution analysis should be carried out in combination with regional planning, and then the load balance results should be determined, that is, the distribution and capacity planning of substations should be determined, and the network optimization planning should be carried out on the basis of load forecasting vibration and wear-resistant experimental machine and the determination of substation layout. Generally speaking, the goal of network planning is to meet the optimal frame design of system active load, which can be divided into static planning and dynamic planning. Static planning considers the frame planning for a certain load level, which is generally carried out annually from the base year, and the existing frame needs to be considered. At the same time, the frame structure planning of the next year generally selects excellent alloy structural steel, and the erection of the previous year needs to be defined as the existing frame. Therefore, the frame planning of each planning target year should not only look ahead, but also look back, so as to achieve the coordination and mutual echo from the time series, so as to save construction investment. However, the evaluation index of the planning and design scheme generally considers the optimal overall performance index of the whole planning period to evaluate the scheme, and often adds investment analysis, and even includes the time value of funds, so it is called dynamic programming. There are two kinds of optimization methods commonly used in frame planning, namely heuristic method and mathematical optimization method. The mathematical optimal method is to describe the power planning problem with a mathematical model, and then use a certain algorithm to solve it, so as to obtain the optimal planning scheme that meets the requirements of the system. This kind of method can guarantee the optimality of the scheme theoretically, but it generally requires a lot of calculation to get the optimal solution. The heuristic method is to iteratively select the line step by step according to certain rules by defining comprehensive indicators such as the operation performance and investment demand of the scheme until a satisfactory optimal solution is obtained. This kind of method is difficult to guarantee the optimality of the method, but the amount of calculation is smaller than that of mathematical optimization method. It is more convenient to calculate and combine with the inspection of planning and design personnel, so it is a more economical and practical method. 2.1.1 heuristic frame optimization method according to the different measured security indicators, heuristic methods are divided into heuristic methods based on branch performance and heuristic methods based on system performance indicators. In the heuristic analysis method based on the branch performance index, the selection of the line is based on the line power transmission when the system is running. The commonly used indicators are whether the line can meet the load requirements or the degree of line overload; In the heuristic method based on system performance index, the line selection is realized according to the influence of the line on a specific operation performance index of the whole system when the system is running. The commonly used indicators include the gradual selection of the line by the size of the system load shortage index. Heuristic frame planning methods based on line indicators are divided into two kinds: Step-by-Step backward method and step-by-step expansion method. The step-by-step backward method is to form a virtual network according to the data of the target year, which includes all the lines to be selected except the existing lines. In this way, the network is a network with high redundancy but uneconomical. Then, the power flow model is used to analyze the network, compare the role and effectiveness of each line to be selected in the system, and gradually remove the lines with low effectiveness until there is no redundant line in the network. The step-by-step expansion method is to select an appropriate line to the current network according to the effectiveness of each line to be selected to eliminate the overload of the overloaded line until there is no overload in the network. In order to calculate the effectiveness of each line to be selected and quench with processing waste heat, it is necessary to calculate the power flow when the structure is changed. The heuristic method based on branch performance index has the advantages of simple and flexible calculation, but because it usually considers the role of each line to be selected independently, it can not directly reflect the performance index such as the size of the system, while the heuristic method based on system performance index can reflect the system performance index, so it can identify the weak links as a whole and fully consider the overall impact of each line to be selected on the system to select the best expansion line. 2.1.2 mathematical optimization method of frame structure the mathematical method of network optimization can be divided into two optimization methods: deterministic and uncertain. Traditionally, the deterministic network optimization method is often used, that is, the planning problem is expressed as a deterministic optimization problem to solve. However, with the increasingly complex planning environment and related requirements, and the uncertainties of load, equipment cost, line path and other factors, these uncertainties have a significant impact on power planning, so it is necessary to consider the uncertainties in the planning. According to the different characteristics of considering uncertain factors, uncertain network optimization can be divided into random optimization method and fuzzy optimization method. Stochastic optimization method is often used to deal with the uncertainty of whether an event occurs and when it occurs, while fuzzy optimization method is often used to deal with the uncertainty of unclear expression of relevant things. Under normal circumstances, on the premise of ensuring the power supply of the load, there may be a variety of selection of wiring methods and conductor sections. To compare and select multiple schemes, it is necessary to select the objective function. The objective functions commonly used in power planning and design include the total investment in frame construction, power loss, maintenance and operation cost as the objective function. Due to the particularity of electric energy, it is necessary to