Reasons and Analysis of Electric Energy Loss in Transmission and Distribution System

In today's world, the reform of the power industry has transformed the traditional monopoly power industry into openness and competition. An open and fair transmission network is a necessary condition for fair competition in the electricity market. Transmission and distribution system in the normal operation at the same time, the transmission of electrical energy consumption accounted for the entire transmission capacity of 5% -10%, power consumption of the power consumption is to reach a certain scale. In a fair competitive electricity market environment, these power losses need to be distributed equitably to all users of the transmission and distribution network. And how fair and reasonable distribution, in recent years has aroused widespread concern of scholars at home and abroad, a hot spot in the electricity market research.
Analysis of the Cause of Power Loss in 1 Transmission and Distribution System
Power transmission and distribution system power loss is the transmission system and power distribution system running in the process of generating network power consumption in general. The types of power loss are mainly composed of two parts: technical loss and management loss. Management loss is not good estimate, there is a power transmission and distribution enterprises caused by human or management factors, need to improve the management system through less loss. This article discusses the main technical loss, power transmission and distribution system, power loss, including the loss of power transmission lines and transformer losses, according to whether the loss of change, but also can be divided into lines and transformers due to series impedance fluctuations and voltage-related Of the fixed loss.
1.1 Line power loss
The power loss of the power line is the product of the corresponding power loss and time. The power loss of the line is related to the square of the active power of the transmission circuit, the square of the reactive power, the line resistance and the transmission voltage. Among them, the greater the sum of active power and reactive power, the greater the line line resistance, the greater the power loss, the higher the transmission voltage, the smaller the power loss. The specific relationship can be expressed by the following formula:
Where: ΔPL refers to the line power loss; P1 and Q1, respectively, said active power and reactive power; U1 said the transmission voltage; R for the line line resistance.
1.2 transformer power loss
Transformer power loss due to double-winding transformer, three-winding transformer and other types of different, calculate the power loss formula is not the same. As the power transmission process, active power and reactive power are caused by power loss, so in the distribution transformer process, the power loss can also be divided into active loss and reactive power loss. The power loss of the transformer is inversely proportional to the power factor, proportional to the transformer's no-load loss, load loss, no-load current percentage, and impedance voltage percentage.
When the power loss ΔP of the known transmission and distribution lines is known, the power loss during a period of time is the definite integral of the power loss from time 0 to t,
The main distribution method of power loss in transmission and distribution system
The distribution of power loss in transmission and distribution system has been one of the hot spots of scholars at home and abroad. From the algorithm point of view, it is divided into two categories: trend tracking and partition coefficient. At present, the main distribution methods are proportional distribution method, distribution coefficient method, power decomposition method, game theory based on Shapley value method.
2.1 Direct Proportion Assignment
Proportional distribution method is one of the most commonly used methods of power loss distribution. It is divided into several nodes according to the proportion of power generation capacity of each node. Proportional allocation does not take into account the relative position of the load in the transmission network and the effect of reactive power on the coupling effect and the transaction, and the need to specify the corresponding power generation and load ratio.
2.2 Distribution coefficient method
The marginal net loss coefficient method is a typical method of the distribution coefficient method. It is based on the unit change of the input power, which is the size of the network loss change of all transmission and distribution networks. The method is based on monitoring and sensitivity analysis, taking into account the impact of active power and reactive power on network loss.
2.3 power decomposition method
Power flow decomposition of the power flow algorithm is different power in the same line through the power and the resulting power loss decomposition. This decomposition is based on the total loss expression of the grid or the loss expression of the branch, and the decomposition expression of the loss is further calculated by combining the impedance or admittance matrix equations deduced according to the circuit theorem. In mathematics, this distribution is not the only one.
2.4 Shapley method based on game theory
Based on the game theory Shapley value method is different from the previous distribution method, this method is not only based on circuit theory, but was given a new economic significance. It takes into account the impact of each transaction on the power loss of the transmission and distribution grid from the perspective of market competition. The distribution result does not take into account the order of addition of the transaction and the power factor of the grid. Therefore, it can be applied to any power factor and any order of transmission and distribution Network, have a good application prospects. However, the shortcomings of the method is the need to calculate the trend of each transaction mode, the calculation of the workload, with the development of computing technology, this problem is expected to be improved.
By summarizing the existing distribution methods, the following problems are prevalent in China's modern loss distribution. The use of proportional distribution method, the need to specify the distribution of power and load on the proportion of the complex power market model is difficult to apply. Based on the circuit theory, the distribution coefficient method and the power decomposition method are used to eliminate the corresponding economic significance under the condition of market competition, and the distribution method of game theory with economic significance has the shortcomings of large computation. How to further summarize the advantages of various distribution methods, the development of a reasonable scientific and feasible distribution program, transmission and distribution system is the power consumption of the distribution of research trends.
3 Suggestions on Reducing Power Loss of Transmission and Distribution
Through the analysis of the causes of the power loss of the transmission and distribution network, it can be concluded that the reduction of the power loss is to reduce the loss of the transmission line and the loss of the transformer. The specific work to reduce the power loss can be carried out from the following aspects.
3.1 to enhance the transmission and distribution grid boost and equipment transformation
It is known that when the power loss of the grid is analyzed, the generation of the power loss is inversely proportional to the voltage and is inversely proportional to the resistance. Therefore, to reduce the power loss, you can upgrade the distribution network, such as the 6 kV to 10 kV power supply voltage, 35 kV substation into 110 kV or 220 kV substation. Replace the original small cross-section wire, in the case of economic conditions allowed to replace the large cross-section of the wire, so that the line resistance becomes smaller, reducing network power loss. The use of energy-saving transformers, energy-saving type of distribution transformer active and reactive power requirements are less than the general transformer, so that part of the transformer power loss.
3.2 optimize the transmission and distribution network structure
Scientific and reasonable grid structure, is essential to reduce power consumption. A design ideal, structural optimization, rational distribution of the transmission and distribution network, can improve the efficiency of the entire power grid to reduce unnecessary power transmission, reduce power consumption. The main measures can be in the selection of equipment, select the appropriate side with the load side of the design, the transformer position as far as possible in the load center to shorten the power supply radius, for rural and urban areas to choose a different power point configuration, the wiring is as much as possible Radiation type of wiring to set up the network, to avoid the use of unilateral power supply wiring and so on.
4 concluding remarks
In the process of power industry reform, the problem of power loss of transmission and distribution system has been the focus of domestic and foreign scholars. Based on the analysis of the main causes of the power loss, this paper analyzes the existing methods of energy loss distribution and puts forward the main ways to reduce the power loss, which provides a certain energy saving and emission reduction work for the transmission and distribution enterprises. reference.