Network Loss Calculation And Analysis Of Power Grid Contains Renewable Energy

The network loss is the inevitable cost of the transmission power of the power grid that relates to the planning,operation level and operating efficiency of the power grid.Calculating and analyzing the network loss can effectively point out the direction for the next construction of the power grid and provide effective guidance advice to the economic operation of the power grid.With the deepening reforms of the electricity market and the rapid development of renewable energy power generation,Because the rationality of network loss allocation largely affects the interests of transmission and distribution users and the development of renewable energy integration has changed the system’s structure and the power and also caused new problems in the calculation and analysis of power network losses.Therefore,in this paper an in-depth research has been conducted around the methods of network loss allocation,calculation methods and the impact of renewable energy on grid connection.The main contents are as follows:First of all,aiming at the problem of neglecting the network loss in the calculation process of the traditional DC power flow model,the DC optimal power flow improvement model that considers the network loss is proposed.Traditional DC optimal power flow model does not consider the resistance,so that its calculation of locational marginal price does not include the marginal network loss cost,and it is difficult to reflect the impact of network loss on the marginal price of the locational marginal price.This paper combines node fictitious nodal demand and power transmission distribution factor to the traditional DC optimal power flow.The traditional DC optimal power flow model is corrected in the aspect of network loss,and finally the locational marginal price calculation result can reflect the marginal network loss cost.And the network loss allocation is performed according to the locational marginal price calculation results of the improved DC power flow model.The simulation analysis shows that the proposed method can effectively correct the shortage of traditional DC optimal power flow model and play a fair and reasonable role in the network loss allocation.The model can also be used to analyze the changes in the locational marginal prices of power grid that contains renewable energy sources and the impact of renewable energy on the assessed net loss of each bus.Secondly,based on the analysis of several typical distribution network power flow calculation methods,the application of Newton method based on node injection current in power flow calculation of distribution network is discussed.Traditional Newton method is no longer suitable for distribution power flow calculation because of distribution network parameters.Newton method based on node injection current converts the power imbalance into the unbalanced amount of injected current,which greatly improves the calculation speed of the distribution network power flow.The simulation of the example proves that this algorithm can deal with the three-phase unbalanced operation of distribution network and the situation of multiple PV bus.Finally,focusing on the current status of ’more and more grid-connected renewable energy,theoretical analysis and numerical examples are used to analyze the impact of distributed generation access capacity and access location on distribution network loss.Based on the application of "The network loss theory calculation and loss reduction analysis and decision system" in the actual power grid,the influence of renewable energy sources into the transmission grid on the network loss and the original distribution power flow is discussed.In a word,this paper improves the traditional DC power flow model,makes progress in the use of locational marginal price to allocate network loss,distribution power flow calculation and network loss analysis direction,and has positive significance for transmission loss allocation and more efficient distribution network loss calculation.