The Discipline Analysis And Application Research Of The Electric Power Loss

The electric power loss is inevitable in the process of power transmission, and it is a key indication to measure the system performance, management level as well as the transmission efficiency. Losses per unit time are known as power loss, and losses accumulated during a certain period are called energy losses, and the change in system losses due to unit generation or load changing is known as incremental transmission losses (ITL). The discipline and mechanism how losses are produced in the transmission network is not only the basic problem in power system operation and dispatch, but also an economic issue in this deregulated market environment. In view of this, to study deeply in loss has an important theoretical meaning and significant practical value.This paper takes the electric power loss and its changing rules as a clue. Based on the review of many domestic and abroad research results, the paper explores the relationship and expression of power loss and power flow further and in depth. According to this, it provides the model and algorithm of rapid security constrained economic dispatch, as well as a rapid power losses assessment methodology based on timed-process oriented theory.Firstly, the paper looks into the load flow equations in rectangular coordinates, and discusses the relations between net loss and generalized injections. The system power loss is a nonlinear function of injections. But after linearizing in a reliable range, we can get a linear loss function of generalized injections. Based on the predecessors' research results, the paper further testifies and discusses the convexity of the system loss function on certain condition, and gives several examples to validate the conclusion effectively.Secondly, according to the convex system loss express of injections, the timed-process oriented theory is drawn into the estimation of energy loss, and a rapid assessment methodology of energy loss is proposed. Based on the average flow, the result is revised by the induced variables fluctuations, to deduce the power loss calculation format in any power injection space. The paper makes interpretations from accurate ones to rapid ones, in order to realize the rapid energy loss calculation.Finally, the paper analyzes the influencing mechanisms of losses in the optimal dispatching of electric system operation and the complexity of the algorithm, and then proposes a new method which combines the advantages of classical approach and modern optimized mathematical model. This method embeds convex characteristic of the incremental power loss model into the active optimal power flow model, and forms an incremental linear iterative model. This model simplifies the security constrained economic dispatch with network losses considered, and greatly improves the speed of calculation.Above all, power losses could be linearized in a reliable range in the power system under normal working conditions. Under condition of fitting for accuracy target and not influencing the law of variability, a short cut incremental linear model can be formed in order to simplify the complex calculation. Also, there are not only active decision variables but also reactive and voltage control variables included in the induced variables of this linear analytic expression. In this way, the contributions of all kinds of variables to system loss could be expressed clearly. And this is instructive for loss assessment, operation and dispatch, as well as decision making process of power system.