Analysis Of Continuation Interface Power Flow And Regulation Method Of Voltage Tense State And Tendency

With the development of electric power system, new characters have been emerging and this has brought increasing problems and challenges in the field of reactive power and voltage stability. For example, the demanding of promotion the transmission capabilities of AC or ACDC transmission interface is likely to deteriorate the voltage states of buses in sending and receiving areas which have relation with transmission interfaces. The continuous fast increasing of load, lagging of deploying reactive power equipments and unsound models of reactive power compensation can also make voltage states tense. This thesis is focused on the problems caused by the increase of power transmitted through interface and the methods of how to mitigate the intensified voltage states are proposed.Continuous power flow method is frequently employed when analyze electric power system voltage stability problems. But until now, this method has been mainly used in dealing with reactive and voltage problems caused by load increasing of buses. In a real power system, the objects of analyzing and adjusting are not only buses but also power flow interfaces. In the process of power flow increasing of interfaces, attention should also be paid to the voltage states of relative buses. So, the continuous power flow algorithm is extended from analysis of bus's load to that of power flow of transmission interfaces in this thesis. The continuous power flow algorithm which synthetically considers reactive power compensation methods can calculate the character curves which show the relationship of voltage character of relative buses and power flow transferred through transmission interfaces. And the information about the limit and margin of power transferred through interfaces, the critical voltage and margin of voltage stability, the reactive power compensation schedules with the increasing of power flow through interfaces can also be gave, which supports the efforts of promoting level of controlling and running conditions of power flow interfaces.The transmission interfaces can also include DC transmission lines. In order to analyze the reactive power and voltage problem caused by increases of power flow through transmission interfaces, a simple and practical ACDC power flow calculation algorithm is proposed by this thesis. When dealing with the changing of control models, complex pretreatments will not be needed when forming the Jacobian matrix. Control models changing process in power flow calculation have been simplified as setting zero in matrix in the calculation process. The calculation result show this method will improve the convergence character and effectiveness of calculation. Based on the algorithm proposed, a continuous collapse point method is proposed. Observing that eigen vectors which correspond to collapse point will change continuously with the slowly changing parameter, continuous power flow algorithm is used to get collapse points with the help of critical condition equations, start from a known collapse point other collapse points will be calculated. This algorithm combines continuous power flow algorithm and collapse point method, it will improve convergence condition of collapse point method when several collapse points are needed. Simulation result shows compared with calculating several collapse points by repeatedly use continuous power flow calculations, the effectiveness of calculation by this method will be improved.Under the condition of tense voltage state, the generation schedule can be adjusted or redispached to improve power supplying capability of power system. Considering the differences of capability of mitigating tense voltage state and different fuel consuming character of different generators, a new redispatching algorithm which considers mitigating voltage tense state and reducing energy consuming character in the same time is proposed in this thesis. Redispatching direction and relative redispatching step value are calculated according to model participating elements which have been modified by average unit energy consuming indexes, with the help of continuous power flow and by monitoring the minimum value of loss of reactive power of system, redispatching schedule is achieved. The redispatching generation schedule can mitigate the voltage tense state and to some extent reduce energy consuming caused by redispatching procedure.Mitigating voltage tense state, especially in the condition in which voltage tense is caused by fast increasing of load, reactive power compensation model should be adjusted in the view of time sequence. In order to solve the reactive power predispatching problem, a optimal time sequence reactive power compendating decision making model is built, and corresponding resolve solution is given. The time sequence compensation decision of reactive power can give the answer of when to use dynamic reactive power resources or discrete compensationg equipments and what is the value of reactive power compensation in the process of load's fast increasing. This schedule can mitigate voltage tense state in the time of load's fast increasing.