Research On Transmission Loss Calculation And Reactive Power Optimization For AC/DC Hybrid Power System

With the urgent demand of cross regional super long distance transmission, China invested a lot of manpower and financial resources in the construction of UHVDC transmission project. China would form large AC/DC power grid structure, which had lower power loss, and the control mode was various. Reactive power optimization was one of the effective measures to realize the safe and economic operation of the power system. In this paper, we mainly study the AC/DC hybrid system loss increment rate calculation and reactive power optimization operation problem of two aspects, is to consider the DC system without power characteristics to achieve the goal of reducing the power loss of network in the communication system on the basis of the research.Due to the high current DC power system transmission capacity, converter station configuration of reactive power device was mainly used for improving the voltage quality, ensuring the stability of the system operation. The converter owned abundant capacity to adjust, coupled with DC system has the characteristics of flexible, fast, so the study of AC/DC hybrid linked network loss research had very important significance. In this paper, the previous on communication system network loss increment rate based on DC system transmission loss calculation is active and no reactive power voltage associated with the AC load, corresponding to nodes in the Jacobian matrix of factor correction, put forward a gauge and balance the node AC and DC mixed joint system network loss increment rate algorithm, based on the foundation of former study on AC system transmission loss calculation, The DC system's active and reactive power was treated as AC voltage load for modifying the augmented Jacobian matrix,proposed an AC/DC hybrid system incremental transmission losses algorithm that slack node can be taken into accounted. This algorithm could directly calculate incremental transmission losses of all the nodes including slack node, and the calculation results wouldn't be influenced no matter which node was chosen to be the slack node. The calculation validate the reasonableness of the proposed algorithm and higher superiority in computing precision and computing speed.In the view of the problem that the interior point algorithm can not be used to deal with the discrete variables, proposing an nonlinear primal-dual interior point algorithm based on variable transformation method. Using its superior ability to deal with discrete variable, preprocessing the variables, unifying the discrete and continuous variables into the same virtual continuous form and brought it in the original optimization problem to solve and then it has been a nonlinear continuous optimization problem.,and after that, we use the nonlinear primal-dual interior point algorithm to calculating, and put the virtual variable into the transform expression, the we can get the results. This method's principle is simple, and there is no rounding approximation. It don't change the original nature of the variables, in mathematic it is an exact algorithm and the optimization of the program is convincing.Finally, calculation results of different sized examples verify the validity and the effectiveness of the AC/DC hybrid system incremental transmission losses algorithm,the reactive power optimization model. These two methods both have decent performance under different DC control modes and good application prospects.