Research And Implementation Of Power Flow Calculation In The Reactive Power Optimization Based On Regional Power Networks

Reactive Power Optimization (RPO) of power system can effectively reduce the energy losses caused by power transmission and distribution,which can not only improve voltage quality and power system stability obviously, but also economize energy. Therefore, the study of RPO of local power network is of great significance. Power flow calculation is the most fundamental tool for the planning and analysis of power system, and for RPO as well. The thesis proposes power flow calculation which is suited to RPO of local power network.Regional power network is consisted of high-voltage transmission network and middle and low-voltage distribution network, the structure of which constitutes of the transmission network in form of rings and the distribution network in form of trees. The complex network structure cannot be calculated accurately with this single flow algorithm. With regard to the master and slaves network structure, the thesis proposes the comprehensive method of alternative and iterative algorithm to calculate power flow of the whole network. That is, Newton-Raphson algorithm is used to calculate the transmission network power flow, and forward/back sweep method is used to calculate the subordinate power flow in the distribution network. The two algorithms exchange data through the boundary conditions between the principal and subordinate networks. The large-scale problem of GPFC is divided into a transmission power flow and a series of small-scale distribution network power flows with the application of the alternative and iterative algorithm in calculation. Hence the calculation scale can be reduced, and the accuracy and convergence precision can be guaranteed, and the accurate calculation of the fixed flow of global network can be achieved.In order to simulate the unsure operation status of the true network exactly and to meet the requirement of load regulation and power dynamically, the thesis adopts the auto adaptive method of load increment adjustment to obtain the varying range in accordance with the power flow, the method demonstrate that imbalance power was adjusted by all generator of power net, and was not only balanced by balance node, which add the mismatch value of voltage and power owing to imbalance power on fixed calculation result, therefore the method increases the efficiency and convenience of the calculation software.As mentioned above, the methods of both alternative and iterative algorithm and the auto adaptive load increment adjustment solve the overall problem of the multi-storey power network flow, and the calculation results accurately simulate the operation situation of the realistic power system and meet the requirement of RPO as well. Therefore, the two methods are the ideal tools to analyse the operation mode of power networks.