Study On Security Protection For Electric Network Based On The Sensitivity And The Compensation Methods

Chain overload due to power transfer which causes branches successive breaking and overload after the initial disturbance cancellation by the view of the development process of the previous blackout accidents at home and abroad. When a line of the system disconnected after a fault, other lines should be promptly forecasted whether they are overload or not, overloading must be eliminated to avoid triggering a chain failure. The key issue to achieve online security protection is the rapid flow calculation and overload control.This paper proposes a new algorithm based on the sensitivity and the compensation methods of the traditional safety analysis theory. The basic idea is similar with the traditional sensitivity method. But it deduces the dynamic sensitivity formula with the wide area information by the reason of the branch active power flow has a relationship with the voltage phase angle and the injected power of nodes. Through the study of traditional compensation method, a new equation simulating power into the node has been deduced.Line breaking easily leads to other branch overload. If the circuit overload, sensitivity about the branch and nodes should be calculated. Choose the bigger ones as the control nodes and write down the mathematical model on the removal of unit and load. Control scheme are obtained by solving the optimal power flow equations.Compared with the Newton-laphson algorithm and the DC power flow method, the results of the new algorithm about on-line security analysis based on the sensitivity and the compensation methods approaches Newton-laphson algorithm's and iterative calculation isn't required in the process that would greatly save computation time. Active power security correction measures can be quickly obtained by the application of the sensitivity method and the optimal power flow method. All above analysis shows that the security protection program is feasible.