The Voltage Security Region Calculation Method of Receiving-End Power System Based on the Equivalence of Transient Process

Abstract

In order to ensure the voltage security of the receiving-end power grid under both steady state and N-1 faults, it is necessary to conduct an accurate dynamic reactive power reserve assessment to ensure its normal voltage operation range at steady state. In other words, it’s to determine the power grid voltage security region which is a transient stability constrained optimal power flow (TSCOPF) problem essentially. However, it needs to consider a large amount operational snapshots and corresponding transient constraints under each snapshot, which increases the computational burden heavily. To overcome this issue, this paper proposes a calculation method for the voltage security region of receiving-end power grid through the equivalence of the transient process. Firstly, based on the power grid partition and the matrix of graph theory, the different snapshots are selected to obtain typical snapshots, and then for the typical snapshots sought, the transient stability constraints under the fault are transformed into steady-state constraints. In other words, the form is consistent with the steady-state equation but the impedance matrix parameters are equivalently adjusted. In essence, it is equally to replace the constraints of the optimization problem under the premise of ensuring that the consistency of the boundary conditions, so as to greatly accelerate the solution speed under the premise of ensuring the accuracy of the solution, and the calculation cases made in the modified IEEE9 system and the modified IEEE39 system prove the effectiveness and reliability of the proposed method in this paper.