Abstract
With the rapid load increase in some countries such as China, power grids are becoming more strongly interconnected, and the differences between peak and valley loads are also increasing. As a result, some bulk power systems are facing high voltage limit violations during light-load periods. This paper proposes to utilize transmission switching (TS) to eliminate voltage violations. The TS problem is formed as a mixed-integer nonlinear program (MINLP) with AC power flow constraints and binary variables. The proposed MINLP problem is non-deterministic polynomial hard. To efficiently solve the problem, a decomposition approach is developed. This approach decomposes the original problem into a mixed-integer linear programming master problem and an AC optimal power flow slave problem that is used to check the AC feasibility. Prevention of islanding is also taken into consideration to ensure the feasibility of the TS results. The modified IEEE 39-bus and IEEE 57-bus test systems are used to demonstrate the applicability and effectiveness of the proposed method.
Highlights
As the transmission network is expanded and reinforced with load increase and more power generation integrations, it is difficult to maintain the nodal voltage magnitude in allowable ranges under all operational conditions
In [16,17,18], the AC optimal TS (ACOTS) problems are formulated as semi-definite programming (SDP) and second-order cone programming (SOCP) models by AC power flow relaxation
The results demonstrate that the DC power flow model is not reliable for obtaining optimal line switching results, while the heuristic algorithms can be valuable for finding AC feasible solutions, and the relaxation method is instrumental in guaranteeing the optimization objective
Summary
As the transmission network is expanded and reinforced with load increase and more power generation integrations, it is difficult to maintain the nodal voltage magnitude in allowable ranges under all operational conditions. In [16,17,18], the ACOTS problems are formulated as semi-definite programming (SDP) and second-order cone programming (SOCP) models by AC power flow relaxation. The results demonstrate that the DC power flow model is not reliable for obtaining optimal line switching results, while the heuristic algorithms can be valuable for finding AC feasible solutions, and the relaxation method is instrumental in guaranteeing the optimization objective. We study the optimal TS problem with AC power flow to eliminate the voltage violation during the light-load periods. The main contributions of the paper are as follows: 1) The model solving the voltage violation problems by optimal TS is built in ACOTS formulation. 2) A decomposition method is employed to decompose the ACOTS model into solvable master and slave problems, which can be solved efficiently by iteration.
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