Abstract
Nowadays, the changes of economic, environment, and regulations are forcing the electric utilities to operate systems at maximum capacity. Therefore, the operation and control of power system to improve the system stability has been receiving a great deal of attention. This paper presents an approach for enhancing the static voltage stability margin and reducing the power losses of the system with voltage security-constrained optimal power flow (VSC-OPF) that is based on static line voltage stability indices. The control approaches incorporate the voltage stability criteria into the conventional OPF. The minimization of the summation of fast voltage stability index (FVSI), line stability index (Lmn), and line voltage stability index (LVSI) is used as the objective functions. The performance and effectiveness of the proposed control approaches are evaluated on the standard IEEE 30-bus, 57-bus, and 118-bus test systems under normal and contingency conditions. The comparison analysis is carried out with different cases including minimization of generation cost. The proposed control approaches indicate the promising results and offer efficient countermeasures against the voltage instability of the system.
Highlights
Voltage instability is recognized as the major sources of power system insecurity, for which several partial or full power interruptions have been related to this problem
One example is the objective function to minimize the sum of the squares of L-index, which can provide the optimal setting of various control devices against voltage collapse [8]. e modified objective function based on the L-index enhances the voltage stability margin for normal and contingency conditions in some research studies [9,10,11,12,13]. e minimal eigenvalue of the nonsingular Jacobian matrix improves the voltage stability [14, 15]. e system loadability was formulated into a multiobjective optimization technique; the problem formulation is to minimize the generation cost and maximize the voltage security margin [16, 17]
Four different cases will be individually considered as part of the objective function in each system. e details of these cases are as follows: (i) Case 1: the minimization of the generation cost is the objective function as shown in equation (6). e coefficients of generation cost are defined as in [33]. is study uses the results of this case as the base case to compare the performance with proposed approaches
Summary
Voltage instability is recognized as the major sources of power system insecurity, for which several partial or full power interruptions have been related to this problem. E voltage security-constrained OPF (VSC-OPF) formulation that incorporates margin enhancement constraints (MEC) was proposed in [24] to control the reactive power for the given voltage stability criteria. E incorporation of line voltage collapse index (VCI) was proposed for line-wise optimal power flow as the set of voltage stability constraint and objective function [28]. E VSC-OPF approach based on the voltage collapse proximity indicator (VCPI) has been presented and included in OPF formulation in two ways, the proposed objective function and constraint [29]. Line voltage stability index (LVSI), operating cost, and emission effects were proposed as the objective function of stochastic optimal power flow problem with the presence of uncertain wind power generations [32].
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