Quadratic Interior Point Research Articles

Power System Security Enhancement by OPF with Phase Shifter

This paper presents an integrated optimal power flow (OPF) with phase shifter approach to enhance power system security. The general OPF calculations are hourly based and the control variables of OPF are continuous. However, the calculations of phase shifter are daily based, and the variables related to phase shifter are discrete. Therefore, the general OPF cannot be directly used to solve this problem. The paper develops the rule-based OPF with phase shifter scheme to bridge the problems. In order to effectively alleviate the line overloads, the ranking of phase shifter locations is conducted based on contingency analysis and sensitivity analysis. The best phase shifter sites are identified and selected into a rule-based system accordingly. The handshaking procedure between the adjustment of the selected phase shifters and OPF calculation is proposed using a rule-based method. The hourly-based OPF problem is solved by the extended quadratic interior point method. The IEEE 30-bus system is used to test the proposed scheme.

Power system security enhancement by OPF with phase shifter

This paper presents an integrated optimal power flow (OPF) with phase shifter approach to enhance power system security. The general OPF calculations are hourly based and the control variables of OPF are continuous. However, the calculations of phase shifter are daily based, and the variables related to phase shifter are discrete. Therefore, the general OPF cannot be directly used to solve this problem. The paper develops the rule-based OPF with phase shifter scheme to bridge the problems. In order to effectively alleviate the line overloads, the ranking of phase shifter locations is conducted based on contingency analysis and sensitivity analysis. The best phase shifter sites are identified and selected into a rule-based system accordingly. The handshaking procedure between the adjustment of the selected phase shifters and OPF calculation is proposed using a rule-based method. The hourly-based OPF problem is solved by the extended quadratic interior point method. The IEEE 30-bus system is used to test the proposed scheme.

Improved interior point method for OPF problems

Since conventional optimal power flow (OPF) algorithms are limited and too slow for operational planning, power system operation and planning engineers have been seeking efficient OPF algorithms for three decades. The interior point method is one of the most efficient algorithms. In this paper, an improved quadratic interior point (IQIP) method is used to solve comprehensive OPF problems with a variety of objective functions, including economic dispatch, VAr planning and loss minimization. The IQIP method features a general starting point (rather than selected good point as in the general interior point method) and fast convergence. Consequently, the OPF package described in this paper offers huge improvements in speed, accuracy and convergence in solving multi-objective and multi-constraint optimization problems. It will be a very useful tool for the power industry.

Economic operation and planning of multi-area interconnected power systems

Optimal power flow (OPF) for both operations and planning has been exhaustively dealt with over the last few decades. In large interconnected systems, local area optimization is more desirable for speedier solutions, while the optimization of a large interconnected system in order to solve a local area problem is unnecessary. In this paper, an optimization tool to solve either the operations or the planning problem using partitioned area optimization is presented. Its features also include automatic selection of the objective for each local area and the facility to select constraints from specified set. The quadratic interior point method extended to handle nonlinear constraints is used in the optimization. It is concluded that the OPF package described in this paper handles in one environment, many issues that are not commonly dealt with in most available OFF programs. Its production grade version incorporating the Bonneville Power Administration power flow (BPAPF) will be a very useful tool to the power industry. >

The quadratic interior point method solving power system optimization problems

Karmarkar's interior point method as a computation method for solving linear programming (LP) has attracted interest in the operation research community, due to its efficiency, reliability, and accuracy. This paper presents an extended quadratic interior point (EQIP) method, based on improvement of initial condition for solving both linear and quadratic programming problems, to solve power system optimization problem (PSOP), such as economic dispatch (ED) and VAr planning (VP) problems. The EQIP method is able to accommodate the nonlinearity in objectives and constraints. The scheme is demonstrated on several IEEE standard systems and is capable of achieving fast convergence and improvement in computational speed over an existing efficient Simplex, such as the MINOS code. The number of iterations during the computation is relatively insensitive to numbers of controls and constraints. Moreover, the proposed EQIP method guarantees a global optimum within the interior feasible region. >