Applied Sciences (Switzerland) (20763417)11(8)
This paper presents a method for coordinated network expansion planning (CNEP) in which the difference between the total cost and the flexibility benefit is minimized. In the proposed method, the generation expansion planning (GEP) of wind farms is coordinated with the transmission expansion planning (TEP) problem by using energy storage systems (ESSs) to improve network flexibility. To consider the impact of the reactive power in the CNEP problem, the AC power flow model is used. The CNEP constraints include the AC power flow equations, planning constraints of the different equipment, and the system operating limits. Therefore, this model imposes hard nonlinearity onto the problem, which is linearized by the use of first-order Taylor’s series and the big-M method as well as the linearization of the circular plane. The uncertainty of loads, the energy price, and the wind farm generation are modeled by scenario-based stochastic programming (SBSP). To determine the effectiveness of the proposed solution approach, it is tested on the IEEE 6-bus and 24-bus test systems using GAMS software. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.
Majlesi Journal Of Electrical Engineering (2345377X)14(3)pp. 1-9
This paper presents an AC Optimal Power flow (AC-OPF) problem of a power system, considering wind energy. Wind energy is an environmental-friendly energy source to produce electrical power and it includes less operating costs compared with other sources of electrical power production. Wind generators also affect the operation cost of a power system as well as transmission losses, based on generators locations and speed of wind. In addition, wind speed is a parameter with uncertainty and considering this uncertainty is an important issue in operation of wind generators in the AC-OPF problem. The proposed AC-OPF formulation includes the integer variables in addition to continuous variables and studies the effects of wind energy, transformer tap settings, and shunt capacitors on fuel cost, transmission losses as well as up and down spinning reserves. To solve the AC-OPF model, an Improved Particle Swarm Optimization (IPSO) is presented. The IPSO algorithm in this work includes velocity mirror effect that causes improvement in the quality of the results. The proposed method is applied on modified IEEE 30 bus test system, and obtained results approve the validity and effectiveness of the proposed method. © 2020
Majlesi Journal Of Electrical Engineering (2345377X)12(1)pp. 79-86
This paper presents a simulation of the dynamic voltage stability in power system. In application of modern power system, dynamic assessment of voltage stability is known as basic concept. In order to study dynamic voltage stability in a power system, different dynamic boundaries are defined such as, Hopf bifurcation (HB) boundary. HB point is an oscillatory boundary in power system. For recognition of the bifurcations, it is unavoidable to study the eigenvalues of power system. In spite of this, determination of these eigenvalues needs to dynamic Jacobian matrix of power system and modal analysis that is very time consuming and complex in large systems. Also, different industrial loads (static and dynamic) e.g. induction motors can effect on dynamic voltage stability boundaries. In this paper, we proposed a solution method based on analyzing the eigenvalues of reduced Jacobian matrix and time domain simulation for assessment of dynamic voltage stability. In addition, effects of industrial electrical loads on the small disturbance voltage stability are evaluated by the proposed method. To show the effectiveness of the proposed solution method, it is tested on IEEE 14 bus and New England test systems. © Majlesi Journal of Electrical Engineering, 2018.
International Transactions on Electrical Energy Systems (20507038)24(6)pp. 842-857
This paper presents a comprehensive formulation for the security constrained optimal power flow (SCOPF) problem considering valve loading effect, multiple fuel option, and prohibited operating zones of units as well as alternating current network modeling and contingency constraints. Also, the SCOPF formulation includes the integer variables, such as discrete transformer tap settings, in addition to continuous variables, such as generation of units. Thus, the suggested SCOPF model is a mixed integer, nonlinear, non-convex, and non-smooth optimization problem. To solve this problem, a new solution method composed of Benders decomposition and special ordered sets is presented. The proposed formulation decomposes the problem into a master problem and a sub-problem. The master problem relaxes the nonlinear constraints of the model using a convex linear outer approximation based on the concept of special ordered sets, whereas the sub-problem contains the nonlinear and non-convex SCOPF formulation with fixed integer and binary variables. To show the effectiveness of the proposed solution method, it is tested on the well-known test systems and compared with several other recently published solution methods. These comparisons confirm the validity of the developed approach. Copyright © 2013 John Wiley & Sons, Ltd.
IET Generation, Transmission and Distribution (17518687)8(12)pp. 1900-1915
This study presents a new stochastic security-constrained hydrothermal unit commitment (SSCHTUC) model considering the uncertainty of load forecast, prediction of inflows to hydro reservoirs and unavailability of units. In addition, the proposed SSCHTUC includes AC network modelling. To cope with the large-scale and mixed-integer non-linear nature of the model, a new hybrid decomposition strategy composed of generalised Benders decomposition and outer approximation/equality relaxation (OA/ER) is proposed. In addition, to handle the uncertainty sources, a combination of scenario approach and two-stage stochastic programming is suggested. The proposed SSCHTUC model and decomposition strategy are tested on the IEEE 9-bus and 118-bus test systems. Obtained results illustrate the effectiveness of the developed approach. © The Institution of Engineering and Technology 2014.
Electric Power Components and Systems (15325016)40(13)pp. 1445-1469
This article presents a new hybrid solution approach based on Benders decomposition and outer approximation to solve the security-constrained unit commitment problem. The security-constrained unit commitment model includes both thermal and hydro unit commitment as well as AC network modeling. The proposed solution method decomposes the security-constrained unit commitment formulation into a master problem and sub-problem. The master problem includes a mixed-integer linear model of unit commitment, while the sub-problem contains a non-linear formulation for security-constrained economic dispatch of each time interval. The master problem accumulates linearizations (outer approximations) and Benders cuts obtained from the solution of the sub-problem. The proposed method can efficiently solve the security-constrained unit commitment problem with a low computation burden, completely satisfying diverse constraints of the problem with zero penalty terms. The proposed hybrid solution approach is tested on the well-known 9-bus and IEEE 118-bus test systems and compared with some other recently published solution methods. These comparisons confirm the validity of the developed approach. © 2012 Taylor and Francis Group, LLC.
Energy Conversion and Management (01968904)49(10)pp. 2629-2641
The introduction of liberalized electricity markets in many countries has resulted in more highly stressed power systems. On the other hand, operating points of a power system are acceptable in the feasible region, which is surrounded by the borders of different stabilities. Power system instability is critical for all participants of the electricity market. Determination of different stability margins can result in the optimum utilization of power system with minimum risk. This paper focuses on the small disturbance voltage stability, which is an important subset of the power system global stability. This kind of voltage stability is usually evaluated by static analysis tools such as continuation power flow, while it essentially has dynamic nature. Besides, a combination of linear and nonlinear analysis tools is required to correctly analyze it. In this paper, a hybrid evaluation method composed of static, dynamic, linear, and nonlinear analysis tools is proposed for this purpose. Effect of load scenario, generation pattern, branch and generator contingency on the small disturbance voltage stability are evaluated by the hybrid method. The test results are given for New England and IEEE68 bus test systems. © 2008 Elsevier Ltd. All rights reserved.
Loading of today power systems continuously increases especially in the developed countries and liberalized electricity markets. On the other hand, operating points of a power system are acceptable in the feasible region usually surrounded by the borders of different stabilities. Power system instability is critical for all participants of the electricity market. Determination of different stability margins can result in the optimum utilization of power system with minimum risk. This paper focuses on the small disturbance voltage stability, a major concern of the power system global stability. This kind of voltage stability is usually evaluated by static analysis tools such as continuation power flow, while it essentially has dynamic nature. Besides, a combination of linear and nonlinear analysis tools is required to correctly analyze it. In this paper, a hybrid evaluation method composed of static, dynamic, linear, and nonlinear analysis tools is proposed for this purpose. Effect of load scenario, generation pattern, branch and generator contingency on the small disturbance voltage stability are evaluated by the hybrid method. The test results are given for two bus, New England and IEEE 68 bus test systems. ©2008 IEEE.
