International Journal of Applied Power Engineering (IJAPE)
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Probabilistic Q-margin Calculations Considering Dependency of Uncertain Load and Wind Generation
Get PDFThis paper presents a novel probabilistic approach for computation of the reactive power margin (or Q-margin) of a power system with large-scale uncertain wind generation. Conventionally, Q-margin has been used as an index for indicating the system voltage stability level on system operation and planning. The conventional Q-margin method needs to be modified to fully accommodate uncertainties due to wind generation. This paper proposes a new Q-margin computation method using Q-matrix and the expected Q-margin (EQM). Q-matrix is a generic uncertainty matrix representing a discrete joint distribution of load and wind generation and the EQM, calculated from the Q-matrix, is a specific probabilistic variable that supersedes the conventional Q-margin. The proposed method is verified with the IEEE 39-bus test system including wind generation
Optimal Placement of D-STATCOM Using Hybrid Genetic and Ant Colony Algorithm to Losses Reduction
Get PDFIn this work, a modern algorithm by hybrid genetic algorithm and ant colony algorithm is designed to placement and then simulated to determine the amount of reactive power by D-STATCOM. Also this method will be able to minimize the power system losses that contain power loss in transmission lines. Furthermore, in this design a IEEE 30-bus model depicted and three D-STATCOM are located in this system according to Economic Considerations. The optimal placement of each D-STATCOM is computed by the ant colony algorithm. In order to optimize placement for each D-STATCOM, two groups of ant are selected, which respectively located in near nest and far from the nest. Moreover, for every output simulation of D-STATCOM that is used to produce or absorb of reactive power, a genetic algorithm to minimizing the total network losses is applied. Finally, the result of this simulation shows net losses reduction about 150% that it verifies the new algorithm performance
Power Flow Study and Performance of STATCOM and TCSC in Improvement Voltage Stability and Loadability Amplification in Power System
Get PDFPower systems operation becomes more important as the load demand increases all over the world. This rapid increase in load demand forces power systems to operate near critical limits due to economical and environmental constraints. The objective in power systems operation is to serve energy with acceptable voltage and frequency to consumers at minimum cost. This paper studies the important power system phenomenon and voltage stability by using continuation power flow method and steady-state modeling of Static Synchronous Compensator (STATCOM) and Thyristor Controlled Series Capacitor (TCSC) for continuation power flow studies has been represented and discussed in details.also this paper studies voltage stability by using continuation power flow method and Comparison between performance of TCSC and STATCOM for improve voltage stability has been done. Case studies are carried on 9 bus network. Simulation is done with PSAT in MATLAB. Power Flow and Continuation Power Flow is was implemented using Newton-Raphson method. Simulation results show the proper performance of TCSC and STATCOM to improve voltage control and power flows on the lines and significantly increase the loadability margin of power systems
Photovoltaic Solar Energy Systems: Market Trends In The United States
Get PDFThe world today uses more energy than ever before. As a global society we must find more renewable and efficient sources to obtain our energy. One of these sources might come in the form of something that we interact with everyday, the sun. Photovoltaic solar cells are a growing market in the renewable energy sector. Basic PV cell materials are discussed and the PV market in the United States is analyzed; are PV solar energy systems the answer to our current and future energy needs
Techno-economical Unit Commitment Using Harmony Search Optimization Approach
Get PDFIn this paper, Security-Constrained Unit Commitment (SCUC) model is proposed in a restructured power system. This model consists of a closed-loop modified Unit Commitment (UC) and Security-constrained Optimal Power Flow (SCOPF). The objective of this SCUC model is to obtain the maximum social welfare-based system operating cost while maintaining the system security. In conventional power systems, the demand was forecasted before market operation and determined as a fixed constant. Supplying this demand was therefore considered as a constraint. However, in restructured power system which is based on Standard Market Design (SMD), DISCOs offer the demand and their proposed prices; therefore the demand is modeled as an elastic load. Independent System Operator (ISO) is responsible for operating the power market. The ISO performed the power market using the SCUC software to obtain feasible and economical operation as much as possible. In this paper, Harmony Search Algorithm (HSA) has been implemented to solve SCUC problem. Since the SCUC problem is a non-linear, mixed integer, large scale and non-convex problem, harmony search optimization is addressed as an efficient technique to overcome the aforementioned challenges. The simulation results show that the presented method is both satisfactory and consistent with expectation
Security Constraint Unit Commitment Considering Line and Unit Contingencies-particle Swarm Optimization
Get PDFThis paper presents a new approach for considering all possible contingencies in short-term power system operation. Based on this new approach, both generator and transmission line outages would be modeled in network-based power system analysis. Multi generator and also parallel transmission lines is modeled in this methodology. We also investigate this claim that feasibility and applicability of this approach is much more than the previous analytical methodologies. Security Constrained Unit commitment (SCUC) program which is carried out by Independent System Operator (ISO), is one of the complex problems which would be handled by this approach. In this paper, a DC-Optimal Power Flow (DCOPF) methodology has been implemented by particle swarm optimization technique. The Lagrangian Relaxation technique is based on the derivatives and the PSO is a non- derivative technique. These approaches are effective tools which can be implemented for short-term and long-term power system analysis, especially for economic analysis of restructured power systems. The DCOPF methodology has been considered for LMP calculation in LR, which is not available in PSO techniques. In the other hand, PSO technique may be able to provide the optimal solution, where LR usually getting stuck at a local optimum in a large scale power system. The simulation results show that the presented methods are both satisfactory and consistent with expectation.
Compensation of Single-Phase and Three-Phase Voltage Sag and Swell Using Dynamic Voltage Restorer
Get PDFDVR is a equipment which was connected in series and adjusting the loading voltage by feeding the voltage in system. The first installation was in 1996. usually DVR installed between sensitive loads feeder and source in distribution system .The main duty, fast support load voltage (by fast detection algorithm) during disturbance to avoid any disconnection. in this paper approaches to compensate for voltage sag and swell as a common disturbance in voltage transmission and distribution networks is presented. A dynamic voltage restorer based on the dq0 algorithm for three-phase and dynamic voltage restorer based on the average detection method for single-phase are discussed, also in this paper we compare the two methods used to compensate the single-phase and three-phase process. result of three-phase and single-phase voltage sag and swell simulation has been presented by MATLAB/SIMULINK
Impact of Thyristor Controlled Series Capacitor Insertion on Short-circuit Calculation in Presence Phase to Earth Fault
Get PDFThis research paper presents a study on phase to earth fault short-circuit calculation with fault resistance on a single transmission line 400 kV in eastern Algerian transmission networks at Algerian Company of Electricity and Gas (Sonelgaz Group) compensated by series Flexible AC Transmission System (FACTS) i.e. Thyristor Controlled Series Capacitor (TCSC) installed in midline. The facts are used for controlling transmission voltage, power flow, reactive power, and damping of power system oscillations at high power transfer levels. The direct impacts of TCSC insertion on the total impedance, active power and reactive power a electrical transmission line and also parameters of short-circuit : symmetrical currents, line currents, symmetrical voltages and line voltages are carried out. More the effects of injected voltage by TCSC for three case studies are presented
Improving Control Performance in DC Micro-Grids with Distributed Generations
Get PDFDC micro-grids are attracting more and more attention due to their capability to lead to more efficient integration of distributed generation compared with traditional AC micro-grids. In this paper, a hierarchical control architecture is proposed to improve the control performance of DC micro-grid with distributed generations (DGs), which utilize a global controller (GC) to optimize the overall process and a number of distributed local controllers (LCs) associated with each subsystem. The measurement reliability of each LC is guaranteed by an associated measurement validation module which is developed based on Polynomial Chaos Theory (PCT). The system efficiency and robust is counted in the design of GC, where synergetic control theory is adopted. Numerical simulations have been done to verify the proposed method, and the simulation results show good consistency with theoretical analysis
Voltage Stability Based Formation of Voltage Control Areas Considering Impact of Contingencies
Get PDFVoltage instability has been considered as a major threat to power system networks since last three decades. Frequent incidences of grid failures caused by voltage instability have been observed in different parts of the world. Fast voltage stability assessment of power system may be done by formation of voltage control areas, clubbing group of buses in geographically compact region having similar voltage instability problem. This paper presents a new approach for formation of voltage control areas (VCAs) based on sensitivity of reactive power generations with respect to reactive power demands, together with bus voltage variations under voltage stability based critical contingencies. The load buses in geographically compact region showing similar sensitivity of reactive power demand to reactive generations have been clubbed together to form voltage control areas. Since, voltage control areas formed should remain valid under change in operating conditions and network topology, the areas formed based on reactive power sensitivitieshave been modified considering voltage variations at different loadings points under voltage stability based critical contingencies. Voltage stability based Critical contingencies have been selected based on maximum loadability criterion. Case studies have been performed on IEEE 14-bus system. Simulation results performed on IEEE 14-bus system validate VCAs formed even under change in network topology caused by line outages and change in operating conditions caused by variations in real and reactive power demands. The VCAs formed by proposed method have been compared with VCAs formed by few existing approaches. The superiority of proposed approach of voltage control areas formation over few existing approaches has been established on the test system considered