Majlesi Journal of Energy Management
Volume:4 Issue: 3, Sep 2015

Managing and controlling voltage unbalance in power systems due to economic issues and satisfying customers is crucial. Any changes in quantities of voltage, current and frequency which result in damage or incorrect performance of equipment is called power quality. Regarding this definition, it is actually voltage quality that is expressed in definition of power quality. Therefore, this study is to analyze a radial distribution feeder and present a comprehensive formulation in order to determine portion of each effective factors including existing loads in the system, lines among buses, and voltage source. Regarding the required information from extracted formulas and information of radial distribution system of lines impedance, load power or load impedance is from specifications and specific information of the system. MATLAB and Power Factory Dgsilent were used in order to validate the relations from analysis of unbalance load distribution. Such a structure can provide more research opportunities for statistical techniques in international standards about managing voltage unbalance factor.

For large scale power systems, it is important to keep the frequency and inter area tie line power near to the scheduled values. In current scenario the use of renewable energy sources are given higher priority for the energy generation due to environmental concerns. As the penetration of wind energy using doubly fed induction generator (DFIG) in power system is increasing, it results more disturbance in load frequency due to unbalance between load and demand. This paper presents a novel approach using Linear Quadratic Regulator (LQR) and Superconducting Magnetic Energy Storage (SMES) along with the DFIG to control the frequency and tie-line power deviation. The LQR is designed and the kinetic energy of DFIG is extracted to control the interconnected two area power system. SMES unit is introduced to realize the quick response on load frequency control. The improvement in response after participation of LQR, DFIG & SMES will be observed by the time domain simulation response in MATLAB.

This paper presents a new model of GenCo strategy for bidding and optimal energy in a centralized market to achieve the greatest profit. Market problem in the modeling of this paper has been considered in a period of time, by considering uncertainties of value prediction and consumption load bidding and uncertainty for GenCo prices’ prediction. Given prediction error and Normal curve-based Monte Carlo method has been used for uncertainty modeling. Due to the problem’s high volume and scenarios’ high number, scenario’s reduction techniques along maintaining uncertainties modeling precision has been used to reduce computation volume and speed up the program implementation. In this paper, PBUC and the market-clearing problem has been modeled simultaneously by a multilevel problem (Bi-Level) with two levels; top level PBUC and low level market clearing. Then, this bi-level problem using Lagrange coefficients and by Karush-Kuhn-Tucker (KKT) conditions has been changed into a single level mixed integer linear problem (MILP) for optimization through typical mathematical techniques. In this paper, GAMS program and CPLEX method have been used in order to solve the MILP problems. Finally, 6-bus network (IEEE) has been examined to prove the efficiency of this new model.

In this paper, Flexible AC Transmission Systems (FACTS) devices are used as a powerful tool for controlling power flow in power system to reduce active power losses and manage transmission lines congestion which are two main factors to restrict transmitted power in the network. Optimal location and size of these devices are specified by using artificial bee colony (ABC) algorithm which is one of the most effective method for solving optimization problems by taking into consideration minimizing active power losses and transmission lines congestion as objective functions in order to relieve the line loading of the overloaded transmission lines and increase the loadability in the transmission system. The proposed method is also able to improve voltage profile in the network. The effectiveness of proposed method is tested with IEEE 30-bus system and the test results are evaluated.

The main purpose of the economic dispatch (ED) is Minimize of costs in power plants, so that the constraints of governing system installations are considered. Classical problem of ED that is performed for minimizing the total costs of the fuel, cant considered in isolation, therefore considered the emission that occur cause of the operation of fossil fuel generators in ED problem. Considering the emission in the ED problem converts the classical issue to multiple issue with as: Combined Economic and Emission Dispatch (CEED). In this paper bio-geography based optimization algorithm (BBO) is used to solve the problem of CEED. Then proposed method is performed on the standard IEEE 24-bus test system and its results with genetic algorithm and other several optimization algorithms are compared.

Electricity generation by the wind power in the recent years has increased a lot. The main reason is that it doesn’t use fossil fuels and consequently has no environmental pollution and reduces greenhouse gases. But due to the fact that wind farms are not available at everywhere, so generation by this method is not always economical and reachable. Wind speed is variable and can be destructive, so induction generators are used in wind farms because design, construction, and maintenance of these machines are much easier than synchronous machines. But these generators have some disadvantages too for example they use a lot of reactive power and cause voltage instability. Also due to the unpredictable behavior of the wind speed, output voltage of wind farm is unstable too. One solution to this problem is using of Flexible AC Transmission System (FACTS) for the reactive power compensation. In this article the use of STATCOM has been investigated and analyzed. At first a wind farm in the variable wind speed has been simulated by Matlab (Simulink) and the effects of STATCOM and SVC in the transient and steady state conditions have been investigated and compared. Finally due to the simulation results and previous researches, it has been proved that STATCOM is the best compensator in the wind farm.

The electricity retailers try to obtain the consumers’ electricity energy at the minimum cost from different energy resources such as self-generation facilities, bilateral contracts, and pool market purchases in the restructured electricity markets. Hence, more attention should be paid on the demand response programs (DRP) which aims to energy purchased cost reduction. This paper develops a stochastic energy procurement management for electricity retailers with multiple options considering DRP. The pool market price uncertainty is modeled based on a scenario distribution curve approach such as the normal distribution curve. The curve is divided into several areas, where each area is identified as a scenario, and the problem is solved using the stochastic programming. Also, this paper is focused on investigating the effect of DRP on the total expected procurement cost. Finally, a new stochastic framework is presented for reduction of the expected procurement cost of retailers by using the demand response programs.

This paper presents an algorithm for solving the multi-objective reactive power dispatch problem in a power system. Modal analysis of the system is used for static voltage stability assessment. Loss minimization and maximization of voltage stability margin are taken as the objectives. Generator terminal voltages, reactive power generation of the capacitor banks and tap changing transformer setting are taken as the optimization variables. Evolutionary algorithm and Swarm Intelligence algorithm (EA, SI), a part of Bio inspired optimization algorithm, have been widely used to solve numerous optimization problem in various science and engineering domains. This paper presents, a new novel cuckoo search optimization algorithm (NCSA) based on Gauss distribution is presented to solve the reactive power dispatch problem. The simulation results demonstrate good performance of the NCSA in solving an optimal reactive power dispatch problem. In order to evaluate the proposed algorithm, it has been tested on IEEE 30 bus system and compared to other algorithms reported those before in literature. Results show that NCSA is more efficient than others for solution of single-objective ORPD problem.