نشریه تحقیقات نوین در سیستم های قدرت هوشمند
پیاپی 3 (زمستان 1391)

One of the very important ways to save the electrical energy in distribution system is network reconfiguration for loss reduction. This paper proposes a hybrid methodology integrating bee colony optimization with sequential quadratic programming for solving distribution feeder reconfiguration problem. This hybrid method incorporates bee colony optimization as a base level search which can give a good direction to the optimal region and sequential quadratic programming as a local search procedure which is used to fine tune that region for achieving the final solution. Save the electrical energy in distribution system is network reconfiguration for loss reduction is determined through the software code written in MATLAB. Numerical results of a three system have been presented to demonstrate the performance and applicability of the proposed method. The results obtained from the proposed method are compared with those obtained from other methods.

in this paper the reference signal method has been   offered to control the DVR for solving power quality problems including sag, swell and flicker. Simulation of the recommended method was carried out on Matlab simulink software. This method is very simple without any complexity of calculations. The results of simulation show that the strategy is able to provide the desirable power quality in the presence of voltage disturbances.

One of the most important issues in the operation of power systems is dynamic economic load dispatch. In reality, there are practical constraints which should be taken into account in this problem. The impact of some constraints such as prohibited operating zones and valve-point effect could result in nonlinearity and non-convexity in this task. To find the optimal point of the system which satisfies constraints, a proper optimization method should be used. This study is presenting a developed version of Harmony Search Algorithm which uses Roulette Wheel concept and a new approach to handle constraints. The proposed method has been used to solve the dynamic economic load dispatch in IEEE 30-bus system. Results demonstrate the capability of the proposed method in solving dynamic economic load dispatch.

The Renewable Energy reasons to economical issues, environmental and rising demand of energy consumption are expanding the day to day. Due to capabilities-aligned decentralized this equipment, Placement program and sizing its, important problem of power system operation. In this paper, a combined approach is presented for optimal placement and sizing recent technology developments of photovoltaic units, DFIG based wind turbine and fuel cell units, only these generators are considered. This work presents a multi objective optimization algorithm for the sitting and sizing of renewable electricity generators. The objectives consist of minimization of costs, active and reactive losses of distributed system. Optimal Placement and sizing of the equipment is carried out by using Particle Swarm Optimization algorithm continuously. Fuzzy logic is used in order to compare the composition of active and reactive losses in optimization. In this paper, softwares DIgSILENT/MatLab , which has bilateral information relation, is also used for the simulations. The studies are executed on a typical IEEE 33 bus test system. The results show that the proposed algorithm can improve performance & efficiency of system.

Reconfiguration of distribution networks means changing network configurations by changing the normally open and normally closed switches in the network with a variety of purposes including loss reduction, load balancing, improve voltage profile, or a combination of these occurs. Reconfiguration takes place on both daily and seasonal time horizon. Most of the studies in this field have been focusing on power loss. Given the importance of energy losses from an economic perspective, this paper presents a method for the reconfiguration season radial distribution networks, with the aim of reducing energy losses can be developed. Due to the current approach of the electricity industry and the expected increase in the presence of distributed generation (DG) in distribution network, distribution network reconfiguration in the presence of DG are study. The propose models solved by using genetic algorithm and its efficient implementation on a 32-bus test network is investigated. The results suggest the importance of choosing the objective function and show its effectiveness.

In this paper a new Lyapunov–based controller for optimal unified power flow controller (OUPFC) is introduced. The Lyapunov energy function is used to mitigate power oscillation damping in power systems by using local control parameters.The OUPFC is a hybrid FACTS device which is constructed by combination of a UPFC and a PST. The considered energy function is derived by using a power injection model of series FACTS in a preserving structure model. In order to have a comparison between UPFC and OUPFC, simulations of both controllers are done on MATLAB – simpower. Transientstability improvementsshown in simulation resultsaresign of capabilities of OUPFC.

By quick technological advancements in industrial control processes, major industries demand higher power quality. According to IEEE 1159-1995 Standard, any problems in voltage, current or frequency that lead to the error or malfunctions in electrical equipment are considered as a power quality problem. Among the power quality phenomena, voltage sag has been an important problem for power systems in meeting advanced industries. In this paper, following a general review on the voltage sag phenomenon, short circuit faults, starting big inductive motors and energization of the transformer are considered as the main factors of providing this event. Then voltage sag characteristics are presented. And then the suggested strategies to reduce this event are evaluated. Applying conventional methods for voltage sag compensation is not able to meet this event completely. In recent years, with rapidly developing in semi-conductor industries and control systems, using compensators which are based on controllable electronic devices with higher speed, has attracted many power experts' attentions. At the end, voltage sag compensation style has been studied through applying different compensators.

In today's electric grid, due to demand growth, environmental issues and limited energy resources, distributed energy resources (DERs) application and demand-side management methods have received special attention. High penetration of DERs and implementation of demand response (DR) programs, especially in distribution networks, have affected several issues on these networks such as their control and operation. Although DERs can reduce the required network operation and planning costs, control and operation of a large number of DERs with different characteristics is a major challenge for the secure and efficient operation of power system. This challenge is introducing a new concept as microgrid which is a MV/LV grid with embedded DERs interconnected with the upstream grid to exchange thesurplus or deficit of electrical power locally produced respect to the load. Therefore, according to the key role of distribution networks in restructured environment, optimal energy management in this new environment requires considerable research. Due to these reasons, this thesis presents a comprehensive energy management framework for an active distribution network considering high penetration of distributed energy resources and demand response programs. In the proposed model, microgrid maximizes its profit by participating in energy and reserve markets and selling energy to its end-use customers; this is achieved by optimal scheduling of its internal resources during 24 hours time horizon. The proposed method can assess various DERs (both dispatchable and non-dispatchable units) along with their technical and economical constraints. It also considers distribution network security constraints, the possibility of power exchange with the neighboring microgrid, and uncertainties associated with renewable production and load pattern.

Also, a real-time pricing (RTP) in a smart grid environment is presented. Using the RTP, microgrid maximizes its profit considering customers’ benefit. This pricing scheme could be used as an efficient tool to manage customers’ energy consumption and distribution grid operation costs. Finally, a comprehensive model for energy management in an active distribution network in presence of DERs and proposed pricing scheme is presented in order to participate in energy and reserve markets. The proposed model is a mixed-integer nonlinear programming (MINLP) problem which is solved in GAMS software using DICOPT solver. A 32-bus distribution network including dispatchable generators, electric energy storage, wind turbine units, interruptible loads, and interties is used to evaluate the effectiveness and feasibility of the proposed method. Numerical studies show that by applying the proposed method, in comparison with fixed electricity price tariff, the distribution companies could increase the revenue of participants by modifying the consumption pattern. Also, they can operate the distributed energy sources in distribution network more efficiently