Majlesi Journal of Energy Management
Volume:3 Issue: 1, Mar 2014

Load shedding can be defined as the amount of load that must almost be instantly removed from a power system to maintain the remaining part of the system operational. Market-driven load shedding in restructured power system consider in this paper. This paper presents the design and implementation of a new method that consider optimal under frequency load shedding scheme in competitive electricity market. The proposed method includes two steps. In first step essential amount of load shedding is achieved to restitute the power system stability and put steady state frequency in allowable range after contingency occurring. Then in the second step technoeconomic function is presented in market-driven scheme, to specify an optimal load shedding amount for each loads. The proposed problem include maximum generating companies profits considering penalty cost of electricity power not supplied and minimizing congestion rent of branch in competitive electricity market. In order to solve multi objective function, a particle swarm optimization (PSO) is used to find the optimal value of load shedding. Generating output associated with the price of each generator, power output and price of dispatchable and sensitive loads are calculated through performing smart market procedure. The obtained results represent the advantageous of the proposed methodology in designing the optimal load shedding to restore system frequency in a restructured environment through technoeconomic procedure.

Studied and monitoring for eliminating the power network weaknesses is always continuously required. By increasing load, the transmission expansion planning should be capable, in the required time, to meet the economical and technical requirements of power production centers and provide the needed electrical energy consumers. Network expansion planning is required when the network adequacy requirements for energy consumers is not certain in special year. In restructured system, researchers have considered other variables such as the agents profit and finally refined their plan to have an (n-1) secure network. In this paper, a new method for transmission expansion planning under market environment is discussed. Considering the responsibility for developing and transition networks, the owner can candidate the most important and influential selection (new lines).

One of the most important components of fluid transfer systems are control valves which are seen in different routes of oil and gas pipelines and etc. The most important issue of control valves is flow property to achieve good behavior of valve for controlling the flow rate or pressure. In the present study, a flow control valve with appropriate flow property is designed and modeled in order to reduce the effect of vibration and intensive noise. Using fluid modeling of control valve, the valve flow is simulated by numerical solution in CFX software to develop analytical result for designing the internal profile of the flow control valve such that the flow properties and flow rate considering needs. In this study, an internal profile of a valve sample with certain control properties is designed in Catia software and then analyzed using CFX software. To assess the accuracy of the modeling results, the results obtained here are compared with information on the location of the pipeline.

In this paper, new indexes for evaluating the dynamic stability of smart power systems in different operation conditions are proposed. The proposed indexes do not require any dynamic model of the power system and only use data obtained from the output signal of the Phasor Measurement Unit (PMU). This data can include voltage signal, current signal, power and speed of the generators. In this paper the voltage signals are applied. For this purpose, initially a key index based on the length of the error vector is proposed. Then three dynamic stability assessment indexes due to specific statuses of the fundamental index are introduced. These indexes are investigated in four operation conditions. Two of the indexes proposed need output signal of the PMU and the other index needs dominant poles that are estimated by analyzing Prony. The effectiveness of the proposed dynamic stability index is tested on IEEE 39-bus standard system.

This paper presents the design of Static var compensator (SVC) controller for damping power system low frequency oscillations considering delayed arrival of feedback signals. The controller is designed based on H∞ mixed-sensitivity method and the controller parameters are resolved by the Linear Matrix Inequality (LMI) technique. The designed controller is applied on a Single machine infinite bus (SMIB) system model. The computer simulations are performed for pulse disturbance as well as system operating changes and the results show improvement of damping in low frequency oscillations and keeps robustness with load variations. It was founds that time delay has significant influence to damping power system oscillations, especially when the time lag is large.Therefore, for reduce effect of time delay, the robust controller is designed considering time delay of feedback Signals

In Iran, the emphasis is on use of declining oil and gas resources. Thus, in the next decade due to limited fossil fuel energy resources, novel renewable energy should be sought as a global need. In this paper, necessity of considering solar energy and its advantages compared to fossil-based energies. Then, we deal with interactions and analysis of positive and negative points of solar energy development. Finally, with regard to results obtained from this paper, an approach to solar energy is demonstrated from the viewpoint of less dependence on fossil sources and reduction of emissions in energy production and consumption sectors as well as fulfillment of a socioeconomic development.

This paper presents an algorithm for solving the multi-objective reactive power dispatch problem in 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 Swarm Intelligence algorithms have been extensively applied to solve optimization problems. However, some of them, such as Particle Swarm Optimization, may not present the ability to generate diversity after environmental changes. In this paper we propose a hybrid algorithm to overcome this problem by applying a very interesting feature of the Fish School Search algorithm to the Particle Swarm Optimization algorithm, the collective volitive operator. We demonstrated that our proposed HPSO(hybrid particle swarm optimization)presents a better performance when compared to the FSS algorithm and some PSO variations in dynamic environments. In order to evaluate the proposed algorithm, it has been tested on IEEE 30 bus system and compared to other algorithms and simulation results show that HPSO is more efficient then other algorithms in reducing the real power losses and enhancing the voltage stability index.