JOURNAL OF ENERGY MANAGEMENT
Year:2016 | Volume:6 | Issue:1|Papers Count:6

In order to prevent energy waste by throttle valve in gas pressure reducing station of Neka thermal power plant, a turbo-expander with a capacity of 9.8 MW for the power plant was prepared and installed. Due to the absorption of 63 MVAr reactive powers at the moment of turbo-expander starting, resulted in severe voltage drops in the power plant auxiliary service system. In this paper, while pathology of fault effect on turbo-expander operation will be considered its performance Improvement in the event of grid fault using modified DVR and STATCOM is also considered. To improve performance of DVR, a review of all topologies and control strategies of DVR compensator and improved topology is presented. Then, for optimal performance of compensators the possible points presence on the auxiliary service system of Neka power plant in various scenarios under conditions of sever disturbance, synchronization of fault occurring conditions and starting are tested. The results of PSCAD / EMTDC software simulation show by using improved topology and minimum injection active power strategy of DVR, severe voltage sag compensated in various scenarios and can provide the total auxiliary service system power consumption of this power plant by turbo-expander instead of using the generation of power plant.

This paper deals with the analysis of the grid side converter (GSC) dynamics and dc-link controller design in doubly fed induction generator (DFIG) based wind turbines. In this way, at first the current controller design for the GSC is proposed, and then power flow direction in rotor-side and grid-side converters at different slips is determined. Next, the dc link dynamics is extracted based on the instantaneous power exchanged between the converters and the dc-link capacitor. For the dc-link dynamics extraction, the dynamics of the GSC interface filter is taken into account. It is shown that the dynamics of the dc-link voltage by taking the dynamics of the interfaced filter into account exhibits no minimum phase behavior, and this in turn results in limitation on the achievable appropriate dynamic response. Then, the paper deals with the dc link controller design and selection of controller parameters. Finally, performance of the system under study is examined by the time domain simulations using MATLAB-SIMULINK software.

One of the major challenges in standalone micro-grids (MG), is the frequency control. In this paper, a method for frequency control in a hybrid system based on wind turbine / photovoltaic / fuel cell and super capacitor is proposed. The proposed method is a combination of load frequency control and super capacitor voltage control. To determine the references power, PI controller and modified droop controller are used. System performance based on wind speed, solar radiation and the demand curve has been studied. The simulation results show that the control with modified droop method is better for damping the frequency deviations, due to sending appropriate control signals to the generation units for balancing the network. MATLAB/ Simulink software environment is used for computer simulation.

An important source of energy which has been considered in recent years in advanced countries is the wind energy which is very cheap, clean, and always available. The layout of turbines in the wind farm needs accurate calculations due to limited land and investment, so as to obtain the maximum energy from the wind farm. In this research to locate the turbines in a wind farm three approaches has been considered to obtain maximum power, achieving the least cost of cabling between the turbines individually and the hybrid mode the maximum power and the minimum cost. In this study using the Wake equations, the effects of turbines on each other are also considered. For solving the issue a new genetic algorithm is employed. To evaluate the performance of the proposed algorithm, the results of this algorithm are compared with typical genetic algorithm and several basic questions. The results showed that the proposed algorithm has a better performance.

Public pricing of products is one of the most important economical issues, since any changes in the pricing, affects both the welfare of consumers and quantity of goods and Services which are produced.In this paper which is done for natural gas pricing in Iran, the purpose is giving a price that the government can consider it as a suitable choice for using in subsidies targeting project. These prices have two advantages: first, they try to maximum the social economical welfare (summation of producer and consumer surplus) second, this method solve the problem that the producer has in covering their costs (by marginal cost pricing) because of increasing returns to scale.This paper deals with the optimal gas pricing in industrial sector in Iran by the Ramsey method of pricing. In this regard we have used fuzzy regression (because of its accuracy and devoid of classic regression restrictions) and the available data from 1356 to 1390 for estimating production function and returns to scale in natural gas production side. Also for estimating demand function and elasticity we have used Auto Regressive Distributed Lag Method (ARDL) and the data from 1350 to 1389. The results show that the current prices aren’t optimum and despite implementation of subsidies targeting project the prices are low.

In this paper, by using a mathematical model, potential for power generation of a Solar Chimney Power Plant (SCPP), has been studied in Semnan city conditions. Conceptual model of solar chimney power plant was developed. Governing equations were developed for a solar chimney power plant based on the conceptual model. The iteration technique (try and error) are applied for solving the mathematical model.Mathematical model was validated by experimental data from Manzanares plant and also data from literature. Then model was run for different weather conditions in Semnan city. Given results showed that generated power in Semnan city conditions is lower than in Manzanares plant at the different selected times.In April this power plant produces power of 49 kW. When inlet temperature at collector inlet is increased 5 oC, generated power of plants is decreased approximately 3%. Among the geometric dimensions of the plant, Chimney height has the most influence on generated power. Also it was found that radiation has the most influence on power plants performance.