فصلنامه مهندسی و مدیریت انرژی
سال ششم شماره 1 (پیاپی 19، بهار 1395)

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. Presence of turbo-expander in Neka power plant due to the absorption of 63 MVAr reactive power at the moment of starting, resulted in severe voltage drops in the auxiliary service system and outage of sensitive equipment to voltage level, which makes impossible the operation of the turbo-expander. In this paper, while pathology of turbo-expander and their performance Improvement using compensator, to review all topologies of dynamic voltage restorer compensator and improved topology will be presented. Then, for optimal performance of compensators the possible points presence of them on the auxiliary service system of Neka power plant in various scenarios under synchronization of fault occurring conditions and starting will be tested. The results of PSCAD / EMTDC software simulation show by using improved topology of dynamic voltage restorer, voltage sag of turbo-expander starting compensated in various scenarios and can be provide the total auxiliary service system power consumption of this power plant by turbo-expander instead of using the generation of power plant.

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 the combine of load frequency control and super capacitor voltage control. To determine the references power, PI controller and modified droop control 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 of 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.

Wind energy is an important source of energy that is very inexpensive, clean, and always is available which has been considered much by advanced countries in recent years. The layout of turbines to obtain the maximum energy from the wind farm regarding limited land and investment requires accurate calculations. To determine the location of turbines in a wind farm we have considered a hybrid model in which the objectives are to minimize the cost of cabling between the turbines and maximum power acquired from farm the same time. In this study Wake equations and the effects of turbines on each other are also considered. To solve the issue a new genetic algorithm is presented. In order to evaluate the performance of the proposed algorithm, the results of this algorithm is compared with typical genetic algorithm and several basic questions. The results showed that proposed algorithm has 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 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 ARDL method and data from 1350 to 1389. The results shows 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 °C, 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.