مجله کیفیت و بهره وری صنعت برق ایران
سال پنجم شماره 1 (پیاپی 9، بهار و تابستان 1395)

The purpose of this article is to answer this question that what kind of power bases that regional electricity company managers use, will lead to more stress in their employees. The Statistical population included all workers of regional electricity company of Rasht and sample by using non-probability sampling method, 260 personnel were chosen. The data collection tool was standard questionnaire, as well as for reliability, the Cronbach's alpha coefficient was used. For the analysis of questionnaire data, descriptive statistics (mean and standard deviation) and inferential statistics (Friedman test and Pearson's correlation coefficient) were used. The analysis results showed that Stress is affects of type of power is applied and there is a significant relationship between the managers power bases include the official power and the personal power and employees stress. Also, all components of official power positively associated with employees job stress, While that the dimensions of personal power have a negative relationship with stress this means that as much as the manager use the formal power includes legitimate power, coercive power and reward power the rate of subordinate’s job stress will increase and on the contrary, as much as manager take advantage of personal power in the management staff stress will be reduced.

Decrease energy consumption, improve equipment efficiency and utilizing waste energy are very important factors to optimize power plant performance. The purpose of this study is to analyze some methods to decrease energy consumption in Kerman combined cycle power plant. To find the energy trend, the power plant was thermodynamically modeled in THERMO FLOW software. The results showed that gas turbine and HRSG have the largest portion in power plant exergy destruction. Therefore the main concern of the present study was devoted to reduce energy consumption in these two parts. The analysis showed that recovery of blow down waste energy leads to saving of 5,100,000 cubic meter fuel per year. Also by using an expansion turbine in gas pressure reduction station for cooling of compressor intake air leads to enhance 11.6 MW in plant net output power and to increase 0.67 in plant efficiency in warmest month.

In this paper, with a new point of view, an innovative multi-objective approach is proposed for active power filters (APFs) planning. In the proposed approach, total harmonic distortion of voltage (THDV), motor load loss function (MLLF), harmonic transmission line loss (HTLL) and total current of the APFs (Iaf) are considered as the objectives of the multi-objective optimization problem; while, the individual and total harmonic distortions of voltage, and maximum permissible APFs size are taken as constraint into account. The proposed approach is a non-convex, non-linear mixed-integer optimization problem. Hence, a new melody search algorithm (MSA) is used to obtain the Pareto optimal set solutions and followed by fuzzy satisfying method (FSM) to find final optimal solution. The feasibility and effectiveness of the proposed multi-objective approach of the APFs planning are demonstrated on the IEEE 18-bus test system under several different scenarios and cases. The obtained simulation results illustrate the sufficiency and profitableness of the newly proposed approach in the APFs planning, when compared with other methods.

In this paper, a multi-level benchmarking method is presented for assessing efficiency of electrical distribution companies’ expenditures. Proposed method considers mutual cooperation of capital expenditure (CAPEX) and operational expenditure (OPEX) for improving quality and decreasing energy losses. Firstly, weighted fuzzy c-means clustering (WFCM) is used by proposed method to find similar companies. Then, proposed method utilizes data envelopment analysis (DEA) and slack analysis in multi levels and through creating pseudo competition between companies, estimates companies’ efficiency scores and slacks in their expenditures. Finally, proposed IBRS is applied on Iranian distribution companies and its results are discussed.

Previous studies focused on evaluation criteria, grouping them and using different techniques to evaluate maintenance systems. But the main question of this study was to determine the relationship between processes and objectives of maintenance systems to use of feedback from evaluation to improve the maintenance system and organization performance. This Research is a qualitative research approach that used the meta-synthesis analysis and Grounded Theory for analysis. Collecting qualitative studies related to research, analyzing findings, discovering the essential points and combined them into an overall alternative, to determine the characteristics of a model is done by meta-synthesis analysis. Then Grounded theory used for designing of the new model to assess the maintenance systems in the power industry. Finally, the designed model validated and approved by experts in the power industry and academic experts from the perspective of simplicity, flexibility and being understandable, practical and functional, integrity, focus and continuous improvement.

Microgrids are a new generation of power systems in small scale, which can fulfils the power requirements of their customers independently from the main power system. One of the characteristics of these systems is their ability to integrate distributed generation units with renewable energy sources, which are inherently probabilistic and intermittent. This, highlights the necessity of studying the reliability of the microgrid to make sure that enough reliability is maintained, and if necessary, to take measures to improve the reliability. In this paper, using the probabilistic methods, it is tried to optimize the combination of distributed generation units and electric vehicles with the goal of improving the reliability of the microgrid. Optimization of a combination of generating units along with electric vehicles to improve the reliability of microgrid, presenting a new method in charge and discharge plans for electric vehicles, and probabilistic modeling of the power injected to the microgrid are amongst the contributions of the present paper.

In this paper, a novel algorithm is proposed to protect the first zone of distance relay in series-compensated double-circuit transmission lines for cross-country faults. Cross-country fault is considered as two single-phase faults that occurs in different phases and locations in double-circuit transmission lines. The relation between the sending end of the line current and the receiving end of the line current is obtained. The proposed algorithm using the one-end sampling data from line, determine different locations of two single-phase faults that occurs on the line. Performance of this method is studied for 300km long double-circuit transmission line compensated by series capacitor in both ends and in impedance grounded network using simulation in MATLAB / SIMULINK software.

The use of distributed generation (DG) resources is seen as a key important factor in improving technical and economic aspects of distribution systems. However, little research exists concerning the optimal location and operation of DGs. This paper proposes a novel method to find simultaneously the optimal location and operation of DGs. The method is developed in two phases. Phase 1 deals with the optimal location of DGs using a multiobjective optimization problem in which active power loss reduction, voltage profile improvement, and voltage regulation are the objectives. A MPSO algorithm is developed to solve the multiobjective problem. Phase 2 copes with the optimal income of the DGs’ owners along with the optimal total payment of the distribution company by adopting a bi-level optimization method with two agents. Game theory is employed to assist in finding optimal contract prices. The performance of the proposed method is evaluated by using two IEEE, 33-bus, standard distribution network. This paper concludes that the proposed method can serve as an accurate tool for practitioners in finding the optimal location and operation strategy of DGs.

In this paper a new power sharing control method is proposed for islanding microgrids. With regard to low dynamic distributed generators like fuel cells, microgrid capability is enhanced to face the different load scenarios. In the new method there is not the need for energy storage devices like batteries and super capacitors in coordination with low dynamic energy resources. So the productivity of the installed capacity is enhanced. Any change in the load is automatically detected by the proposed method and the controller manages the dynamic distributed generator power in its transient time. Back to back voltage and current controllers are also embedded beside power controller to enhance the transient stability of the microgrid in sudden load changes. In order to evaluate the new method, a sample microgrid is considered. Simulation results show the proper power sharing among the generators while satisfying the frequency stability of the system. Technical and economical comparison show the effectiveness of the proposed power sharing method with respect to the conventional methods.