Volume 20, Issue 3 -

Increasing the fossil fuels consumption, pollution and rising prices of these fuels have led to the expansion of renewable resources and their replacement with conventional sources. In this paper, a robust algorithm for a micro-grid (MG) planning with the goal of maximizing profits is presented in day-ahead market. The energy resources in MG are wind farms (WFs), photovoltaic (PV), fuel cell (FC), combined heat and power(CHP) units, tidal steam turbine (TST) and energy storage devices (ESDs). This algorithm is divided into two main parts: (1) Optimal planning of each energy resource; (2) Using the Nash equilibrium –genetic algorithm (NE-GA) hybrid method to determine the optimal MG strategy. In energy resources optimal planning, using a stochastic formulation, the generation bids of each energy resource is determined in such a way that the profit of each one is maximized. Also, the constraints of renewable and load demands and selection the best method of demand response (DR) program are investigated. Then the Nash equilibrium point is determined using the primary population produced in the previous step using the NE-GA hybrid method to determine the optimal MG strategy. Thus, using the ability of the genetic algorithm method, the Nash equilibrium point of the generation units is obtained at an acceptable time, and This means that none of the units are willing to change their strategy and that the optimal strategy is extracted. Comparison of results with previous studies shows that the expected profit in the proposed method is more than other method.

In this paper a multiagent based communication framework for gridable electric vehicle (GEV) aggregation in power distribution network is proposed. Also, multi objective optimization is presented for the minimization of power losses and maximization of voltage. Furthermore multiagent system (MAS) based analytical model is proposed for GEV aggregation. Comprehensive case studies are conducted on IEEE 33 and 69 bus test distribution systems using MATLAB and it is observed that the timely and optimal placement of GEV aggregation in distribution network using multiagent communication (MAC) will lead to reduction in power losses and improvement in voltage profile. MATLAB and MOBILE C were used for the simulation studies and results demonstrate significant benefits of GEV aggregation in distribution network.

Development of smart grids for power supply to rural consumers assumes the creation of adaptive voltage regulation systems in 0.38 … 10 kV electrical networks as one of the directions. This paper considers a new approach to create an algorithm for controlling the technical means of regulation and voltage stabilization. The proposed adaptive voltage regulation system allows collecting and processing information on the actual voltage at the consumer inputs and automatically determine the voltage regulation coefficient. The developed mathematical model allows calculating the voltage regulation coefficient depending on the voltage at various points of the 0.38 kV electric network. In the paper there are also new methods of adaptive automatic voltage regulation in the 0.38 kV electrical networks and the requirements to the functional capabilities of this system. The article suggests technical solutions for the implementation of adaptive automatic voltage regulation system. The successful tests of experimental model of this system have been carried out.

This paper presents a detailed comparative analysis between Symmetrical and Asymmetrical Quasi Z-Source Cascaded Multilevel Inverter (QZS-CMI). The comparative analysis investigates for boost operation in both Symmetrical and Asymmetrical System. Analysis is done based on the achieved input current, capacitor voltage of the upper capacitor and parallel capacitor and the two inductors current of DC link (Quasi Z-Source network) which is combined with H-bridge. In Asymmetrical QZS-CMI, the input voltage for three DC sources are given in the ratio of 1:3:9, i. e. the system is designed for 27 level. Asymmetrical QZS-CMI is new system and proposed in this paper for comparative analysis with Symmetrical QZS-CMI. An advanced optimal Alternative Phase Opposition Disposition (APOD) technique is developed and implemented. Symmetrical system has high boosting capability of output voltage, reducing the switching losses, high voltage gain and lower spikes in switching voltage. The comparative study is done and results are verified with Experimental 250   W prototype model and also verified by using MATLAB/ Simulink.

Power sector, as one of the least progressed division, is limiting the socioeconomic development in Afghanistan. Although the country has a vast solar energy potential with a bright prospect for growth, however inadequate endorsement and attention have prevented its proper use. Meanwhile, Kabul the capital city and one of the fastest growing cities in the world, is suffering severe challenges to supply its energy needs. Presently, Kabul electrical system is subjected to insecure and insufficient supply due to the lack of integrated networks and deployment of Renewable Energy (RE) sources. This research investigates an appropriate approach by introducing two Linear Fresnel Reflector (LFR) plants with a total capacity of 120 MW to overcome the present challenges in Kabul city. The proposed LFR units are incorporated with an energy storage system of full capacity production for five hours to cover the power shortage at night. The design aspect of LFR is specified by using of System Adviser Model (SAM). Levelized Cost of Electricity (LCOE) and the total annual output of the proposed LFR units are estimated as 0.2508$/kWh and 294,657.28 kWh respectively. To minimize the total operating costs of the integrated model and mitigate CO 2 emissions, an optimal Unit Commitment is (UC) fulfilled as well. UC is accomplished by using MATLAB INTLINPROG optimization toolbox.

This paper proposes a methodology to repair crews dispatch during distribution feeders restoration immediately after remotely controlled actions have been taken. Our method determines the sectors patrol sequence using the expected number of faults for each sector considering a previously calculated fault probability. Next, a road graph mapping of the buses is obtained by associating each bus with its real-world position. The crews’ route inside each sector is determined by the application of the nearest neighbor algorithm on that mapping. The case studies analyzed 24 real faults available in the database of a Brazilian power distribution company, and, a comparison was made between the time spent to locate the failures by simulating both the proposed methodology and the usual greedy strategy. The average time spent in localizing all the failures was from 9.49 % to 41.81 % shorter than in the usual method. Moreover, the speed and distance of repair crews showed weak influence in the crew dispatch methodology efficiency. Such results indicate an enhancement of the power distribution QoS indicators by using the proposed methodology to deal with faults.

Occurrences of High Impedance Faults are common in Power Distribution between substation to substation, substation to rural area and within rural area. High Impedance Faults are detected based on Fault current measured by Fault Detection devices But an important fault is the Downed or Broken power line Fault not touching the ground cannot be detected when there is not enough faults current to operate fault detection devices in Over Head power distribution. Many methods to find High Impedance Faults exist. However, no proper method exists to find the Detection and location of Downed or broken power line Fault not touching the ground .Such a condition represents no electrical abnormality and till now its detection would probably have to depend on visual sighting. This paper proposes methods F-PLCCG and Hybrid AD method going to solve above problem.

This paper proposes a methodology for developing Price Responsive Demand Shifting (PRDS) based bidding strategy of an industrial buyer, who can reschedule its production plan, considering power system network constraints. Locational Marginal Price (LMP) methodology, which is being used in PJM, California, New York, and New England electricity markets, has been utilized to manage the congestion. In this work, a stochastic linear optimization formulation comprising of two sub-problems has been proposed to obtain the optimal bidding strategy of an industrial buyer considering PRDS bidding. The first sub-problem is formulated as to maximize the social welfare of market participants subject to operational constraints and security constraints to facilitate market clearing process, while the second sub-problem represents the industrial buyer’s purchase cost saving maximization. The PRDS based bidding strategy, which is able to shift the demand, from high price periods to low price periods, has been obtained by solving two subproblems. The effectiveness of the proposed method has been tested on a 5-bus system and modified IEEE 30-bus system considering the hourly day-ahead market. Results obtained with the PRDS based bidding strategy have been compared with those obtained with a Conventional Price-Quantity (CPQ) bid. In simulation studies, it is observed that the PRDS approach can control the LMPs and congestion at the system buses. It is also found that PRDS can mitigate the market power by flattening the demand, which led to more saving and satisfying demand.

This paper presents a novel method to mitigate the overvoltage transients caused by the circuit breaker operation in the low voltage DC (LVDC) systems. This method is based on using the existing supercapacitor energy storage system (ESS) in the DC grids to limit the switching overvoltage within the standard range. The supercapacitor sizing is performed with considering instability problems of the constant power loads (CPLs) and the boundary between underdamped and overdamped modes. Firstly, a simplified DC system is considered and the analytical expressions are presented to determine the boundary values of the supercapacitor. Effects of the system parameters on the allowable range of the supercapacitor are also discussed. Then, an approach is introduced to determine the boundary values of the supercapacitor for more detailed models of the LVDC systems. This approach applies SimPowerSystems and Control System Toolbox of the MATLAB software. Finally, the effectiveness of the proposed method is verified using simulation.

Congestion in the power system network is a threat to security, reliability, and economy of the power industry. Congestion management in deregulated power markets has become one of the significant tasks of system operators to address congestion in the transmission network. Many methods have been presented in literature with the aim of congestion management, improvement of the security and efficiency of the deregulated power market in the past few decades. This review paper explains various approaches/methods of congestion management in past few years and provides a comprehensive overview of congestion management methods. A comparative study was done among the different well known CM methods in this work. These methods were tested and analysed on modified 6-bus system, modified IEEE 14-bus system, and modified IEEE 30-bus system.