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Impact of DGs on Reconfiguration of Unbalanced Radial Distribution Systems
Abstract
In this paper a new approach using the 0-1 integer programming method for reconfiguration of unbalanced radial distribution systems with the presence of distributed generators for voltage profile improvement and power loss minimization is presented. In practice, unbalanced distribution feeders of power utilities are characterized by low power quality, low voltage profile, more investment and high operating costs. By installing Distributed generators, voltage profile and reliability of unbalanced power distribution systems can be improved with minimization of power losses. In this paper the distributed generators have been modeled as photovoltaic (PV) systems in the unbalanced distribution system. Reconfiguration of unbalanced feeders is a good technique to balance the unbalanced distribution systems to improve the voltage profile and minimize the power losses. The results obtained with the proposed methodology on an example unbalanced power distribution system demonstrate its applicability.
... Furthermore, a method to achieve the optimum reconfiguration of distribution systems using Pareto-Genetic Algorithm was presented in [15]. A new approach using 0-1 integer programming method for reconfiguration of unbalanced radial distribution systems with the presence of DG was deduced in [16]. A technique was suggested in [17] to address the problem of feeder reconfiguration in the context of feeder loss reduction. ...
This paper proposes a new method for loss reduction in distribution networks through network
reconfiguration taking into consideration the bus voltage limits and the thermal limits of the
network branches. The method presents the load flow equations in a simplified form which is
suitable for radial feeders. The load flow equations are formulated in a modified form that can
be adequate for network reconfiguration through opening and closing sectionalized and tie
switches while keeping its radial structure and ensuring the supply of all connected loads. The
Distributed Generation (DG) that is recently applied in distribution systems has been
considered in this paper. The validity of the proposed method has been verified using IEEE 16-
bus and 33-bus distribution systems. Furthermore, the comparative results confirm the
applicability and suitability of the proposed method.
In recent decades, there has been an increase in the use of renewable energy sources, which serve as the basis for the concept of distributed generation, that is, facilities that produce electricity at the location of consumers. The large-scale introduction of distributed generation affects the reliability and stability of electric power systems, including by reducing power losses in them by reducing the current in the lines. Taking into account the forecasts of many experts on the growth of distributed energy resources, the issue of studying methods for reducing electrical energy losses in distribution grids containing renewable energy sources is relevant. (Research purpose) The research purpose is determining methods for reducing electricity losses in electric grids containing renewable energy sources. (Materials and methods) Presented an information search, including an overview of Internet sources and sources of scientific literature devoted to methods of reducing electricity losses in electric grids. (Results and discussion) They used Yandex and Google search engines, Scopus, Web of Science and Google Scholar scientific databases, Cyberlenink electronic libraries as sources of information, eLIBRARY.ru , Elsevier, Springer, IEEE Xplore. It was shown that the literary analysis included 59 sources most suitable for the research topic, of which 8 sources of information are given in Russian, 51 in English. In the course of the information search, we determined methods for reducing electricity losses both in traditional electric grids and in electric grids containing renewable energy sources. (Conclusions) It was found out that the considered methods inherent in traditional power supply grids are also relevant for networks with renewable energy sources. It was revealed that the use of renewable energy sources in itself also allows to significantly reduce electricity losses in electric grids due to distributed generation
A reconfigurable network can change its topology by opening and closing switches on power lines. We use real wind, solar, load, and cost data and a model of a reconfigurable distribution grid to show that reconfiguration allows a grid operator to reduce operational losses as well as to accept more intermittent renewable generation than a static configuration can. Net present value analysis of automated switch technology shows that the return on investment is negative for this test network when considering only loss reduction, but that the investment is attractive under certain conditions when reconfiguration is used to minimize curtailment.
Recently, in many countries the power systems are going to move toward creating a competition structure for selling and buying electrical energy. These changes and the numerous advantages of the Distributed Generations (DGs) in term of their technology enhancement and economical consideration, which are mostly connected to the distribution networks, have created more incentives to use these kinds of generators than before. Therefore, it is necessary to study the impact of DGs on the power systems, especially on the distribution networks. The distribution feeder reconfiguration is one of the most important control schemes in the distribution networks, which can be affected by DGs. This paper presents an approach for distribution reconfiguration considering Distributed Generators (DGs). The objective function is cost summation of electrical energy generated by DGs and substation buses (main buses). Genetic algorithm is used to solve the optimal operation problem. The approach is tested on a real distribution feeder.
This paper presents a network reconfiguration method for power flow optimization and, consequently, loss reduction in distribution networks with Distributed Generation (DG). The network reconfiguration problem is formulated and solved using a simple linear programming approach. Optimal configurations are determined by considering the effects of DG outputs, load variations, and various other contingences such as faults and maintenance outages. Demand Side Management actions have also been taken into account. Simulation results for test distribution network confirmed the effectiveness of the proposed method.
This work presents a methodology for evaluating the impact of DG units installation on electric losses, reliability and voltage profile of distribution networks. The losses and voltage profile evaluation is based on a power flow method with the representation of generators as PV buses. The reliability indices evaluation is based on analytic methods modified to handle multiple generations. The methodology may be used to evaluate the influence of the local of installation and the capacity of DG on these system performance characteristics for different generation expansion planning alternatives. The results obtained with the proposed methodology for systems extracted from the literature demonstrates its applicability.
The allocation of the system losses to suppliers and consumers is a challenging issue for the restructured electricity business. Meaningful loss allocation techniques have to be adopted to set up appropriate economic penalties or rewards. The allocation factors should depend on size, location, and time evolution of the resources connected to the system. In the presence of distributed generation, the variety of the power flows in distribution systems calls for adopting mechanisms able to discriminate among the contributions that increase or reduce the total losses. Some loss allocation techniques already developed in the literature have shown consistent behavior. However, their application requires computing a set of additional quantities with respect to those provided by the distribution system power flow solved with the backward/forward sweep approach. This paper presents a new circuit-based loss allocation technique, based on the decomposition of the branch currents, specifically developed for radial distribution systems with distributed generation. The proposed technique is simple and effective and is only based on the information provided by the network data and by the power flow solution. Examples of application are shown to confirm its effectiveness
This paper aims at analysing the potential impacts that distributed generation might have on the stability of electrical power networks. In particular, the performance of a power system with significant penetration of distributed resources is described to assess different types of stability of the bulk network. For this purpose, a hypothetical network is simulated, assuming a large number of fuel cells and micro-turbines as dispersed units in the low-voltage area. The investigation is carried out at constant load demands but with different contributions from fuel cells and micro-turbines. Thus, the rated and supplied powers of the conventional synchronous generators are adjusted to achieve the power balance in the network. With each penetration level of the distributed generation, the performance of the network is studied and different stability classes are analysed. The results are compared with the performance of the network without any distributed generation, as a reference case, to highlight the influence of penetration levels of such units on the stability of the entire network.
This paper introduces concept of decoupled power controller for tracking load demand of an inverter-interfaced distributed generation (DG) system. The approach suggested in the paper uses reference frame theory to decouple quadrature axis and direct axis currents. As compared to the power-frequency droop based controller, the proposed controller design involves exact mathematical formulation in terms of quadrature and direct axis powers. It also relinquishes forced relationship between the DG variables like power and frequency. The controller has been simulated using MATLAB/SIMULINK for single DG feeding a three phase balanced load. Step changes in quadrature axis and direct axis load are simulated to illustrate the performance of the controller. Results showing response of the DG controller to the load change are presented and discussed in the paper.
The general feeder switching problem is essentially combinatorial,
i.e. suitable for analysis by heuristic search methods. An explicit
search method is developed to identify feasible switching options under
the constraint of a radial structure. Feeder overload, transformer
overload, phase current over-unbalance, service restoration after
faults, and maintenance are considered. The number of switching
operations for resolution of these problems is an important factor for
practical use. An explicit search structure is proposed. Based on this
search structure heuristic rules and evaluation functions are exploited
to quickly find a solution with relatively few switching operations and
even balancing of system load. The method is efficient and reliable. A
distribution system of the Taiwan Power Company is used to test the
results
A Genetic algorithm for network reconfiguration using three phase unbalanced load flow, International journal of engineering intelligent systems for electrical engineering and communications
- Hiroyuki
- Fudou
- Genji Takamu
Hiroyuki,Fudou,Takamu,Genji, A Genetic algorithm for network
reconfiguration using three phase unbalanced load flow,
International journal of engineering intelligent systems for
electrical engineering and communications, ISSN 0969 1170,
Vol.8, 2000.