Insertion Of Distributed Generation Research Articles

AVALIAÇÃO DA INFLUÊNCIA DA INSERÇÃO DA GERAÇÃO DISTRIBUÍDA EM SISTEMAS DE DISTRIBUIÇÃO DE ENERGIA ELÉTRICA

This paper seeks to evaluate the impacts arising from the insertion of distributed generation (DG) in electrical power distribution systems. In this circumstance, using the OpenDSS computational tool, simulations of four different scenarios were carried out, varying the DG penetration levels as a function of the total feeder load, considering a specific point of operation. Finally, the same feeder was simulated with photovoltaic generating sources distributed in bars next to the loads, in order to analyze the temporal characteristic of solar generation as a function of demand. Through the simulations, it was possible to analyze, interpret and highlight the impacts that the insertion of DG produces in the electrical power distribution systems. It was evident that the increase in DG penetration led to an improvement in the feeder voltage profile, power flow inversion and reduction of electrical losses in the feeder. It should be noted that the insertion of DG from renewable sources is a Brazilian reality and a path to be followed, since the diversification of the energy matrix in line with the use of new technologies, such as smart grids, will provide electrical power systems with greater safety, operational efficiency and quality in the product delivered to consumers.

A travelling wave-based fault locator for radial distribution systems using decision trees to mitigate multiple estimations

Electrical systems have been facing transformations, such as distributed generation insertion, system expansion and regulatory standards in order to increase reliability and quality of the power supply. Thus, fault location methods must be updated to ensure accuracy in estimating the location of electrical faults. The delay in restoring the system causes damage to utilities and consumers. Considering this, the current work presents an approach capable of locating faults accurately in radial distribution systems. At first, the distance is estimated using the travelling wave theory with data acquired from two terminals. Next, due to the radial characteristic of the system, the proposal aims to mitigate the problem of multiple estimation of faults. Thus, features are extracted from the voltage and current signals, which are used as inputs of decision trees to identify the fault region. The proposed approach was validated in a medium voltage distribution system, in which the results presented an average error of 0.79% (with a standard deviation of 0.4%) in estimating the fault distances and an average accuracy above 88.7% in identifying the region under fault. Thus, it was demonstrated that the proposed methodology is efficient to locate faults, mitigating the problem of multiple estimation.

VOLTAGE REGULATION IN RURAL NETWORKS WITH DISTRIBUTED GENERATION

The increase in distributed generation (DG) interferes with the energy distribution system, which may present low voltages due to voltage drops and high voltages due to the insertion of distributed generation, resulting from renewable energy sources in rural areas. These voltage levels must be controlled to comply with the limits imposed by the distribution rules and procedures (PRODIST). This study aims to evaluate the voltage rise caused by DG, simulating three DG insertion scenarios, as well as simulate strategies to correct these voltage levels, such as the limitation of the active power supply, the reactive supply by the consumer and the utility, and the installation of on-load tap changers. The simulations were performed using the MATLAB® program, more specifically the PSAT toolbox. Correction techniques were simulated using the active power supply limitation method, the reactive power supply method by consumers, and the voltage regulator process once the voltage rise effect was identified. The first two proved to be ineffective in this case, while the last one meets the voltage levels required by the National Electric Energy Agency.

Optimal Solution for Frequency and Voltage Control of an Islanded Microgrid Using Square Root Gray Wolf Optimization

Voltage and frequency deviation in the islanded operation of a microgrid (MG), due to the uncertainty and lack of inertia in the selection of optimal proportional integral (PI) controller gain, is a challenging task. Although various optimization algorithms have been proposed to achieve this task, most of them require a large number of iterations and are time intensive, making them inefficient for real-time applications. Gray wolf optimization (GWO), a new meta-heuristic algorithm, addresses these issues and has many advantages, including simplicity due to fewer control parameters, flexibility, and globalism. This paper proposes a simple and efficient modified algorithm, called square root gray wolf optimization (SRGWO) algorithm, to realize superior hunting performance. SRGWO is verified using twenty-three benchmark test functions. The algorithm is applied for optimal voltage and frequency regulation of a photovoltaic-based microgrid system operating in the islanded mode during distributed generation insertion and load change conditions. The voltage and frequency gain parameters of the PI controller are optimized. A comparison of the simulation results of the SRGWO algorithm with those of the original gray wolf algorithm (GWO), particle swarm optimization (PSO), augmented gray wolf optimization (AGWO), enhanced gray wolf optimization (EGWO), and gravitational search algorithm (GSA) reveal that the proposed SRGWO algorithm significantly improves system performance while maintaining its simplicity and easy implementation. Furthermore, the SRGWO algorithm obtains the minimum fitness function value in fewer iterations than other algorithms. Moreover, it improves the power quality of the system with regard to minimum total harmonic distortion.

OPTIMIZATION OF DG UNIT SIZE AND PLACEMENT IN RADIAL DISTRIBUTION NETWORKS USING AN SLFO-BPSO HYBRID APPROACH

The addition of distributed generation (DG) to an integrated delivery system has significantly increased the system's performance and efficiency. Researchers have proposed a number of alternative approaches to delivery system planning with DG insertion. In this article, a multiobjective approach is introduced to optimise both the delivery system operator's and the DG owner's reciprocal benefits. The reason behind this multi-objective approach is the inconsistent relationship between DG MVA rating reduction and device power losses reduction. To minimize system active power loss while also reducing DG size, the best compromise size of DGs in MVA, their operating power factors, and positions are obtained. The radial delivery system of IEEE-69 buses is called test system. Using the multi-objective Shuffle Frog Leap Algorithm (SFLA) for optimization, the Pareto-front of nondominated solutions can be found. The SFLA algorithm's efficiency is equivalent to that of the Binary PSO (BPSO) algorithm. The result of the best compromised solution of DGs placement in the delivery system is measured using various system operating indices such as active power loss, reactive power loss, and voltage variance.

Optimal management of electrical power systems for losses reduction in the presence of active distribution networks

Encouraged by the increasing electric energy consumption, the distributed generation has been widely included in the electrical power system. However, renewable energy resources have intermittent characteristics. When the distributed generation is high at certain times of the day, the energy generation at distribution systems can become higher than the required power. The surplus energy is returned to the transmission system, giving rise to active distribution networks. This paper proposes an approach to optimally managing the existing distributed generation and voltage control devices. The management is performed by solving an optimal power flow problem, aiming to find an operating condition for the system in which the losses are minimized, and the voltage profiles are improved. A combined transmission and distribution system is proposed. Some scenarios are considered to assess the impact of distributed generation insertion and the contribution of these sources in support of reactive power. The results indicate the need for adequate active distribution networks management, which depends on the distribution generation insertion level and the generation sources’ power factor.

Harmonic Based Strategy for Location and Sizing of Distributed Generation Insertion (Dept.E)

Technical advances and institutional changes in the electric power industry have resulted in a constantly increasing penetration of distributed generation (DG) integrated with distribution networks. For the connection of new DG installations to the networks a variety of factors have to be taken into account, including technical requirements imposed by utilities to ensure that the DG doesn't adversely affect the operation and power quality of the networks. The use of power electronics at the front end of many DG types poses harmonic control requirements for their insertion into the grid. The attention is focused on the harmonic emissions. This paper introduces a harmonic based strategy for the best location and size of DG sources integrated with distribution network. Also, this paper introduces a new index called unified harmonic index (UHI) that is based on the values of voltage harmonic distortion, current harmonic distortion, and hosting capacity. The procedure is used to rank the available locations of DG and then examined optimum capacities of DGs in the ranked sites based on both the UHI and harmonic limit consideration in IEEE-519. The strategy is applied to an actual Egyptian feeder to indicate the best location and size of DG connected to the feeder as a preliminary study for the distribution network in Egypt for the near future as planned to allow the DG to be inserted.

A decomposition heuristic algorithm for dynamic reconfiguration after contingency situations in distribution systems considering island operations

This paper presents a decision-making model for the dynamic reconfiguration of distribution networks after contingency situations based on formulations of the self-healing problem with islanding. This paper develops a three-stage algorithm. The first stage applies a greedy reconfiguration heuristic, which calculates the criteria values for each viable network configuration in each hour. To address the variety of criteria, the analytic hierarchy process method is applied to define the weights. The second stage addresses the problem statically to reduce the number of configurations and, therefore, the combinations of step 3. In the third stage, the problem is approached dynamically, generating the optimal sequence of topologies for the analyzed period, while considering the time-varying operational conditions of the system. The proposed heuristic significantly reduces the complexity of the problem while minimizing the following criteria: energy not supplied, losses, number of interrupted consumers and switch operations. The physical constraints of the power grid considered in the proposed model are the line limits, protective equipment settings, voltage limits, distributed generators (DG) limits and network radiality. The proposed model is analyzed in different scenarios in the IEEE 123-bus system, modified with the insertion of DGs. The proposed method is compared with a conventional benchmark model.

Computational algorithm for stability analysis of distribution networks with distributed generation

Abstract With the insertion of distributed generation in distribution networks, security analysis becomes crucial, in islanded operation or when the system is connected to the grid. Dynamic stability analyses are necessary in order to achieve minimum levels of security and reliability. Such analyses are obtained through the solution of the algebraic-differential set of equations that model the distribution grid and their generators, which requires numerical solution methods. Therefore, this paper presents a computational tool for transient stability and large disturbance frequency stability analysis, considering distribution systems with the insertion of biomass-fed distributed generation, which may, or may not, have speed regulation systems. The presented tool may be employed to assess assorted system indexes, such as the severity of disturbances, the quality of a given operating condition, in terms of voltage and frequency operating limits, and the response of both the system and the generators in face of the action of speed regulators.

Matheuristic for emergency response in the electric distribution system with unforeseen islanding

Since power supply may suffer interruptions, caused by climate events or even due to equipment and human failures, these interruptions are associated with procedures commonly referred as emergency orders. These emergency orders must be attended by repair crews in an attempt to reestablish the power supply all over the system. Assuming a set of these emergency orders, the network operation center (NOC) must find a scheduling so that they are all attended by the repair crews and the power supply reestablished as soon as possible, while considering the minimization of the total service cost. Distributed generation (DG) may be one alternative for furnishing temporally power supply, such as photovoltaic and wind power generation sources. In such approach, the islanding operation confers such a complexity when considering how much time should be needed to supply the affected loads and which ones may be even selected. This study proposes a novel matheuristic for emergency response to the contingency planning problem related to electric distribution operations, considering unforeseen islanding of DG. From using a mixed integer linear programming (MILP) model, based on the emergency order scheduling problem (EOSP) with islanding operation formulations, the optimization criteria involves the minimization of the cost of non-supplied energy and the penalties related to high important customers, while respecting electrical constraints. Computational results on the IEEE 33-bus system, modified with the insertion of DGs, show the effectiveness of the proposed solution on reducing the total attendance cost when compared to a traditional scheduling solution without considering the islanding operation.

A multi objective approach for placement of multiple DGs in the radial distribution system

Insertion of distributed generation (DG) in existing distribution system has effectively improved its performance and operation. Many different approaches for the planning of distribution system with DG insertion are presented by researchers. In this paper a multi objective approach has been proposed to maximize the mutual benefits of both the distribution system operator and DG owner. The contradictory relationship between reduction in MVA rating of DGs and reduction of power losses of the system is the motivation for this multi-objective approach. The best compromised size of DGs in MVA, their operating power factors and positions are obtained to reduce the system active power loss along with the reduction of DGs size. The 69-bus and 85-bus radial distribution system are considered as test systems. The Pareto-front of non-dominated solutions is obtained by using multi-objective differential evolution (MODE) optimization algorithm. The performance of MODE algorithm is also compared with that of multi-objective particle swarm optimization (MOPSO) algorithm. The different system operating indices such as active power loss, reactive power loss and voltage deviation are evaluated to show the effect of the best compromised solution of DGs placement in distribution system.

Earth fault location determination independent of fault impedance for distribution networks

Summary This article introduces a new earth fault location algorithm for both single and parallel feeders in distribution networks with single end measurements. The proposed algorithm depends on using the equality between the computed sequence components of the current at the fault point. The algorithm is independent of the dynamic arcing or static fault impedances. Then the faulted network can be decomposed into a prefault network and a pure fault network. The different types of connections of load transformer are considered in the study. This is because of their known influence on the direction of earth fault current in the faulty network. Moreover, the existence of distributed generation is considered during formulating the mathematical core of the proposed algorithm. Hence, the sequence current components at the faulty point can be derived without the need to measure the distributed generation current contribution or its terminal voltage with all varieties of load transformer connection. The proposed algorithm is tested via simulating a real 11 kV cascaded parallel-radial earthed distribution feeder from the Egyptian distribution network using Matlab. Different test cases are examined to visualize the performance of the proposed algorithm with a variety of fault conditions, including the fault impedance, loading, load transformer connection, and existence of distributed generations. All applied simulation tests ensure the efficacy of the proposed algorithm for estimating the fault distance in distribution systems with considerable distributed generation insertion and considering all possibilities of load transformer connection.

Evaluation of Optimal Access Location and Capacity of DG for Insertion in distribution System with Condensed Power Losses showing improved Critical Bus Voltage Stipulation

This paper intent to enhance the revenue of optimally planned distributed generation (DG) insertion in distribution system in terms of condensed active and reactive power losses, improved critical bus voltage and system voltage profile which may undeniably ensures aided load expansion and system stability. The novelty of this paper is a multi-objective approach based on two port transmission parameters for optimally determining the size and access point for DG insertion in distribution system. To validate the proposed method the results obtained are compared with already published Analytical Method and the well known Exhaustive Load Flow method. The Comparative study presented has shown that the proposed method leads existing methods in terms of its ease, reduced computational time and handling less number of variables. Despite of that cross verification of results with multi-objective approach assures the optimality of estimated parameters with improved efficiency. To exhibit the utility of the method, it is implemented on standard IEEE 16 bus, 33 bus and 69 bus test radial distribution systems. The simulation is carried out in MATLAB environment for execution of the proposed algorithm.

A Novel Hybrid Network Architecture to Increase DG Insertion in Electrical Distribution Systems

Distribution networks will experience a deep mutation concerning their planning and operation rules due to the expected increase of distributed generation (DG) interconnection to the grid. Indeed, the opening of the electricity market or the growing global concern for environmental issues will lead to a massive development of DGs. Yet, a too large amount of DGs could raise technical problems on distribution networks which have not been planned to operate with bi-directional power flow. The existing solutions to solve marginal DG connections could be no longer relevant. The distribution network definitely has to evolve towards a smarter and more flexible network. Two possible ways to reach this goal are through new architectures and developing intelligent systems. This paper focuses on new architectures and operating modes. The traditional radial distribution network could accept more DGs by introducing appropriately specific loops. A new hybrid structure enabling the coexistence of the radial and meshed operation is proposed. It is equipped with autonomous circuit-breakers and automated switches that improve its reliability. A heuristic algorithm is also proposed to build this new architecture while ensuring the equality of consumers with respect to the continuity of service and while minimizing the global cost.

Performance Enhancement of Electrical Distribution Systems with Multiple Distributed Generation Sources

The recent trends in electrical power distribution system operationand management are aimed at improving system conditions in order torender good service to the customer. Reforms in the distribution sectorhave given major scope for employment of distributed generation (DG)resources which will boost system performance. This article proposesa heuristic technique for allocation of multiple distribution generationsources in a distribution system. The allocation is determined based onoverall improvement in network performance parameters like reductionin system losses, improvement in voltage stability, improvement in volt-age profile. The hybrid of Genetic Algorithm with the proposed NetworkPerformance Enhancement Index (NPEI) along with the heuristic rulesfacilitates determination of feasible location for insertion of DG sources.A priority list is prepared with decreasing values of NPEI so that thedesigner can select most feasible locations. The developed approach istested with different test systems to ascertain its effectiveness.