Kinds Of Distributed Generation Research Articles

Load flow analysis using newton raphson method in presence of distributed generation

<p>Distributed generations (DG), specially including renewable sources such as wind and sun are offering several opportunities for the currently in existence distribution networks and becoming one of the keys of treatment of its problems. Knowing the effects of each kind of DG on distribution networks is a primordial task because DG impacts differ from one kind to another. In this paper, we have analyzed and compared the effects of two kinds of DG, DG which provides real power only and DG which provides real power and reactive power at the same time connected at the critical bus in DN on the voltage profile, real and reactive power losses. We have proposed Newton Raphson method using Matlab to investigate the impacts of these two kinds of DG on 57-bus IEEE distribution test system. The obtained results have been exposed in detail at the end of this paper.</p>

Performance Enhancement for Microgrids Under the Demand Uncertainties with the Presence of Multiple DGs Through Stochastic Ranking Algorithm

The integration of Distributed Generators (DGs) in the reconfigurable microgrid is evolved to enhance the power delivery performance. The DGs are categorized as controllable and uncontrollable based on their power generation control behaviors. In addition to the control behavior, under the uncertain conditions of the microgrid, the performance of DGs is limited due to their respective drawbacks. Therefore, the identification of the most suitable DG under uncertain situation becomes more critical. This paper investigates the performance behavior of the hybrid DG, which uses the benefits of two kinds of DGs and overcomes their limitations. This work addresses five objective functions namely minimization of power loss, total generation cost, total emission cost and voltage deviation, and the maximization of the percentage DG penetration. The performance investigation of DGs is carried out for the system under five different test cases, including the uncertainty in power supply and demand. The modeling of the demand variation is done with the support of Probability Density Function (PDF). The many objective multi-indicator Stochastic Ranking Algorithm (SRA) is used for the optimization purposes. The simulations are performed on IEEE 33-bus Radial Distribution System (RDS) to assess the capability of the proposed investigation. Furthermore, the proposed strategy is applied under 24-h timely varying load pattern of IEEE 33-bus RDS to verify its applicability in uncertain load conditions. Moreover, the performance enhancement realization with the presence of hybrid DG is observed from the obtained simulation results.

Load Flow Analysis for AC/DC Distribution Systems with Distributed Generations

Hybrid AC/DC distribution systems are rapidly growing due to the recent developments in power electronic technologies and increasing deployment of DC output type distributed generations (DGs) in distribution voltage levels. The presence of DGs in DC distribution systems imposes new challenges in load flow calculations. In response, this paper is dealing with the load flow calculation problem in AC/DC distribution systems in the presence of different kinds of DGs. For this purpose, mathematical models of different kinds of DGs are presented, and then, the models are incorporated into the sensitivity matrix method for using in load flow calculations. Since the large number of load buses and the high R/X ratios in the AC part of the system can lead to the divergence of Jacobian matrix based methods, the suggested method is based on backward forward sweep (BFS) method. The proposed method is simulated on a test system equipped with different kinds of DGs and converters and the results are presented.

Reliability Evaluation of Distribution Network Considering Islanded Operation of Microgrid

A novel reliability evaluation method suitable for both traditional distribution network and distribution network connected with distributed generations(DG) is proposed. Firstly, according to the islanded operation mode of Microgrid the fault classification mode for traditional distribution network is modified; secondly, through the research on the generation characteristics of traditional DG and renewable DG, probabilistic models of various kinds of DG are given; finally, synthetically considering load shedding and load rejection, a probabilistic model of the abundance of supplying power by DG during islanded operation of microgrid to consumers is put forward and successfully applied in the reliability evaluation of complex distribution network containing microgrids. The effectiveness of the proposed evaluation method is validated by simulation results of RBTS-BUS6, to which the DG is added.

An Application of Improved Newton-Ralph Method in Microgrid Power Flow Calculation

The traditional methods of power flow calculation are no longer applicable for microgrid for the reason that there are many kinds of DG(distributed generation) in it, the mathematical models of these DGs are different from traditional generations. An unified method is proposed to improve Newton-Raphson power flow calculation method for the bus types of PQ(V) and PI after analyzing and establishing power flow calculation model for each kind of DG. It is proved that this method is correct by comparing the results with the simulation results of DigSILENT. The influences on voltage and power loss in microggirds brought by DGs are studied at last.

The Influence of Inverter-Based DGs and Their Controllers on Distribution Network Protection

The ever growing penetration of distributed generation (DG) in a distribution network has a profound impact on network protection and stability. Traditional protection schemes and algorithms need to be extensively investigated as more and more DGs get introduced into the network. The current version of IEEE Standard 1547 does not present a comprehensive solution for fault current detection in the presence of various kinds of DGs. Power electronic inverter-based DGs (IBDGs) are of special concern in distribution network protection as they are often incapable of providing sufficient fault current and their controllers play a principal role in the DG behavior. In this paper, the effects of voltage and current controllers for IBDGs on industrial and commercial power system protection schemes are investigated. It is shown that the inverter control mode has a direct impact on its fault current levels and duration. A simplified distribution network model with IBDG operating under voltage and current control modes was tested to verify the effects of these controllers. This paper also proposes an adaptive relaying algorithm to detect the faults in the presence of IBDGs with various types of controllers.

The Study on Coordinated Control Strategy for Micro-Grid Containing Various Distributed Generators

According to external dual power line supply and the grid-connected and islanded operating modes of micro-grid and the changeover among them, a control strategy of micro-grid with different kinds of DG (Distributed Generation) is proposed. It monitors the operating states of both micro-grid and power network and provides the unified coordinating control by the controller of micro-grid. In grid-connected mode, all kinds of DG work in constant power mode (P-Q mode) to generate power output for load. In islanded mode, energy storage system works in constant voltage-frequency mode (V-f mode), which is selected as the master power for supporting the voltage and frequency in micro-grid. And the rest works in P-Q mode. The application at one smart community in Shanghai proved its feasibility. The proposed strategy keeps the stable operation of micro-grid and implements the seamless transition between two operating modes by synchronizing device in grid-connected point.

Optimal Allocation of Distributed Generation in Micro-Grid Based on the Theory of Life Cycle Cost

In order to solve the problems of the optimal locations, types and sizes of DG (distributed generation) in an islanded micro-grid, which contains wind turbine, photovoltaic, diesel engine, energy storage device and micro gas turbine. The economic model of optimal allocation was built with the objective function that took LCC (life cycle cost) of DGs and active power loss cost into account. The GA (genetic algorithm) was used to optimize the planning of DG and the optimal scheme was attained. The model comprehensively evaluates the economy of the five kinds of DG in the view of LCC theory, and simultaneously realizes the optimal locations, types and sizes considering the differences of DGs and active power loss of the network. Through the case analysis, the results show this model and method can solve the problem of optimal allocation of DG effectively. It is very practical to guide investing and constructing micro-grid for the investors.