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This paper reviews the methods employed for the optima! planning of Distributed Generation (DG) for the past few years to overcome power quality issues. The motivations, advantages of DG and the research planning are inserted to impart a brief understanding on the need of optimal DG's planning. Three types of method commonly applied by researchers in order to ascertain the proper location and size of DGs are discussed, which are analytical, heuristic and numerical methods. DGs are unavoidable from having power quality events. The most common power quality issues experienced by distribution network are voltage sags and harmonic distortion. This paper presents some methods commonly used by researchers to improve the power quality of the distribution system network. [ABSTRACT FROM AUTHOR]

Summary: This paper proposes a two‐stage planning approach for the efficient utilization of distributed generation (DG) and capacitor banks (CBs) for the simultaneous grid‐connected and islanded operations of the balanced distribution networks. The first stage determines the optimal installation locations and capacities of DGs and CBs using an improved variant of the Jaya optimization algorithm (IJaya) to minimize the power losses and voltage deviation during the grid‐connected operation of the distribution network. The second stage identifies the optimal operating point of the DG and CB combination to carry the maximum load during the islanded network operation under power supply‐demand imbalance conditions. For the second stage, an analytical approach is proposed to identify the best operating power factor for the DG‐CB combination, calculating the power loss, and under‐utilization of the installed real‐reactive power sources. Simulation results on the IEEE 33‐bus grid‐dependent distribution network demonstrate that the proposed IJaya significantly improved the network performance and outperforms various existing optimization methods. In addition, during the network's islanded operation, maintaining the network power factor equal to the source power factor (pfsource) makes the DG‐CB combination operate at their rated capacities. [ABSTRACT FROM AUTHOR]

In case of a failure in the feeders of the distribution network, some of the customers located on DG-side can directly connect to the Distributed Generative unit (DG). Many researches have so far performed in the field of evaluating the distribution network's reliability in the presence of renewable DG sources. In these researches, it is assumed that, during the failure restoration interval, which results in separating a part of distribution network from its main feeder, the renewable DG unit is able to completely supply the load of the created island, and the rates of generative and consumption of the separated island, in this state, are the same. While the consumer's consumed power has a random nature actually, so it cannot expect that the island consumed power to remain constant always. Also, if the renewable DG unit is a kind of the uncontrollable units (solar and wind units), because of the permanent fluctuation of the unit initial energy, its output generation power fluctuates, and it is possible, sometimes, to be less than the island consumed load. Therefore, the accurate evaluation of distribution network's reliability with the uncontrollable renewable distributed generations requires developing the previous methods and innovating a new method. In this paper, a probability analytical solution is used to evaluate the distribution network reliability the uncontrollable renewable DG sources. In order to evaluate the distribution network reliability, two indexes are used: "system average interruption duration index" (SAIDI) and "system average interruption frequency index" (SAIFI). [ABSTRACT FROM AUTHOR]

Presence of Distributed Generation (DG) in electric distribution systems affects the system reliability and different methods for evaluation of system reliability indices are needed. In this paper, reliability evaluation of distribution system in various operation modes of DG is attended and a new analytical method is proposed in order to evaluate system reliability indices. This method is developed based on the classification of hourly load and calculation of the restoration probability according to restoration priority of each section. This method has less calculations and accurate results, so that its accuracy is comparable to that of Monte-Carlo simulation. [ABSTRACT FROM AUTHOR]

This paper proposes a new analytical method for placement and sizing of distributed generation (DG) units for loss reduction. This analytical method for DG placement in the distribution network is developed based on a new mathematical formulation which does not require bus impedance matrix. This is the main advantage of the proposed method. This paper also proposes the placement and sizing of DG unit considering two novel bus types, i.e., P and PQV buses. The ‘ P ’ bus is represented by real power specification only whereas the ‘ PQV ’ bus is one whose voltage magnitude is remotely controlled by the ‘ P ’ bus. A simple method is suggested to select ‘ P ’ bus in a distribution network to control the voltage magnitude of ‘ PQV ’ bus. The effectiveness of the proposed method is demonstrated through examples of 33 bus and 69 bus distribution networks. [ABSTRACT FROM AUTHOR]