Papers by Keyword: Distributed Generation (DG)

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Authors: Bing Bing Tong, Gui Bin Zou, Ming Lei Shi
Abstract: High penetration level of distributed generation (DG) connected to distribution network makes the protection and control in the traditional distribution network face great difficulties, so this paper proposed a protection and control technology based on advanced feeder terminal unit (AFTU). According to DGs capability and load, the scheme divides the distribution network into several zones in advance, each of which can operate in island mode. Circuit breakers (CB) together with AFTU are installed at the beginning of feeder, the border of two zones and the point of DG connection. AFTUs interconnect with each other through the fiber optic network. AFTU detects the local electrical quantities in real-time and exchanges information with others through the fiber optic network. It can locate the faulted zone quickly to achieve fault isolation and island operation according to local and neighboring information. The reclosing of CB and the control of reconnection of DG are also designed. The case analysis illustrates the feasibility of the proposed distributed protection and control scheme.
Authors: R.M. Sasiraja, V. Suresh Kumar, S. Sudha
Abstract: A distribution system is known as an interface between the central power system and its consumers. DGs are defined as small scale generation units that are connected near to customer load centres. DGs have the potential of altering power flows, system voltages, and even the performance of the integrated network. With the principle of minimizing line losses in the power systems, it is remarkably imperative to define the optimal size and location of local generations. This paper proposes Genetic Algorithm (GA) for optimal placement and sizing of distributed generation (DG) in radial distribution system by minimizing the real power loss and thus improving the voltage shape. The developed algorithm is tested on 33-bus radial distribution system. The proposed method has outperformed than the other methods in terms of the quality of solution and computational competence.
Authors: Ke Zhu, Xiao Hui Lu, Bo Zhang
Abstract: This paper presents a novel method to reduce the inrush currents produced by interconnecting induction generators. The method is based on the sequential energization of the contactors and a grounding resistor connected at the neutral point of a wye-connected stator. Analytical developments are presented, which permit to determine the optimum value of the neutral resistor directly. Theoretical and simulation analysis show that the proposed method can be almost as effective as the traditional three series resistor method. The proposed method requires only one resistor and one bypass contactor and is therefore more cost-effective than the traditional methods.
Authors: Dong Xie, Xing Zhang
Abstract: In the area of renewable energy technologies, islanding of distributed generation system needs to be prevented due to safety reasons and to ensure quality of power supplied to the customers. Several islanding detection methods based on passive and active schemes have been proposed in the literature. Passive methods have a large non detection zone (NDZ), While active schemes degrade power quality. This paper proposed a new passive islanding detection method which combines the Wavelet-transform and neural network techniques. This method can reduce the NDZ to zero without any perturbation that deteriorates the power quality. The simulation results show that the proposed islanding detection method is effective and robust in all kind of conditions.
Authors: Yu Hui, Xin Wang, Dong Mei Zhao, Jian Su, Peng Wang, Hai Tao Liu
Abstract: Adaptation evaluation index system is established according to the influences brought by the distributed generations (DGs) interconnected with the distribution network. Evaluation indicators are proposed to reflect the operating conditions of distribution lines, switches and other important devices of distribution network. Combine Analytic Hierarchy Process (AHP) and Principal Component Analysis (PCA) method is used to determine the weights of the evaluation indicators. Whereby obtain the comprehensive evaluation results of distribution equipment adaptation to DGs integration. A study of a practical grid is made in the cases of the DGs centralized integration, decentralized integration, and without DGs. The simulated result shows that a large number of DGs connected with the distribution network would deteriorate a majority of the equipment operating indicators, especially to the indexes related to switches and protection devices. Meanwhile, when a distribution network is connected into the same capacity of DGs, the distribution equipment would show a better adaptation to DGs' decentralized integration.
Authors: Hui Bin Sui, Ying Sun, Wei Jen Lee, Meng Liu
Abstract: An AMI platform for DG energy management is proposed to provide service both utilities and customers in this paper. By enabling the interactive and efficient communication platform, the proposed AMI facilitates utilities to perform the energy management of DGs, economic dispatch and demand response effectively. Base on the CIM model, OSGi platform leads the AMI extendibility and Interoperability. The communication network includes several advanced communication technology which are used in distributed systems, if the AMI for DG can share the communication network and smart terminal even some advance application software in the utility information platform, it will work more powerfully and effectively.
Authors: Han Ping Zhang
Abstract: 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.
Authors: Han Guo Yu, Jian Ru Wan, Ran Liu
Abstract: According to the power quality problems of micro-grid, this paper presents a control program of the Unified Power Quality Conditioner (UPQC) to improve the micro-grid power quality.The shunt side of UPQC is used to eliminate the harmonic current brought by nonlinear load into the micro-grid. And the conditioner series part is used to suppress distributed new energy generation intermittence. In the paper synchronous coordinate transformation is used to detect compensated components and tracking control method is adopted to control the converter. The simulation results demonstrate the effectiveness of the UPQC on improving the power quality of the micro-grid.
Authors: Yong Hong Ma, Dan Dan Cui, Xiu Yu Wang
Abstract: This paper studies network security of the multi-microgrid distribution system (MMDS) composing of a large number of distributed power-islands. First, a hierarchical communication model for MMDS is designed . Then we analyze the security vulnerabilities. Finally, proposes an efficient secure key management protocol by combining Iolus framework and logical key hierarchy (LKH).
Authors: Yuan Liu, Ming Sun, Gao Fei Ge
Abstract: Reliable and accurate microgrid protection is significant for micro-grid operation.traditional proection methods can not meet the requirements of microgrid.this paper discusses the problems of the existing micro-grid protection methods. Then proposed a new microgrid protection scheme which uses integrated protection as the main protection of microgrid. this protection scheme is based on bi-directional blocking principle,which will send blocking signal if there is no fault .thus protects microgrid. The proposed method is proved to be an effective method for microgrid.
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