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This paper presents an overall analysis of how the penetration of distributed generation in low-voltage secondary distribution networks affects voltage stability. It is critical that the voltage collapse point be carefully studied under different system operating points to prevent degradation of service. System components have been sophisticatedly modeled in ATP/EMTP. DGs are allocated in a probabilistic...
In this paper, a modeling technique for small-signal stability assessment of unbalanced power systems is presented. Since power distribution systems are inherently unbalanced, due to its lines and loads characteristics, and the penetration of distributed generation into these systems is increasing nowadays, such a tool is needed in order to ensure a secure and reliable operation of these systems....
Hawaii Electric Light operates an autonomous power system on the island of Hawaii with a diverse mix of generating resources. Although the system is small, with an annual peak in 2009 of less than 200 MW, the power system balancing and frequency control is provided through a conventional centralized Automatic Generation Control system. The mix of generation resources on the Hawaii Electric Light System...
A microgrid is a controllable component of the smart grid defined as a part of distribution network capable of supplying its own local load even in the case of disconnection from the upstream network. Microgrids incorporate large amount of renewable and non-renewable distributed generation (DG) that are connected to the system either directly or by power electronics (PE) interface. The diversity of...
The microgrid concept has the potential to solve major problems arising from large penetration of distributed generation in distribution systems. A microgrid is not a robust system when compared to a power system. Therefore, proper control strategies should be implemented for a successful operation of a microgrid. This paper proposes the use of a coordinated control of reactive sources for the improvement...
The small-signal or steady-state stability analysis of an autonomous Microgrid and the impact of various parameters are investigated in this paper. This subject has drawn a lot of attention as the penetration of distributed generation is rapidly growing. The control system for an autonomous Microgrid with distributed control is described and the small-signal modeling approach is discussed. The model...
This paper presents three models for dynamic analysis of inverter-based distributed generators equipped with voltage positive-feedback anti-islanding protection. The models analyzed are: the switched model, where the switches are represented in details, the average model, where the switches and signal generators are replaced by controlled voltage sources, and the small-signal model, where the average...
This paper investigates the problem of appropriate load sharing in an autonomous microgrid. High gain angle droop control ensures proper load sharing, especially under weak system conditions. However, it has a negative impact on overall stability. Frequency-domain modeling, eigenvalue analysis, and time-domain simulations are used to demonstrate this conflict. A supplementary loop is proposed around...
Simultaneous dropout of a large amount of distributed generators caused by a fault in a power line with voltage drop and/or phase change may worsen power stability of a trunk power system. A reduced model of distributed generators in secondary systems considering partial dropout is proposed for the stability analyses. To verify the reduced model, a detailed model and the proposed reduced model are...
Due to the ongoing integration of Renewable Energy Sources (RES) at all levels, the structures of Electric Power Networks (EPN's) are transforming from vertical to horizontal. During this evolutional process the utility companies have to control, protect, maintain and manage properly their networks, with minimal financial, operational, efficiency, quality and availability impact. System Developers...
The state-space model and implementation results of a power conditioning system are presented in this paper. Eigenvalues with different controller gains and load conditions for grid-tie mode and standalone mode are utilized to analyze the system stability. For standalone mode, higher controller gain and higher load resistance tend to make system more unstable. In grid-tie mode, higher controller gain...
The frequency stability analysis in an autonomous microgrid (MG) with renewable energy sources (RES) is a continuously studied issue. This paper presents an original method for modeling an autonomous MG with a battery energy storage system (BESS) and a wind power plant (WPP), with the purpose of frequency stability analysis. A reduced order model is developed, considering only the dominant elements...
This paper widens the knowledge about the microgeneration transient response under faulted conditions. The paper provides the following significant contributions: Firstly, a range of microgeneration transient models have been developed in PSCAD/EMTDC and tested on a typical distribution network. Two types of technologies are considered: a small diesel engine driving a three-phase synchronous machine...
This paper presents the simulation of electrical loads from consumers and from a distributed generation (DG) in network nodes in using a neural network method and an algorithm of feed-forward neural networks. The factor dasiatimepsila is the unique independent value, which influences the studied parameter. In the algorithm, we introduce a process for the stability of the equilibrium of impulsive delay...
Distributed Generation is increasing in nowadays power systems. Small scale systems such as photovoltaic, biomass or small cogeneration plants are connected to the distribution level, while large wind farms will be connected to the transmission level. Both trends lead to a replacement of large synchronous generators as the dominating generation technology. Up to now, transient stability of transmission...
This paper investigates the influence of a synchronous distributed generation on a Brazilian real network. The distributed generation represents a small hydro power plant with total capacity of 30 MW. The model of the network is developed in a professional computer software package. Simulations are carried out considering voltage dependency of static loads and different DG penetration levels. The...
Presence of distributed generation (DG) can represent a significant impact on the distribution networks, such as system reliability, power flow, relay protection, voltage profile and stability. It brings great challenge to the traditional distribution networks. Voltage profile is of great importance to consumers because itpsilas a basic demand for electrical equipments running near the rated voltage...
Distributed generations have become an important part of electrical generation in many countries and its importance is continuing to increase. The exact models of distributed generations are important for load flow program, stability analyses and other applies in distribution systems. But the absence of basic data results in the difficulty of modeling for distributed generator. Based on the knowledge...
Based on the structure-preserving power system model, the linearized state space with detailed generator model, excitation system model and dynamic load model has developed. The novel method for calculating low frequency oscillatory active power increment distribution by employing the eigenvalues and eigenvectors of the linearized state matrix is presented. The method not only can be applied to calculate...
This paper presents the application of black-box terminal characterization models (BBTC) for the simulation and analysis of distributed power electronics systems composed by commercial power electronics converters and filter modules. The models are shown to effectively predict the transient and steady state response of interconnected distributed power systems. They are also used to predict the small-signal...
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