The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
Grid synchronization of distributed generation (DG) plays an important role for effective power transfer from DG units to the utility grid. Usually, the synchronous reference frame based phase-locked loop (PLL) is a common technique. However, there is a compromise between steady-state accuracy and dynamic performance of PLL especially when the grid voltages contain harmonics and /or unbalances. In...
This paper presents the procedures of developing a load modelling software called LM_ID (Load Model Identification), and also describes the procedures of applying the LM_ID to Taiwan power system. LM_ID can identify five static load models and seven dynamic load models. Numerical approaches to estimating load model parameters are analytical and iterative ones. LM_ID uses the least linear square error...
Unlike the traditional optimal PMU placement problems which are assumed that PMUs have unlimited capability of monitoring remote buses via propagation rules, we formulate this problem with considering the depth of observability propagation (DOP) in this paper. Two problem formulations described by mixed integer linear programming (MILP) are proposed. Under this framework, interactions between the...
This paper presents a distributed communication-based droop control mechanism for accurate active and reactive power sharing in isolated converter-fed micro-grids(MG). Under this framework, the power converters and loads in the MG are regarded as multi-agent system (MAS). Then, one special MAS control, known as pinning control, is used as a secondary controller to improve the performance of the power...
A back-EMF model reference adaptive system (MRAS)-based sensorless control scheme is proposed for a grid-connected doubly-fed induction generator (DFIG). Based on the stator-side and the rotor-side dynamic models of the DFIG, both the reference model and the adaptive model of the proposed back-EMF-based DFIG are investigated. The adaptation mechanism of the proposed controller and the stability of...
As an extreme contingency struck Kinmen island power system, it is very likely to cause blackouts. Although underfrequency protection scheme had been applied, some drawbacks of the scheme hinder Kinmen power system from avoiding blackouts. In the past one decade, several blackouts have occurred in Kinmen power system. To avoid blackouts, a special protection system (SPS) is summoned up. This paper...
An efficient method for small-signal stability assessment of P − ƒ/Q − V̇ droop control methods for multiple converters in an isolated micro-grid (MG) is proposed in this paper. A MG model described with arbitrary number of converters is explored first. If there are more number of converters in a chosen MG, only dominant eigenvalues related to droop control are of primary interest. Therefore, constructing...
As penetration of renewable energy sources is increasing, Long-Term Voltage Stability of FSIGs has raised major concern for distribution power networks since they will always consume reactive power. When either the voltage profile of FSIG severely declines due to load consumption increasing in nearby area, or mechanical power of wind turbine increases owing to wind speed increasing, the loss of stable...
This paper reports real-time Available Transfer Capability (ATC) assessment of multi-area power systems in a distributed computational framework. Calculation of ATC is formulated as a non-linear optimal power flow problem which is solved by Optimality Conditions Decomposition (OCD) techniques. This coordination and decomposition methodology is implemented in a distributed computing environment which...
Accurate active power and reactive power sharing is one of the key control objectives for autonomous operations of isolated micro-grids (MGs). Traditionally, this task is achieved by decentralized droop control. Since such class of decentralized droop control may lead to inaccurate power sharing under the system with non-uniform transmission lines, various methods have been proposed to overcome this...
High penetration of distributed interface converters (DICs) in the isolated AC micro-grid (MG) may result in poor frequency and voltage response due to low inertia of conventional DICs. In order to overcome this difficulty, the concept of the virtual synchronous generators was proposed recently. meanwhile, in order to improve the convergence rate of the conventional consensus-based droop control and...
Due to recent advocating of the high renewable generation penetration and continuous increasing in load demands, interconnected power systems are subjected to over-rating of circuit breakers and substation equipments. Although various technologies can overcome high short-circuit level problems, none of conventional solutions provides extra transmission capability or ability to control or redirect...
To prevent line outage contingencies which are the most severe disturbance impact on voltage stability is the most important issue in a PMU placement problem. We focus on the line outage contingencies PMU placement problem and are the first to propose a decomposition-coordination approach. The original problem with thousands of constraints are decomposed by Alternating Direction Method of Multipliers...
Recent advocates of distributed multi-agent systems (MAS) have been widely adopted as promising solutions for micro-grid (MG) control and operations. In this paper, we propose an alternating direction multipliers method (ADMM) for consensus-based distributed droop control for proper real power and reactive power sharing. In comparison with the conventional first-order consensus method, this ADMM implementation...
Reliable and efficient distributed algorithms for power restoration are essential for self-healing electrical smart grids. Therefore, this paper presents a Multi-Agent System (MAS) for automatic restoration in power distribution networks. Moreover, as electrical demand fluctuates on the hourly and daily basis, an ensemble learning algorithm has been adopted for short-term forecasting of electrical...
The task of autonomous power sharing in a micro-grid is usually achieved by decentralized droop control on individual interface power converters, which may suffer from the dependence on output line impedances. Inaccurate reactive power sharing will occur under strongly non-uniform line impedances. Due to inherently distributed and heterogeneous nature of the micro-grid, it becomes an ideal platform...
Since distributed interface converters (DICs) embedded in the isolated micro-grid (MG) usually have low inertia, high penetration of DIC-based MGs may result in poor voltage and frequency response when the grid experiences large disturbances. The synchronverter is proposed recently in which the DIC mimics conventional synchronous generators (SGs) by designing parameters of the SG into the droop control...
This paper studies consensus-based P-f/Q-V droop control in autonomous micro-grids with wind generators and energy storage systems. The consensus control is achieved by deploying sparse and band-limited communication networks such that neighbouring DICs can communicate each other. Two droop control schemes, including (i) the uniform droop gain ratio scheme and (ii) the non-uniform droop gain ratio...
This paper studies iterative distributed algorithms for on-line voltage stability assessment (VSA) in energy management systems of modern smart power grids. Since VSA can be modelled as a special non-linear optimal power flow (OPF) problem, iterative decomposition-coordination approaches based on constrained augmented Lagrangian methods can be applied. The distributed scheme of Auxiliary Problem Principle...
The short-term voltage instability of induction generators (IGs) is the phenomenon of the unstable high slip when the output power exceeds its maximum power transfer. As the penetration of renewable energy distributed source is increasing, the voltage stability issue of large-scale power system with the intermittent source will become increasing important. As severe voltage sags due to a fault in...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.