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.
This paper presents the hardware-in-the-loop (HIL) test of the demand as frequency controlled reserve (DFR). The HIL test refers to a test in which parts of a pure simulation have been replaced by actual physical components. It is used to understand the behavior of a new device or controller. The DFR has been tested by offline simulations to illustrate the efficacy of this technology. The DFR control...
Most of existing fault-ride-through (FRT) control strategies are based on the vector power control, which is suitable for wind turbine generators (WTGs) connected to strong power grid, but not for the synchronized control generally designed for the weak grid and islanded grid. To solve the FRT problem for the synchronized-control DFIG, a novel FRT control strategy is proposed. Compared with previous...
The railway represents a large power consumer that can cause uneven loading of the phases in the high voltage grid. These unbalanced loads supplied by the utility may lead to voltage unbalance problems in the system and thereby affects the other consumers connected to the same network. It is fact that, voltage unbalance appears mainly as a result of unbalanced currents at the points of common coupling...
With higher energy efficiency and less carbon intensive, widespread application of electric vehicle (EV) becomes a big trend in many transportation systems. Many cities start their green energy revolution of electric bus and taxi in public transportation systems. In this paper, value chain analysis and life cycle cost (LCC) are utilized to compare the operation feasibility of battery-charging-mode...
This paper proposes the idea of evaluation system, with trend and loss evaluation model of secondary device set up, which is useful for equipment condition monitoring and assessment in smart substation. Multi-parameter identification method is firstly introduced, by “horizontal comparison and longitudinal check”, the correction of device state can be guaranteed. Standard of score for different parameters...
Since the power systems become complicated, the probability and perniciousness of multi-concurrent outages keep rising, especially under some extreme weather conditions like typhoon. Thus, operational risk assessment methods are very useful for system operation to evaluate the reliability of power grids under extreme weather. To calculate the forced outage rate (FOR) for components, common reliability...
The installed capacity of photovoltaic (PV) generation in residential distribution system is growing rapidly around the world. While integrating PV into the distribution systems can provide a range of benefits, a severe issue caused by high-level PV penetration is the reverse power flow along the distribution feeder. Due to the high R/X ratio in the distribution systems, real power exporting can lead...
Despite of the high reliability of power transformers, in view of the serious consequences of failures, it is important that an effective condition assessment system as condition based maintenance under smart grid operations is vitally important so that faults can be detected at an early stage in order to improve the prospects for repairs and minimize the impact of any failures, under more optimization...
This paper presents a H∞ dynamic output feedback control scheme for load frequency control (LFC) of interconnected power systems with multiple input time-delays. In this study, electric vehicles (EVs) are participated in the LFC to support reheated thermal power units to rapidly suppress load and frequency fluctuations. A mathematical model of an interconnected power system is first introduced. This...
This paper presents an improved stability criterion for load frequency control (LFC) of time-delay power systems including AC/HVDC transmission links and EVs. By employing a novel refined Jensen-based inequality, an improved stability condition is derived in terms of feasible linear matrix inequalities (LMIs) which allow us to compute the maximal upper bounds of time-delay ensuring stability of the...
This short note tries to propose a somewhat different structure of the prevalent power system analysis approaches as a research idea for the near future power grids. It proposes a change in attitude to deal with power system basic analysis such as load flow, fault analysis, transient stability, harmonic analysis, and so on; the new attitude seem more suitable than prevalent frameworks for the coming...
In recent year Distributed generation (DG) has become a point of interest in many countries due to several advantages such as improvement in power reliability, reduction of loss in transmission system, improved efficiency in network and lower environment impact. With this much benefit many networks working on integrate renewable energy source DG to the grid connection. Although it has many advantages,...
When wind blows through a wind farm with multiple rows of wind turbines, the wind speed on a downstream wind turbine is usually lower than that on an upstream wind turbine. This phenomenon is called wake effect. During the design stage of a wind farm, the study of wake effects will affect the most suitable location of each wind turbine. The major factors influencing the wake losses include the incoming...
This paper deals with control of a linear magnetic-geared permanent-magnet generator for wave power generation using maximum power point tracking (MPPT) algorithm. Firstly, the linear magnetic-geared permanent-magnet generator structure is presented. The machine modeling is established based on the finite element analysis (FEA). Secondly, by analyzing the dynamic model of the wave power, the MPPT...
The main work during the initial stage of power system restoration is to restart the generators. At present, searching the optimal recovery path is mainly based on the objective of restoring the whole system. Considering that the DC converter station is able to supply large amounts of power generation, it can accelerate the restoration, if the DC converter station is restarted preferentially. However,...
Microgrid cluster is a multi-microgrid system containing cluster-level control. Compared to single microgrid, whether microgrid cluster is able to improve the reliability effectively is a crucial problem in the developing process of microgrid technology, which is thoroughly analyzed in this paper. Topology of a typical microgrid cluster is presented first. Because the reliability of microgrid cluster...
In recent years, the development of offshore wind farms has increasingly become larger in scale. The integration of large-scale wind farms increases the potential risk to the stable operation of power grids. One of the challenges comes from the possible switching overvoltage of the power system in offshore wind farms because insulation accidents caused by overvoltage have become one of the prominent...
Distributed control can be applied to a virtual power plant (VPP) to allocate electrical power among distributed generators (DGs). By using consensus algorithm and selecting the incremental cost of each DG as the consensus variable, economic dispatch of the VPP can be realized in a distributed manner. Therefore, only local communication among DGs is required and some performance limitations caused...
In this paper, limitations of the online DSA based on the real-time data are analyzed. And thus three kinds of DSA application modes are proposed including real-time analysis mode, intervention analysis mode and trend analysis mode. Concrete research purpose, source data and processing flow of proposed application modes are expounded respectively. Overall work flow of on-line DSA involved proposed...
Control of three-phase grid-connected voltage source converter under unbalanced grid faults greatly depends on the active and reactive powers processed by the converter. The instantaneous active power theory with sequence decomposition is employed to analyze the instantaneous power components, especially the second-order oscillation power. Study shows that the second-order oscillation power comprises...
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.