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Due to the high risk of cascading failures, an online solution for N-2 failure control becomes increasingly important. Dual short-circuit fault, as one of the simplest N-2 failure, was studied in this article. Some explorations were made aiming at the composition rules of critical cluster (CC) and the relationship between the dual short-circuit fault's conservative control quantity and the individual...
With rapid growth of installed wind power capacity worldwide and significant development of wind turbine generator (WTG) technologies, WTGs gradually have capability to participate in system frequency regulation. To this regard, the typical WTG frequency control strategies, such as inertial emulation, de-loading control, over-production and droop control are investigated in detail to reflect the development...
This paper is dedicated to analyze the economic issues related to the operation of microgrid system as well as exploring its benefits in improving reliability, energy saving and consumption reduction, environmental protection, investment deferral in transmission and distribution grids from the social perspective. It analyzes its cost and benefits in typical situations by the 2 typical cases of grid-connected...
The increased penetration of wind power generation has introduced significant uncertainty and complexity to power system operations, making the real-time dynamic security assessment (DSA) a necessity to protect the system against the risk of blackouts. As a promising strategy for real-time DSA, the intelligent system (IS)-based approach extracts the DSA knowledge from a dynamic security knowledgebase...
With the rapid development of smart grid and information technology, Energy Internet has been attracting increasing attention from government as well industry. Some landmark proposals in development of Energy Internet concept are reviewed and some basic features have been discussed. These include physical connection, protocol design, safety rules and the most important one, energy router design. Within...
Integrating a wind farm with a battery energy storage system (BESS) could improve the intermittence and randomness of the output power of the wind farm, and hence reduce the negative impacts on the security and economics of the power system concerned. Given this background, an improved control strategy is first proposed with the interactions between the current charging/discharging status of BESS...
A blackout usually starts with the failure of electrical power equipment, especially transmission lines. However, the fault probability of a transmission line is often assumed to have a specific value in the existing risk analysis, regardless of the complicated conditions and effectiveness. In this paper, we first decompose the transmission line risk sources into six components: line swaying, thunderstorms,...
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...
This paper discusses the framework and function of the integrated supervision and control system in a 220kV smart substation. Researching based on the device configuration schemes and network structures of the integration system have been carried out. An optimization design and feasibility analysis are proposed, which results to the capital cost of the substation reduction, the reliability of operation...
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...
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