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A decentralized coordinated control is researched based on multi-agent structure for transient stability improvement of large-scale power system in this paper. First, a multi-agent system (MAS) model is structured based on the wide-area measurement system (WAMS), which consists of both upper and lower level agents. The upper level coordinated agents are mainly responsible for coordinating and controlling...
Progress in the development of communication network technology continues apace and Ethernet technology, once limited to local area network applications, is increasingly being considered for use as the backbone technology for wide area communication networks. The technology, most commonly referred to as “Carrier Ethernet”, seems likely to become the dominant technology within wide area networks ultimately...
Although there has been a practice of transposition of transmission lines, most of the real life EHV/UHV lines are untransposed. The distance protection of such lines becomes very complicated. With the advent of Global Positioning System (GPS) and Fiber optics technology, current differential protection can be a better choice for such lines. This paper proposes current differential protection scheme...
The paper describes the concept of synchrophasors and the introduction of synchrophasors for protection applications in IEEE PC37.118.1 and then discusses different substation and transmission line protection applications. Requirements for reporting rate, time synchronization and communications architecture are discussed. Testing of protection systems based on PMUs is described at the end of the paper.
A transient fault information based IED integrating protection fault location, fault record, measurement and control functions for transmission line is proposed in this paper. IED hardware scheme adopts multiple CPU distributed structure, and includes mainly the following modules: process level communication module, protection module, fault location and record module, measurement and control module,...
There were many accidents of large-scale wind turbines disconnecting from power grid in 2011. Single-phase-to-ground fault cannot be correctly detected. Single-phase-to-ground evolved to phase-to-phase fault. Phase-to-phase fault was isolated slowly, which led to low voltage. And wind turbines without enough low voltage ride-through capacity disconnected from the grid. After some wind turbines disconnected...
A large-scale implementation of distributed generation (DG) for households involves each house generating its energy from photovoltaic (PV) cells. This approach is particularly suitable in rural electrification projects where demand is relatively low and yet grid connection is costly. A meshed microgrid is an attractive solution for energy generation and sharing in domestic electrification projects...
This paper proposed a new power grid fault diagnosis model combining Petri nets and grid computing. It includes the power grid computing system's structure, software service and algorithm. The model can use the high performance computing method and distributed environment of grid computing. At the same time, Data grid system can offer table, efficient and unified information resources for the power...
The paper presents a novel idea to detect transient single-phase-to-ground fault based on current travelling waves in power distribution system with neutral non-effectively grounded, and an implemented scheme of protective relays based on current travelling waves and power-frequency voltages, which can identify not only permanent single-phase-to-ground faulted feeder but transient faulted feeder,...
A single-machine-equivalent (SIME) based emergency control (EC) scheme that incorporates synchronized measurements is described in the paper. This EC scheme resolves the transient stability problems experienced when serious disturbance occurs on critical transmission lines. The control actions are based on modifying the impedance of a thyristor controlled series compensator (TCSC). The SIME approach...
This paper presents a combined method for discrimination between inrush current and internal fault current of power transformers. The mentioned method is based on wavelet analysis of power system frequency which is estimated by Prony method. The Prony method is utilized to estimate power system frequency with three consecutive samples rapidly and also Daubechies wavelet family uses the estimated frequency...
This paper introduces a method for marine system fault location which uses the voltage and current transient information measured at a power supply point and the remote point beyond the fault location to estimate the fault position. The proposed algorithm is demonstrated by computer simulation and also a laboratory experimental test.
Since electrical load forecasting plays significant role in effective and economic operation of power utilities, it has long been of interest to researchers and academics. This paper combined artificial neural network and regression modelling methods to predict electrical load. We propose an approach for specific day, week and/or month load forecasting for electrical companies taking into account...
Fuse-saving practices have coordination limitations at higher current levels — it is common for the upline device to trip and the fuse to operate at the same time. The result is frequent momentary outages for many customers and blown fuses, even for temporary faults. These challenges have led some utilities to abandon the practice of fuse-saving and instead migrate to a fuse-blowing philosophy. The...
Over the years, different methods have been used in order to avoid problems with load encroachment, and each method presents its own set of advantages and disadvantages. Regardless of the method used, each relay will have a maximum "loadability limit" that will cause the relay to operate under high load conditions. Therefore, it is important for the relay engineer to understand and take...
The standard IEC 61850 contributes the manufacturers and the end users. But it also makes many obstacles to the modification of the conventional substation. This paper presents a scheme which modifies an in-service conventional substation gradually to a modern substation which conforms to IEC 61850 standards. The procedure of the modification is divided into three stages. During the first stage, all...
This paper presents the measured impedance at the relaying point in the presence of Static Var Compensator (SVC), one of the shunt connected Flexible Alternating Current Transmission System (FACTS) devices; in the case of inter phase, phase to phase and three phase, faults. The presence of SVC on a transmission line has a great influence on the measured impedance at the relaying point. In the presence...
Busbar protection is described for a bus with current inputs for up to 32 bays. For busbar protection with IEDs and MUs using IEC61850–9–2 process bus, communication traffic jams are the main concern, due to transferring 80 samples/cycle data from all bay MUs to IED via 100BASE-FX. This paper describes peer-to-peer connection between MUs and IED in order to segrigate the SV messages of 32 bays on...
This paper describes how increased functionality of the Network Rail Integrated Protection and Control (IPC) extended IEC 61850 station bus solution unlocks the ability to rationalise the electrification system design, and hence achieve a substantial reduction in primary plant requirements when delivering the new railway electrification schemes committed by the Government.
The project to install new cables in the Woodhead Tunnel forming part of National Grid's (NGET) 400kV transmission system running across the Pennines, requires a state of the art cable monitoring and protection system. The availability of IEC61850 offers the opportunity to provide a simple but effective system in an early long haul application.
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