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Locating high-resistance grounding faults poses a tough and challenging problem for the safety of DC railway systems. High-resistance grounding fault current isn't sufficient to trigger switches, which may expand the accident or turn into potential hazards. In order to overcome the limits of the existing methods (such as signal injecting method, resistance method and so), developing a novel fault...
Considering future smart distribution grid (SDG), the protection and control technology of traditional distribution networks is facing new opportunities and challenges. This paper proposes a Multi-Agent System (MAS) based protection and control method for smart distribution grid. The MAS is consist of intelligent distributed terminal (IDT), control master and communication network. Each IDT is regarded...
The paper presents a brief overview of the standard IEC60255–121 and focusses on the challenges and advantages of using transient simulation for assessing protective relays. The importance of the use of statistical methods to investigate the behaviour of algorithms is discussed. Finally a new solution for performing these kinds of tests is introduced.
Since IEC 61850 became the widely used standard for substation communication with a lot of implementations. Testing is an important issue. The standard in its current version covers some possibilities and approaches for testing in general and for measures of performance. Nevertheless some issues came out which needed to be clarified with the new edition of the standard. Edition 2 will be available...
This paper investigates a number of design, operation and lifetime management experiences of feeder unit protection systems installed on National Grid Electricity Transmission (NGET) UK networks. The paper will consider the policy, application design and operational experiences under the following categories in particular since the move to numeric protection: Policy and application design SDH communication...
This paper presents a new power controller for inverter-based renewable power generators, which is based on direct power control of active and reactive power. The controller included fast PLL and ROCOF units in order to function in both grid-connection and islanding operations. The controller's performance was tested by detailed computer simulation of a 2MVA renewable power generator with a DC-link...
This paper investigates how an on-load tap changer (OLTC) can be used to regulate the unbalanced three-phase voltages when single phase unbalanced loads are connected to a radial LV distribution feeder. An overview of current voltage regulation technologies for distribution network is presented. Two voltage regulation strategies are developed to eliminate the effect of the unbalanced single phase...
Domestic photovoltaic (PV) based microgrid refers to a distributed group of small solar PV systems installed at each household in a residential area. The distributed systems may be integrated to form a meshed microgrid structure which can operate in both islanded and grid-connected modes. Grid-connected microgrids of domestic solar PV systems can supplement energy needs of homeowners. They are a potentially...
This paper investigates a number of design, operation and lifetime management experiences of transformer protection systems installed on National Grid Electricity Transmission (NGET) networks. The paper will consider the policy, application design and operational experiences under the following categories particularly since the move to numeric protection: Policy and application design Operational...
The increasing integration of distributed and renewable energy sources into the electrical power network presents challenges for the operation and management of the network. New techniques are required to ensure the effective management of the balance between supply and demand, and the proper maintenance of voltage stability and power quality in the network. A new energy management system, designed...
Traction transformer is often on short-time overload state to meet the needs of traction load. In order to prevent the damage to the traction transformer caused by overthermal which is produced by load current, inverse time overcurrent protection is often used in China. Firstly, this paper introduces inverse time overcurrent protection and three standard characteristic equations of inverse time overcurrent...
Pantograph of an en-energized train may never run through n neutral section. As it does so, the arc generated across the pantograph will likely short the two feeding lines together at both sides of the neutral section where two phases are separated, The fault is called out-of-phase short-circuit fault for which short two out-of-phase feeding lines. Traditional feeder distance protection and current...
One of the main characteristics of Smart Grids is self healing. This means that the grid should rapidly detects, analyzes, acts and restores for system instabilities. Controlled islanding is one of the techniques used to mitigate these system instabilities. System islanding is often considered as the final stage of power system defense plans. The goal is to preserve stable areas of the faulted power...
Modern power supplies must provide reliable, high-quality power. Therefore, it is important that a transmission line fault be identified accurately, reliably and corrected as soon as possible. A method for classifying fault type based on short time Fourier transform (STFT) is provided in this paper. STFT is a means of signal processing in which a Fourier transform (FT) is performed by setting a window...
Most of current arc suppression coil compensation system works based on the magnitude of post-fault distributed capacitance. This system can not offer compensation before fault, so in power system with large distributed capacitance current, short circuit shock is inevitable. This paper proposes an automatic arc suppression coil compensation technology based on fixed-frequency signal injection, it...
Historically, the distribution network has been planned in order to operate in radial configuration. Protective relays are adopted to detect system abnormalities and to execute appropriate commands to isolate swiftly only the faulty component from the healthy system. Nowadays, the regulation schemes implemented by Regulators require that Distribution Companies reduce number and duration of supply...
A new method for detection occurrences of CT saturation is presented in this paper. The presented algorithm applies only first order derivatives of signals which is possible it has been designed in a new innovative methodology in which phase current signals are considered as coordinates of a 3D vector. The proposed algorithm is compared with standard one applying secondary current signal combined...
This paper proposes a novel transmission line protection scheme based on frequency-domain model identification method with distributed parameter. Integrated impedance is defined by voltages and currents of two end terminals of transmission line. By analyzing the frequency-domain expressions of integrated impedance in internal and external fault states, the amplitude-frequency characteristics of the...
This paper addresses the new method of controlling wind turbine connected to the grid and presents the approach for implementing wind energy as a distributed generation in a power system. With the aid of a fuzzy controller that regulates the modulation index of PWM inverter in an AC-DC-AC converter, and controllable battery storage connected to DC Bus, output of voltage even during changing wind speed...
Worldwide analysis of recent wide area cascading failures has shown that very often they were mainly caused by the maloperation of the third zone of a distance protection relay. The load encroachment and power swing phenomena are the two dire problems to solve when dealing with the third zone of distance protection. The vast number of blackouts could have been avoided or the consequences lowered if...
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