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A novel current differential relay principle based on Marti model is proposed in this paper. Compared with Bergeron model based differential protection, the frequency-dependent characteristic of line parameters is taken into account in the new principle, so that the calculating result is more accurate. Simulating comparison have been carried out between the proposed protective principle and Bergeron...
The paper will present a utility experience from a project where protection and control for the whole substation is done by using IEC 61850 Standard. The special attention will be given to the control of parallel transformers with on-load tap-changer (OLTC), which has been achieved by using IEC 61850 analogue GOOSE messages between the regulators. In this substation, there are two 20MVA, 110/20kV,...
Protective systems are essential for the safe operation of electrical power systems. The correct operation of a protection relay needs to be verified during its lifecycle, through production, to on-site commissioning and periodic maintenance. This paper presents an application designed to simulate the substation and power system protection of CEMIG GT in Brazil by means of a virtual reality environment...
Operational Telecommunications (OpTel) play a vital role in the safe, reliable and efficient operation of a power distribution network. Over the time, different OpTel services and technologies have developed around individual power system applications. This has resulted in the creation of isolated islands of telecommunication technologies. The technologies associated with telecommunication services,...
Short term load forecasting (STLF) is necessary for economic and reliable timely information to operate an energy system and secure electricity. In this study, STLF systems were developed for nine load distribution regions of Turkey using artificial neural networks (ANN) approach. To our knowledge this is the first study that estimated the short term hourly load of all load distribution regions of...
Throughout the years different testing tools have been used successfully for all types of relays. Traditional methods like current ramping applied in many cases. These traditional methods work well with classical protection functions and equipment. But the requirements on the protection system are changing and so does the protection system; examples: - Increasing complexity of multifunctional equipment...
In this paper, we first review backup protection concepts and analyze the impact of breaker failure protection on power system stability. We then show the importance of having different breaker failure operating times for different types of faults. Finally, we discuss the effect of fault detector reset time and describe fast-reset instantaneous overcurrent elements.
As busbar is one of the most important power system nodes, the busbar protection is an essential component in network design, considering the power system stability and security. So busbar protection should fulfill the requirements of fast operating times for all kinds of busbar faults, security for external faults with heavy current-transformer (CT) saturation, and minimum delay for evolving faults...
Due to integration of distributed generation the operation of medium-voltage distribution networks is becoming more difficult. This paper decribes a dedicated simulation tool that can be used to study the protection coordination n the network‥ One of the main advantages of the program is that it systematically analyses a complete network in one simulation. It simulates faults in the whole network...
The autoreclose function contained within protection relays can be applied to various EHV/HV network configurations and provides three main types: single-phase, three-phase and multi-phase.
The paper investigates the current capabilities in communication-aided protection made possible by the IEC 61850 standard. Additionally, it explicitly describes the concept of integrated protection unit and the IEC61850-9-2 process bus concept. It also discusses techniques to encompass intersubstation communications and examines issues that need to be addressed to create a successful, secure and dependable...
This paper puts forward a new transformer self-adaptive protection principle. The principle is based on equivalent equation. The principle mainly includes three components: parameter estimation unit, high speed protection unit and fault component protection unit. When there is serious fault in transformer, the high speed protection unit can act quickly. When there is weak fault in transformer, the...
In radial distribution systems, three step current protection, also called overcurrent protection, has been widely used for many years. When distributed generators (DGs) are connected to a radial distribution system, they will have some effects on the traditional overcurrent protection scheme and may lead to false tripping. This paper proposed a new communication supported fast current protection...
An improved differential equation method for earth fault location in non-effectively earthed system is proposed. Karrenbauer transformation is used to construct the compound mode network of single phase earth fault. Based on the mode network, the fault equation including mode voltage, mode current, line parameters and earthed resistance is derived .The fault distance can be gotten by solving the equation...
This paper investigates the use of wide area measurements to estimate the damping of power system oscillations. At present, most damping estimation methods use a single measurement. Two test systems are simulated and a subspace identification method is used to demonstrate that having multiple measurements can improve the estimate.
Shunt reactors are installed on long lines (in this case a 435km 765kV line) to reduce over voltages experienced when the load is suddenly lost and to control voltages under lightly loaded conditions. When the compensated line is opened to clear a fault, it is found that the open-phase voltage does not disappear. A transient voltage waveform with a resonant frequency between 35Hz and 45Hz can be seen...
Potential transformer (PT) ferroresonance might happen due to a capacitance when a circuit breaker is opened. In this case, the iron core repeats saturation and unsaturation. This paper describes an analytical analysis of PT ferroresonance in the transient-state. In this paper, the iron core is modelled by simplified two-segment core model to analyze ferroresonance analytically. Thus, a nonlinear...
Modern electric power protection, monitoring, and control systems rely on the availability of high-accuracy time. Precise time enables technologies like synchrophasors, IEC 61850 Process Bus, and highly accurate, wide-area power system event reporting. Today, high-accuracy time is generally provided by Global Positioning System (GPS) clocks. However, if GPS is the only source of accurate time, it...
There are increasing uptaking of distributed generation in distribution networks in the UK due to the increased usage of renewable generations such as windfarms and biomass. Distribution networks were not designed for this purpose and there are concerns on the impact of the generator connection on network protection. This paper gives a brief review of the arrangements of network protection and auto...
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