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 an analysis of the main operating conditions that may lead to inappropriate differential protection operation. These conditions were simulated using the Alternative Transients Program (ATP) and the model of a real system. The saturable transformer was the main component of the ATP/EMTP simulations. The saturation and hysteresis effects are represented by a non-linear model of the...
This paper presents a novel approach designed for centralize substation level protection to determine the faulty feeder in a distribution network In opposite to phase-to-earth faults in the transmission networks (HV), which neutral points are solidly earthed, fault-loops in a fault-to-earth case in MV distribution networks have big impedance. Additionally during the earth-fault the transient component...
IEC 61850 supports the use of functional designs for specifying substation automation systems. However, specifying such systems is not standardized within IEC 61850. This means that utilities are somehow left in the dark regarding the use of the engineering process defined in IEC 61850–6 and therefore often revert to using traditional and proprietary ways to specify their requirements. To overcome...
Magnitude and duration of voltage sags are the most important two factors to the Lower Voltage Ride Through (LVRT) capacity of the wind generator. Since most voltage sags are caused by the system faults, and sag durations are controlled by the tripping time of overcurrent relay in power collection lines based on the sags' magnitude. The specification of the LVRT capacity of wind generator is introduced...
On distribution systems similar to that shown in Figure 1, in the event of a single phase to earth fault, the source protection will trip on earth fault. After the source has cleared, an unearthed network is left, backfed via the primary substation. Other than a very low level charging current, no fault current will flow. UK Power Networks detect this by neutral voltage displacement (NVD). Where a...
In this paper wide-area protection is discussed in smart microgrids. Smart grids inherently propose opportunities to enhance the protection of the lines due to the communication capabilities that present. Smart distribution microgrids would have a communication infrastructure that promotes the performance of their protection decisions. The paper considers a sample microgrid with the required communication...
In this paper, the application of static series compensator as a fault current limiter is proposed to preserve the integrity of the overcurrent relays' settings in a microgrid for both modes of operations, i.e., utility-grid connected and autonomous (islanded). Static series compensator could be multiple low-power single-phase inverters that attach to the overhead conductor and dynamically control...
The authors plan to roll out a next generation platform for protection and control solutions, with the aim of mobilising the latest developments in information and communication technology, in order to deliver new opportunities to the user. The goal of the next generation platform is to fully satisfy the requirements of all users in terms of functionality and performance, while achieving the highest...
In this paper, the capability of the numerical relays within the microgrid is sophisticatedly used to adapt the settings of the relays to the status of the microgrid. Different settings for the overcurrent relays are calculated off-line and saved in the relays. Whenever the microgrid is disconnected from the grid, the settings are automatically changed to the associated group of settings. This would...
Due to its current limitation, Inverter-interfaced Distributed Generation (IIDG) is supposed to have little impact on protection system of distribution networks. However, in case of high power IIDG, the situation could be changed. This paper aims to show situations in which IIDG could provoke false tripping to overcurrent protections along distribution feeders. Proposed solution is to provide directional...
Transformer differential protection schemes normally use multi slope characteristics to provide stability during CT saturation with 2nd harmonic restraint or blocking for inrush conditions. This paper presents new algorithms that have been developed to improve the performance of the differential protection. Extensive testing has been used to demonstrate that the transient bias algorithm can reduce...
Effective voltage control is essential for the satisfactory operation of distribution networks. The increased connection of distributed generation to existing distribution networks challenges the current methods of controlling network voltages. Network voltage is primarily controlled by changing tap position of the primary transformers. The transformer secondary voltage will be automatically increased...
Transformers are critical to the successful operation of the electrical power systems. Their reliability and availability is therefore key to flawless and optimum power generation and transmission. Effective condition monitoring is essential to evaluate transformer performance and safe operating conditions. Over the past few years many stand-alone devices have been developed for transformer condition...
This paper aims to present the modeling and simulation of numerical differential protection of power transformers using the software ATP/ATPDraw and its MODELS environment. In order to validate the relay model, simulations were carried out using a simplified electrical power system whose parameters were obtained from a real system. The results reveal the advantages of using this type of modeling,...
Injection-based 100% stator earth-fault protection has been used for many years. However traditionally signals with frequency between 10Hz and 25Hz have been injected into the stator winding. To inject such a signal, either a dedicated grounding transformer with secondary grounding resistor or injection on primary side of the grounding circuit, is normally used. This paper will present a novel approach...
IEC 61850 is the new standard for communications in substations that defines a new generation of protection applications based on high speed peer-to-peer communications between different substation devices. Accelerated protection schemes use permissive or blocking signals exchanged between relays at the two or more ends of the protected transmission line in order to provide fast fault clearing for...
This paper proposes a Multi-agent System (MAS) approach to coordinate overcurrent relays, aiming to protect distribution systems with distributed generators. The connection of distributed generation (DG) units causes a reduction in the efficacy of protection systems coordination and, in some cases, an increase of operating times. Coordination studies aim to guarantee the protection selectivity in...
A dispatch-oriented risk perception and fault disposal decision support technique for online monitoring and control is proposed in this paper. It helps to improve the sensitivity and accuracy of risk perception by multi-source information mining based on data from SCADA, relay, WAMS and other measurement systems. And it provides a direct means to grasp the whole process of incident handling by online...
The increase of the electric power demand is at the level 2–3% per year, and in some regions of the world may become much higher. In the same time the infrastructure of power systems develop much slower. The smart grid technology is to use modern telecommunication and informatics to bridge the gap. The aim is to integrate generation, transmission, distribution and consumption of the electrical energy...
Adaptive power system protection can be used to improve the performance of existing protection schemes under certain network conditions. However, their deployment in the field is impeded by their perceived inferior reliability compared to existing protection arrangements. Moreover, their validation can be problematic due to the perceived high likelihood of the occurrence of failure modes or incorrect...
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.