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A common practice for improving electric service reliability is to provide an alternate source of supply. On the distribution system, two feeders — each with one or more mid-line overcurrent protective devices — can be tied together through a normally-open tie point to restore service to unfaulted sections of line. Conventional looped distribution systems rely on overcurrent coordination to ensure...
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 protective concept for EHV Three-terminal transmission line, teed circuit. The proposed protective relaying techniques use the fourth sequential overlapping derivative, SOD, concept at all line terminals. The SOD signals represent the transient components initiated due to fault occurrence. Such signals are free of both dc and fundamental components. Two protective relaying...
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...
Generation schedule optimization means scheduling unit commitment, economic dispatch and auxiliary service of generators to minimize total cost for specified time scope by considering system balance constraints, generator operation constraints, grid security constraints, energy saving and emission reduction constraints. Generation schedule optimization is a continuous promoting procedure. In order...
High impedance fault (HIF) exposes great hazard for personal safety and property security. High impedance fault (HIF) in MV distribution with restricted fault current cannot be detected and cleared by conventional over current relays. In this paper, an integrated scheme utilizing different features of HIF is presented. Various documented field data has been investigated and summarized to get the most...
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...
This paper presents a novel approach for the detection of abnormal power system states that force systems into blackout. K-means clustering techniques and two types of distances for identifying pattern clusters are used to detect abnormal conditions. PCA is used for the reduction of the data matrix for faster calculations. The proposed hybrid technique is then demonstrated on an IEEE 14-bus system.
In this paper, the impacts of DERs on the designed SPSs are investigated and some solutions based on the progressively developing communication infrastructure of the newly evolving smart grids are proposed to maintain the integrity of the power system in extreme contingencies. A sample system with high penetration of DERs is considered and a SPS is designed for the system. Afterwards the impact of...
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...
Protection of an inverter dominated microgrid is always a great challenge, as inverters are well known for their insufficient contribution to the fault current, undermining the accuracy and viability of traditional overcurrent protection schemes. Based on the wide review of solutions developed in the past, this paper proposes a novel protection strategy, with the main protection method based on the...
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...
Recently the importance of Wide-Area Situational Awareness (WASA) has increased as it can form the basis for power system stabilisation systems or be part of a smart grid. The standardisation of communication interfaces with the ability to integrate many kinds of sub systems becomes increasingly important in enabling the build of a standard WASA system. In Japan, Wide Area Monitoring, Protection and...
Wide-area Situational Awareness (WASA) is of key importance in power system operators' decision-making. Lack of WASA can set in motion cascading failures, or contribute to the development of a blackout. Inadequate WASA was actually identified as one of the major causes of several blackouts in the last decade. A variety of factors in a power system control centre can affect the formation of WASA, especially...
Testing of Phasor Measurement Units (PMU devices) is necessary for any PMU application, be it a simple visualization and archiving system or a more complex set of real-time system operations tools. PMUs are available from virtually every manufacturer of protection and monitoring equipment. They are often implemented as embedded functions within relays or disturbance recorders. This paper describes...
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