Turn-to-turn fault protection technique for synchronous machines without additional voltage transformers

This paper presents a novel protection technique for the detection of inter-turn faults in synchronous machines. It is based on the calculation of voltage in the stator windings from the usual phases and neutral voltage, typically available in allgenerator protection relays. The existing turn-to-turn protection mechanisms require additional voltage transformers. The main contribution of this technique is that it can be implemented without using any additional voltage transformers. Thistechnique has been successfully tested in a special synchronous machine with taps in the stator windings, where turn-to-turn faults have been created

Application of Advanced Early Warning Systems with Adaptive Protection

This project developed and field-tested two methods of Adaptive Protection systems utilizing synchrophasor data. One method detects conditions of system stress that can lead to unintended relay operation, and initiates a supervisory signal to modify relay response in real time to avoid false trips. The second method detects the possibility of false trips of impedance relays as stable system swings “encroach” on the relays’ impedance zones, and produces an early warning so that relay engineers can re-evaluate relay settings. In addition, real-time synchrophasor data produced by this project was used to develop advanced visualization techniques for display of synchrophasor data to utility operators and engineers

Studi Metode Penggantian Relai Mekanis Menjadi Elektris Panel Tegangan Menengah Pltu Unit 4 Muara Karang

Protective Relay is a device that provides alarm and trip / open signals to circuit breakers due to interference with protected equipment. Replacement of protection relay at the switchgear location of PLTU unit 4 Muara karang has been planned since 2010 and realized in December 2016 this coincides with Over Houl Mean Inspection. There are several problems encountered in the replacement of switchgear protection relays. The problem faced in performing this switchgear protective relay replacement is on mechanical relays that are replaced into electrical relays requiring many modifications and work steps. So in conducting this research is needed a proper method of research in order to produce a system of protection that is feasible operatio

Standardization of power system protection settings using IEC 61850 for improved interoperability

One of the potential benefits of smart grid development is that data becomes more open and available for use by multiple applications. Many existing protection relays use proprietary formats for storing protection settings. This paper proposes to apply the IEC 61850 data model and System Configuration description Language (SCL), which are formally defined, to represent protection settings. Protection setting files in proprietary formats are parsed using rule-based reasoning, mapped to the IEC 61850 data model, and exported as SCL files. An important application of using SCL-based protection setting files is to achieve protection setting interoperability, which could bring multiple compelling benefits, such as significantly streamlining the IED configuration process and releasing utilities from being “locked in” to one particular vendor. For this purpose, this paper proposes a uniform configuration process for future IEDs. The challenges involved in the implementation of the proposed approach are discussed and possible solutions are presented

An Adaptive Overcurrent Coordination Scheme to Improve Relay Sensitivity and Overcome Drawbacks due to Distributed Generation in Smart Grids

Distributed Generation (DG) brought new challenges for protection engineers since standard relay settings of traditional system may no longer function properly under increasing presence of DG. The extreme case is coordination loss between primary and backup relays. The directional overcurrent relay (DOCR) which is the most implemented protective device in the electrical network also suffers performance degradation in presence of DG. Therefore, this paper proposes the mitigation of DG impact on DOCR coordination employing adaptive protection scheme (APS) using differential evolution algorithm (DE) while improving overall sensitivity of relays . The impacts of DG prior and after the application of APS are presented based on interconnected 6 bus and IEEE 14 bus system. As a consequence, general sensitivity improvement and mitigation scheme is proposed

Influence of fault-ride-through requirements for distributed generators on the protection coordination of an actual distribution system with reclosers

This paper analyses the existing protection scheme of a real distribution system with distributed generators, in Greece. Network protection utilizes three successive reclosers at the main trunk and fuses at the laterals. The generating units are protected by overcurrent and voltage/frequency relays. The analysis focuses on the fault-ride-through capability of the generating units and proposes the resetting of the generators and network protection relays so as to conform to the requirements imposed by distribution system operators and international standards. The proposed protection system guarantees selectivity for any short-circuits occurring inside or outside the distribution system, irrelative if the generating units are connected to the network or not. Meaningful conclusions are derived from the application of the proposed protection coordination principle

Distance Protection for Microgrids in Distribution System

Owing to the increasing penetration of distributed generation, there are some challenges for the conventional protection in distribution system. Bidirectional power flow and variable fault current because of the various operation modes may lead to the selectivity and sensitivity of the overcurrent protection decreased. This paper adopts distance protection for one mid-voltage level microgrid in Aalborg, Denmark. Different operation modes of the network are analyzed and tested in the paper. The simulation results show that the variations of the fault currents seen by the forward relays are much larger than the backward relays. Meanwhile, the fault currents change little with the randomness of renewable energy except the intermittence. Finally, it shows that the designed distance protection has satisfactory performance to clear the various faults

Protection of Short Transmission Lines Using Microprocessor-Based Distance Relay

Distance protection is used for the protection of transmission or sub-transmission lines, usually 33 KV, 66 KV and 132 KV lines. A distance relay measures the distance between the relay location and the point of fault in terms of impedance, reactance, etc. An mpedance relay measures the line impedance between the fault point and relay location; a reactance relay measures reactance, and mho relay measures a component of admittance. With advances in technology, protective relays have progressed from electromechanical, to solid state to microprocessor-based relays. The increased growth of power systems both in size and complexity has brought about the need for fast and reliable relays to protect major equipment and to maintain system stability. With the development of economical, powerful and sophisticated microprocessors, there is a growing interest in developing microprocessor-based protective relays which are more flexible because of being programmable and are superior to conventional electromagnetic and static relays. The main features which have encouraged the design and development of microprocessor-based protective relays are their economy, compactness, reliability,flexibility and improved performance over conventional relays. The distance relays are preferred to over current relays because they are not nearly so much affected by changes in short-circuit-current magnitude as over current relays are, and, hence are much less affected by changes in generating capacity and in system configuration. This is because distance relays achieve selectivity on the basis of impedance rather than current. This thesis presents the design and operation technique for protection of short transmission lines using microprocessor-based distance relay. The characteristics of a distance relay is realised by comparing voltage and current at the relay location. The ratio of voltage (V) to current (I) gives the impedance of the line section between the relay location and the fault point. The signal will be taken from the transmission line and it will be converted to digital signal then goes to the microprocessor which has a program written in assembly language to estimate the resistance of the protected line, then the decision will be made according to this signal whether it is a fault signal or otherwise, and identify the faulty phases. The faults that have been tested are phase faults and the results have been indicated by giving the indication of the faulty phase at the same time giving signal to trip and isolate the faulty area. Different tests have been made successfully. The thesis presents one of these tests made practicall

Modeling of the behavior of AC undervoltage relays during voltage dips

This paper proposes a dynamic model for the behavior of an AC undervoltage protection relay during voltage dips. The behavior is expressed by means of standardized voltage tolerance curves and highly depends on the point on-wave (phase angle) of the dip initiation. Using the model, it can be explained that AC undervoltage relays are much more sensitive to voltage dips of e.g. 50% Urated than to short interruptions (0% Urated), caused by the magnetic behavior. The model takes into account the electrical, magnetic and mechanical system equations. An experimental set-up with a programmable power source as dipgenerator is build to validate the model. Finally, a complete weaving machine is represented to analyze the influence towards voltage dip immunity by adding an undervoltage protection relay