• Journal of Electrical Engineering and Technology
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• 제12권2호
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• pp.612-620
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• 2017

Relay coordination in power system is a complex problem and so far, meta-heuristic algorithms and other methods as an alternative approach may not properly deal with large scale relay coordination due to their huge time consuming computation. In some cases the relay coordination could be unachievable. As the urgency for a proper approach is essential, in this paper an innovative and simple relay coordination method is introduced that is able to be applied on optimization algorithms for relay protection coordination. The objective function equation of operating time of relays are divided into two separate functions with less constraints. As the analytical results show here, this equivalent method has a remarkable speed with high accuracy to coordinate directional relays. Two distribution systems including directional overcurrent relays are studied in DigSILENT software and the collected data are examined in MATLAB. The relay settings of this method are compared with particle swarm optimization and genetic algorithm. The analytical results show the correctness of this mathematical and practical approach. This fast coordination method has a proper velocity of convergence with low iteration that can be used in large scale systems in practice and also to provide a feasible solution for protection coordination in smart grids as online or offline protection coordination.

• 전기학회논문지
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• 제56권9호
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• pp.1521-1526
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• 2007

This paper presents the application of Adaptive Evolutionary Algorithm (AEA) to search an optimal setting of overcurrent relay coordination to protect ring distribution systems. The AEA takes the merits of both a genetic algorithm (GA) and an evolution strategy (ES) in an adaptive manner to use the global search capability of GA and the local search capability of ES. The overcurrent relay settings and coordination requirements are formulated into a set of constraint equations and an objective function is developed to manage the overcurrent relay settings by the Time Coordination Method. The domain of overcurrent relays coordination for the ring-fed distribution systems is a non-linear system with a lot of local optimum points and a highly constrained optimization problem. Thus conventional methods fail in searching for the global optimum. AEA is employed to search for the optimum relay settings with maximum satisfaction of coordination constraints. The simulation results show that the proposed method can optimize the overcurrent relay settings, reduce relay mis-coordinated operations, and find better optimal overcurrent relay settings than the present available methods.

• 전기학회논문지
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• 제66권8호
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• pp.1187-1194
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• 2017

After North American wide area black out on August 14, 2003, various studies have been conducted to find out the reason of the disaster. One of main reasons was misoperation of generator protection system. Since then, protective coordination between generator protection system and excitation system controls has been hot issue among electrical engineers. Among various generator protection relays, in this paper, we focused on generator overvoltage and overexcitation relay, which protect the over-flux condition of the generator. Thus, at first, we modeled the generator overvoltage, overexcitation relay and detailed power system including excitation system, governor and etc., based on actual field data. And then, we reviewed the protective coordination of generator overvoltage and overexcitation relay using electromagnetic transient program. In addition, we discussed the protective coordination method for redundant protection relays in both automatic voltage regulator and generator side.

• 대한전기학회논문지:전력기술부문A
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• 제51권10호
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• pp.518-524
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• 2002

A software system that has functions of setting and coordination checking of protective relays in power transmission system has been developed. The developed system utilizes database system to store the setting values of protective relays, power system parameters, checks the relay operation and evaluates coordination of relays in real Power system or test system. The fault data to simulates a fault to evaluate the coordination of relays is generated by PSS/E and EMTP. A universal logic generator module is added to adopt the variation of each relay＇s trip logic. The proposed system has been verified through many tests in the case study, and proved to be very powerful in inspecting the setting values and coordination of relays.

• Journal of Electrical Engineering and Technology
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• 제7권2호
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• pp.151-156
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• 2012

The current study presents a zero-one integer programming approach to determine the minimum break point set for the coordination of directional relays. First, the network is reduced if there are any parallel lines or three-end nodes. Second, all the directed loops are enumerated to reduce the iteration. Finally, the problem is formulated as a set-covering problem, and the break point set is determined using the zero-one integer programming technique. Arbitrary starting relay locations and the arbitrary consideration of relay sequence to set and coordinate relays result in navigating the loops many times and futile attempts to achieve system-wide relay coordination. These algorithms are compared with the existing methods, and the results are presented. The problem is formulated as a setcovering problem solved by the zero-one integer programming approach using LINGO 12, an optimization modeling software.

• 전기학회논문지
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• 제60권1호
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• pp.43-49
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• 2011

A distance relay scheme is commonly used for backup protection. This scheme, called a step distance protection, is comprised of 3 steps for graded zones having different operating time. As for the conventional step distance protection scheme, Zone 2 can exceed the ordinary coverage excessively in case of a transformer protection relay especially. In this case, there can be overlapped protection area from a backup protection relay and, therefore, malfunctions can occur when any fault occurs in the overlapped protection area. Distance relays and overcurrent relays are used for backup protection generally, and both relays have normally this problem, the maloperation, caused by a fault in the overlapped protection area. Corresponding to an IEEE standard, this problem can be solved with the modification of the operating time. On the other hand, in Korea, zones are modified to cope with this problem in some specific conditions. These two methods may not be obvious to handle this problem correctly because these methods, modifying the common rules, can cause another coordination problem. To overcome this problem clearly, this paper describes an improved backup protection coordination scheme using an IEC 61850-based distance relay for transformer backup protection. IEC 61850-based IED(Intelligent Electronic Device) and the network system based on the kernel 2.6 LINUX are realized to verify the proposed method. And laboratory tests to estimate the communication time show that the proposed coordination method is reliable enough for the improved backup protection scheme.

• KIEE International Transactions on Power Engineering
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• 제2A권3호
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• pp.83-88
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• 2002

An over current relay(OCR), one of the most frequently used protective devices, has time-current characteristics (TCC) to control its trip time according to the current level. It is because an appropriate operating time interval is necessary for coordination with other protective devices. A set of TCC curves of an OCR is, in general, given by the supplier from which a curve is selected by the operator. Therefore, in many cases, it is impossible to consider the operation condition of the given power system exactly. A novel concept of an OCR is suggested in this paper. The proposed OCR has an internal correction module so that it may produce the most adequate TCC curve according to the given protective information for coordination with other devices. With the generated TCC curve, a variety of operation and coordination conditions can be taken into consideration in an effective manner. The suggested OCR is applied to a simple test power system to show very promising results from a coordination point of view.

• 한국정보전자통신기술학회논문지
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• 제13권6호
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• pp.562-567
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• 2020

본 논문은 저장 탱크용 임시전력설비를 보호하기 위한 목적으로 특히 변압기를 감시하고 절연파괴 등과 같은 고장을 차단하고 보호하기 위한 보호계전기 정정에 관한 연구이다. 전력계통에 단락 또는 지락고장 등과 같은 이상이 발생하였을 때 이를 검출하여 고장이 발생한 기기 및 설비를 신속하게 차단하고 전력계통으로부터 분리하여 전력공급에 지장이 없도록 하여야 한다. 전력계통의 이상 상태를 빠르고 정확하게 감지할 수 있는 보호계전기의 정정이 중요하다. 또한 보호협조를 위해 고장종류와 고장의 원인을 정확히 적용한 고장전류 계산이 보호계전기 정정에 가장 중요한 요소이다. 저장 탱크용 임시전력설비 보호를 위해 적용하는 과전류계전기, 지락과전류계전기, 부족전압계전기, 지락과전압계전기 등이 보호협조가 가능하도록 보호계전기 정정 방법에 대해 연구하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 하계학술대회 논문집
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• pp.437-439
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• 1991

This paper deals with the development of computer programs that can be used for fuse and relay coordination in power station and also with the characteristics of these protective devices. The coordination of protective devices is determined by caculation from the lowest voltage level back to the power source. The minimum time difference between two different characteristics on the time- current curves is determined by the Golden Section searching routine.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.209-210
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• 2011

This paper proposed protective coordination on HTS(High Temperature Superconducting) cable on 22.9kV distributed system. HTS cable transient model is developed and tested using EMTP-RV, system protective coordination is studied with ETAP. Possible contingency and protective scheme are considered real distribution system in Icheon substation. The simulation results was showed, in protective case to apply conventional relay, that appeared problem on HTS cable inner part. The HTS cable couldn't protection on contingency state of power system. It was using high-speed relay system instead of conventional relay system. Then, the HTS cable was protected contingency by circuit breaker.