• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.1
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• pp.17-28
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• 2003

Digital technology has advanced very significantly over the years both in terms of software tools and hardware available. It is now applied extensively in many area of electrical engineering including protective relaying in power systems. Digital relays based on digital technology have many advantages over the traditional analog relays. The digital relay is able to do what is difficult or impossible in the analog relays. However, the complex algorithms associated with the digital relays are difficult to test and verify in real time on real power systems. Although non real-time simulators like PSCAD/EMTDC are employed to test the algorithms, such simulations have the disadvantage that they cannot test the relay dynamically. Hence, real-time simulators like RTDS are used, but the latter needs large space and it is very expensive. This paper uses EMTP MODELS to simulate the power system and the distance relay. The distance relay algorithm is constructed and the distance relay is interfaced with a test power system. The distance relays performance is then assessed interactively under various fault types, fault distances and fault inception angles. The test results show that we can simulate the distance relay effectively and we can examine the operation of the distance relay very closely including debugging by using EMTP MODELS.

• KIEE International Transactions on Power Engineering
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• v.4A no.1
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• pp.26-32
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• 2004

Digital technology has advanced significantly over the years both in terms of software tools and hardware availability. It is now applied extensively throughout many area of electrical engineering including protective relaying in power systems. Digital relays have numerous advantages over traditional analog relays, such as the ability to accomplish what is difficult or impossible using analog relays. Although non real-time simulators like PSCAD/EMTDC are employed to test the algorithms, such simulations are disadvantaged in that they cannot test the relay dynamically. Hence, real-time simulators like RTDS are used. However, the latter requires large space and is very expensive. This paper uses EMTP MODELS to simulate the power system and the distance relay. The distance relay algorithm is implemented and the distance relay is interfaced with a test power system. The distance relay's performance is then assessed interactively under various fault types, fault distances and fault inception angles. The test results show that we can simulate the distance relay effectively and we can examine the operation of the distance relay very closely including its drawbacks/limitations by using EMTP MODELS. Equally important, this approach facilitates any changes that need to be carried out in order to enhance the Distance Relay under test/examination.

• Journal of Electrical Engineering and Technology
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• v.3 no.3
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• pp.346-353
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• 2008

This paper defines the concept of “protectability” for the performance evaluation of distance relay considering its sensitivity and selectivity. The paper starts from the probabilistic modeling of the errors, and based on this model, a detailed explanation of protectability calculation for each zone of the distance relay is presented. An effect of the Weighting Rate and the Measurement Deviation on the protectability evaluation is also given. By considering this effect, the optimization of relay setting can be realized. The proposed method is applied to a typical model system to show its effectiveness

• Proceedings of the KIEE Conference
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• 2003.11a
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• pp.82-84
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• 2003

This paper presented a method to develop a relay model by the user-written model function of PSS/E. As for the voltage instability, although generator current limiters, transformer's tap-changers and dynamic loads have been considered as the dominant components, the protection system is also very important because it may influence the system's dynamic behaviour. Hence a distance relay model implemented with the suggested method was added, and then the operating characteristics of the distance relay under the voltage instability condition were investigated.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.29-30
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• 2008

This paper defines a concept of "protectability" for the performance evaluation of distance relay considering its sensitivity and selectivity. The paper starts from the probabilistic modeling of the errors, and based on this model, a detailed explanation of protectability calculation for each zone of the distance relay is presented. An effect of the Weighting Rate and the Measurement Deviation on the protectability evaluation is also given. By considering this effect, the optimization of relay setting can be realized. The proposed method is applied to a typical model system to show its effectiveness.

• Journal of Electrical Engineering and Technology
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• v.5 no.3
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• pp.407-414
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• 2010

This paper proposes a probability measure for the evaluation of relay performance from two aspects, namely, correct trip and no-unwanted trip. They are developed based on the relationship between relay settings and relay measurements, which follow a Gaussian probability model. The proposed method based on strict mathematical derivation is applied to protection capability evaluation of distance relays under various settings. Considering the specific attributes of each protection zone, the optimal settings are also determined accordingly. The protection capability could demonstrate clearly the relay performance under various settings and the optimal settings could provide good references for engineering applications.

• Proceedings of the KIEE Conference
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• 1997.07c
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• pp.997-999
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• 1997

This Paper presents a relay modeling technique to deal with the relay transient characteristics. Existing relay models are based on steady-state concepts. The ninth-order state space mathematical model of the Mho distance relay has been constructed. Computer modeling of a typical distance relay is done within the Transient Analysis of Control System(TACS) subsection of the ElectroMagnetic Transient Program(EMTP).

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.3
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• pp.227-236
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• 1992

In this paper, a simulation program of relaying system including the CT and CPD ( capacitive potential device ) is developed to study the effect of its operation under various system conditions. To deal with the dynamic characteristics of relaying system, state space technique is applied, and then the state equations of CT, CPD and mho distance relay are constructed. Also the dynamic response characteristics of overall relaying system is verified by digital simulation. Since the proposed model is capable of taking arbitrary input waveforms from EMTP in analyzing its dynamic responses, the effects of CT-saturation and CPD-subsidence transient characteristics on the operating points of who distance relay can be accurately prodicted. It gives more effective results, compared with the model without considering those characteristics by checking the exprimental data.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.7
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• pp.393-400
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• 2003

This paper discusses how to implement and verify a software model of the digital relay that can be added to real time digital simulator(RTDS) model library and is then subjected to the same outputs as the actual relay. The software model is stand-alone and can be used with real relays. It is also possible to conduct interactive real-time tests when the system effects of the relay action need to be investigated. The characteristics of mho type and the quadrilateral type, which is commonly used in recently developed relays, are modeled in this paper. Single circuit line and double circuit line system are used for model verification. The transmission lines are each 100 km in length and are modeled as distributed parameter lines but not frequency dependent. The transmission lines in the single circuit system are modeled as ideally transposed line. The mutual coupling data with the parallel line was taken account in the transmission lines for the double circuit system. The main CTs and PTs are included and operated in their linear region during the tests. For the purpose of testing the relay model accuracy the faults have been applied at various points on the protected line. Its accuracy is assessed against theoretical values.

• Proceedings of the KIEE Conference
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• 1997.07c
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• pp.1038-1040
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• 1997

This paper describes dynamic characteristics test of distance relay and current differential relay using Real Time Digital Simulator on double circuit transmission line. First, The double circuit T/L modeling on RTDS was proposed and the results from the proposed model were compared with those of PSS/E. This comparison shows the possibility of dynamic test using the RTDS. The relay included about 20 test items which are apt to include maloperation of protective relays in critical situations.