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This paper investigates the applicability of IEC 61850-9-2 LE-sampled values in transients-based protection by implementing a line protection intelligent electronic device (IED), incorporating a transients-based hybrid protection algorithm suitable for series-compensated transmission lines. The IED is capable of subscribing, decoding, and processing sampled values to be used in the implemented protection algorithms. The proposed method of protection can distinguish between internal and external faults by comparing the polarities of wavelet coefficients of the line currents at either end of the line. The power system section, which the proposed protection scheme is tested upon, is implemented in a real-time digital simulator. Attention is given to replicate the constraints faced by an actual relay in the implementations of the IED. The results indicate that IEC 61850-sampled values can be effectively used in a transients-based protection scheme that is capable of operating under challenging conditions. [ABSTRACT FROM PUBLISHER]

Part I of this paper describes the design and implementation of an islanding detection method based on transient signals. The proposed method utilizes discrete wavelet transform to extract features from transient current and voltage signals. A decision-tree classifier uses the energy content in the wavelet coefficients to distinguish islanding events from other transient generating events. The verification tests performed in Part I, for a two generator test system having a synchronous generator and a wind farm, showed more than 98% classification accuracy with 95% confidence and a response time of less than two cycles. In Part II, the proposed methodology is applied to an extended test system with a voltage-source converter-based dc source. The proposed relay's performance is compared with the existing passive islanding detection methods under different scenarios. Furthermore, the effect of noise on the performance of the proposed method is studied. The transient-based islanding detection methodology exhibits very high reliability and fast response compared to all other passive islanding detection methods and shows that the relay can be designed with a zero nondetection zone for a particular system. [ABSTRACT FROM AUTHOR]

This paper presents the development and hardware implementation of a classification scheme to distinguish the transients originated by faults from other types of transients. In the proposed scheme, a set of Hidden Markov Model-based classifiers is employed to recognize the fault transients. Input features for the classifiers are the energy contained in wavelet coefficients of the measured current waveforms. A laboratory prototype of the fault recognition system was implemented on a floating-point digital–signal-processor (DSP)-based hardware platform. The classification system was tested using the transient signals generated by a real-time waveform playback unit. The test waveforms were generated by simulating an actual extra-high-voltage transmission system on an electromagnetic transient simulation program. The operation of the classification system was further verified using waveforms obtained from an actual fault recorder. The performance of the classifier was investigated under different practical scenarios, such as current transformer saturation, measurement noise, and lightning faults. [ABSTRACT FROM PUBLISHER]

This paper presents a novel algorithm to determine the location of dc line faults in an HVDC system with a mixed transmission media consisting of overhead lines and cables, using only the measurements taken at the rectifier and inverter ends of the composite transmission line. The algorithm relies on the traveling-wave principle, and requires the fault-generated surge arrival times at two ends of the dc line as inputs. With accurate surge arrival times obtained from time-synchronized measurements, the proposed algorithm can accurately predict the faulty segment as well as the exact fault location. Continuous wavelet transform coefficients of the input signal are used to determine the precise time of arrival of traveling waves at the dc line terminals. Two possible input signals–the dc voltage measured at the converter terminal and the current through the surge capacitors connected at the dc line end–are examined and both signals are found to be equally effective for detecting the traveling-wave arrival times. Performance of the proposed fault-location scheme is analyzed through detailed simulations carried out using the electromagnetic transient simulation software PSCAD. The impact of measurement noise on the fault-location accuracy is also studied in this paper. [ABSTRACT FROM PUBLISHER]