P. Suresh Babu

A wide-area prospective on power system protection: A state-of-art

As the increase in demand for electricity is not been supplied by adequate increase in electrical power generation, the pressure on the electric grids is tremendously growing. so, reliability and integrity is becoming more difficult, sometimes, which may leads to large blackout. In addition, the grid experiences sudden changes due to the inability of the relays to adjust to the prevailing network conditions on the occurrence of a disturbance. This can be reduced by continuous monitoring of system transmission capacity margins and increasing stress on the system. The invention of measuring device, called Phasor Measuring Unit (PMU), that measures the phasor data across the system and communicates to dispatch center through a communication channel, made it possible to redesign network protection schemes to make them more adaptive and thus improve the security of the system. This paper presents the applications of the PMU data in making the relays more adaptive and in the monitoring of grids behavior under disturbances.

Power swing protection of series compensated transmission line with novel fault detection technique

Fault detection during power swing condition is a challenge for stable operation of power system due to several reasons. This paper proposes a negative-sequence current-based technique for detecting presence of fault, classification of fault occurred, estimated zone and location of the fault occurred and the fault inception time with respect to system reference clock during the power swing condition in a series compensated line. The technique is tested for different series-compensated power systems including a SMIB system and a WSCC-9bus-3machine power system with their different configurations and contingency combinations. Power swing caused by various faults are simulated with PSCAD / EMTDC and MATLAB/SIMULINK and compared with available techniques to prove the effectiveness of the proposed technique algorithm.

A back-up protection of teed-transmission line using Taylor-Kalman-Fourier filter

A second order Taylor-Kalman-Fourier (T2KF) filter based backup protection of teed-transmission network is demonstrated in this paper. The measured current and voltage signals at relaying end will be supplied to the proposed T2KF filter to estimation of the faulty section from relaying point. This algorithm has considered the out-feeding effect in the presence of practical load for estimating the fault impedance accurately. The proposed method is tested on a teed-transmission network. The results show that this method has identified the faults in backup zones successfully.

A novel approach for transmission line fault location using synchro phasor measurement

Now a days the power system structure is growing continuously. So the reliability has become a big task for the protection engineers. This paper presents a fast and accurate fault detection technique which is very much useful for reliable operation of the power systems. To achieve fastness and reliable operation various new technologies have been used but out of all the available equipment the use of phasor measurement unit have brought the reliability index to a significant level. An intelligent approach for fault detection has been used in this paper which adapts for changes in the operation level. It uses synchronized samples of the operation voltages and currents from both the ends of the transmission line to detect, and classify the fault. This technique has been implemented on IEEE 57 bus system and it was found that this method has given better results than the methods proposed earlier. With the use of modern equipment which limits the time of operation for few cycles, the time window can be reduced significantly.

A Smart Discrete Fourier Transform Algorithm Based Digital Multifunction Relay for Power System Protection

Many large scale system blackouts involve relay misoperations. Technical advancements in relaying technology has replaced the concept of specific relay for specific action with digital multifunction relays where only single relay can perform different types of relaying functions with the help of digital processor programming. Traditional relay algorithms and settings need to be evaluated under variety of fault and no- fault system wide scenarios to better understand the cause of misoperation of relays. The fault diagnosis algorithm also need to be developed to assure improved relaying performance and then evaluated under various system conditions. This paper presents a novel digital multifunction relay based on Smart Discrete Fourier Transform Algorithm (SDFTA) that derived from Discrete Fourier Transform (DFT) which can estimate exact magnitude of DC offset component and completely eliminates it from operating quantities during faults and also makes use of smoothing window to filter out noise if any. The proposed digital multifunction relays performance is tested on 6-bus power system with the data generated by EMTP/PSCAD. The results had shown the efficient operation of the proposed SDFTA based digital multifunction relay.