A differential protection scheme, based on real time analysis of a time-frequency based technique, is proposed for transmission line with mid-point connected static synchronous compensator (STATCOM). The first intrinsic mode function obtained from the decomposition of current signals from both ends of the transmission system, processed through Ensemble Empirical Mode Decomposition technique, is used to estimate the Discrete Teager Energy (DTE) through online Hilbert-Huang transformation. The differential DTE from both ends of the line is used to detect the exact faulty phase. For analysis, a mid-point STATCOM compensated transmission line model is considered and simulated using EMTDC/PSCAD. Test cases, such as high fault resistance, fault inception angle, reverse power flow, current transformer saturation and variation in source impedance are generated for different operating modes of the STATCOM. The method is also tested for cross-country fault in double circuit transmission system. Comparative assessment reports with other conventional approaches verify the reliability, speed and feasibility of the proposed method.

Bat algorithm is a recent addition to the bioinspired algorithms, considered as a new metaheuristic algorithm based on Bat behaviour. This work presents, the optimal solution of economic load dispatch (ELD) is obtained using the proposed bat algorithm. Here the operating cost of a thermal power plant is optimized using Bat algorithm. Numerical results show that the proposed method has good convergence property and better in quality of solution than PSO and IWD reported in recent literature. The main advantage of the proposed technique is easy is implement and capable of finding feasible near global optimal solution with less computational effort. BAT algorithm is easy to implement and priory in terms of accuracy and efficiency compared to other algorithms. In order to illustrate the effectiveness of the proposed method, it has been tested on 3 and 6-unit system.

This study introduces the implementation of intrinsic time decomposition (ITD) based passive islanding detection technique for distributed generation (DG) system. The proposed method utilises voltage signals and decomposes it into a baseline signal and residual signal. The performance index in terms of energy computed from baseline signal is defined to discriminate between islanding and non‐islanding events. The proposed ITD based technique for islanding detection has been analysed on different types of DGs connected to the system. The performance of the proposed technique is validated via simulation of distribution system modelled in EMTDC/PSCAD. The different critical operating conditions: lower end active and reactive power mismatch and events like capacitor switching, load switching, inception of fault, have been simulated to test the performance of the proposed scheme. The obtained results suggest that the proposed technique exhibits high reliability and has quick response time to detect islanding situation as compared to other passive islanding detection methods.

In this work, a fault detection methodology during power swing is demonstrated. Modern distance relays are embedded with power swing blocking (PSB) function to preserve the security and reliable operation of power system during swing. However, the operation of PSB should be unblocked and let the distance relay allow to operate for any fault during swing. However, sometimes, distance relay unable to make a proper discrimination between swing and fault event leading cascading failures. In order to accomplish the fault detection task, first online empirical mode decomposition is used and processed through Hilbert–Huang transform to compute the amplitude and instantaneous frequency of that signal. Next, discrete teager energy approach is applied to estimate the teager energy. The energy operator functions as a reliable index for fault detection task during power swing. To evaluate the performance of the proposed method, different power system structures are considered and simulated using EMTDC/PSCAD. Results for current transformer saturation, single‐pole tripping, and in presence of noise are provided. The response of the proposed method is compared with the conventional and existing methods. Results and comparative assessment reports demonstrate that the method is more efficient and robust in maintaining both selectivity and dependability.

Ferro-resonance phenomenon (FP) in coupling capacitor voltage transformer (CCVT) profoundly deforms the voltage waveform. Transient over-voltage due to transmission line switching, particularly in series and shunt compensated power systems, is one of the most important issues that increases the exposure level of the CCVT to FP. A probabilistic study focused on the impact of transient over-voltages on the FP in CCVT is conducted. Through this framework the behavior of different types of ferro-resonance damping circuits (FDC) is investigated. By investigating the effect of several factors, such as switching instance and different fault types in the presence of series and shunt compensation in the power system, the probability density function of the CCVT primary (bus voltage) and secondary (CCVT output) voltage signals with/without different FDCs is obtained. A criterion based on total harmonic distortion, designed to identify and determine the severity of the FP, is also introduced. Simulation results confirm that over-voltages in a series and shunt compensated power system will enhance the vulnerability of the CCVT against FP.