Bipolar dc grid systems are fast gaining attraction for renewable energy source integration, because of their merits of higher reliability, efficiency, and robustness as compared to the unipolar dc grids. However, the progress in multiport converters, resulting into lower cost and more compact design for bipolar microgrid systems, is fairly slow. Therefore, this article proposes a novel family of five nonisolated multiport dc–dc converter topologies with bipolar symmetric outputs. The performance and key operational features of the proposed converters under varying input voltages, duty cycles and loads are numerically verified and experimentally on an in-house test setup to prove the concept of the proposed converters. In the experimental validation, the operation of the converter under simultaneous and arbitrary individual power transfer from two input ports is tested. Furthermore, the easy integration of the proposed converters with a multilevel inverter to achieve high-quality ac voltages is demonstrated. As compared to the few existing counterparts, the proposed converters have a competitive edge in terms of higher number of input ports and voltage gains. Alongside the possibility of arbitrary independent power flow from the input ports, inherently symmetrical outputs require a simple balance control for asymmetrical members of the family.

In this paper, transient response of the microgrid caused due to unintended switching events and faults have been investigated in distributed generation (DG) system. The proposed technique is based on two new criteria; i) transient index value (TIV) and ii) positive sequence superimposed current angle at PCC. The proposed method utilizes three phase voltage signals at DG end to compute the TIV. The performance of the proposed integrated approach has been evaluated on a sample test system and a practical distribution network consisting of combined heat and power plant, wind turbine generators, and photovoltaic system. The simulation results demonstrate that the proposed technique exhibits high reliability and leads to faster detection of islanding condition as compared to the existing passive islanding detection methods not only for zero active and reactive power mismatch conditions, but also for transient events caused due to nonlinear loads.

Load frequency control (LFC) scheme communicates from remote terminal units to control centre, followed by control centre action on the corresponding plant units. The conventional dedicated communication channels have constant time delay, while open communication channel, i.e. shared one has time‐varying delay. These delays degrade the dynamic performance or even lead to system instability. In an interconnected system, communications delays cannot be ignored and therefore the time delay is introduced in the area control error signal. In this study, a time delay‐dependent H _∞ ‐based non‐linear sliding mode controller for LFC scheme has been proposed for N area power system. The approach uses Lyapunov–Krasovskii functional based on time delay‐dependent stability criteria and linear matrix inequalities optimisation. Simulation studies are presented for two‐area LFC scheme against step and random step load disturbance and generation rate constraints. Comparison is also made with recently reported; two‐term controller design. The simulation results establish the superiority and applicability of the proposed design for LFC application. The results illustrate that the proposed scheme can effectively enhance the frequency stability via improving the damping of the system.

The potential application of signal processing techniques is not only to detect the event but also to characterize them according to physical disturbance. In this paper, event detection and its characterization algorithm is presented. The event detection scheme uses computation of spectral kurtosis on sum of intrinsic mode functions. The algorithm is capable of detecting the event in phasor measurement units data by comparing the maximum energy and root-mean square of energy content of present analysis segment with respect to previous segment. The statistical indices applied are capable to flag specific data and thus the timely detection of events. Further, statistical features extracted from event-related segment suggest that the transient signals from different regions are distinct and thus can be classified. The signal characterization is further represented in terms of short-term energy and group delay. The analysis on event triggered signal demonstrates the related physical phenomenon in each event type. The study suggests the most relevant signal associated with a particular type of event.

The real-time analysis of power quality (PQ) disturbances and islanding detection for distributed generation (DG) system using signal processing algorithms are yet at premature stage. Quick and reliable detection of islanding and power quality disturbances needs renewed focus. This paper is concentrated on the implementation of advanced signal processing techniques in field-programmable gate array (FPGA) to identify PQ and islanding events in real-time. The proposed scheme is based on orthogonal empirical mode decomposition (OEMD) implemented in FPGA. This technique does not suffer from loss of signal characteristics with successive decomposition levels. The performance of said technique is demonstrated for different PQ and islanding events simulated on IEEE 13 bus DG system and experiments conducted on laboratory set up. The detection ability has been compared with discrete wavelet transform (DWT) and basic empirical mode decomposition (EMD). It is found that DWT completely fails for the signal with noise content, while the performance of basic EMD deteriorates with an increased level of noise content. On other hands, OEMD reliably and accurately detects the disturbances conducted in the study, both simulated and experiment.