Supplementary frequency regulation in non-synchronous AC system connected via MTDC

Abstract In smart grid power system operation, frequency regulation is one of the most critical tasks towards power balance in the grid. This paper presents the schemes for improvement in operation of secondary loop of turbine-generator unit for frequency regulation in non-synchronous AC areas connected via multi-terminal direct current (MTDC) network. Two schemes have been discussed; (i) voltage droop based lead/lag compensator and (ii) DC power modulation at converter terminal depending upon frequency deviation from each AC area. In the first scheme, droop design based on lead/lag compensator using DC voltage deviation is introduced as supplementary signal at turbine-generator unit in eac…

Load frequency regulation using observer based non-linear sliding mode control

Abstract In this paper, the generalized extended state observer (GESO) and non-linear sliding mode control (SMC) are merged together to study the frequency deviation problem in multi-area power system. In study, the GESO is used not only for state and disturbance estimation but also for disturbance rejection of the system. The said observer ensures accurate estimation of the actual states leading to convergence of estimation error to zero. The non-linear SMC is used to increase the damping ratio of the system whenever, any perturbations occurs. The proposed observer based controller is compared with an existing two-layer active disturbance rejection control (ADRC) and also validated on larg…

Spectral identification of forced oscillation in PMU signal using mode decomposition

This article gives a new method to identify the frequency of Forced Oscillation (FO) in phasor measurement units (PMUs) signals. The processing of the signal by Empirical Mode Decomposition (EMD) technique leads to effective detection with improvement in accuracy. After testing some improved versions of EMD, it is observed that ‘improved Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (CEEMDAN-2014)’ is the best version to use in processing. The developed methodology is able to spot the frequency of FOs even if there exist multiple modes with mode mixing and multiple events. In such cases, self-coherence method fails to spot FO. Spectral analysis is conducted on the decom…

Novel Isolated Multiple-Input Buck-Boost DC-DC Converter for Renewable Energy Sources

An isolated multiple input dc-dc converter (MIC) with unidirectional buck-boost characteristics and simultaneous power transfer is proposed for multi-sources in renewable energy systems in this paper. When compared to existing isolated MICs, the proposed MIC significantly reduces the component count and control complexity since it requires a fixed coupled inductor with only one primary and secondary winding each for any number of inputs and does not require any phase-shifted pulse-width modulation. The operation of the proposed converter for simultaneous power transfer from multiple sources with varying voltages is numerically verified in simulation and validated on OPAL-RT’s OP5700 hardwar…

Event-Triggered Nonlinear Control of OWC Ocean Wave Energy Plant

This paper presents event-triggered nonlinear controllers for oscillating water column (OWC) ocean wave energy plant. The study is based on event-triggered backstepping controller (ET-BSC) and event-triggered sliding mode controller (ET-SMC) to control the rotational speed of an OWC turbine coupled to a generator. The designed controllers are capable to avoid the stalling of the Wells turbine so as to maximize its output power. The aim of event-triggered control is to minimize the control updates, thus providing efficient utilization of resources without compromising the OWC performance. In this regard, aperiodic sampling has been applied using an event-triggering rule derived from Lyapunov…

Wide area monitoring of sustained oscillations using double-stage mode decomposition

Four Quadrant Switch Based Multiple-Input DC-DC Converter

In this paper, a novel non-isolated multiple input dc-dc converter (MIC) is proposed. The MIC uses four-quadrant switches, only one inductor and capacitor. It is capable of bidirectional operation in non-inverting buck-boost configuration and can accommodate the simultaneous transfer of energy from more than one source of different voltage levels to the DC bus. This MIC is analysed for two inputs in this paper. As compared to existing MICs in literature, the proposed converter utilizes less number of inductors and requires only one switch to integrate any extra energy storage. Different operation modes of the proposed MIC are numerically verified and validated on a high-fidelity hardware-in…

Event signal characterization for disturbance interpretation in power grid

This paper presents the signal processing approach to detect and characterize the physical events that occur in power system using PMUs signals. A small window is applied so that the extracted spectral features belong to a stationary signal. This is based on applying empirical mode decomposition, followed by square root of spectral kurtosis (SRSK) for computation of statistical indices to indicate the event occurrence. Subsequently, features from these events are extracted using mel frequency cepstral coefficients on SRSK. © 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/re…

Real-Time Implementation of Signal Processing Techniques for Disturbances Detection

The real-time analysis of power quality (PQ) disturbances and islanding detection for distributed generation (DG) system using signal processing algorithms are still at a premature stage. Quick and reliable detection of islanding and PQ 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 the loss of signal characteristics with successive decomposition levels. The performance of said technique is de…