Adaptive Control for Power System Voltage and Frequency Regulation

Variable and uncertain wind power output introduces new challenges to power system voltage and frequency stability. To guarantee the safe and stable operation of power systems, the control for voltage and frequency regulation is studied in this work. Static Synchronous Compensator (STATCOM) can provide fast and efficient reactive power support to regulate system voltage. In the literature, various STATCOM control methods have been discussed, including many applications of proportional–integral (PI) controllers. However, these previous works obtain the PI gains via a trial and error approach or extensive studies with a tradeoff of performance and applicability. Hence, control parameters for the optimal performance at a given operating point may not be effective at a different operating point. To improve the controller’s performance, this work proposes a new control model based on adaptive PI control, which can self-adjust the control gains during disturbance, such that the performance always matches a desired response in relation to operating condition changes. Further, a new method called the flatness-based adaptive control (FBAC), for STATCOM is also proposed. By this method, the nonlinear STATCOM variables can easily and exactly be controlled by controlling the flat output without solving differential equations. Further, the control gains can be dynamically tuned to satisfy the time-varying operation condition requirement. In addition to the voltage control, frequency control is also investigated in this work. Automatic generation control (AGC) is used to regulate the system frequency in power systems. Various control methods have been discussed in order to design control gains and obtain good frequency response performances. However, the control gains obtained by existing control methods are usually fixed and designed for specific scenarios in the studied power system. The desired response may not be obtained when variable wind power is integrated into power systems. To address these challenges, an adaptive gain-tuning control (AGTC) for AGC with effects of wind resources is presented in this dissertation. By AGTC, the PI control parameters can be automatically and dynamically calculated during the disturbance to make AGC consistently provide excellent performance under variable wind power. Simulation result verifies the advantages of the proposed control strategy

Advances and Trends in Mathematical Modelling, Control and Identification of Vibrating Systems

This book introduces novel results on mathematical modelling, parameter identification, and automatic control for a wide range of applications of mechanical, electric, and mechatronic systems, where undesirable oscillations or vibrations are manifested. The six chapters of the book written by experts from international scientific community cover a wide range of interesting research topics related to: algebraic identification of rotordynamic parameters in rotor-bearing system using finite element models; model predictive control for active automotive suspension systems by means of hydraulic actuators; model-free data-driven-based control for a Voltage Source Converter-based Static Synchronous Compensator to improve the dynamic power grid performance under transient scenarios; an exact elasto-dynamics theory for bending vibrations for a class of flexible structures; motion profile tracking control and vibrating disturbance suppression for quadrotor aerial vehicles using artificial neural networks and particle swarm optimization; and multiple adaptive controllers based on B-Spline artificial neural networks for regulation and attenuation of low frequency oscillations for large-scale power systems. The book is addressed for both academic and industrial researchers and practitioners, as well as for postgraduate and undergraduate engineering students and other experts in a wide variety of disciplines seeking to know more about the advances and trends in mathematical modelling, control and identification of engineering systems in which undesirable oscillations or vibrations could be presented during their operation

A new supervisory energy managmement control strategy of a modified D-STATCOM configuration and dual DC source in distribution grids.

A microgrid is a state-of-the-art, next generation of electric distribution grid that provides a fundamental paradigm shift from passive grid networks to active networks. Power electronic technologies play a vital role in enabling microgrids to meet their system level requirements of power quality, reliability and demand response capability. A conventional distribution static compensator (D-STATCOM) is a power electronic converter which acts as a reactive power compensator and voltage controller at the point of common coupling in a grid system. However, these devices have limited ability to mitigate voltage fluctuations caused by active power disturbances. By integrating energy storage into the DC link of a D-STATCOM, controllable active power from the storage device can result in enhanced voltage compensating capability. The active and reactive power control between the D-STATCOM and AC power point is achieved by suitable tuning of the phase and magnitude of the output voltage of the D-STATCOM’s converter. Recent advances and innovations in energy storage systems such as super-capacitors and batteries allow the combination of battery-supercapacitor hybrid energy storage systems to act as an effective solution for energy management in smart grid operation. However, the concept and control of the hybridisation of energy storage are relatively new, and there are great challenges to the development of control management systems, for example, reduce battery current stresses. This study presents a novel approach in applying a fuzzy-PI controller to a D-STATCOM based energy storage unit to provide enhanced power quality and voltage stability in distribution grids. Full information is provided concerning the implementation of the system, and the dynamic controls devised during the research programme. A second novel approach is the use of sugeno fuzzy logic controller based decision making for power management of the D-STATCOM based HESS to achieve a robust and superior performance for voltage regulation. Recent developments in this field have tended to converge on intelligent control as the best approach to achieve an effective strategy for power sharing with HESSs by using a high-power storage unit (supercapacitor) and high energy storage unit (battery) in combination with the D-STATCOM to avoid the drawbacks of a single storage unit. This development is considered one of the main ways to upgrade energy storage technology, with gains of faster voltage regulation and decreased battery current peak value. Verification of the control designs has been achieved through simulation using MATLAB/SIMULINK based on the derived analytical model in state-space form. Comprehensive simulation results show that the proposed fuzzy controller demonstrates significant improvements over conventional controllers in supporting voltage stability in distribution networksPhD in Energy and Powe

The Modeling and Advanced Controller Design of Wind, PV and Battery Inverters

Renewable energies such as wind power and solar energy have become alternatives to fossil energy due to the improved energy security and sustainability. This trend leads to the rapid growth of wind and Photovoltaic (PV) farm installations worldwide. Power electronic equipments are commonly employed to interface the renewable energy generation with the grid. The intermittent nature of renewable and the large scale utilization of power electronic devices bring forth numerous challenges to system operation and design. Methods for studying and improving the operation of the interconnection of renewable energy such as wind and PV are proposed in this Ph.D. dissertation.;A multi-objective controller including is proposed for PV inverter to perform voltage flicker suppression, harmonic reduction and unbalance compensation. A novel supervisory control scheme is designed to coordinate PV and battery inverters to provide high quality power to the grid. This proposed control scheme provides a comprehensive solution to both active and reactive power issues caused by the intermittency of PV energy. A novel real-time experimental method for connecting physical PV panel and battery storage is proposed, and the proposed coordinated controller is tested in a Hardware in the Loop (HIL) experimental platform based on Real Time Digital Simulator (RTDS).;This work also explores the operation and controller design of a microgrid consisting of a direct drive wind generator and a battery storage system. A Model Predictive Control (MPC) strategy for the AC-DC-AC converter of wind system is derived and implemented to capture the maximum wind energy as well as provide desired reactive power. The MPC increases the accuracy of maximum wind energy capture as well as minimizes the power oscillations caused by varying wind speed. An advanced supervisory controller is presented and employed to ensure the power balance while regulating the PCC bus voltage within acceptable range in both grid-connected and islanded operation.;The high variability and uncertainty of renewable energies introduces unexpected fast power variation and hence the operation conditions continuously change in distribution networks. A three-layers advanced optimization and intelligent control algorithm for a microgrid with multiple renewable resources is proposed. A Dual Heuristic Programming (DHP) based system control layer is used to ensure the dynamic reliability and voltage stability of the entire microgrid as the system operation condition changes. A local layer maximizes the capability of the Photovoltaic (PV), wind power generators and battery systems, and a Model Predictive Control (MPC) based device layer increases the tracking accuracy of the converter control. The detail design of the proposed SWAPSC scheme are presented and tested on an IEEE 13 node feeder with a PV farm, a wind farm and two battery-based energy storage systems

Power Converters in Power Electronics

In recent years, power converters have played an important role in power electronics technology for different applications, such as renewable energy systems, electric vehicles, pulsed power generation, and biomedical sciences. Power converters, in the realm of power electronics, are becoming essential for generating electrical power energy in various ways. This Special Issue focuses on the development of novel power converter topologies in power electronics. The topics of interest include, but are not limited to: Z-source converters; multilevel power converter topologies; switched-capacitor-based power converters; power converters for battery management systems; power converters in wireless power transfer techniques; the reliability of power conversion systems; and modulation techniques for advanced power converters