ANGLIA RUSKIN UNIVERSITY FACULTY OF SCIENCE AND TECHNOLOGY CONCEPTUAL DEVELOPMENT OF A NOVEL DIGITAL CONTROLLER FOR OPTIMISED OPERATION OF A HYBRID RENEWABLE ENERGY SYSTEM JOHN DARVILL A thesis in partial fulfilment of the requirements of Anglia Ruskin University for the degree of Doctor of Philosophy Submitted January 2018 Acknowledgements I would like to express my deep gratitude to my supervisor, Dr Alin Tisan, for his consistent support and guidance over the last five years. I would also like to offer my thanks to my second supervisor, Professor Marcian Cirstea, not only for his support during my PhD but also for inspiring me during my undergraduate degree and sparking my interest in this topic. This project would not have been possible without the invaluable input you both offered. i ANGLIA RUSKIN UNIVERSITY ABSTRACT FACULTY OF SCIENCE AND TECHNOLOGY CONCEPTUAL DEVELOPMENT OF A NOVEL DIGITAL CONTROLLER FOR OPTIMISED OPERATION OF A HYBRID RENEWABLE ENERGY SYSTEM JOHN DARVILL January 2018 The popularity of renewable energy has increased dramatically in the last decade as it becomes increasingly apparent that an alternative to fossil fuel is required. In order for this market to continue to grow, there are a number of technical issues which must be overcome. One such issue is the instability of power supplies which rely on unpredictable natural resources. A popular solution to this problem is the use of a number of complementary renewable power sources to create a stable power network serving a small geographical area. In this project, a novel control solution for such a system is proposed and modelled using a new approach. A comprehensive review of the existing research literature was used to place in context the hybrid renewable energy concept. This included identification of a system topology as well as the novel control solution. A model of the system has been developed using a combination of PSim and MATLAB. This model allowed for the operation of the system to be simulated and subsequently verified. Upon completion of successful system level simulation testing, VHDL implementations of the control solution were created and incorporated into the model. Further simulations were then carried out based on a specific hardware target, an All Programmable System-on-Chip (APSOC) device featuring a dual-core CPU and an FPGA fabric. The novel control solution is primarily aimed at the optimal control of the system’s power converters. This controller employs a Neuro-Fuzzy algorithm to provide gain scheduling for a PI type controller. The test results indicate that improvements were achieved in the stability of the power converters in comparison to more traditional approaches, offering improved response times and a reduction of the output voltage error. Moreover, a state-based algorithm is utilised, which was demonstrated to ensure that the renewable energy sources are optimally complementary. ii Table of Contents 1 Introduction .................................................................................................................... 1 1.1 Research Objectives ............................................................................................... 1 1.2 Methodology ........................................................................................................... 2 1.3 Original Contributions ............................................................................................. 3 1.4 Structure of the Thesis ............................................................................................ 3 2 Review of Existing Renewable Power System Technologies and Advanced Research Trends .................................................................................................................................. 5 2.1 Renewable Energy Sources and Technologies Employed ...................................... 9 2.1.1 Wind Systems .................................................................................................. 9 2.1.2 PV Systems ................................................................................................... 10 2.1.3 Fuel Cells ....................................................................................................... 12 2.1.4 Other Sources ................................................................................................ 14 2.2 Main Power Converter Topologies used in Renewable Applications ..................... 14 2.2.1 History of Power Converters .......................................................................... 14 2.2.2 Rectifiers ........................................................................................................ 15 2.2.3 Inverters ......................................................................................................... 16 2.2.4 AC to AC Converters ..................................................................................... 18 2.2.5 DC to DC Converters ..................................................................................... 21 2.3 Modern Trends in Wind and PV Systems .............................................................. 26 3 Review of Control Technologies and Advanced Research Trends ............................... 29 3.1 Control Systems for Power Converters ................................................................. 29 3.1.1 Control Principles and Traditional Systems .................................................... 29 3.1.2 PID Control .................................................................................................... 31 3.1.3 Intelligent Controllers ..................................................................................... 32 3.2 AI-Based Controllers for Integrated Renewable Systems ...................................... 43 3.2.1 Fuzzy Control ................................................................................................. 43 3.2.2 Neural Networks ............................................................................................ 45 3.2.3 Neuro-Fuzzy Control ...................................................................................... 46 3.2.4 Evolutionary Algorithms in Control ................................................................. 47 4 Modelling and Hardware Tools ..................................................................................... 48 4.1 Review of Modelling Tools .................................................................................... 48 4.1.1 Matlab ............................................................................................................ 48 4.1.2 SystemC and Handel-C ................................................................................. 49 4.1.3 VHDL and Verilog .......................................................................................... 50 iii 4.1.4 VHDL-AMS and System Verilog..................................................................... 51 4.1.5 PSim .............................................................................................................. 52 4.2 Potential Hardware Solutions ................................................................................ 53 4.2.1 Microprocessors and DSPs ............................................................................ 53 4.2.2 FPGAs ........................................................................................................... 54 4.2.3 ASIC .............................................................................................................. 55 4.2.4 All Programmable System-on-Chip (APSOC) ................................................ 56 4.3 Methodology and Tools Used in this Project ......................................................... 57 5 Modelling of Local Renewable Power Converters ........................................................ 61 5.1 Photovoltaic Power Converter ............................................................................... 63 5.1.1 Topology ........................................................................................................ 63 5.1.2 Modelling ....................................................................................................... 65 5.1.3 Simulations .................................................................................................... 77 5.2 Wind Power Converter .......................................................................................... 82 5.2.1 Topology ........................................................................................................ 82 5.2.2 Modelling ....................................................................................................... 82 5.2.3 Simulation ...................................................................................................... 84 5.3 Super Capacitor Power Converter ........................................................................ 87 5.3.1 Topology ........................................................................................................ 87 5.3.2 Modelling ....................................................................................................... 89 5.3.3 Simulation ...................................................................................................... 91 5.4 Battery Power Converter ....................................................................................... 95 5.4.1 Topology .......................................................................................................