This book explains the topologies, modulation and control of grid converters for both photovoltaic and wind power applications. In addition to power electronics, coverage focuses on the specific applications in photovoltaic and wind power systems where grid condition is an essential factor.
With a review of the most recent grid requirements for photovoltaic and wind power systems, the relevant issues are discussed:
- Modern grid inverter topologies for photovoltaic and wind turbines
- Islanding detection methods for photovoltaic systems
- Synchronization techniques based on second order generalized integrators (SOGI)
- Advanced synchronization techniques with robust operation under grid unbalance condition
- Resonant controller techniques for current control and harmonic compensation
- Grid filter design and active damping techniques
- Power control under grid fault conditions, considering both positive and negative sequences
Throughout, the authors include practical examples, exercises, and simulation models and an accompanying website sets out further modeling techniques using MATLAB® and Simulink environments and physical security information management (PSIM) software.
Grid Converters for Photovoltaic and Wind Power Systems is intended as a course book for graduate students with a background in electrical engineering and for professionals in the evolving renewable energy industry. For professors interested in adopting the course, a set of slides is available for download from the website.
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1.1 Wind Power Development.
1.2 Photovoltaic Power Development.
1.3 The Grid Converter The Key Element in Grid Integration of WT and PV Systems.
2 Photovoltaic Inverter Structures.
2.2 Inverter Structures Derived from H–Bridge Topology.
2.3 Inverter Structures Derived from NPC Topology.
2.4 Typical PV Inverter Structures.
2.5 Three–Phase PV Inverters.
2.6 Control Structures.
2.7 Conclusions and Future Trends.
3 Grid Requirements for PV.
3.2 International Regulations.
3.3 Response to Abnormal Grid Conditions.
3.4 Power Quality.
3.5 Anti–islanding Requirements.
4 Grid Synchronization in Single–Phase Power Converters.
4.2 Grid Synchronization Techniques for Single–Phase Systems.
4.3 Phase Detection Based on In–Quadrature Signals.
4.4 Some PLLs Based on In–Quadrature Signal Generation.
4.5 Some PLLs Based on Adaptive Filtering.
4.6 The SOGI Frequency–Locked Loop.
5 Islanding Detection.
5.2 Nondetection Zone.
5.3 Overview of Islanding Detection Methods.
5.4 Passive Islanding Detection Methods.
5.5 Active Islanding Detection Methods.
6 Grid Converter Structures forWind Turbine Systems.
6.2 WTS Power Configurations.
6.3 Grid Power Converter Topologies.
6.4 WTS Control.
7 Grid Requirements for WT Systems.
7.2 Grid Code Evolution.
7.3 Frequency and Voltage Deviation under Normal Operation.
7.4 Active Power Control in Normal Operation.
7.5 Reactive Power Control in Normal Operation.
7.6 Behaviour under Grid Disturbances.
7.7 Discussion of Harmonization of Grid Codes.
7.8 Future Trends.
8 Grid Synchronization in Three–Phase Power Converters.
8.2 The Three–Phase Voltage Vector under Grid Faults.
8.3 The Synchronous Reference Frame PLL under Unbalanced and Distorted Grid Conditions.
8.4 The Decoupled Double Synchronous Reference Frame PLL (DDSRF–PLL).
8.5 The Double Second–Order Generalized Integrator FLL (DSOGI–FLL).
9 Grid Converter Control for WTS.
9.2 Model of the Converter.
9.3 AC Voltage and DC Voltage Control.
9.4 Voltage Oriented Control and Direct Power Control.
9.5 Stand–alone, Micro–grid, Droop Control and Grid Supporting.
10 Control of Grid Converters under Grid Faults.
10.2 Overview of Control Techniques for Grid–Connected Converters under Unbalanced Grid Voltage Conditions.
10.3 Control Structures for Unbalanced Current Injection.
10.4 Power Control under Unbalanced Grid Conditions.
10.5 Flexible Power Control with Current Limitation.
11 Grid Filter Design.
11.2 Filter Topologies.
11.3 Design Considerations.
11.4 Practical Examples of LCL Filters and Grid Interactions.
11.5 Resonance Problem and Damping Solutions.
11.6 Nonlinear Behaviour of the Filter.
12 Grid Current Control.
12.2 Current Harmonic Requirements.
12.3 Linear Current Control with Separated Modulation.
12.4 Modulation Techniques.
12.5 Operating Limits of the Current–Controlled Converter.
12.6 Practical Example.
Appendix A Space Vector Transformations of Three–Phase Systems.
A.2 Symmetrical Components in the Frequency Domain.
A.3 Symmetrical Components in the Time Domain.
A.4 Components 0 on the Stationary Reference Frame.
A.5 Components dq0 on the Synchronous Reference Frame.
Appendix B Instantaneous Power Theories.
B.2 Origin of Power Definitions at the Time Domain for Single–Phase Systems.
B.3 Origin of Active Currents in Multiphase Systems.
B.4 Instantaneous Calculation of Power Currents in Multiphase Systems.
B.5 The p–q Theory.
B.6 Generalization of the p–q Theory to Arbitrary Multiphase Systems.
B.7 The Modified p–q Theory.
B.8 Generalized Instantaneous Reactive Power Theory for Three–Phase Power Systems.
Appendix C Resonant Controller.
C.2 Internal Model Principle.
C.3 Equivalence of the PI Controller in the dq Frame and the P+Resonant Controller in the Frame.