Table of Contents

Title Page

Chapter 1: Overview

1.1 Wind Energy and Wind Energy Resources
1.2 Characteristics of Wind Power Generation
1.3 Present Situation and Development of Wind Power Generation
1.4 Wind Power Conversion System and Technical Route
1.5 WF-Included Electrical Power System
1.6 Outline of the Book
References

Chapter 2: Wind Power Generation and Wind Power Generation System

2.1 Wind Power Generation System and WFs
2.2 Wind Turbine
2.3 Wind Turbine Generator System
2.4 Power Electronic Technology in Wind Power Conversion System
References

Chapter 3: Operation of Grid-Connected WTGS

3.1 Wind Turbine Grid Connection
3.2 Power Regulation of Wind Turbines
3.3 Wind Energy Converters and Basic Control Methods
3.4 Voltage/Reactive Power Control Characteristics of Three Mainstream Wind Turbines
References

Chapter 4: Connection of WFs to Power Systems

4.1 Requirements of the Power System for Grid Connection of WFs
4.2 Connection of WFs to Power Distribution Grids or Transmission Grids
4.3 Direct Connection to AC grids
4.4 WFs Interconnection via Conventional HVDC (PCC—HVDC)
4.5 WFs Interconnection via VSC-HVDC
4.6 Contrast of WF Integration Schemes
4.7 Integration of Large-Scale WFs into the Grid
4.8 Determination of Maximum Wind Power Capacity Allowed to be Integrated into the Grid
References

Chapter 5: WF Electrical Systems

5.1 Power Collection Systems
5.2 WF Grounding Systems
5.3 WF Lightning Protection
5.4 WF Electrical Protection
5.5 WF Reactive Power Compensation
5.6 WF Energy Storage Systems
References

Chapter 6: OWFs

6.1 OWF and Its Characteristics
6.2 OWF Electrical System
6.3 Redundancy Design of Collection System
6.4 OWF Transmission System
6.5 A New Type of Offshore Wind Energy Conversion System
6.6 OWF Electrical System Optimization Design
6.7 Examples of Typical OWF
References

Chapter 7: Analysis of Power Systems Containing Wind Power

7.1 Overview
7.2 Mathematical Models of Wind Power Generation System
7.3 Power Flow Analysis of Power System Containing Wind Power
7.4 Short-Circuit Analysis of Power Systems Containing Wind Power
7.5 Voltage Stability Analysis of Power System Containing Wind Power
7.6 Transient Stability Analysis of Power Systems Containing Wind Power
7.7 Small Signal Stability Analysis on Power System Containing Wind Power
7.8 Frequency Stability Analysis of Power System Containing Wind Turbines
References

Chapter 8: WF Power Quality and Its Improvements

8.1 Overview
8.2 Power Quality and Its Characteristics
8.3 Power Quality Problems of WFs Associated with the Grid
8.4 Frequency Quality and Frequency Regulation
8.5 Voltage Quality and Voltage Regulation
8.6 WF Voltage Flicker
8.7 Harmonics and Interharmonics of the WF
8.8 Measures to Improve Power Quality of WFs
References

Chapter 9: Wind Velocity and Generated Power Forecasts in WF

9.1 Overview
9.2 Variability of Wind Power
9.3 Wind Power Forecast Model and Method
9.4 Wind Velocity Forecast
9.5 Generated Power Forecast in WF
9.6 Accuracy of Wind Power Forecast
9.7 Application and Challenge of Wind Power Forecast
References

Chapter 10: WF Control and Protection Technologies

10.1 Overview
10.2 Active Power and Frequency Control
10.3 Reactive Power and Voltage Regulation
10.4 Fault Ride-Through (FRT) or Low/High-Voltage Ride-Through (L/HVRT) of WTGS
10.5 AGC of a Wind Power Contained Power System
10.6 WF Monitoring and Control
10.7 Control of WF Energy Storage System
References

Chapter 11: Operation and Dispatch of a Power System Containing Wind Power

11.1 Overview
11.2 General Requirements for WF Operation
11.3 Power Balance and System Reserve Capacity
11.4 Optimal Dispatch of Power Systems Containing Wind Power
11.5 Wind Power Generation and Power Market
11.6 Main Technology of WFs to be Conventional Power Plants
References

Chapter 12: The Evaluation Technology for An Wind Power Integrated Power System

12.1 Reliability Evaluation of Wind Power Integrated Power System
12.2 Wind Power Generation CC
12.3 Wind Power Value Analysis
12.4 Analysis of Maximum Penetrating Capacity of Wind Power
References

Index

End User License Agreement

List of Illustrations

Chapter 1: Overview

Figure 1.1 Wind direction frequency rose diagram and corresponding average wind speed rose diagram.
Figure 1.2 Generation efficiency of WF with different wind speeds and wind directions.
Figure 1.3 Energy conversion process in wind power generation.
Figure 1.4 Composition of wind power generation system.
Figure 1.5 WF-included modern electrical power system.

Chapter 2: Wind Power Generation and Wind Power Generation System

Figure 2.1 Wind turbines: (a) horizontal axis wind turbine (b) vertical axis wind turbine.
Figure 2.2 Wind turbine structure diagram.
Figure 2.3 Rotor composition diagram.
Figure 2.4 Steering wheel wind alignment device.
Figure 2.5 Electrical wind alignment device and automatic wind alignment device. (a) electrical wind alignment device (b) automatic wind alignment rotor.
Figure 2.6 Wind force converted into lift force and drag force of the blade.
Figure 2.7 Lift force and drag force of horizontal axis wind turbine.
Figure 2.8 Vertical axis S type blade rotor.
Figure 2.9 Torque coefficient characteristic curve.
Figure 2.10 Typical power curve of fixed speed stall wind turbine (dotted line); typical power curve of variable speed variable pitch wind turbine (full line).
Figure 2.11 Stalled flows around the wing.
Figure 2.12 Constant speed constant frequency cage asynchronous wind power generation system.
Figure 2.13 Structure of cage asynchronous generator.
Figure 2.14 Using slip ratio s to indicate the operation state of the asynchronous generator.
Figure 2.15 Asynchronous generator equivalent circuit and power transfer relationship.
Figure 2.16 Double-fed asynchronous generator system.
Figure 2.17 Winding rotor three-phase asynchronous generator structure. (a) Double-fed asynchronous generator structure (b) stator and rotor connections.
Figure 2.18 Multi-pole winding synchronous generator type wind power generation system.
Figure 2.19 Permanent magnet synchronous generator type DC power generation system.
Figure 2.20 Direct-drive permanent magnet synchronous generator type wind power generation system.
Figure 2.21 High voltage permanent magnet synchronous generator type wind power generation system.
Figure 2.22 Principle and structure of high voltage permanent magnet generator (Windformer^TM). 1—wind turbine; 2—armature core; 3—high voltage cable armature winding; 4—winding end; 5—cable joint; 6—permanent magnet rotor.
Figure 2.23 AC/DC/AC wind power generation system.
Figure 2.24 Magnetic field-modulated generator system.
Figure 2.25 Brushless doubly fed generator system in grid integration operation.
Figure 2.26 Switched reluctance generator type wind power generation system.
Figure 2.27 Power conversion through power converter.
Figure 2.28 Schematic diagram of AC-AC converter basic circuit principle.
Figure 2.29 Indirect (AC-DC-AC) converter.
Figure 2.30 Buck chopper.
Figure 2.31 Equivalent circuit of boost chopper.
Figure 2.32 Structure of back-to-back voltage source power converter.
Figure 2.33 Variable speed wind turbine with synchronous generator and full rated power converter.
Figure 2.34 Wind turbine with permanent magnet synchronous generator and full rated power converter.
Figure 2.35 Multilevel topology. a) One arm of the three-level diode-clamped converter; b) One arm of the three-level converter with interconnection of the bidirectional switches; c) One arm of the three-level converter with flying capacitors; d) Three-level converter using three two-level converters; e) One arm of the cascaded three-level H-bridge converters. Initially, the main purpose of the multilevel converter is to achieve higher performance of voltage. With the increase of rated value of the components and the improving of the performance of the switch and the breakover, the second effect of using multilevel converter becomes more and more favorable. It reduces the harmonic content and the electromagnetic interference (EMI) in the input and output voltage. Under the same harmonic conditions, the switching frequency of the multilevel converter is reduced; the switch loss is small; the conduction loss is large; the total loss is determined by the proportion of the two.
Figure 2.36 Full power converter-based wind turbine with n parallel power converters.
Figure 2.37 Matric converter brushless double-fed generator power generation system.

Chapter 3: Operation of Grid-Connected WTGS

Figure 3.1 Grid-connected wind turbine-driven synchronous generator.
Figure 3.2 Quasi-synchronous grid connection of cage asynchronous wind turbine.
Figure 3.3 Soft grid connection of cage asynchronous wind turbine.
Figure 3.4 Diagram of permanent magnet synchronous generator connected to power grid.
Figure 3.5 Diagram of working principle of double-fed asynchronous generator.
Figure 3.6 Schematic diagram of independent load grid connection control.
Figure 3.7 Schematic diagram of “islanded” gird connection.
Figure 3.8 Schematic diagram of grid connection by connection resistance in series with rotor.
Figure 3.9 Characteristics of power angle of synchronous generator.
Figure 3.10 Torque-speed characteristics of asynchronous generator.
Figure 3.11 Voltage source converter connected to power grid. (a) Voltage source converter (inverter) connected to power grid; (b) VSC equivalent circuit connected to power grid; (c) phase diagram; (d) P-Q axis phase diagram.
Figure 3.12 Equivalent circuit of double-fed asynchronous generator.
Figure 3.13 Typical structure of variable speed WEC.
Figure 3.14 Wind turbine P—n_R curve.
Figure 3.15 Optimal rotor speed control block diagram.
Figure 3.16 Flow chart of random dynamic optimal control.
Figure 3.17 Power (P, Q)-slip characteristics of cage asynchronous generator. (a) Relationship between active power and rotor speed of cage asynchronous generator with different generator terminal voltage U₁ (b) Relationship between reactive power and rotor speed of cage asynchronous generator with different generator terminal voltage U_{1 s}.
Figure 3.18 Operating range of double-fed asynchronous generator.
Figure 3.19 Operating range of wind turbine equipped with direct-drive synchronous generator with terminal voltage U₁ as variable; the curves show the boundary of operating range when the terminal voltage U₁ changes.
Figure 3.20 Test system used to study the voltage control capability of various wind turbines. U₁-terminal voltage of generator; P-active power; Q–reactive power; Z_L–line impedance; $c03-math-0022$ .
Figure 3.21 Results of the steady state analysis of the constant speed wind turbine with the test system shown in Figure 3.20.
Figure 3.22 Results of the steady state analysis of the variable speed wind Turbine equipped with voltage controller with the test system shown in Figure 3.20.
Figure 3.23 Results of the steady state analysis of the variable speed wind Turbine in the unit power factor operation mode with the test system shown in Figure 3.20.
Figure 3.24 Simulation results of dynamic voltage/reactive control capability of various wind turbines. (a) wind speed series; (b) active power; (c) reactive power; (d) terminal voltage.

Chapter 4: Connection of WFs to Power Systems

Figure 4.1 WF grid connection; Scheme 1.
Figure 4.2 WF grid connection; Scheme 2.
Figure 4.3 Basic model for transmission of active power and reactive power.
Figure 4.4 Small WFs connected to the distribution line.
Figure 4.5 Voltage distribution of the distribution line connected with WFs.
Figure 4.6 Generation capacity at various voltage classes in Denmark ELTRA.
Figure 4.7 HVDC scheme for WFs.
Figure 4.8 Wind turbine generator systems using DC power transmission. (a) synchronous generator + diode rectifier + chopper; (b) conventional asynchronous generator + VSC; (c) asynchronous generator + diode rectifier + chopper + VSC provides excitation.
Figure 4.9 Schematic diagram of VSC-HVDC transmission.
Figure 4.10 Single-phase diagram of the VSC converter consisting of IGBT.
Figure 4.11 VSC waveforms.
Figure 4.12 Contrast of PQ diagrams of PCC and VSC.
Figure 4.13 Applications of HVAC, PCC-HVDC, and VSC-HVDC.
Figure 4.14 Diagram of WFs integration into the power system. (a) with local load; (b) without local load.
Figure 4.15 System wiring diagram.
Figure 4.16 WF terminal voltage changes with the WF output under different U_s values.
Figure 4.17 (U_s = 1.02) WF voltage changes with WF power output under different loads (U_s = 1.02).
Figure 4.18 WF voltage changes with the wind power output under different compensation capacities.
Figure 4.19 WF voltage changes with wind power output when the link line x/r is in change.
Figure 4.20 Asynchronous generator power factor changes with slip.
Figure 4.21 Changes in WF voltage and equivalent wind turbine generator set slip.
Figure 4.24 Changes in WF voltage and equivalent wind turbine generator set slip.

Chapter 5: WF Electrical Systems

Figure 5.1 Fixed speed wind turbine electrical system schematic.
Figure 5.2 Connection of generator and transformer. (a) connection of multiple wind turbines to one transformer (b) connection of one wind turbine to one transformer.
Figure 5.3 Large WF power collection system.
Figure 5.4 Schemes of WF grounding systems.
Figure 5.5 Wind turbine lightning protection zoning.
Figure 5.6 Blade lightning protection methods.
Figure 5.7 Nacelle lightning protection design.
Figure 5.8 Induction generator terminal three-phase fault current.
Figure 5.9 A typical configuration of the WF protection.
Figure 5.10 Protection of WFs with 35 kV circuits.
Figure 5.11 DFAG single-line diagram.
Figure 5.12 Equivalent circuit of asynchronous generators and power-factor correction capacitor.
Figure 5.13 Simplified equivalent circuit of the PFC and asynchronous generators.
Figure 5.14 Description of self-excitation of two frequencies.
Figure 5.15 Analysis of distribution protection action caused by wind turbines.
Figure 5.16 Output and voltage change of FSAG WFs.
Figure 5.17 WF equivalent system.
Figure 5.18 WF simplified wiring.
Figure 5.19 P-Q relation curve of different voltages at the connection point.
Figure 5.20 PQ curve without medium-voltage compensation.
Figure 5.21 Effects of centralized reactive power compensation at substation medium-voltage side.
Figure 5.22 Feature-related storage system classification.
Figure 5.23 WF energy storage system structures. (a) Centralized; (b) Decentralized.
Figure 5.24 Energy storage system units and interfaces. (a) centralized configuration; (b) decentralized configuration.
Figure 5.25 Application of hybrid energy storage systems in WFs.

Chapter 6: OWFs

Figure 6.1 Single line diagram of typical electrical system for OWFs.
Figure 6.2 OWF main electrical wiring system.
Figure 6.3 Structures of OWF power collection system.
Figure 6.4 Transmission line reactive compensation. (a) The transmission cable has no reactive compensation; (b) Reactive compensation is provided along the transmission cable; (c) Reactive compensation is provided at both ends of the transmission cable.
Figure 6.5 Transmission limit of AC transmission cable (132 kV).
Figure 6.6 The transmission line has no reactor, and requires offshore and onshore compensation.
Figure 6.7 The transmission line has reactor, and requires offshore and onshore compensation.
Figure 6.8 Topological structure of OWFs using VSC-HVDC for grid connection.
Figure 6.9 Thyristor-based PCC-HVDC and IGBT-based VSC-HVDC.
Figure 6.10 Control mode 1 of PCC -HVDC and VSC-HVDC parallel operation.
Figure 6.11 Control model 2 of PCC-HVDC and VSC-HVDC parallel operation.
Figure 6.12 Multi-terminal HVDC system based on PWM-VSC.
Figure 6.13 Pulse-width modulated voltage source converter circuit. (a) PWM-VSC; (b) Simplified block diagram of PWM-VSC.
Figure 6.14 PWM-VSC voltage waveform. (a) Typical voltage waveform; (b) Input modulation signal m (t).
Figure 6.15 Feedforward and feedback control (* refer to obtain the corresponding variable values by table lookup).
Figure 6.16 A 200 MW WF of MCSI-HVDC transmission with series connection.
Figure 6.17 Two connection modes of OWFs. (a) Connection in parallel, MVSC-HVDC; (b) Two-terminal VSC-HVDC.
Figure 6.18 VSC-based HVDC connection.
Figure 6.19 VSC bridge and valve structure. (a) single-level VSC bridge; (b) VSC valve structure.
Figure 6.20 VSC-HVDC-based connection and its control circuit diagram.
Figure 6.21 Angular frequency modulator controls system FCS₁.
Figure 6.22 MFs of fuzzy set $c06-math-0021$ .
Figure 6.23 MFs of d $c06-math-0022$ .
Figure 6.24 MFs of δ₁.
Figure 6.25 DC voltage regulator control system AFCS₂.
Figure 6.26 AC voltage regulator (FCS_1,2).
Figure 6.27 Topology of proposed WF. (a) Wind turbine unit with a permanent magnetic generator and intermediate frequency transformer; (b) OWF with wind turbines of series or parallel connection.
Figure 6.28 Wind energy conversion systems and two-mass model. (a) Mechanical diagram of the wind energy conversion system; (b) Two-mass model of the wind turbine generator system.
Figure 6.29 Circuit structure of ac/dc converter driven by PM motor. (a) Detailed structure of a single generator; (b) Converter structure of four generators using multi-phase superposition, SMx in the Figure represents the switching mode.
Figure 6.30 Losses in the converter.
Figure 6.31 33 kV cable life-cycle cost.
Figure 6.32 Determination of electrical energy loss caused by transmission capacity constraints.
Figure 6.33 Radial series feed lines.
Figure 6.34 Optimization of the offshore transformer platforms.
Figure 6.35 Comparison of 132 kV cable cost and life-cycle cost.
Figure 6.36 100 MW WF AC connection system.
Figure 6.37 100 MW WF DC connection system.
Figure 6.38 200 MW WF AC connection system.
Figure 6.39 Electrical system of a 500 MW WF using two 150 kV submarine cables for AC connection.
Figure 6.40 Annual power distribution transmitted to the shore and gain of additional cable.
Figure 6.41 Main structures of optimization platform.
Figure 6.42 Cage asynchronous generators of Lillgrund OWF was grid-connected through VSC.
Figure 6.43 Lillgrund OWF substation.
Figure 6.44 33 kV internal network of Lillgrund offshore substation.
Figure 6.45 Different cross-sectional areas are used to feeder cables in the WF.
Figure 6.46 Single-line diagram of Lillgrund WF electrical system.
Figure 6.47 Single-line diagram of switchgear equipped with advance inserted resistor.

Chapter 7: Analysis of Power Systems Containing Wind Power

Figure 7.1 Spatio-temporal map of study on grid-connected wind power.
Figure 7.2 Diagram of wind power generation system.
Figure 7.3 Wind turbine transmission system.
Figure 7.4 Block diagram of wind turbine model that has included the drive shaft flexibility.
Figure 7.5 Regulating links of variable speed wind turbine pitch angle.
Figure 7.6 Variable pitch power regulation system.
Figure 7.7 CIG wind power generation system architecture.
Figure 7.8 Asynchronous generator steady state equivalent circuit.
Figure 7.9 CIG wind turbine dynamic equivalent circuit.
Figure 7.10 Double-fed asynchronous generator steady state equivalent circuit.
Figure 7.11 DFAG wind power generation system structure.
Figure 7.12 DFAG dynamic equivalent circuit.
Figure 7.13 Equivalent circuit of PM synchronous generator.
Figure 7.14 PMSG dynamic equivalent circuit under dq coordinates. (a) q- axis equivalent circuit; (b) d-axis equivalent circuit.
Figure 7.15 Simplified asynchronous generator steady-state model.
Figure 7.16 CIG wind turbine power curve.
Figure 7.17 Equivalent mode of CIG wind turbines of the WF.
Figure 7.18 DFAG wind turbine generation P_s–Q_s limit curve.
Figure 7.19 DFAG wind turbine power curve.
Figure 7.20 DFAG wind turbine generator equivalent model.
Figure 7.21 A single-line diagram of an equivalent wind turbine connected to the substation.
Figure 7.22 Chain structure circuit of multiple wind turbines on a feeder. (a) Single-chain wiring (b) the equivalent circuit of Figure (a).
Figure 7.23 Three wind turbine sets connected in parallel through the series impedance Z₁, Z₂ and Z₃.
Figure 7.24 Parallel series connection of three wind turbine sets.
Figure 7.25 Representation of WF circuit susceptance.
Figure 7.26 The steady-state model of the cage asynchronous generator (with terminal capacitor compensation).
Figure 7.27 Induction generator-power relationship.
Figure 7.28 Simplified equivalent circuit of the asynchronous generator.
Figure 7.29 DFAG power flow model.
Figure 7.30 Steady state equivalent circuit of double-fed asynchronous generator.
Figure 7.31 Wind turbine speed control law.
Figure 7.32 System wiring diagram.
Figure 7.33 Synchronous/asynchronous generator stator short-circuit current curve. (a) Synchronous generator short-circuit current curve (b) Asynchronous generator short-circuit current curve.
Figure 7.34 The testing systems being studied.
Figure 7.35 DC side damp load control block diagram.
Figure 7.36 Crowbar rotor protection in DFAG rotor circuit.
Figure 7.37 When with crowbar protection, DFAG stator phase A current in stator terminal short circuit. (a) 3 MW wind turbine; (b) 2.75 MW wind turbine; (c) 660 k wind turbine.
Figure 7.38 P-V curve: Basic working conditions and accident conditions.
Figure 7.39 Voltage secure region of operation domain (VSROp).
Figure 7.40 Voltage security assessment power flow diagram.
Figure 7.41 Node 39 test system wiring diagram.
Figure 7.42 IEEE39 node system PV curve. (a) system PV curve of Node 39 without WFs (b) system PV curve of Node 39 with WFs.
Figure 7.43 Wind speed probability map of WF at the height of 55 m.
Figure 7.44 Probability distribution of voltage stability margin.
Figure 7.45 The static power capacity curves of WFs with DFAG.
Figure 7.46 Torque-slip characteristics.
Figure 7.47 Torque-time characteristics.
Figure 7.48 Model system.
Figure 7.49 Structure of a local planning grid.
Figure 7.50 IEEE-14 bus system.
Figure 7.51 Changes in CCT when faults occur on the high-voltage bus 5 (LV/HV network connection).
Figure 7.52 Changes in CCT when faults occur on the low-voltage bus 14 (LV/HV network connection).
Figure 7.53 Changes in the CCT when faults occur on high-voltage bus 5.
Figure 7.54 Changes in the CCT when faults occur on high-voltage bus 14.
Figure 7.55 FSAG connected to infinite bus.
Figure 7.56 DFAG system equivalent circuit. (a) DFAG equivalent circuit; (b) feedback converter equivalent circuit.
Figure 7.57 DFAG control block diagram. (a) rotor-side converter control block diagram; (b) grid-side converter control block diagram; (c) pitch control block diagram.
Figure 7.58 DFAG and grid interface. (a) SMIB system; (b) d−q coordinate to x−y coordinate.
Figure 7.59 DDDPMSG equivalent circuit.
Figure 7.60 Full power back to back converter.
Figure 7.64 The simple system studied.
Figure 7.61 Generator-side converter control block diagram.
Figure 7.62 Grid-side converter control block diagram.
Figure 7.63 DDPMG and grid interface.
Figure 7.65 The active power-frequency static characteristics of generator.
Figure 7.66 Active power-frequency static characteristics of the power system.
Figure 7.67 Parallel move of active power-frequency static characteristic.
Figure 7.68 Secondary frequency regulation.
Figure 7.69 Response of cage asynchronous generators to system frequency drop (p.u.).
Figure 7.70 DFAG wind turbine speed control block diagram.
Figure 7.71 Realization of inertia response.
Figure 7.72 DFAG wind turbine droop characteristic control block.
Figure 7.73 WF structure diagram.
Figure 7.74 Comparison of frequency deviation after loss of 2.5 % power by the system.
Figure 7.75 Comparison of control schemes.
Figure 7.76 Full converter variable speed wind turbine and converter control system.
Figure 7.77 Pitch angle control system.
Figure 7.78 A complete frequency control system.
Figure 7.79 General FCWTG droop control structure.
Figure 7.80 Frequency support control system.

Chapter 8: WF Power Quality and Its Improvements

Figure 8.1 Origin of power quality problems of the WF. (a) Impact of the power grid on wind turbines; (b) Impact of wind turbines on the grid.
Figure 8.2 Requirements for WF operation frequency range of some countries.
Figure 8.3 Modulation of fluctuation voltage u on root-mean-square voltage U. (a) Power grid rms voltage U(t); (b) Amplitude-modulated volage u(t). 1—Root-mean-square voltage; 2—sine-modulated wave. .
Figure 8.4 Generator/motor equivalent circuits and phasor diagrams at the grid. (a) Generator equivalent circuit, (b) Motor equivalent circuit; (c) Generator phasor diagram; (d) Motor phase diagram.
Figure 8.5 Equivalent circuit and voltage variations with and without wind turbines at the PCC.
Figure 8.6 The PCC voltage changes with the impedance phrase angle (a) and the capacity of short circuit (b).
Figure 8.7 The U-Q state curves of PCC in different active and reactive power injection.
Figure 8.8 Flicker passes along the transmission line.
Figure 8.9 Transmission of flicker along the transmission line with distributed power generation units.
Figure 8.10 Flicker transmission estimation based on short-circuit capability.
Figure 8.11 Block diagram of Voltage flicker meter design.
Figure 8.12 Huitengxile WF system wiring diagram.
Figure 8.13 Test system single-line diagram.
Figure 8.14 Soft starter device (had drawn only single phase).
Figure 8.15 Six pulsed two-level IGBT voltage source converter.
Figure 8.16 Series ferroresonance resonance circuit.
Figure 8.17 Nanao WF grid-connection wiring diagram.
Figure 8.18 Inverter coupled to the synchronous generator (SG).
Figure 8.19 Double-fed asynchronous generator (DFAG).

Chapter 9: Wind Velocity and Generated Power Forecasts in WF

Figure 9.1 A typical time series of wind velocity.
Figure 9.2 Decomposition of WF power output. (a) Power component P_a(t); (b) Power component P_t(t); (c) Power component P_r(t).
Figure 9.3 Types of models for short-term wind power forecast.
Figure 9.4 Accuracy comparison of time series model with NWP-based physical model of wind power forecast (I) NWP model.
Figure 9.5 Steps of establishing wind power forecast by using NWP-based physical model.
Figure 9.6 GRNN network assumption diagram.
Figure 9.7 Result of forecasting wind velocity in time series combined with neural network method 10 minutes in advance.
Figure 9.8 Results of wind velocity forecasts with combination method of time series and neural network in different lead time. (a) 20 minutes early; (b) 30 minutes early.
Figure 9.9 Basic structure of WF power forecast system.
Figure 9.10 Deduction of wind velocity at height of wind turbine hub with given NWP.
Figure 9.11 Typical wind power forecast schedule for day-ahead trade.
Figure 9.12 Progress of forecast errors of day-ahead wind power forecast operated in one controlled region.
Figure 9.13 Structure of wind power forecast model.
Figure 9.14 Classification of the data input into NWP according to forecasted wind velocities.
Figure 9.15 Radial base neural network.
Figure 9.16 Structure of primary wind power forecast model.
Figure 9.18 Fuzzy set of difference between primary wind power forecast model and output trained by RBF network with forecasted wind velocity value.
Figure 9.17 Distribution of normalization errors of wind power forecasts before 1, 6, 18, and 36 hours.
Figure 9.19 Change of forecast errors of typical method with time.
Figure 9.20 Total forecast absolute error within 1 year and forecast time range.
Figure 9.21 Relationship between annual wind power operation value and wind power forecast variance.
Figure 9.22 Forecast error (MW) in different regional range.
Figure 9.23 Total error of relative planned reserve and error of demand (load) forecast, power plant operation, and wind forecast.
Figure 9.24 Comparison among forecast errors obtained by different artificial intelligent methods.

Chapter 10: WF Control and Protection Technologies

Figure 10.1 Structure of DCS.
Figure 10.2 Typical wind power system.
Figure 10.3 Operating voltage of a wind turbine and of a power system.
Figure 10.4 Setup of generator frequency protection and requirements of load-shedding frequency (50 Hz system).
Figure 10.5 Single-line diagram of a DFAG.
Figure 10.6 Single-line diagram of a typical WF.
Figure 10.7 Common wiring topologies of feeders.
Figure 10.8 Active power regulator and its equipment configuration.
Figure 10.9 Frequency regulator and its equipment configuration.
Figure 10.10 Frequency regulator, two examples with frequency response curves.
Figure 10.11 Active power regulator, WF balance control.
Figure 10.12 Reactive power regulator and its equipment configuration.
Figure 10.13 Voltage regulator and its equipment configuration.
Figure 10.14 Apparent power control mode of a WF regulator.
Figure 10.15 Control structure of a DFAG.
Figure 10.16 Typical active/reactive power limitation.
Figure 10.17 WF model.
Figure 10.18 Typical LVRT rule of a wind turbine.
Figure 10.19 LVRT requirements of E.ON Netz.
Figure 10.20 Two LVRT realization methods for PMSGs. (a) Connection with an energy storage system (ESS); (b) Connection with a resistor (R) for consumption of residual energy.
Figure 10.21 Possible LVRT realization of DFAG. (a) Short circuit protection (Crowbar); (b) Connected with an energy storage system (UPS).
Figure 10.22 Crowbar protection.
Figure 10.23 LVRT requirements of STI.
Figure 10.24 LVRT topology based on a STI scheme.
Figure 10.25 Requirements of the Australian power grid specification for HVRT.
Figure 10.26 Requirements of E.ON Netz (Germany) for reactive power in HVRT.
Figure 10.27 Operating principle of voltage rise compensation by FACTS controllers. (a) Serial compensation; (b) Parallel compensation.
Figure 10.28 Structure of a DFAG system with HVRT.
Figure 10.29 LSC circuit.
Figure 10.30 Control of line side converter (LSC). (a) Direct voltage control and reactive power control of LSC; (b) Current control of LSC.
Figure 10.31 Structure of active power control and reactive power control of a DFAG.
Figure 10.32 Current control structure of a MSC.
Figure 10.33 Phase diagram of the voltage and current of a LSC for HVRT.
Figure 10.34 ACE in AGC.
Figure 10.35 AGC when there is wind power.
Figure 10.36 Structure of a variable-speed variable-pitch wind turbine.
Figure 10.37 Block diagram of a monitoring and control system.
Figure 10.38 Monitoring and control over WFs with external energy storage. (WFC—WF controller; ESC—energy storage controller; ES—energy storage; K—frequency controller).
Figure 10.39 Wind turbine characteristic.
Figure 10.40 Model of wind turbine control system.
Figure 10.41 Monitoring and control over WFs with power reserve, (WFC—WF controller, PRC—power reserve controller, K—frequency controller).
Figure 10.42 Frequency response to power fluctuation G(s)=Δω(s)/ΔPw(s).
Figure 10.43 Operation area and curve k of ESS (solid line, Pw ≥0; dotted line, Pw <0).
Figure 10.44 Reactive power controller for voltage regulation.
Figure 10.45 Power of decentralized ESS and centralized ESS (p.u.).
Figure 10.46 Box diagram of voltage control.
Figure 10.47 Block diagram of synchronous control over ESS converter.
Figure 10.48 Block diagram about constant frequency control of the ESS converter.
Figure 10.49 General expression of ESS planning method.

Chapter 11: Operation and Dispatch of a Power System Containing Wind Power

Figure 11.1 Integrated power curve related to installed capacity of wind power in western Denmark.
Figure 11.2 Increase of reserve capacity with wind power penetration evaluated in different European studies.
Figure 11.3 Curve of variation of LSI and reserve capacity probability with time (during the complete outage of a generator). PLSNO: Probability of LSI in the normal operation hours. PLSFO: Immediate PLS following the complete outage of generator i.
Figure 11.4 Gaussian distribution of total forecast error of a power system in hour h.
Figure 11.5 Curve about loads and wind power generation in a day.
Figure 11.6 Conventional power generation capacity needed in different operation modes.
Figure 11.7 General structure of a power system with wind power.
Figure 11.8 Structure of a nine-bus grid.
Figure 11.9 Active power generation of bus 8.
Figure 11.10 MCP.
Figure 11.11 Curve of bidding by supply bidders and in-demand bidders.
Figure 11.12 Linear bids of power suppliers with fixed demand.
Figure 11.13 MCPs with different bidding success ratios (m_s) of wind power.
Figure 11.14 Linear bid curve on supply side and demand side.
Figure 11.15 Power supply curve of block bids based on a fixed demand.
Figure 11.16 Curve of block bids on supply side and demand side.
Figure 11.17 WF cluster management system.

Chapter 12: The Evaluation Technology for An Wind Power Integrated Power System

Figure 12.1 Structure of an wind power integrated generation system.
Figure 12.2 Wake effect model (Jensen model) for a flat terrain.
Figure 12.3 Diagram of the Lissaman model.
Figure 12.4 Typical output power characteristic curve of a WTGS.
Figure 12.5 Output power linear characteristic curve of a WTGS.
Figure 12.6 Example of CC. (a) CC when there is no wind power; (b) CC when there is wind power; (c) CC when there is wind power (the load is 300 MW larger than that in a).
Figure 12.7 Curve of changes of LOLE with peak load of a power system.
Figure 12.8 Curve of changes of LOLE with WTGS quantity.
Figure 12.9 Wind power CC.
Figure 12.10 Probability density function about load fluctuation.
Figure 12.11 Probability density function about load forecast deviation.
Figure 12.12 Relation between wind power penetration and annual operation value.
Figure 12.13 Relation between the capacity factor and annual operation value of WF.
Figure 12.14 Relation between reserve capacity price and critical installed capacity.
Figure 12.15 Relation between waste gas emission cost and critical installed capacity.
Figure 12.16 Relation between the deviation and advanced duration of wind power forecast.
Figure 12.17 Relation between annual operation value and advanced duration of forecast of wind power.

List of Tables

Chapter 1: Overview

Table 1.1 Average perennial wind direction frequency (f_w) and corresponding wind speed (v)
Table 1.2 Impact of different types of wind turbines on local grid [10]

Chapter 2: Wind Power Generation and Wind Power Generation System

Table 2.1 Wind turbine generator system and characteristic descriptions [1]
Table 2.2 Comparison of Three Kinds of Wind Turbines [2]
Table 2.3 Comparison of generators in the AC/DC/AC system [10]
Table 2.4 Comparison of some technical parameters of wind turbine generators
Table 2.5 Comparison of main characteristics of current type converter and voltage type converter [11]
Table 2.6 Comparison of main characteristics of thyristor AC-DC-AC converter and AC-AC converter

Chapter 3: Operation of Grid-Connected WTGS

Table 3.1 Requirements for rated current of converter of double-fed asynchronous generator and direct-drive synchronous generator

Chapter 4: Connection of WFs to Power Systems

Table 4.1 Basic requirements of the grid code on wind turbines
Table 4.2 Voltage fluctuation allowed by the 35 KV system and the corresponding time
Table 4.3 Connecting capacities of WFs (United Kingdom)
Table 4.4 Connecting capacities of WFs (France)
Table 4.5 Contrast of main technical indicators of VSC-HVDC and PCC-HVDC
Table 4.6 VSC-HVDC project profile
Table 4.7 Contrast of schemes of WFs integration into power grids
Table 4.8 Single asynchronous wind generator parameters (with the rated capacity as the base value)
Table 4.9 Calculation results with different U_s values
Table 4.10 Calculation results when the load is reduced by a half
Table 4.11 Calculation results under different compensation capacities
Table 4.12 Calculation results when x/r is in change

Chapter 5: WF Electrical Systems

Table 5.1 Grounding impedance values measured from two WFs
Table 5.2 Relationship between the building height h and the general lightning strike rate n.
Table 5.3 Impact of lightning on different parts of the wind turbine
Table 5.4 Hazard frequency of lightning on wind turbines
Table 5.5 Lightning protection level parameters
Table 5.6 Requirements of manufacturers on wind turbine resistance
Table 5.7 Wind generator power factor compensation
Table 5.8 List of modern energy storage systems

Chapter 6: OWFs

Table 6.1 System ratings related to OWF topologies
Table 6.2 Comparison of multi-terminal HVDC topologies
Table 6.3 Comparison of OWF transmission schemes
Table 6.4 Fuzzy rules for FC₁
Table 6.5 Fuzzy control rules of FC₃
Table 6.6 Fuzzy rules of FC₂
Table 6.7 Fuzzy rules of FC4 and FC₅
Table 6.8 Wind turbine performance specifications
Table 6.9 132 kV cable costs and losses
Table 6.10 Performance of DC and AC cables
Table 6.11 Comparison of annual energy losses of the three cases being studied
Table 6.12 Unavailability of transmission connection to the shore and the corresponding annual energy not supplied
Table 6.13 Economic analysis results of all schemes
Table 6.14 Part of the OWFs have been put into operation in Europe [2–4]
Table 6.15 Development status of offshore wind turbines
Table 6.16 Planned OWFs in China

Chapter 7: Analysis of Power Systems Containing Wind Power

Table 7.1 Line power flow between Node 1 and Node 2 under different schemes
Table 7.2 Voltage changes at Node 9 under different schemes
Table 7.3 Current components in the stator and rotor during stator short-circuit
Table 7.4 Short-circuit currents provided by wind turbines in occurrence of three-phase short-circuit fault on the transformer high-voltage side
Table 7.5 Comparison of short-circuit currents provided by WFs in occurrence of short-circuit in distant WFs
Table 7.6 Data of load buses in the simulation system
Table 7.7 Gram-Charlier series of the WF

Chapter 8: WF Power Quality and Its Improvements

Table 8.1 Voltage fluctuation limit at all levels
Table 8.2 IEC flicker compatible value and flicker planning value
Table 8.3 Flicker limits at all voltage levels
Table 8.4 Flicker coefficient of a wind turbine (the value in the Table is only for example)
Table 8.5 110 kV bus voltage flicker test results (P_st, and A_st)
Table 8.6 Flicker test results during the period of 70% wind turbine power output
Table 8.7 Flicker test results during the period of no wind turbine power output
Table 8.8 The flicker transmission coefficient obtained at 70% of the rated power
Table 8.9 Limits of voltage sinusoidal waveform distortion rate
Table 8.10 Technical parameters of six types of wind turbines
Table 8.11 Low-voltage current and harmonics of six types of wind turbines
Table 8.12 Current and voltage harmonic parameters on low voltage and medium voltage side

Chapter 9: Wind Velocity and Generated Power Forecasts in WF

Table 9.1 Greatest change of wind power output [6]
Table 9.2 Introduction to early operated short-term wind power forecasts

Chapter 10: WF Control and Protection Technologies

Table 10.1 Time series of transfer trip
Table 10.2 Comparison of different LVRT rules
Table 10.3 Comparison of FRT characteristics in the rotor-side method and that in the stator-side method
Table 10.4 Comparison of the costs of several LVRT technologies
Table 10.5 Estimated rated capacities of ESS and converters based on different ESS technologies and structures
Table 10.6 FHCs of wind power
Table 10.7 Maximum system frequency deviation caused by wind power (Hz)
Table 10.8 Research about rated values of converter and ESS on a WF in a power system

Chapter 11: Operation and Dispatch of a Power System Containing Wind Power

Table 11.1 Impacts of wind power on a power system [3]
Table 11.2 Basic requirements of a grid specification for a WF [3–5]
Table 11.3 Standard deviation of power system forecast error (wind power capacity: 1,500 MW)
Table 11.4 Balance requirements and costs in different time ranges
Table 11.5 Mean daily reserve capacity needed in different operation modes
Table 11.6 Annual cost of reserve capacity
Table 11.7 Parameters of linear bidders
Table 11.8 Output power and payment (Case 1)
Table 11.9 Parameters of in-demand quotation
Table 11.10 Output power and payment
Table 11.11 Data of block bids
Table 11.12 Block bids on demand side
Table 11.13 Time characteristics necessary for energy storage

Chapter 12: The Evaluation Technology for An Wind Power Integrated Power System

Table 12.1 Average wind velocity of WF
Table 12.2 Incidence matrix of WF
Table 12.3 Generation CC
Table 12.4 Impact of average wind velocity of a WF on the maximum penetrating capacity of the WF
Table 12.5 Impact of the on-grid price of wind power on the maximum penetrating capacity of a WF

Integration of Large ScaleWind Energy with Electrical Power Systems in China

Zongxiang Lu and Shuangxi Zhou

Tsinghua University, China

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