- Electra
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Technical Brochures
- TB 717 2018 Protocol for reporting operational performance of FACTS
- TB 713 2018 Designing HVDC grids for optimal reliability and availability performance
- TB 699 2017 Control methodologies for direct voltage and power flow in a meshed HVDC grid
- TB 697 2017 Testing and commissioning of VSC HVDC systems
- TB 684 2017 Recommended voltages for HVDC grids
- TB 683 2017 Technical requirements and specifications of state-of-the-art HVDC switching equipment
- TB 675 2017 General guidelines for HVDC electrode design
- TB 671 2016 Connection of wind farms to weak AC networks
- TB 663 Guidelines for the procurement and testing of STATCOMS
- TB 657 2016 Guidelines for the preparation of "connection agreements" or "Grid Codes" for multi-terminal schemes and DC Grids
- TB 649 2016 GUIDELINES FOR LIFE EXTENSION OF EXISTING HVDC SYSTEMS
- TB 619 2015 HVDC CONNECTION OF OFFSHORE WIND POWER PLANTS
- TB 617 2015 HVDC LCC Converter Transformers - CONVERTER TRANSFORMER FAILURE SURVEY RESULTS FROM 2003 TO 2012
- TB 609 2015 Study of Converter Transients Imposed on the HVDC Converter Transformers
- TB 604 2014 Guide for the Development of Models for HVDC Converters in a HVDC Grid
- TB 590 2014 B4-04 Protocol for reporting the operational performance of HVDC Transmission Systems
- TB 563 2013 B4-38 Modelling and Simulation Studies to be performed during the lifecycle of HVDC Systems
- TB 554 2013 B4-49 Performance Evaluation and Applications Review of Existing Thyristor Control Series Capacitor Devices – TCSC
- TB 553 2013 B4-47 Special Aspects of AC Filter Design for HVDC Systems
- TB 536 2013 C4/B4/C1.604 Influence of Embedded HVDC Transmission on System Security and AC Network Performance
- TB 533 2013 B4-52 HVDC Grid Feasibility Study
- TB 508 2012 B4-44 HVDC Environmental Planning Guidelines
- TB 492 2012 B4-46 Voltage Source Converter (VSC) HVDC for Power Transmission - Economic Aspects and Comparison with other AC and DC Technologies
- TB 447 2011 B4-48 Components Testing of VSC System for HVDC Applications
- TB 417 2010 B4-45 Technological Assessment of 800kV HVDC Applications
- TB 407 2010 JWG A2/B4.28 HVDC Converter Transformers - Guidelines for conducting design reviews for HVDC converter transformers
- TB 406 2010 JWG A2/B4.28 HVDC Converter Transformers - Design review, test procedures, ageing evaluation and reliability in service
- TB 388 2009 JWG B2/B4/C1.17 IMPACTS OF HVDC LINES ON THE ECONOMICS OF HVDC PROJECTS
- TB 371 2009 WG B4.40 Static Synchronous Series Compensator (SSSC)
- TB 370 2009WG B4.39 Integration of large Scale Wind Generation using HVDC and Power Electronics
- TB 364 2008 WG B4.41 Systems with multiple DC Infeed
- TB 352 2008 WG B4.34 Capacitor Commutated Converted (CCC) HVDC Interconnections: Digital modeling and Benchmark Circuit
- TB 337 2007 JWG B4/A3/B3.43 Increased System Efficiency by Use of New Generations of Power Semiconductors
- TB 280 2005 SC B4 WG B4.33 HVDC and FACTS for distribution systems
- TB 269 2005 SC B4 WG B4.37 VSC Transmission
- TB 242 2004 SC B4 WG B4.35 Thyristor controlled voltage regulators: Parts 1 and 2
- TB 240 2004 SC B4/A2 JTF B4.04/A2.01 Analysis of HVDC thyristor converter transformer performance
- TB 237 2003 SC B4 WG B4.19 Static synchronous compensator (STATCOM) for arc furnace and flicker compensation
- TB 223 2003 SC B4 WG B4.28 Active filters in HVDC applications
- TB 222 2003 SC B4 WG B4.05 On voltage and power stability in AC/DC systems
- TB 215 2002 SC 14 WG 14.32 HVDC converter stations for voltages above +/- 600 kV
- TB 205 2002 SC 14 WG 14.31 Custom power - State of the art.
- TB 202 2002 SC 14 WG 14.26 HVDC stations audible noise
- TB 186 2001 SC 14 WG 14.20 Economic assessment of HVDC links
- TB 183 2001 SC 14/37/38/39 JWG 14/37/38/39.24 FACTS technology for open access
- TB 160 2000 SC 14 WG 14.27 Unified power flow controller (UPFC)
- TB 149 1999 SC 14 WG 14.29 Coordination of controls of multiple FACTS/HVDC links in the same system.
- TB 144 1999 SC 14 WG 14.19 Static synchronous compensator (STATCOM)
- TB 143 1999 SC 14 WG 14.25 Cross-modulation of harmonics in HVDC schemes
- TB 139 1999 SC 14 WG 14.30 Guide to the specification and design evaluation of AC filters for HVDC systems.
- TB 136 1999 SC 14 TF 14.01.04 Fire aspects of HVDC thyristor valves and valve halls.
- TB 130 1998 SC 14 WG 14.23 Operational guidelines and monitoring of HVDC systems
- TB 127 1998 SC 14 WG 14.11 Guide for upgrading transmission systems with HVDC transmission
- TB 123 1997 SC 14 WG 14.18 Thyristor controlled series compensation
- TB 119 1997 SC 14 WG 14.05 Interaction between HVDC convertors and nearby synchronous machines.
- TB 116 1997 SC 11/14 JWG 11/14.09 Guide for preliminary design and specification of hydro stations with HVDC unit connected generators.
- TB 115 1997 SC 14 WG 14.07 Guide for planning DC links terminating at AC system locations having low short-circuit capacities. Part II : Planning guidelines.
- TB 114 1997 SC 13/14 WG 13/14.08 Circuit-breakers for meshed multiterminal HVDC system.
- TB 113 1997 SC 14 WG 14.01.03 Test circuits for HVDC thyristor valves.
- TB 112 1997 SC 14 WG 14.17 Semiconductor power devices for use in HVDC and FACTS controllers.
- TB 103 1996 SC 14 WG 14.05 Commutation failures. Causes and consequences.
- TB 097 1995 SC 14 WG 14.12 System tests for HVDC installations.
- TB 093 1995 SC 14 WG 14.01.02 Guidelines for testing of thyristor valves for static var compensators.
- TB 092 1995 SC 14 WG 14.03.02 DC side harmonics and filtering in HVDC transmission systems
- TB 086 1994 SC 33 /21/14 JWG 33/21/14.16 Overvoltages on HVDC cables.
- TB 082 1994 SC 38 WG 38.01.05 Use of DC converters for VAR control.
- TB 078 1994 SC 14 WG 14.01.02 Voltage and current stresses on thyristor valves for static var compensators.
- TB 077 1993 SC 38 WG 38.05.04 Analysis and optimisation of SVC use in transmission systems.
- TB 068 1992 SC 14 WG 14.07 Guide for planning DC links terminating at AC locations having low short-circuit capacities. Part 1. AC/DC interaction phenomena.
- TB 065 1992 SC 14 WG 14.03 AC harmonic filters and reactive compensation for HVDC with particular reference to noncharacteristic harmonics.
- TB 051 1996 SC 38 WG 38.01.06 Load flow control in high voltage systems using FACTS controllers.
- TB 034 1989 SC 33/14 JWG 33/14.05 Guidelines for the applications of metal oxide arresters without gaps for HVDC converter stations.
- TB 025 1986 SC 38 TF 38.01.02 Static var compensators.
- TB 003 1987 SC 14 WG 14.04 Compendium of HVDC schemes throughout the world.
- TB 000 1994 SC 14 WG 14.02 A summary of the report on survey of controls and control performance in HVDC schemes.
- Session papers
- Other Documents
- SC Library
- Documents related to the development of HVDC Grids
TB 116 1997 SC 11/14 JWG 11/14.09 Guide for preliminary design and specification of hydro stations with HVDC unit connected generators.
Several technical and economical reasons strongly suggest that in certain HVDC applications it is of great advantage to simplify the rectifier station via a direct connection of hydro generating sets to 12 pulse converter groups. The proposed arrangement is referred to in HVDC literature as "Unit Connection".
TABLE OF CONTENTS
1 INTRODUCTION
1.1 General
1.2 The Unit Connection Concept
1.3 Adjustable Speed Operation of HVDC Unit Connected Hydro Stations
1.4 Impact of Adjustable Speed Operation on Generating and Converter Station Equipment
1.5 Summary of CIGRÉ JWG 11/14-09 Findings
2 THE HVDC UNIT CONNECTED HYDRO STATION
2.1 Arrangement and Main Characteristics of HVDC Sending End Converter Station
2.1.1 Conventional Connection
2.1.2 Independent Generator-Converter Units (The HVDC Generating Unit)
2.1.3 Group Connection
2.1.4 Adjustable Series Connection
2.1.5 Diode (uncontrolled) Rectifier Unit Connection
2.1.6 Main Applications
2.2 Operational Characteristics of HVDC Unit Connected Hydro Station
2.2.1 Classification of Hydro-Generating Stations According to their Power/Energy Parameters
2.2.2 Overview of Characteristics Specific to Stations Operating in the Adjustable Speed Mode
2.2.3 Station Auxiliaries, Circuit Breakers, Control and Protection Equipment
2.3 Economic Implications
2.3.1 Sending end Converter Station Capital Cost Comparison
2.3.2 Other Economical Impacts
2.3.2.1 Capital Savings if Designing for Adjustable Speed Operation
2.3.2.2 Long Term Economic Impacts of Adjustable Speed Operation.
3 ADJUSTABLE SPEED OPERATIONS OF HYDRO TURBINES
3.1 Introduction
3.2 Limits
3.2.1 Output Limits
3.2.2 Water Head Limits
3.2.3 Speed Limits
3.3 Gains
3.3.1 Efficiency
3.3.2 Cavitation at Fixed and Adjustable Speed
3.4 Governing
3.5 Basic Theory, Turbine Types and Characteristics
3.5.1 General
3.5.2 Basic Theory
3.5.3 Potential Impact of Adjustable Speed on Different Turbines
3.5.4 Operational Characteristics
3.6 Practical Consequences of Adjustable Speed Operation
3.6.1 Capital Costs, Overall Optimization and Savings in Civil Works
3.6.2 Energy Gains and Environmental Benefits
3.6.3 Efficiency, Cavitation and Water Head Variations
3.6.3.1 Operation at Rated Head
3.6.3.2 Operation at Low Heads
3.6.3.3 Operation at Higher Than Normal Heads
3.6.4 Cavitation Control
3.6.5 Margin for Correction of Undetected Design Flaws
3.6.6 Reliability, Availability and Maintenance Costs
3.6.7 Capability of the Generating Set and Generator Rating for Adjustable Speed
3.7 Concluding Remarks
3.7.1 General
3.7.2 Special Turbine Designs
3.7.3 Upgrading of Old Stations
4 SYNCHRONOUS GENERATORS IN HVDC UNIT CONNECTION
4.1 Introductory Comments and General Assessment
4.2 Commutation Reactance, Converter Reactive Load and Generator Fundamental Frequency Terminal Power Factor in Unit Connection
4.2.1 Nature of the Fundamental Frequency Converter Reactive Load in Unit Connection
4.2.2 Specification of the Generator Nominal Fundamental Frequency Power Factor
4.3 Generator Reactance
4.3.1 Fundamental Frequency Generator-Converter Interaction
4.3.1.1 Commutations
4.3.1.2 Variation of Reactance with Speed
4.3.1.3 Typical Values of Commutation Reactance for 12 Pulse Unit Connections
4.3.1.4 Non Standard Generator Subtransient and Transformer Leakage Reactances
4.3.1.5 Damper Windings
4.3.1.6 Variation Due to Machine Load
4.3.1.7 Influence of Dampers Resistance
4.3.2 Generator Operational Inductances over a Range of Speed
4.3.2.1 Hydro Generator Operational Inductances
4.3.2.2 Hydro Generator Frequency Response
4.3.2.3 Generator Subtransient Reactance as Affected by Operating Conditions
4.3.2.4 Generator Harmonic Reactance in Adjustable Speed Operation
4.4 Generator Excitation
4.4.1 Auxiliary 3 phase Generator
4.4.2 Fully Independent Auxiliary Generators
4.5 Cycling and Fatigue
4.5.1 Fatigue Aging due to Adjustable Speed Operation
4.5.2 Stator Windings
4.5.3 Electromechanical Effects of Converter Harmonics on Large Hydro-Generators
4.6 Insulation Stresses
4.6.1 Rotating Machine Insulation Degradation in Power Electronic Applications
4.6.1.1 Repetitive Impulse Voltage
4.6.1.2 Insulation Problems of Rotating Machines
4.6.1.3 Insulation Degradation of Form Wound Windings for Large Machines
4.6.1.4 Partial Discharges Inception Voltages
4.6.2 Insulation of Unit Connected Generators
4.7 Generator Losses
4.7.1 Windage Losses
4.7.2 Iron Losses
4.7.3 Stray Losses in Stator Copper
4.7.4 Losses on Pole Shoes and Damper Windings
4.8 Generator Rating
4.8.1 Generator Rating at Fixed Speed
4.8.2 Generator Rating at Adjustable Speed
4.8.3 Generator Voltage
4.8.4 Generator Inertia Parameters (GD2)
4.9 New Zealand Field Tests of Unit Connection Operation
4.9.1 TransPower Benmore Station
4.9.2 1993 Test Conditions and Results
4.9.3 1995 Test Conditions and Results
4.10 Concluding Remarks
4.10.1 Concluding Remarks on Cycling and Fatigue
4.10.2 Insulation Aging of HVDC Unit Connected Generator
4.10.3 Concluding Remarks on HVDC Unit Connected Generators Design and Rating
5 SENDING AND RECEIVING END STATION: GENERAL EQUIPMENT AND REQUIREMENTS
5.1 Introduction
5.2 Unit Connected Rectifier Station
5.2.1 Operating Parameters
5.2.2 Converter a.c. Voltage Uv
5.2.3 Converter d.c. Voltage Ud
5.2.4 Operation with Adjustable Speed
5.2.4.1 Generator EMF
5.2.4.2 Valve Voltage
5.2.4.3 Angle of Overlap
5.2.5 Some Additional Points
5.2.5.1 Tap Charger Range under Adjustable Speed
5.2.5.2 HVDC Line Efficiency Estimates
5.3 “Generator-Converter” Transformer
5.3.1 On Load Tap Charger
5.3.2 Transformer Ratings
5.3.3 Operation with Adjustable Speed
5.3.4 General Guidelines Concerning the “Generator-Converter Transformer” Specification
5.4 Smoothing Reactors
5.5 d.c. Filters
5.5.1 Conventional Filtering Scheme
5.5.2 Alternative Filtering Schemes
5.6 Valve Bridges
5.6.1 Fundamental Considerations
5.6.2 Rectifier Station Valve Requirements
5.6.3 Considerations of Valve Ratings for Unit Connected Stations
5.6.4 Rectifier Station Auxiliaries
5.6.5 Circuit-Breakers
5.6.6 Control and Protection Equipment
5.7 Inverter Station
5.7.1 Receiving end Requirements
5.7.2 Implications of Receiving end Station Current Control
5.8 Insulation Requirements
5.8.1 Introduction
5.8.2 Arrester Protection Scheme
5.8.3 Continuous Operating Voltage
5.8.4 Temporary Overvoltages and Switching Surges
5.8.5 Fast Transient Overvoltages
5.8.6 Protection Levels and Test Voltages
5.8.7 Insulation Coordination Studies
5.9 Simplified Steady State Analysis for Preliminary Considerations
6 CONTROL AND PROTECTION FUNCTIONS
6.1 Introduction
6.2 Basic Control Functions
6.2.1 Quantities to be controlled
6.2.2 Steady State Active Power
6.2.3 Machine Speed
6.2.4 Generator Voltage
6.2.5 Direct Current
6.2.6 Direct Voltage
6.2.7 Receiving end Quantities
6.3 Dynamic Control Functions
6.3.1 Definitions and Scope
6.3.2 Dynamic a.c. Voltage Control
6.3.3 Damping of Electro-Mechanical Oscillations
6.3.4 Suppression of Instabilities at Higher Frequencies
6.3.5 Dynamic Interactions with the Power Plant
6.4 Transient Control Functions
6.4.1 Definitions and Scope
6.4.2 Switching Transients without Faults
6.4.3 a.c. System Faults
6.4.4 d.c. overhead Line Faults
6.5 Protection Functions
6.5.1 Protection Philosophy
6.5.2 Differential Protection
6.5.3 Overcurrent Protection
6.5.4 Overvoltage Protection
6.5.5 Equipment Protection
6.5.6 Generator Circuit-Breakers
6.6 Diode-Equipped Rectifier
6.6.1 General
6.6.2 Steady State and Dynamic Control Functions
6.6.3 Transient Control Functions
6.6.4 Application of d.c. Circuit Breakers
6.6.5 Conclusions
6.7 Forced Commutated Inverter
6.7.1 General
6.7.2 Forced Commutation
6.7.3 Forced Commutated Current source Inverter
6.7.4 Other Types of Forced-Commutated Converters
6.7.5 The Capacitor Commutated Converter (CCC)
6.7.6 Conclusions
7 OVERALL PERFORMANCE OF HVDC UNIT CONNECTED STATIONS
7.1 Station Capability
7.1.1 Steady State
7.1.2 Transient Capability
7.2 Arrangements Capabilities: Limitations of Paired, Series Connected Arrangements
7.3 Operational Characteristics
7.3.1 Unit Connected Stations with Thyristor Bridges
7.3.2 Operational Characteristics of Stations with Diode Bridges
7.4 Dynamic Behavior
7.4.1 Dynamic Behavior of Unit Connected Stations with Thyristor Rectifiers
7.4.1.1 Generator Load Rejection
7.4.1.2 Extinction of d.c. Line Faults By the Unit Connected Sending End
7.4.1.3 Station Faults
7.4.2 Dynamic Behavior of Unit Connected Stations with Diode Rectifiers
7.5 Conclusions
7.5.1 Operational Characteristics of Stations with Thyristor Bridges
7.5.2 Independence from Speed Oscillations Swings
8 MODELING ASPECTS RELATING TO HVDC UNIT CONNECTION
8.1 Introduction
8.2 Generator Modeling
8.2.1. Representation of the Generator
8.2.1.1 Two Axis Model
8.2.1.2 Three Phase, Two Axis Model
8.2.1.3 Finite Element Model
8.2.2 Modeling Details
8.2.2.1 Parameter Prediction for Equivalent Circuit Models
8.2.2.2 Finite Element Modeling Aspects
8.2.2.3 Theory of Finite element Modeling
8.2.2.4 Modeling Rotor Motion
8.2.2.5 Calculation of Winding Voltages and Currents
8.2.2.6 Modeling of the Rectifier Bridge
8.3 Station Modeling for Studies of Reservoir Design
8.3.1. The Simulation Program as an Analysis Tool
8.3.1.1 Hydraulic Reservoir Subsystem
8.3.1.2 Turbine-Generator Subsystem
8.3.2 Operation at Fixed Speed
8.3.3 Operation at Adjustable Speed
8.3.3.1 Representation of the Hydraulic Turbine Object Function
8.3.3.2 Choosing the Number of Generating Units
8.3.3.3 Simulation of Power Plant Operation
8.4 Application to System Studies
8.4.1 Equivalent Circuit Model of the Generator with Full System Representation
8.4.2 Generator Models Validation
8.4.3 Adjustable Speed Mode Long Term Operation Modeling
8.4.4 Finite Element Model Integrated with Simplified Circuit Representation
8.4.5 Finite Element Model Integrated with Transient Circuit Analysis Program
8.4.5.1 Transient Circuit Analysis
8.4.5.2 Finite Element Solution
8.4.6 Concluding Remarks on Finite Element Modeling
8.5. Conclusions