TRANSMISSION PLANNING CRITERIA

PREPARED BY: PETER ANG SYSTEM PLANNING BRANCH
APPROVED BY: BILL BIGNELL TRANSMISSION DIVISION REPORT NO. TDWP 78-97 January 2006

Printed: 22/09/2014
TABLE OF CONTENTS

1. INTRODUCTION 6
2. PLANNING PHILOSOPHY AND FUNDAMENTALS 7
2.1 Safety Criteria 9
2.2 Contingency Criteria 9
2.3 Reliability Criteria 9
2.3.1 Steady-State Criteria 9
2.3.2 Stability Criteria 10
2.4 Quality of Supply Criteria 10
2.5 Environmental Criteria 10
2.6 The Need for System Augmentation 11
2.7 Load Management 11
2.8 Control Modifications 12
2.9 Economic Analysis 12
3. ELEMENTS OF THE TRANSMISSION PLANNING CRITERIA 13
3.1 Safety Criteria 13
3.2 Contingency Criteria 13
3.2.1 Deterministic Criteria 13
3.3 Steady State Criteria 13
3.3.1 Real and Reactive Generating Limits 14
3.3.1.1 Transmission Lines 14
3.3.1.2 Power Transformers 14
3.3.1.3 Loads 14
3.3.1.4 Capacitor and Reactor Banks 14
3.3.1.5 Synchronous Generators 14
3.3.1.6 Static VAr Compensators (SVCs) 14
3.3.2 Voltage Limits 15
3.3.3 Frequency Limits 15
3.3.4 Thermal Rating Limits 16
3.3.5 Fault Rating Limits 16
3.4 Stability Criteria 16
3.4.1 Transient Stability 16
3.4.2 Dynamic Stability 18
3.4.3 Voltage Stability (Voltage collapse, resonant damping) 18
3.4.4 Frequency Stability Criterion 19
3.5 Quality of Supply Criteria 19
3.5.1 Voltage Limits 19
3.5.2 System Frequency 19
3.5.3 Harmonic Voltage and Current 19
3.5.4 Electro-magnetic Interference 20
3.5.5 Voltage Unbalance 20
4. TRANSMISSION PLANNING CRITERIA LIMITS 21
4.1 System Performance Requirements 21
4.2 Contingency Criteria 21
4.2.1 Contingency Criteria for South West Interconnected System (SWIS) Transmission Grid 21
4.2.2 Contingency Criteria for North West Interconnected System (NWIS) Transmission Grid 23
4.3 Steady State Criteria 23
4.3.1 Steady State Criteria Common Throughout the WPC Transmission Systems 23
4.3.2 Steady State Criteria for South West Interconnected System Transmission Grid 24
4.3.3 Steady State Criteria for North West Interconnected System Transmission Grid 25
4.4 Stability Criteria 25
4.4.1 Voltage Stability Limits 25
4.4.2 Frequency Stability Limits 28
4.4.3 Transient Stability Criteria 31
4.4.4 Dynamic Stability Criteria (small disturbances) 34
4.5 Quality of Supply Criteria 34
4.6 Safety Criteria 35
4.7 Environmental Criteria 35
5. Substations Planning Criteria 36
5.1 INTRODUCTION 36
5.1.1 EQUIPMENT RATINGS 36
5.1.2 DISTRIBUTION TRANSFER CAPACITY 37
5.2 SUBSTATION SUPPLY CAPABILITY 38
5.2.1 N-1 Criterion 38
5.2.1.1 Transformers operating in parallel 38
5.2.1.2 Transformers not operating in parallel 39
5.2.1.3 Usable Firm Capacity 39
5.2.2 1% Risk Criterion 39
5.2.2.1 1% Risk Factor “m” Factor 40
5.2.2.2 Applicable Substations 41
5.2.2.3 Load Shedding 42
5.2.2.4 System Spare Transformer 42
5.2.3 NCR Criterion 42
5.2.3.1 Applicable Substations 43
5.2.3.2 Unbalanced Transformer Loadings 43
5.2.3.3 Rating of RRST 44
5.2.3.4 NCR Capacity 44
5.2.3.5 Substations with Dissimilarly Rated Transformers 44
5.2.3.6 NCR Capacity < Firm or 1% Risk Capacity 45
5.2.3.7 Installation of System Spare Transformer Following Deployment of RRST 45
5.3 Three Transformer Double LV Busbar Substation (Special Case) 45
5.4 Perth Central Business District (CBD) Substations 46
5.4.1 CBD Reliability Criteria 47
5.5 Major Zone Substations 49
5.6 Minor Zone Substations 51
6. Undergrounding of Overhead Lines 53
7. UPGRADING OF OVERHEAD LINES 54
8. APPENDICES 55
Appendix A: STANDARD RATINGS 55 STANDARD TERMINAL STATION RATINGS 55
Appendix B: STANDARD LV BUSBAR DESIGN 58
Appendix C: USE OF DTC UNDER NCR CRITERION 59
Appendix D: RATING OF OVERHEAD EARTH WIRES, PHASE CONDUCTORS AND EARTH GRIDS 60

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