AND ITS PRACTICAL APPLICATIONS FOR TRANSMISSION NETWORK FLOW STUDIES
By
DANIEL FREDERIK PAYNE
THESIS
presented in partial fulfillment of the requirements of the degree
DOCTOR PHILOSPHEA (D.Phil)
in the
FACULTY OF ENGINEERING
of the
RAND AFRIKAANS UNIVERSITY
SUPERVISOR: PROF. J.H.C. PRETORIUS CO-SUPERVISOR: P.D. PRETORIUS
MAY 2004
SUMMARY
The prediction of the expected transmission network loads as required for transmission network power flow studies, has become very important and much more complex than ten to twenty years ago. Therefore a single forecast is no longer the answer to the problem.
The modelling of different long-term electrical forecasts makes it possible to compare a number of different forecasts. The modelling provides the further option that each expected load can be entered as a range and then the developed balancing algorithm checks for consensus (feasibility). If feasibility exists, then the different forecasts are reconciled (a feasible solution is determined). Factors such as international and national market trends, economical cycles, different weather patterns, climate cycles and demographic changes are studied. The factors that have significant impact on the transmission electrical loads are integrated in ten different forecasts. It thus gives more insight into the electrical industry and makes the forecast results more informative and therefore reduces the uncertainty in the future expected loads.
BEDANKINGS
Die volgende persone en instansies het elk ‘n unieke bydrae gelewer:
Prof. Cees Roon wat tydens my M.Sc die basis gelê vir die ontwikkeling van die metode.
Prof. Jan Harm Pretorius vir sy leiding en ondersteuning.
Prof. Phillip Pretorius vir sy bedrae en insette.
Henta vir jou aanmoediging, ondersteuning en liefde, ook ons kinders Marilize en Vincent.
Marietjie Snyman en Sougnet Van Niekerk vir julle geduld en die tyd wat julle spandeer het om artikels en handboeke te soek.
ESKOM wat die navorsing moontlik gemaak het.
CONTENTS
1 THE TRANSMISSION ELECTRICAL NETWORKS 1
1.1 INTRODUCTION 1
1.2 THE TRANSMISSION ELECTRICAL NETWORK 2 1.3 ELECTRICAL NETWORK LOAD REQUIREMENTS 6
1.4 ELECTRICAL LOAD MODEL 8
1.5 LITERATURE SURVEY 12
1.6 CONCLUS ION 14
1.7 REFERENCE 15
2 FACTORS 17
2.1 INTRODUCTION 17
2.2 FACTORS 19
2.2.1 Regulatory Aspects 19
2.2.2 End-Use Load Profiles 20
2.2.3 Generation 21
2.2.4 Sectors 23
2.2.5 New Technology Developments 27
2.2.6 Environmental Impacts 27
2.2.7 Networks 28
2.2.8 International and National Trends 30
2.3 CONCLUSION 31
2.4 REFERENCE 31
3 DIFFERENT FORECASTS 33
3.1 INTRODUCTION 33
3.2 FORECASTS 33
3.2.1 Maximum Transmission System Load 33
3.2.2 Generation Pattern 38
3.2.3 Power Stations 40
3.2.4 Transmission Losses 41
3.2.5 International Customers 41
3.2.6 Areas 42
3.2.7 Transmission Substations 46
3.2.8 Distribution Substations 51
3.2.9 Sectors 55
3.2.10 Area per Sector Loads 55
3.3 POINT LOADS 56
3.4 MAXIMUM AND MINIMUM LOADS 56
3.5 FACTORS CONSIDERED IN FORECASTS 57
3.6 MULTIPLE REGRESSION AND NEURAL NETWORKS 57
3.7 CONCLUSION 63
3.8 REFERENCE 63
4 BALANCING ALGORITHM 66
4.1 INTRODUCTION 66
4.2 MATHEMATICAL RELATIONSHIPS 67
4.3 OPERATIONS RESEARCH 71
4.4 BALANCING ALGORITHM 72
4.5 EVALUATION 75
4.6 CONCLUSION 76
4.7 REFERENCE 76
5 RESULTS 77
5.1 INTRODUCTION 77
5.2 FORECAST RESULTS 77
5.3 EVALUATION 111
5.4 GEOGRAPHICAL INFORMATION SYSTEM 111
5.5 CONCLUSION 112
6 CONCLUSION AND EVALUATION 113
6.1 INTRODUCTION 113
6.2 FIELDS COVERED AND RESULTS OBTAINED 113
6.3 EVALUATION 114
6.4 RECOMMENDATIONS 115
6.5 CONCLUSIONS 115
ANEXURE A ANNUAL LOAD PROFILES 116
A.1 INTRODUCTION 116
A.2 AREA LOADS 116
A.3 TRANSMISSION SUBSTATION LOADS 126
ANEXURE B WEEKLY LOAD PROFILES 129
B.1 INTRODUCTION 129
B.2 AREA LOADS 129
LIST OF FIGURES
Figure 1.2.1 - A Typical Transmission Electrical Network Layout 2 Figure 1.2.2 - Single Backbone Substation Arrangement 3 Figure 1.2.3 – A Backbone Substation with Multi-Voltage Arrangement 4 Figure 1.2.4 – Multi-Backbone Substation Arrangement 5 Figure 1.2.5 - A Typical Transmission Electrical Network 6 Figure 1.4.1 – Electrical Load Model: Phase One 9 Figure 1.4.2 – Distribution Substation Selection Criteria 10 Figure 1.4.3 – Electrical Load Model: Phase Two 11 Figure 1.4.4 – Electrical Load Model: Phase Three 12 Figure 2.2.1 – Net Power Output – Power Station 22
Figure 2.2.2 – Load Profile – Substation 23
Figure 2.2.3 – Area With Large Gold Mining Operations 23 Figure 2.2.4 – Area With A Large Stainless Steel Plant Commissioned 24 Figure 2.2.5 – Area With A Large Aluminium Plant Commissioned 24 Figure 2.2.6 – Area with Platinum and Ferrous-Chrome Operations 25 Fig ure 2.2.7 – Load Reduction at An Existing Substation 29 Figure 2.2.8 - Different Network Operations – Substation A 29 Figure 2.2.9 - Different Network Operations – Substation B 30 Figure 3.2.1 - Graphical display scenarios in action 45 Figure 3.2.2 - Markov process in terms of states 49
Figure 3.2.3 - Markov process for K’s Market 50
Figure 3.6.1 - Components of a neuron 60
Figure 3.6.2 - Single Layer Percepton with on neuron in its output layer 60
Figure 4.4.1 – Balancing Algorithm 75
Figure 5.2.1 – Maximum System Load 77
Figure 5.2.2 – Two Curves for Maximum System Load 78 Figure 5.2.3 – Maximum System Load (Close to High Scenario) 78 Figure 5.2.4 – Total Power Station Loads at System Peak 79
Figure 5.2.5 – International Customer Loads 79
Fig ure 5.2.6 – % Transmission Electrical Losses 80 Figure 5.2.7 – Geographical Map of South Africa 81
Figure 5.2.8 – Northwest Annual Load 83
Figure 5.2.9 – KZN Annual Load 84
Figure 5.2.10 – E-Cape Annual Load 85
Figure 5.2.11 – Northeast Annual Load 86
Figure 5.2.12 – Central Annual Load 88
Figure 5.2.13 – Saldanha Steel Plant Launched in 1999 89
Figure 5.2.14 – Western Annual Load 90
Figure 5.2.15 – The Concentrator Plant at Modikwa 91
Figure 5.2.16 – Polokwane Smelter 91
Figure 5.2.17 – Northern Annual Load 92
Figure 5.2.18 – Balanced and S-curve Maximum System Load 99
Figure 5.2.19 – Cycle 99
Figure 5.2.20 – Annual GW System Peak Increase 100
Figure 5.2.21 – Annual Growth 100
Figure 5.2.22 – Generation Required 101
Figure 5.2.23 – Additional Loads 101
Figure 5.2.24 – Hillside Aluminium Smelter 110
Figure 5.2.25 –Richards Bay Harbour 110
Figure A.2.1 – Area 1 Annual Load 116
Figure A.2.2 – Area 2 Annual Load 116
Figure A.2.3 – Area 3 Annual Load 117
Figure A.2.4 – Area 4 Annual Load 117
Figure A.2.5 – Area 5 Annual Load 117
Figure A.2.6 – Area 6 Annual Load 118
Figure A.2.7 – Area 7 Annual Load 118
Figure A.2.8 – Area 8 Annual Load 118
Figure A.2.9 – Area 9 Annual Load 119
Figure A.2.10 – Area 10 Annual Load 119
Figure A.2.11 – Area 11 Annual Load 119
Figure A.2.12 – Area 12 Annual Load 120
Figure A.2.13 – Area 13 Annual Load 120
Figure A.2.14 – Area 14 Annual Load 120
Figure A.2.15 – Area 15 Annual Load 121
Figure A.2.16 – Area 16 Annual Load 121
Figure A.2.17 – Area 17 Annual Load 121
Figure A.2.18 – Area 18 Annual Load 122
Figure A.2.19 – Area 19 Annual Load 122
Figure A.2.20 – Area 20 Annual Load 122
Figure A.2.21 – Area 21 Annual Load 123
Figure A.2.22 – Area 22 Annual Load 123
Figure A.2.23 – Area 23 Annual Load 123
Figure A.2.24 – Area 24 Annual Load 124
Figure A.2.25 – Area 25 Annual Load 124
Figure A.2.26 – Area 26 Annual Load 124
Figure A.2.27 – Area 27 Annual Load 125
Figure A.2.28 – Area 9 Annual and Forecast Load 125 Figure A.2.29 – Area 19 Annual and Forecast Load 125
Figure A.3.1 – Substation 1 Annual Load 126
Figure A.3.2 – Substation 2 Annual Load 126
Figure A.3.3 – Substation 3 Annual Load 126
Figure A.3.4 – Substation 4 Annual Load 127
Figure A.3.5 – Substation 5 Annual Load 127
Figure A.3.6 – Substation 6 Annual Load 127
Figure A.3.7 – Substation 7 Hourly Load 128
Figure B.2.1 – Area 1 Weekly Load 129
Figure B.2.2 – Area 2 Weekly Load 129
Figure B.2.3 – Area 3 Weekly Load 130
Figure B.2.4 – Area 4 Weekly Load 130
Figure B.2.5 – Area 5 Weekly Load 130
Figure B.2.6 – Area 6 Weekly Load 131
Figure B.2.7 – Area 7 Weekly Load 131
Figure B.2.8 – Area 8 Weekly Load 131
Figure B.2.9 – Area 9 Weekly Load 132
Figure B.2.10 – Area 10 Weekly Load 132
Figure B.2.11 – Area 11 Weekly Load 132
Figure B.2.12 – Area 12 Weekly Load 133
Figure B.2.13 – Area 13 Weekly Load 133
Figure B.2.14 – Area 14 Weekly Load 133
Figure B.2.15 – Area 15 Weekly Load 134
Figure B.2.16 – Area 16 Weekly Load 134
Figure B.2.17 – Area 17 Weekly Load 134
Figure B.2.18 – Area 18 Weekly Load 135
Figure B.2.19 – Area 19 Weekly Load 135
Figure B.2.20 – Area 20 Weekly Load 135
Figure B.2.21 – Area 21 Weekly Load 136
Figure B.2.22 – Area 22 Weekly Load 136
Figure B.2.23 – Area 23 Weekly Load 136
Figure B.2.24 – Area 24 Weekly Load 137
Figure B.2.25 – Area 25 Weekly Load 137
Figure B.2.26 – Area 26 Weekly Load 137
Figure B.2.27 – Area 27 Weekly Load 138
LIST OF TABLES
Table 3.5.1 – Summary of Factors 57
Table 4.4.1 Heuristic Solution 74
Table 5.2.1 TOTDX Load s 92
Table 5.2.2 – Area Load Forecasts 93
Table 5.2.3 – Load Dynamics Results 94
Table 5.2.4 – Area and Transmission Substation Results 95 Table 5.2.5 – TX 26 Balanced and Unbalanced Load comparison 98
Table 5.2.6 – Summary of Cycle Results 100
Table 5.2.7 – Balanced Distribution Substation Loads 102 Table 5.2.8 – Comparison between Balanced and Power Flow Loads 103
Table 5.2.9 – Point Loads 103
Table 5.2.10 – Substation Loads determined from Balanced Loads 104
Table 5.2.11 – Minimum & Maximum Loads 106
Table 5.2.12 – Sector Loads 109
Table 5.2.13 – Area per Sector Loads 109
Table 6.3.1 – Maximum System Loads (Actual vs S-curve results) 114