ABSTRACT
In the last decades, the power industry has had a gradual and steady change from the centralized bulk system (grid) where power is injected to the transmission network from generator to a more decentralized system where power is injected directly to a distribution network (embedded generation). Nigeria is not left out in this trend. In this assessment study, the Siemens’ PSS/E software is used to run the Newton-Raphson load flow program to see the effect of EG on loss reduction and voltage profile improvement while comparing the results obtained with the installation of the traditional network compensators alongside their impact on network (element) loading. Furthermore, the load factor and EG level of penetration are determined via mathematical methods. This work shows that EG can reduce the Nigerian transmission network loss by 7% and a section-cut of it; the (Port Harourt) PH Mains network loss to 5.51% from 9.97%. The work further shows that EG improves the per unit (p.u.) voltage of a network especially at the buses directly connected to it as observed from buses 13(0.914 to 1.02 p.u.) and 14 (0.937 to 1.02 p.u.) of the transmission network considered. Similarly, EG greatly improved the overall voltage profile of the Port Harcourt Mains T/S 132/33kV with all bus voltages falling within the statutory voltage profile range (0.95 p.u. to 1.05 p.u.) except the Rumuodumaya Bus that improved from 0.8pu to 0.93pu. A comparison of the network performance with EG and with Fixed Shunt Compensation gives EG a better recommendation in the light of loss reduction, voltage profile improvement capabilities. Also more efficient consumption of power by consumers are achieved with the EG in operation as seen in the Load Factor studies. At a penetration of 14.76%, the EG has a positive effect on the overall network performance which has to be monitored as the level of penetration increases, so as to mitigate the impact on the technical losses of the network.
TABLE OF CONTENTS
Title Page i Approval Page ii Certification iii Dedication iv Acknowledgement v Abstract vi Table of Contents vii List of Tables x List of Figures xiii List of Abbreviations xv CHAPTER ONE: INTRODUCTION 1.1 Background of the Study 1 1.1.1 A Brief History of the Nigeria Electricity Industry 2 1.1.2 Objectives of Restructuring the Electric Power Sector 4 1.2 Statement of the Research Problem 8 1.3 Aim/Objectives of the Study 9 1.4 Justification for the Research 9 1.5 Significance of the Study 11 1.6 Delimitation of Study 11 1.7 Outline of Presentation 12 CHAPTER TWO: LITERATURE REVIEW 2.1 Definition of Embedded Generation 13 2.2 The Operation of Embedded Generation 19 2.3 The Prospects of EG 19 2.4 The Pros and Cons of EG in Nigeria 22 2.5 Barriers to Embedded Generation 23 2.5.1 Environmental Factors 24
2.5.2 Regulation 24
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2.5.3 Technical Factor 25
2.5.4 Commercial Factor 26
2.5.5 Technology 26
2.6 Power Loses and EG Level of Penetration 28 CHAPTER THREE: RESEARCH METHODOLOGY 3.1 Simplified Research Procedure 30 3.2 Methods and Techniques Used 30 3.2.1 Gauss Siedel Method 31 3.2.2 Newton-Raphson Method 31 3.2.3 Fast Decoupled Method 31 3.3 Justification of Load Flow Method. 32 3.4 Research Procedures for Load Flow 32 3.5 Justification of Software Package/Computer Tool Used 37 3.6 Load Flow Analysis in PSS/E 38 3.7 Load Factor (LF) 40 3.8 Degree of Penetration. 40 3.8.1 Average Penetration. 40 3.8.2 Instantaneous Penetration. 40 3.9 Data Collection & Presentation; Input Data Used for the Entire Study Considerations. 41 3.9.1 The Nigerian 330kV 28bus network Data. 41 3.9.2 The Port Harcourt Mains T/S 132/33 Network 50 CHAPTER FOUR: SIMULATION AND RESULTS ANALYSIS
4.1 Presentation of Results and Discussion 61
4.1.1 28 Bus 330kV Transmission Network 61 4.1.2 PH Mains 132/33kV Network Results 76 4.2 Discussion of Results 110 4.2.1 Discussion of the 28-Bus 330kV Network Results. 110 4.2.1a 28-Bus 330kV Network Voltage Profile 110
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4.2.1b 28-Bus 330kV Network Power Loss 113 4.2.2 Discussion of the PH Mains 132/33kV T/S Network Results 115 4.2.2a The PH Mains 132/33kV T/S Network Voltage Profile. 116 4.2.2b The PH Mains 132/33kV T/S Network Power Loss. 120 4.2.2c The PH Mains 132/33kV T/S Network; Percentage loading of Elements 122 4.2.2d Load Factor 122 4.2.2e Level of Penetration 123 CHAPTER FIVE: CONCLUSIONS
5.1 Research Findings 124
5.2 Contribution to Knowledge 125
5.3 Conclusion 125 5.4 Recommendations 126 5.5 Further Research. 127 5.6 Learning Points 128 References 129 APPENDIX 1 136 APPENDIX 2 137 APPENDIX 3 138 APPENDIX 4 141 APPENDIX 5 142 APPENDIX 6 143 APPENDIX 7 144 APPENDIX 8 145 APPENDIX 9 146 APPENDIX 10 147 APPENDIX 11 148 APPENDIX 12 149 APPENDIX 13 150
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CHAPTER ONE
INTRODUCTION 1.1Background of the Study The Nigerian Electricity Supply Industry is besought with a barrage of issues (i.e. technical and non technical) which have placed the industry at the front burner of national discuss for decades now. The issues among others include inadequate generation (to match the country’s growing population, industrial activities and increased power demand that stems from it), poor maintenance/planning, inadequate funding, inadequate gas supply and vandalization of generation facilities etc. The recent World Bank Group data on global access to electricity[1], [2] shows that about 45% of Nigerians are connected to the national grid. Sadly, only about 25% of the country’s population actually have regular access to power [3].This shows that the national grid is limited in reach(with 5523km 330kV and 6801.49km 132kV transmission lines at 2010 against the 911,000km2 landmass of Nigeria[4]) thereby denying over 70% (≈ 100 million) Nigerians who live in rural areas access to constant electricity[5]. More so, the transmission and distribution infrastructure of Nigeria appears to be underfunded and the ―limited‖ infrastructure is stretched with some transformers and substations operated close to/above their design ratings. This has a negative impact on system losses and on the available grid power. Furthermore, the very long transmission distances in the Nigerian grid (310km B’Kebbi T.S – Kainji T.S, 285km Jos T.S – Makurdi T.S, 235km Osogbo T.S- Ikeja-West T.S etc) would normally require the expensive installation of capacitor and reactor banks at low voltage levels ( for power factor improvement and reactive power control) and at high voltage levels respectively. This study looks at how EG can help address these issues.
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1.1.1 A Brief History of the Nigeria Electricity Industry
The history of the Nigeria Electric Supply Industry traced in [6]–[10], narrates that the production of electricity in Nigeria started in Marina, Lagos in 1896/98 about fifteen years after its introduction in England [11] with a total installed capacity of 60KW. After the 1914 amalgamation of the Northern and Southern Protectorates to form Nigeria, other towns started the building of their individual electric power supply system. The towns are [11]; Port Harcourt, Kaduna, Enugu, Maiduguri, Yola, Zaria, Warri and Calabar in the years 1928,1929,1933,1934,1937,1938,1939 and 1939 respectively. For many years, the government and Native Authorities remained and operated as separate entities until 1946 when the Public Works Department (PWD) stopped having control over the generating plants and the distribution system of the nation. This led to the immediate establishment of the Nigerian Government Electricity Undertaking (NGEU); an arm of PWD charged with the responsibility of supplying power to Lagos state. In 1950, the legislative council of the colonial government under ordinance no.15 of 1950, constituted a central body known as the Electricity Corporation of Nigeria (ECN) with the responsibility of overseeing the management and supply of electric power in Nigeria. Around April 1951, the ECN formally took over of the electricity supply business of Nigeria through the integration of all government and native-owned generating plants/systems for a vertically integrated grid-operation of the nation’s power generation, transmission and distribution infrastructure. Some other institutions like the Nigerian Electricity Supply Company (NESCO) also had the license to produce electricity within this period [6]. Meanwhile, a great milestone was reached in the industry in the year1962 with the construction of Kainji Dam (completed six years after) after an Act of the Parliament established the Nigeria Dams Authority, NDA. The NDA was charged with the responsibility of building and maintaining dams in the River Niger and other places, generating of electricity via hydro resource among other functions. Thereafter, the nation’s power grid transmission system started in 1966 through the joint effort of the then ECN and
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NDA by linking Lagos with Kainji. For power distribution to consumers, the NDA sold the power they produced to the ECN. The Kainji-Kaduna link was then also extended to Zaria and Kano. The Oshogbo-Benin-Ughelli and the Benin-Onitsha-Afam(Alaoji) links were subsequently constructed. 1972 saw the merger of both the ECN and the NDA in a new organization known as the Nigeria Electric Power Authority (NEPA) with the following objectives;
…the vesting of the production and distribution of electricity power supply throughout the country in one organization that would assume responsibility for the financial obligations.
integration of the ECN and NDA should result in the more effective utilization of the human, financial and other resources available to the electricity supply industry throughout the country.
In spite of all these changes in the Nigeria Electricity Supply Industry the following (see APPENDIX 1)endured over the years till 2005;
vertically integrated system with the greatest dependency on generation.
monopolistic system managed by the government
growing (peak) demand for power
consumer dissatisfaction with the efficiency and management of the utility company resulting in poor service delivery and high cost of power etc.
In spite of all the efforts of the Nigerian government in the power sector, the ―surmountable‖ challenges of the sector endued (and still endure) for decades now. The general consensus for a sustainable solution was for Nigeria to join the global trend of restructuring the power sector that had already become imperative. This explains why by 1983, Nigeria had engaged two panels of enquiry to work out a model for the restructuring of the then NEPA into an independent body or a model to break its monopolistic operation through privatization. This was followed up
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with the establishment of electrification boards to improve Nigerians access to power. Persistent effort led to the official commissioning of the PHCN on the 5th of May 2005. PHCN was originally modelled as an Initial Holding Company; an IHC that will transfer the assets and liabilities of NEPA to PHCN. This led to the enactment of Electricity Power Sector Reform Act of 2005 and the commencement of the National Integrated Power Projects (NIPPs) initiatives. Eventually, the PHCN was unbundled into eighteen companies comprising
six generating companies- Kainji, Afam, Sapelle, Shiroro, Ughelli and the Egbin Electricity Generating Company
One transmission company i.e. the Transmission Company of Nigeria, completely owned by the federal government but managed by Manitoba Hydro Company of Canada.
Eleven distribution companies- Abuja, Benin, Eko, Enugu, Ibadan, Ikeja, Jos, Kaduna, Kano, Port Harcourt and Yola Distribution Companies all with 80% equity owned by private investors and 20% by the federal government.
To put this history in a better perspective would include a brief look at the objectives of the power sector restructuring in Nigeria which has set the tempo for the present EG concerns in Nigeria. 1.1.2 Objectives of Restructuring the Electric Power Sector As government had the sole control over management of power generation, transmission and distribution in the then monopolistic scenario, the intended separation of the activities of the named constituents of the power system would ensure a better system performance through;
breaking of the monopoly in generation and transmission
encouraging competition in distribution and supply.
Competition in distribution and supply is very necessary as Isola[12] agrees with Penrose view that competition is the most powerful force pushing the economy to
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higher levels of achievement, increasing efficiency in the use of resources, protecting consumers against exploitation and ensuring reasonable opportunities for men to make the most of their abilities and assets. In the light of this, the summary of the objectives of the Nigeria power sector restructuring as provided for in the Nigerian EPSR Act 2005 include the following:
unbundling of the NEPA.
privatization of the unbundled entities.
establishment of a regulatory agency known as National Electricity Regulatory Commission.
establishment of the Rural Electricity Agency (REA) and Fund.
establishment of a power assistance fund.
establishment of West African Power Pool (WAPP).
The incumbent power sector restructuring objectives further aimed at;
costs reduction (i.e. government expenditure and high consumers’ service charges) in generation and supply
allowing Independent Power producers to enter the market
allowing independent transmission owners to invest in the transmission business like in South Africa.
allowing the electricity distribution industry to restructure and provide funds for major electrification schemes like in South Africa.
As the NIPPs were found to stimulate competition in generation and supply and to control the monopoly in transmission and distribution [13], the 2005 EPSR Act, ended the government monopoly (in the vertically integrated power sector) and enabled institutions build a power sector with the private sector as a key partner in the development. According to Amobi[13], the unbundling and deregulation of the electricity industry was purely targeted at increasing our network capacity and reducing the wastage of resources by making the managers’ more efficient.
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The 2005 Act legally ended government monopoly and enabled institutions build a power sector with the private sector as a key partner in the development. The NIPP consists of power plants of 2000MW capacity, the expansion of 330kV and 132kV transmission networks and the expansion of the distribution networks through the constructions of more sub-stations and distribution lines. Note that power plants in Nigeria have three broad classifications based on ownership as[14] puts it;
those owned by the federal government (with most or all of them now privatized).
National Integrated Power Projects (NIPP) – owned by the three tiers of government under the Niger Delta Power Holding Company (NDPHC).
Independent Power Producers (IPPs) – wholly owned by state governments and/or private companies, individuals.
In 2010, the Nigeria’s Ministry of Power launched the Road Map for Power Sector Reform to fast track the implementation of the 2005 Act. The Road Map consists of the design and implementation of extensive rehabilitation, replacement, and maintenance of assets across the fuel-to-power, generation, transmission and distribution chains of the power sector. The scope of the NIPP generation delivery was increased from 2000MW capacity in 2005 to a total of 4770MW target by 2013 with an additional 6000MW to be generated in 2014 by the Independent Power Plants (IPPs) like the Dangote( 150MW in Obajana, Kogi state alone), Lafarge (90MW in Ewekoro, Ogun State), Geometric Power (144MW Aba), Coronation Power and Gas (20MW in Lagos State), Nigeria Agip Oil Company (NOAC) (480MW in Kwale/Okpai, Delta State), AES Barge Power Plant (270MW in Lagos State), Ibom Power Station (190MW in Ikot Abasi, Akwa Ibom State) etc [2] in pursuant of the total generation target of 40,000MW by 2020. There is also a feeling that BUA, Honeywell and Dangote groups with a few other ―consumer industrial groups‖ generate about 15000MW of off-grid power as captive generation[15].
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Today, the Nigerian power infrastructure has become a national grid connecting all the thirty-six capitals of the federation including Abuja, the FCT. See the present transmission grid of Nigeria in APPENDIX 2.Also, See APPENDIX 3 for an understanding of the total generating plants and future generation infrastructure in Nigeria as presented in Sambo et al [8] . The relevance of this history to this study is that it succinctly shows the fact that in Nigeria, power generation actually started as embedded generation. The incumbent restructuring has opened a vista of opportunity especially for investors who missed their chance during the privatization of PHCN and the NIPP assets to once more invest in the power sector through EG. Gas plants bear the greatest dependence for the realization of the 40000MW vision 2020 generation capacity[16]. Nigeria’s short, medium (10000MW- 14000MW by 2014) and long term (>35000MW by 2020) targets for the actualization of the 40000MW goals eludes us every day with the continuous sabotage and vandalism of the gas pipelines by militants. This poses a great future for EG in Nigeria with a likely tendency of a greater investment in EG in Nigeria taking the power sector through a full cycle that guarantees increased accessibility to regular electric power with an increased general system performance.
Some embedded generation plants are derived from renewable resources. Renewable resources refer to all forms of energy that are generated from natural resources like the sunlight, wind, water, tide, geothermal, heat, biomass and bio fuels. They are derived from natural processes that are regenerative; constantly replenished and each of them has characteristics that determine where and how they are used [17]. These plants have a small output like the 15.79kW Kindigi Solar project under construction in Katsina state, the 17.5kW Gaza Solar Project in Shira Local Government Area of Bauchi State and the 10MW wind-farm project in Rimi, Katsina (See APPENDIX 4) and it is uneconomical to connect them to the
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transmission system [4]. Consequently, they are connected to the distribution network i.e. 33kV, 11kV or even 415V. EG technology can also be explored from non-renewable energy sources. Thus, conventional plants that use fossil fuel generation resource(s) like the Trans/Amadi Gas Turbine plant can also be classified under Embedded Generation. 1.2 Statement of the Research Problem In the last decades, the power industry has had a gradual and steady change from the centralized bulk system (grid) where power is injected to the transmission network from generator to a more decentralized system where power is injected directly to a distribution network (embedded generation).
The drift to embedded generation is influenced by power market deregulation, technological advances, environmental issues etc. The Nigeria power industry under the centralized bulk system has had an enduring generation challenge with generation peak oscillating between 1500MW and 5000MW in the past four decades. More so, it is a thing of great concern that Nigeria gifted with huge oil, gas and various energy resources still battles to generate enough power. This has had grave economic impact on the country’s growth and development. Growths made in power generation could not be consolidated for greater network growth and improvement. In the midst of these staggering generation peaks recorded, the country also loses a reasonable amount of active power within the triad of generation, transmission and distribution points in the grid. There is therefore, a dire need to manage our generation and reduce network losses while improving our voltage profile, power quality alongside maintaining a good percentage loading of network elements. Hence, with improved generation, minimal power loss etc the Nigeria Electricity Supply Industry will make more profit which (if plunged back to the power sector) can be utilized in the expansion/maintenance of the existing national power infrastructure; to enhance consumers’ satisfaction as well as reduce
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the tension on the government, consumers etc to subsidize the inefficiencies of the Nigerian power system. 1.3Aim/Objectives of the Study This study aims at evaluating the impact of EG on the Nigeria Electricity Supply Industry. Against this background, the specific objectives are:
the determination of the impact of EG on the Nigerian power system load flow using Newton-Raphsons’ method.
investigating the impact of EG on load factor and
the degree of EG penetration on the Nigerian power system
the effect of EG on the loading of network elements.
1.4 Justification for the Research This research is carried out for the following reasons:
the need to carry out more research on EG in Nigeria especially as Nigeria presently invests in boosting her generation mix through building more EG plants to meet up with the 40000MW generation target by the year 2020 and beyond.
the need to evaluate the prospects/performance of EG on the Nigerian network as the helpful experiences from other countries alone, may not guarantee the operational success of EG in Nigeria. This is because developed countries like the USA, Australia etc ventured into embedded generation as an effective way to defer costs in grid extension while improving the reliability of their already existing system infrastructure ( with over 70% accessibility). On the contrary, the grid in Nigeria has only 45% accessibility to Nigerians (with 70% of the rural dwellers yet to be grid-connected).
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to see how through evaluating the impact of embedded generation on the Nigerian power network, can lead to recommendations to improve the performance of the network with embedded generation. This will include whether the seeming success of embedded generation as recorded in some countries such as USA, UK, and China etc can be felt here on Nigerian network with a view to addressing the power issues of Nigeria. The power demand in Nigeria has been soaring over the past years for understandable reasons and the transmission network is weak and limited in reach. Also the major hydro generation stations in Nigeria (like Kainji, Shiroro, Jebba) are concentrated in the North and the same power generated is consumed nationwide resulting in power flow from the North down to the south. Because of the long distance the transmission network ―travels‖, the voltage profile and power quality has an appreciable change (degradation)with a 40% power loss between transmission and distribution[19]. This, if not well handled can become a major drawback in the power network and it must be resolved technically. One of the approaches is buying more reactive power at times of its occurrence. Another is to build much smaller plants (EGs) along the network path and connect them directly at the load centers. In the long run, it is cheaper to build embedded generators than to be buying reactive power.
This research is also done because of the need for Nigeria (a founding member of the Climate and Clean Air Coalition) to honour the Kyoto commitment which she is a signatory to. Nigeria has to think and engage more renewable energy EG plants to also mitigate our emissions of green house gases and the consequent climate change there from.
It is interesting to note that fossil fuels account for 64% of the fuels used in the power sector alone with carbon being the dominant source at approximately 40% and contributing nearly three quarters of carbon (iv) oxide emissions[17]. The
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world annual generation of electricity is about 18000TWh approximately equal to an average rate of 2000GW consumption. This electrical energy is generated in a very large collection of power stations driven mainly by fossil fuels. The electricity sector is the fastest growing source of emissions and estimated to increase by a factor of four between now and 2050. According to Freris and Infield [17], the electricity sector would need to be at least 60% decarbonized by 2050 for atmospheric concentration to stabilize at 550ppm, thereby mitigating the hazards of atmospheric climate change. This accounts for the paradigm shift from using coal as fuel to the use of gases and to a lesser extent oil for electricity generation and heating over the past two decades [17]. 1.5 Significance of the Study. This assessment study of EG in Nigeria will be beneficial to the following;
1. Research Students- as a study to enhance their literature review for subsequent works on the Nigerian power network and on EG in Nigeria in particular. This work can also guide them on how to use PSS/E software for their load flow studies.
2. Federal Ministry of Power, Works and Housing – as a study to guide future policy formulations for the smooth running of the Nigerian power system/sector.
3. TCN/PHED- as a study showing that EG in Nigeria can increase their revenue earnings through reducing power losses on the power networks they directly operate, maintain and manage.
4. NERC- for future policy formulation(s) in Nigeria.
1.6 Delimitation of Study
As stated in section 1.4, the aim of this research work is to evaluate the impact of Embedded Generation on the Nigeria Network. This work is done on the 28 bus Nigeria 330kV Transmission network and on a section-cut of it- PH Mains 132/33kV Transmission/Distribution Network. The choice case study for this work
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is the Trans Amadi embedded generation plant located in Rivers state of Nigeria. This is seen in the chapter three of this work. The level of assessment is dependent on the available data as at the time of this study. 1.7 Outline of Presentation This work is done and presented in five chapters. Chapter One gives a general introduction to the practical problems of this study and highlights the role of EG in the history of NESI. It further presents the justification, aim, objectives significance and the delimitation of this study. Chapter Two reviews relevant existing literature with the goal of measuring how the theoretical model in them can be adopted or not in the Nigerian power network with a view to improving our network performance. Chapter Three presents the research case studies here considered with the choice research method considered, reason for its usage, the research procedures and used data. Chapter Four looks at the research results; their presentations alongside their analysis and interpretation. Chapter Five ends with the conclusion as seen in this research. Recommendations made will be based on direct network studies and on general knowledge acquired in the course of this research. Also, in chapter five are the following:
Findings
Contribution(s) to knowledge
Conclusion
Recommendations
Area(s) of further research
Learning points.
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