1.0 INTRODUCTION
The operation of transmission lines at high voltage level, above 500-kV, has been embraced by the developed countries as a standard (Candas et al., 2015). A reliable power supply is an essential part of any nation thriving toward economic growth and national development. Nigeria, being the giant of Africa and home to the largest economy in Africa as of 2014, cannot boast of a steady power supply due to the state of the power sector operations. It is no longer news that the national power system has been identified with frequent outages. This advertently caused the cost of living to increase as citizens now have to consider the cost of running their private generators. Furthermore the negative role it plays in industrial and economic development has to be considered. Industries and companies refrain from production activities in the nation because of the outrageous cost of running their power sources. This has also caused some of the existing industries to collapse due to the unavailability of electricity thereby resulting in the loss of jobs in those industries and further increase in the hardship faced by the populace of this country (Nwankwo et al., 2013).
Over the years, there have been reforms in the power sector to curb the many deficiencies which the power sector experiences. Notable progress has been made in the generating sector after the deregulation of the generating wing of PHCN. Regardless of that, the problem of power outages and unavailability of consistent power still plague innocent citizens. The reason is that the grid’s weak infrastructure is characterized by high line losses and unbalance of reactive power between generation and load center due to forced outages and system disturbances (Abdulkareem et al., 2016), and cannot support the effective transmission of power to the areas where it is needed for utilization. The Nigerian power transmission system currently utilizes a 330-kV grid for power transmission across the country. The network is more of radial nature, and its infrastructure comprises effective 31 buses, 6,000 MW total installed power generation capacity, and 4,889.2 km length of transmission lines (Balogun, 2017). Several losses have already occurred in the existing grid inferring the inadequacy of the current transmission to deal effectively with the generation. The nation currently suffers the problem of under capacity and poor transmission due to the huge losses experienced on our transmission lines (Izuegbunam et al., 2011).
In light of this observed challenges, the major objective of the ongoing reform is to expand the existing grid network to a proposed mesh structure and increase the number of buses to a total of 49 buses; 32 buses from existing 330-kV plus 17 buses of the proposed 750-kV. However, this expansion remains a proposed one because no technical analysis shows its viability The rapid increase in the demand for electricity as a result of population growth, industrial development and rise in consumer electrical appliances has necessitated the stepping up of generation and demands similar of the transmission capabilities of the grid network to deliver quality power supply to the consumers. The present Nigerian transmission grid network is prone to evacuating and dispatching reliable and quality electricity supply and maintaining an operational standard of security to prevent any collapses (Abdulkareem et al., 2016). Moreover, there are ever-increasing power demands and restrictions on land and space to build more transmission corridors globally (Abdulkareem et al., 2016). All the above-aforementioned reasons set the platform for the modification of power system analysis of a transmission line and integration to the grid to support the increase in generation, supply a reliable, adequate and economically priced power supply demanded by citizens
Supply of a reliable, adequate and economically priced power supply is vital for the socio-economic development of Nigeria. It has been noted that the growth rate of the Nigeria population has a direct relationship with the growth in the per capital electricity consumption (Compton, 2011). The importance of energy to Nigeria economy cannot be denied; it is underlying currency vital to the economic prosperity of the citizens. The population growth has already raised concerns over supply difficulties, exhaustion of energy resources and substantial environmental impacts (Michaelowa et al., 2011).
The development of every country in the contemporary world is largely depends on electricity. Renewable energy system has significant possibilities of allowing growth and green challenges to be dealt with equally (Sambo, 2019). Nigeria has a large quantity of fossil fuel and renewable energy source, nonetheless, the country is fighting with a serious energy challenges. About 59.8% of Nigerians have access to electricity supply according to the World Bank data in December, 2016 (International Energy Agency, 2013). Poor state of Nigeria’s electricity sector is ascribed to the ineffective power generation plants, outdated transmission and distribution systems, and outmoded metering methods used. The absence of sufficient renewable energy source (RES) to support the maximum load, the deteriorating of the transmission lines to the distribution systems which are not properly sustained, absence of communication systems, unlawful connections of electrical by some consumers and outmoded metering system (Aniefiok et al., 2013).
Economic growth, automation, and modernization mainly depend on the security of energy supply. Global energy demand is rapidly growing, and, presently, the worldwide concern is on how to satisfy the future energy demand. Long-term projections indicate that the energy demand will rapidly increase worldwide. To supply this energy demand, fossil fuels have been used for a long time in Nigeria as primary energy sources. However, the problem with fossil fuels is that it emits greenhouse gases that highly affect the environment and the future generation (Menanteau et al., 2013). The emissions largely depend on the emission factor of primary energy sources (i.e., input fuel of the plant). Among all energy sources, the emission factor of fossil fuels (i.e., coal, natural gas, and oil) is very high. Fossil fuels are widely used as the main fuel in power generation.
In Malaysia, fossil fuels (i.e., natural gas [53.3%] and coal [26.3%]) serve as major power generation sources. Large-scale use of fossil fuels, however, greatly affects the environment. Based on the global CO2 distribution in 2013, the emission breakdown is as follows: coal (43%), oil (33%), gas (18%), cement (5.3%), and gas flare (0.6%).
Meanwhile, renewable energy sources (solar, wind, hydro, geothermal, biomass, etc.) are emission-free energy sources in the world. Renewable energy technologies are an ideal solution because they can contribute significantly to worldwide power production with less emission of greenhouse gases (Painuly, 2011). The “sustainable future” scenario of the International Energy Agency (IEA) shows 57% of world electricity being provided by renewable energy sources by 2050 (International Energy Agency, 2016). Long-term forecast and planning is required to achieve this ultimate target (Painuly, 2011). Renewable energy-based power generation and supply to the national grid for a specific zone are necessary. The conventional grid aggregates the multiple networks, and the regulation system consists of various levels of communication and coordination, in which most of the systems are manually controlled. A smart grid is a new concept that leads to the modernization of the transmission and distribution grid. The smart grid system is the digital upgrade of transmission and new markets for the alternative energy generation of renewable energy sources. Presently, smart grid is an often-cited term in the energy generation and distribution industry (Painuly, 2011).
Renewable energy sources connected with distributed power generation is a new platform that significantly generates reliable security of supply (SOS) and quality of electric energy. This concept is practical and reliable as numerous types of energy sources become available, such as solar, wind, biomass, and tidal. Renewable and nonconventional energy sources are allowed to integrate with the distributed power generation link that has a smart grid. This study therefore highlights the role of renewable energy sources in generating electricity and the integration with the national grid system for energy security.

1.2 BACKGROUND OF THE PROJECT
Environmental pollution of fossil fuel-based electricity generation and depletion of natural resource have drawn burgeoning attentions, which initiate clean and renewable energy technologies for zero carbon emission (Painuly, 2011). Solar, tidal, biomass and wind power generation technologies could be good candidates for the places where electricity is cost effective (Painuly, 2011). Thus, hybrid renewable energy system (HRES) could be an effective approach to reduce the consumption of fossil energy resources for future sustainable development.
With the growth of renewable energy, the electric grid is shifting. To make sure the grid is ready to meet the rising tide of clean energy technologies, advanced integration—including grid modernization and visions for future designs—is needed.
Grid integration of renewable energy means reimagining operation and planning for a reliable, cost-effective, and efficient electricity system with cleaner new energy generators. This includes where it is built, how it is optimized, and how it is used to power a carbon-free future. It means providing grid operators with the situational awareness and control capabilities they need to plan and manage a rapidly changing energy resource mix.
The path forward involves assessing long-range demands and evaluating pathways for efficient performance. For example, projecting atmospheric patterns can help guide—and maximize—siting of solar, biomass, tidal or wind power. It also includes evaluating, scheduling, and optimizing future energy market design using advanced modeling and simulation to understand the operational connections to renewable energy availability, generator performance, grid reliability, and electricity delivery to customers.
Grid integration of renewable energy includes building resilience against threats, such as natural disasters and cyberthreats. It also involves overcoming challenges, such as instantaneous to seasonal unavailability of renewable resources. By developing solutions and mitigative measures across both information technology and operational technology systems, we can prepare for a cleaner, greener, and more resilient energy landscape.
Presently, there is sharp increase in RE utilization and its progressing impact on the world energy sector, evaluating its effect on the environment and sustainable development is limitedly explored and must be investigated. This study aims to discuss the role of RE integration in sustainable development. It provides an up-to-date review of the most recent global trend of various RE integrations into the power sector. The role and impact of this high integration level on the environment and the adverse effects of each RE source are discussed in detail.

1.2 PROBLEM STATEMENT
Nigeria’s electricity system in the recent years has suffered many setbacks resulting in almost five years of load shedding. The electricity situation in Nigeria can be described as epileptic with no sign in view of improvement. The power situation has affected the manufacturing, service and residential sectors of the economy which in turn affects the country’s economic growth. Even with the recent reforms in the energy sector where power was separated from the Energy Ministry to stand as Power Ministry, a larger population does not have access to reliable supply of electricity. The epileptic condition of the power sector can be attributed to the inadequate and inefficient power plants, poor transmission and distribution facilities, outdated metering system and the use of conventional power plant (gas) used by electricity generating stations.
Nigeria has 12,500 megawatts of installed generation capacity, being largely dependent on natural gas, at 87.5 per cent of the on-grid energy supply mix (Ozoegwu et al, 2017). This position is rather unsurprising given the nation’s vast gas resources and the relative cost-efficiency of gas-fired power generation. Due to perennial challenges with grid infrastructure and other well-documented constraints to reliable power supply, a large proportion of the economy is reliant on off-grid, captive energy generation, which is for the most part, powered by petrol and diesel.
As the harmful effects of pollution and greenhouse gas emissions become clearer and the need for sustainable development takes on a more central role in the global energy conversation, there seem to be a consensus among key players across the world that it is imperative to shift focus towards renewable energy (and other clean energy sources) to drive economic growth, not least in developing countries such as Nigeria, where the need for investment is greatest.
This global paradigm shift, along with various policy initiatives by governments to incentivize renewable energy development and financing has led to an unprecedented growth in renewable energy projects in many countries. Even for a country like Nigeria, where renewable energy has always featured in the energy mix (hydropower accounts for about 12.5 per cent of its on-grid energy), the current trend provides an opportunity to promote and attract sustainable investment in its energy sector.
The integration of renewables into the Nigerian electricity grid system remains the only solution to the electricity crisis in the country. This paper attempts to present the way forward for the Nigeria poor electricity situation by reviewing the power sector as a whole and the renewable energy potentials.

1.3 AIM AND OBJECTIVES OF THE STUDY
This paper studies integration of renewable energy resources for electric power supply in a developing economy using PV, wind energy, biomass and tidal energy interfacing with 330kv or standalone. The objectives of the study are:
i. To examine the current energy situation and the idea of introducing renewable energy technology into the system.
ii. To propose a future direction on how smart grid technology integration can transform energy situation in Nigeria’s energy network.
iii. To find out an innovative way to couple renewable energy technologies, and accelerate deployment to enable economic and reliable power grid operation with large shares of renewable energy. This can be accomplished through integration studies, modeling, demonstrations, and assessments at both the transmission and distribution levels, coupled with working directly with utilities to help ensure adoption of best practices.
iv. To identify critical drivers essential to successful Smart Grid technology (SGT) implementation
v. To identify the problems in the national grid and then proposed a smart grid model for the Nigeria power sector which will include renewable energy sources.
vi. To identify the role of integrating renewable energy in Nigeria power system.
vii. To identify the potential sources of renewable energy in Nigeria.
viii. To analyze the current implementation of renewable energy sources in Nigeria.
ix. To study the development and commercialization of renewable energy systems, and the conversion technology available.
x. To determine the constraints and market barriers of renewable energy utilization in order to improve its usage in the country.

1.4 SIGNIFICANCE OF THE STUDY
This study will serve as means of studying the cause of scarcity of energy resources and rising energy prices due primarily to a world of increasing demand, energy security which occurs both for private and public sector alike. At the same time, it shows how energy policies have been shifting and policy changes have become hard to predict because of radical changes in energy supply. The study will also serve as an eye opener that will make the reader to understand how renewable energy will affect the growth of Nigeria’s Gross Domestic Product (GDP) due to challenges in electricity and oil production.
The thesis will provide a platform for scientists and academicians all over the world to promote, share, and discuss various new issues and developments in different areas of smart grid and renewable energy.

1.5 SCOPE OF STUDY
The most important part of this work focuses on integration of renewable energy resources for electric power supply in a developing economy using PV, wind energy, biomass and tidal energy interfacing with 330kv or standalone. The study will also cover the importance of integrating renewable energy to the national grid. Recommendation on how electricity of Nigeria can be improved shall also be made in this work. The territorial scope of this document covers all areas of electricity supply in Nigeria.

1.6 DEFINITION OF TERMS
Renewable energy: Renewable energy is energy that is collected from renewable resources that are naturally replenished on a human timescale. It includes sources such as sunlight, wind, rain, tides, waves, and geothermal heat.
Policies: Policy is a deliberate system of guidelines to guide decisions and achieve rational outcomes. A policy is a statement of intent and is implemented as a procedure or protocol. Policies are generally adopted by a governance body within an organization.
Barriers: obstacle that prevents the access of renewable energy
Renewable energy integration: This is when renewable energy is being interconnected with electric power systems at increasing rates. It can also defined as means of reimagining operation and planning for a reliable, cost-effective, and efficient electricity system with cleaner new energy generators. This includes where it is built, how it is optimized, and how it is used to power a carbon-free future.
Tidal energy: This is a form of power produced by the natural rise and fall of tides caused by the gravitational interaction between Earth, the sun, and the moon. Tidal currents with sufficient energy for harvesting occur when water passes through a constriction, causing the water to move faster.
Photovoltaics: Photovoltaics are best known as a method for generating electric power by using solar cells to convert energy from the sun into a flow of electrons by the photovoltaic effect. Solar cells produce direct current electricity from sunlight which can be used to power equipment or to recharge batteries. PV materials and devices convert sunlight into electrical energy.
Wind Energy: This is described as the process by which the wind is used to generate mechanical power or electricity. Wind turbines convert the kinetic energy in the wind into mechanical power.
Biomass: This is defined as the fuel made from organic matter or wastes of living organisms that can be used as renewable sources of energy. Biomass contains stored chemical energy from the sun. Plants produce biomass through photosynthesis. Biomass can be burned directly for heat or converted to renewable liquid and gaseous fuels through various processes.

1.7 PROJECT ORGANISATION
The work is organized as follows: chapter one discuses the introductory part of the work, chapter two presents the literature review of the study, chapter three describes the methods applied, chapter four discusses the results of the work, chapter five summarizes the research outcomes and the recommendations.