2.1 Review of related works
A renewable energy system, which was designed by some authors, is composed of some renewable sources, and targets a small area such as a village. The system supplies energy to rural area by using renewable sources. The system configuration of renewable energy system varies with site location. Because renewable energy are generally intermittent, it may happen that renewable power is not sufficient to meet the regional demand in some hours. Therefore, the proposed energy system is connected to the distribution grid, and buys electricity as backup whenever the renewable supply is insufficient. In contrast, excess electricity is sold to the electric utilities through the grid.
In their study, they have targeted a local village with a population of 9,000 in Iwate prefecture in northern part of Japan, examining the possibility of installation with four kinds of renewable sources, such as PV, wind electricity, biomass co-generation and geothermal heat pump. These renewable sources are combined with conventional energy systems in which electricity is supplied by the distribution grid, and heat is supplied with petroleum or gas. They have modeled a renewable energy system in rural area using several system modules. The network of the system is shown in figure 1. At the market node which is expressed in the shape of ellipse in figure 1, energy sources at end-users are decided based on the price of energy, and the selected energy is provided to the village. By this means, the most economical energy system will be configured and optimized.
The changes in the quantity of electricity supply are shown in figure. 2. During windy period, the wind generator is running well and the wind electricity constitutes a fairly large portion of total electricity which is supplied to the village. When wind electricity cannot provide enough power to meet the electricity demand, grid electricity will make up for a deficiency. Figure 3 represents the changes in the quantity of electricity supply during wind-less period. The portion of grid electricity is large in the figure, as the production of wind electricity is not sufficient.
The changes in the price of electricity are shown in figure 4. During the windy period, the price of wind electricity hovers around $4,000/MWh, and the price is much lower than that of other power generation. At the electricity market, the lowest price is preferred to supply electricity to consumers. Then the electricity market selects wind electricity as the lowest price, and most of the electricity is provided by wind turbines. However, during wind-less period, the production of wind power goes down and the price of wind electricity rises suddenly because of shortage of wind electricity. If the price of wind electricity becomes higher than that of other power generation, market selects other types of electricity to meet the demand at the village. In our study, alternative power means PV and grid electricity. According to figure 4, the price of PV hovers from 23,500 cents/MWh to 27,500 cents/MWh, while the electricity price of grid electricity shows 23,333 cents/MWh. Under this condition, the electricity market selects grid electricity among alternative electricity. Therefore, in case that wind electricity is in shortage and can’t meet all the electricity demand, grid electricity makes up for a deficiency
2.2 Heat supply
The changes in heat supply produced by different energy sources are shown in figure 5. Geothermal heat pump (GHP) and petroleum are main heat source. Figure 6 represents the changes in heat price. Because the power source of GHP is electricity, the price of heat by GHP is influenced by the electricity price. Compared with the fluctuation of the electricity price, price fluctuation of GHP heat goes along with fluctuation of the electricity price.
In the case of low electricity price, the price of GHP heat is also low. While in the case of high electricity price, the price of GHP heat is also high. During the lower heat price of GHP, the price hovers from 1,000 cents/MWh to 2,000 cents/MWh. Compared with the prices of other heat sources, the price of GHP is the lowest. As a consequence, heat produced by GHP is supplied to the village. On the contrary, when the price of GHP heat is high, the price hovers from 6,000 cents/MWh to 7,000 cents/MWh. Because the price of petrole um heat is 4,728 cents/MWh during that time, the price of GHP heat becomes higher than that of petroleum. Therefore, the heat market selects not GHP but petroleum as a heat source.
Because the prices of other heat sources are higher than petroleum, petroleum is selected as a substitution of GHP by priority. For these reasons, when wind electricity meets all the electricity demand in the village , heat is supplied by GHP, and when the production of wind electricity falls down, petroleum is selected as a heat source.
.2.3 Renewable Energy Development In Nigeria
The use of renewable energy is not new in the country. More than 150 years ago wood supplied most of our energy needs, which is the traditional method of consuming biomass resource.
As the use of coal, petroleum, natural gas expanded and increased, Nigeria became less reliant on wood as an energy source. Today, we are looking again at renewable resources to find new ways of utilizing them to help us meet our domestic energy needs particularly in the electricity sector.(Enugu state Citizens’ , 2009)
Energy, and in particular, oil and gas, has continued to contribute over 70% of Nigeria’s Federal revenue. National development programmes, and security depend largely on these revenue earnings.
Energy, especially crude oil has over the past years contributed an average of about 25%nto Nigeria’s Gross Domestic Product (GPD), representing the highest contributor after crop production. The contribution of energy to GPD is expected to be higher when we take into account renewable energy utilization, which constitutes about 90% of the energy used by the rural population. (A.S Sambo, 2009)
The country is blessed with almost all the renewable energy resources especially solar energy with average sunshine of 5hrs daily(including the rainy season).There are opportunities for small hydro in most of the coastal areas in the southern region of the country.
Beyond the large hydropower capacity, the total contribution of renewable energy in Nigeria’s electricity industry is about 35MW, which consists of small hydropower and about 10MW solar PV representing about 0.12% of total electricity generating capacity in the country. There are still lots of hydro potentials that can be explored especially in the coastal region of the country.
The first independent Power Producer (IPP) in Nigeria was the Nigerian Electricity Supply Company (NESCO),a British-owned company supplying hydroelectricity power to the growing tin mining industry.in 1930,NESCO took over the 2MW hydroelectric power plant at Kwall falls in Plateau State from the Nigerian Power and Tin Fields that had earlier commissioned the plant in 1930.NESCO increased its generating plants to five hydro-electric and one diesel plant serving the tin industry and its environs. The Nigeria utility company, PHCN has taken over the supply to Jos and its environs while the hydroelectric power plant is not well maintained.
In Evboro II, village of Ovia South West Local Government Area in Edo State, a 3KW pico hydro scheme constructed under a culvert by an individual has been in existence. This scheme has for several years served 20 homes in the community.
This is a reference project that serves as call to the local and state government leaders to consider using micro power projects in the state to meet the energy needs of the rural communities and never to rely or wait on the Federal Government for power from the grid.
So far, little has been exploited from the abundant renewable energy resources in the country. Most of the projects carried out by the states are in the areas of solar street lights, solar pumping systems, solar hybrid systems, solar home systems and other solar applications such as refrigerators and solar lanterns. These technologies are deployed in rural communities.
Other technologies include; efficient wood stoves, small hydro schemes in Bauchi, Enugu and Edo state (locally constructed), pilot wind farms and pilot biogas digesters constructed in Sokoto Energy Research Centre of Usman Dan Fodio University of Sokoto State and Mayflower College, Ikene, Ogun state respectively.(Ebonyi State Citizens’ Handbook on Alternative Energy,2009)
Table 2.1: Available Renewable Energy Resources in the Country
S/N Resources Reserve
1 Small Hydro power (provisional) 734MW
2 Fuel Wood 13,071,464 hectares of forestland
3 Animal Waste 61 million tonnes/year (estimated)
4 Crop residue 83 million tonnes/year (estimated)
5 Wind 2- 4 m/s (average)
6 Solar irradiation 3.5-7.0kWh/m2 –day (average)
2.4 Renewable Electricity and Rural Electrification
As the country strives to increase power generation, it is obvious that conventional sources and grid extensions alone will not rapidly achieve the access and expansion targets desired, neither will it be cost-effective. A more reasonable approach would be accelerating rural electrification
coverage. This requires an aggressive deployment of various alternative energy sources to meet the household and commercial power demand in the communities.
The provisions of the Electric Power Sector Reform (EPSR) Act clearly state that the Federal Government will seek to meet national electricity access targets through the following strategies:
i. Grid-based extension for nearby areas;
ii. Independent mini-grids for remote areas with concentrated loads where grid service is not economic or will take many years to come;
iii. Solar Photovoltaic (PV) systems for remote areas with scattered small loads.
Furthermore, it implies that non-conventional renewable energy is a key element in the overall strategy of the Federal Government in rapidly expanding access to electricity services in the country.(Ebonyi State Citizens’ Handbook on Alternative Energy)
2.5 ALTERNATIVE ENERGY OPTIONS IN NIGERIA
2.5.1 Solar Energy Resources in Nigeria
Solar energy is the most burning of the renewable energy sources in view of its apparent limitless potential. The sun radiates its energy at the rate of about 3.8x1023kw per second. Most of this energy is transmitted radially as electromagnetic radiation which comes to about 1.5kw/m2 at the boundary of the atmosphere. After traversing the atmosphere, a square meter of the earth’s surface can receive as much as 1kw of solar power, averaging to about 0.5 over all hours of day light. The huge energy resources potential from the sun is available for about 26% of the day. Nigeria is also having some cold and duty atmosphere which is experienced during the harmattan in the northern part which usually occurs for four months period (November to February) annually. The dust from the harmattan has an attenuating affect on insolation from the sun. Studies relevant to the availability of the solar energy resources in Nigeria (Sambo, 1986; Sambo 1988, Sambo, Doyle 1986; and Bala, 2001; Folayan, 1988) have fully indicated its viability for practical use.
Nigeria is endowed with daily sunshine that average 6.25 hours, which is ranging between about 6.25hours and southern region of the nation respectively. It also has an annual average daily solar radiation of about 3.5kwm2/dm in the coastal area which is the southern part of the country and 7.0kwm2/dwy at the northern boundary (Bala, 2001).
The country also receives average annual sun of 2200kw/m2 in Sokoto,Gusau, Kano, Yobe and Maiduguri in the far north, to 600kw/m2 in port Harcourt, Calabar, Aba in Abia and Warri all in the sun which is equivalent to about 1.082 million tons of oil, it is about 4000 times the current crude oil production per day, and also about 13 thousand times of daily natural gas production based in energy unit. Also, if solar energy appliances with just5% efficient are used to cover only 1% of the country’s surface area, then 2.54x106mwh of electricity can be obtained from solar energy.
This amount of electrical energy is up to 4.66 million barrels of oil per day. Based on the Nigeria land area of 923,768km2 and average of 5.535kwh/m2, the country has an average of 1831.06kwh of solar energy annually.
The annual insolation of the solar energy is valued about 27 times the national conventional energy resources in Nigeria units and also over 117,000 times the amount of electric power that was generated in 1998 (Chendo, 2002). About 3.7% only of the nation’s land area must be utilized in order to equal the nation’s conventional energy retrieve. The Nigerian Federal Ministry of science and Technology estimates, that the total annual energy consumption of about 21x109kwh could be made by converting only 0.1% of the total solar radiation incident on the country at a conversion efficiency of 1% (Bugaje, 1999).
2.5.2 Solar Energy Electrification for Rural Development in Nigeria
Rural communities cannot boast of electricity, water and other basic facilities that make life worth of living. While some people in cities complain of electric power supply, huge bills from power Holding company in Nigeria villages. There are hundreds of densely populated rural communities that were cut-off from the natural grid and home nearer enjoyed one minute of power supply are now corrected with solar mini off grid power supply.
Solar electric power systems offer an excellent alternative for people who are looking for backup power or stand alone power system for their remote/rural residents, business and community development needs, mosques churches centers and rural homes.
Solar electric power supply is clean, affordable and requires little maintenance. More rural homes in some rural communities in Nigeria have been connected using solar panels especially in Zamfara state. Fig 2.3 illustrates how the solar mini grid works. The micro grid design is ultra-energy efficient, it uses renewable power generation house which consist of solar panels, thus four to five panels are sufficient to power an entire village of 100 households and then use battery bank to generate power during the day which is consumed at night, the light is distributed using poles, there poles usually each carry a street light on it which pass through a village over a short distance then to house hold, each house hold is provided with two to four light emitting Diodes(LED) lights as these villages choose solar power for their electric systems.
Renewable power Battery Bank Power for house
Generation Distribution holds.
Fig 2.1: Solar Mini grid
In remote areas where life far from the nearest National power grid extension or because of the difficulties in reaching them due to weather terrain, then solar is a cost effective for these communities, solar electricity is an effective method for improving health and quality of life in the developing world.
Providing reliable cost effective power for rural villages is a long way to go, this will improve their standard of living for our future generation of Bauch, Benue, Bayelsa, Akwa Ibom, Delta, Taraba, Ogun, Zamfarawa, Rivers and Nassarawa. The education tax fund and some few other organizations like United States Development of Energy and Jigawa Alternative Energy Trust fund have sponsored the installation of many pilot solar energy systems for use to various communities across the country.
2.5.3 Sources of Renewable Energy in Enugu State.
The sources of renewable energy in Enugu state include; solar energy, burnass energy, hydro power and wind energy. Enugu state is amongst the south-east states and is located in the derived savanna region (Akinsami, 1991) with typically two seasons (wet and dry). It has 13 local government areas and each local government is richly blessed with natural resources (renewable and non-renewable energy resources). Figure 2.4 shows the countion of Enugu state in Nigeria while figure 2.5 shows the map of Enugu state and the respective local governments (shown in black highlights).
2.5.4 Wind Energy Resources in Nigeria
Wind, which is an effect from the uneven healing of the earth’s surface by the sun and its resultant pressure inequalities, is available at annual average speeds of about 2.0m/s at the coastal region and 4.0m/s at the far northern region of the country. Assuming an air density of 1.1kg/m3, wind energy intensity, perpendicular to the wind direction, ranges between 4.4w/m2 at the coastal areas and 35.2w/m2 at the far northern region.
Wind energy conversion system (wind turbines, wind generators, wind plants, wind machines and wind dynamos) are devices which convert the kinetic energy of the moving air to rotary motion of a shaft, that is, mechanical energy. The technologies for harnessing this energy have over the years been tried in the northern parts of the country, mainly for water pumping from open wells in many secondary schools of old Sokoto and Kano states as well as in Katsina, Bauchi and Plateau states. A 5kw wind electricity conversion system for village electrification has been installed at Sny yan Gidan Gada, in Sokoto state.
Other areas of potential application of wind energy conversion systems in Nigeria are in “green electricity” production for the rural community and for integration into the national grid system. It has been reported that an average annual wind speed of not less than 5m/s at a height of 10m above ground level is the feasible speed for the exploitation of wind energy at today’s cost. Tractors and equipment (T;E) at Division of the united African Company (UAC), at one time, produced wind mills in Nigeria. Promising attempts are been made in Sokoto. Energy research centers (SERC) and Abubakar Tafawa Balewa University Bauchi, to develop capability for the production of wind energy technologies (Abubaka S. Sambo. third quarter 2004).
2.5.5 Small Hydro power (SHP) Development in Nigeria
Hydro energy is the use of gravitational force of falling or flowing water to generate electricity thus, hydro power is the largest and most widely form of renewable energy. Hydro power energy potential of Nigeria is high and it currently account for about 29% of the total electricity power supply in Nigeria.
Rural electrification is given high priority in government efforts to increase the standard of living in rural areas, reduce rural-urban migration trends, release other development objectives, however, the three key challenges for rural electrification are:
i. how to provide sustainable energy (electricity) services to the poorest of the poor, who have
ii. no purchasing power to pay for the services?
iii. how to offer the most cost-effective, clean and reliable electricity to those who are currently spending a significant share of their income on energy ?;
iv. how to set up the commercial infrastructure to provide these services
Power is generated by mechanical conversion of energy into electricity through a turbine, at a usually high efficiency rate. Depending in the volume of water discharged and height of fall, hydro power can be large or small.
2.5.6 Biomass Energy Resources Potentials
Biomass refers to energy derivable from sources of plant origin such as trees, grultes, agricultural crops, and their derivatives, as well as animal wastes. As an energy resources, biomass may be used as solid fuel, or converted through gaseous forms for the generation of electric power heat or fuel motive power (S.A Sambo, 2009).
It is a common knowledge that the associated harmful environmental health and social effect with the use of traditional biomass (wood fuel) and fossil fuels has enhanced the global growing interest in the search for alternate cleaner source of energy. Nigeria depends heavily on wood fuel as a source of fuel for most of her domestic energy needs, contributing over 50% of the primary energy supple with crude oil and hydro power constituting the remainder (Omakaro, 2008; Nwofe, 2014).
Biomass resources are considered renewable as they are naturally occurring and when properly managed, may be harvested without significant depletion. Biomass resources available in the country includes, fuel wood, agricultural waste and crop residue, sawdust and wood sharings, animals dung / poultry droppings, industrial effluents / municipal solid waste.
The availability of biomass resources follows the same pattern as the nation’s vegetation. The rain forest in the south generates the highest quality of woody biomass while the guinea savannah vegetation of the north central region generates more crops residues than the Sudan and Sahel savannah zones. Industrial effluent such as sugar cane molasses is located with the process with which they are associated. Municipal wastes are generated in the high-density urban areas. Table 1.2 shows the estimated biomass resources in Nigeria. (S.A Sambo, 2009)
Table 2.2: Biomass Resources and the Estimated Quantities in Nigeria
Resources Quantity Energy Value
(Million tonnes) (‘000mJ)
Fuel wood 39.1 531.0
Agro waste 1.244 147.7
Sun Dust 1.8 31.433
Municipal Solid waste 4.075 –
In year 2000, national demand was estimated to be 39 million tones of fuel wood. About 95% of the total fuel wood consumption was used in household for cooking and for cottage industrial activities, such as for process cassava and oil seeds, which are closely related to house, hold activities. A small proportion of the fuel wood and charcoal consumption was used in the service sector.
About 350,000 hectares of forest and natural vegetation are lost annually due to various factors with a much lower afforestation rate of 50,000 hectares/ yr. past studies shows that national demand for traditional energy (mostly fuel wood and charcoal) is 39million tones per annum (about 37.4% of the total energy demand and the highest single share of all the energy forms). It is projected to increase to 91million tones by 2030 (world solar programme, 1996 – 2005).
The deforestation rate is expected to similarly increase if no special programme is put in place to discourage the use of fuel wood, promote the use of its alternatives and replenish through deliberate afforestation and fuel wood lots. The three store stove commonly used in the household have been developed locally by the ECN through its energy research centers at the University of Nigeria, Nsukka and Usumanu Dan Fodiyo University in Sokoto.
These stoves which could reduce fuel wood consumption for a particular process by 50% international Institute for Tropical Agriculture (IITA) Cottage cassava industry at Moniya, Ibadan adopted these technologies. Indeed the improved wood-burning stoves are found in many local markets in the north-western part of the country.
Agricultural residue and municipal solid waste Residues associated with agriculture either as on-the-farm crop wastes such as cornstalks or as processing waste such as rice husk, corn shells, palm kernel shell, cassava peels, etc. are also good sources of fuels. They are currently burned directly as starter or supplement materials in addition to fuel wood. These are potentials for further processing higher energy contents. There is, however, other competing demand for crop residues for feeding livestock and roofing thatched houses in the villages. Animal waste ( e.g Cow dung, poultry droppings and abattoir waste) are also available at specific sites (S.A Sambo 2009).
Biogas digester technology has been domesticated and a number of pilot biogas plants have been built. Considerable local capability exists for building both floating dome and fixed dome bio digesters using a variety of bio resources. Examples include a human waste biogas plants at the Zaria Prison, cow dung based biogas plants at the Fodder farm of the National Animal Product on Research Institute (NAPRI), Zaria and My flower Secondary School Ikenne, Ogun state; an 18m3 capacity pig waste biogas plant at the pigry farm of the Ojokoro / Ifelodun, cooperative Agricultural Multipurpose society in Lagos states.
A number of indigenous out fits are producing economically viable systems for converting municipal waste to energy (S.A Sambo, 2009).
Sawdust and wood waste are other important biogas resources associated with the lumbar industry. Small particle biomass stoves already exist for burning sawdust and wood sharing. Biomass utilization as energy resources is currently limited to thermal application as fuel for cooking, crop drying, tobacco curing, etc. there is no existing biomass fired power plant in Nigeria and so no local experience in biogas generation and utilization of fire particle biomass.
2.5.7 Available Biomass Energy in the State
Biomass generation is commonly obtained through anaerobic digestion of organic waste under certain conditions. Biomass has been proven to be a practicable and promising technology which has the potentials of generating clean energy on a large scale. The use of biomass material to generate biogas on a large scale is still yet to be available in the state.
i) Animal Waste
This consists of waste from animals found in abattoir, piggeries, poultries and cattle ranch. The droppings of these animals are rich in methane gas when condition in a digester. The droppings are mixed with vegetable waste and enough wasters at a specified temperature depending on the animal droppings. This will allow the digestion process to take place within 2 – 4wkj. The process requires continuous stirring. The bye product from the process can also be called biogas.
ii) Bio fuels
Bio ethanol: this is a form of bio fuel that can be compared with the usual premium motor spirit (PMS) otherwise called petrol. It has lets of properties which can be compared with PMS. It is used on cars in Brazil in ratio with pms. The feed stock for bio ethanol includes all crops with sugar content such as maize, sorghum, sugar cane etc.
The process simply is conversion through fermentation process.
Bio diesel: This is a form of bio fuel that can be compared with Automatic Gas Oil (AGO) otherwise called diesel. It has lots of properties comparable with AGO. It is used for cars, trucks in big farms, generators and small power plants for rural communities. The feed stock for bio diesel includes most crops with oil contents such as; peanut, soya seed, sun flower, jatropha, safflower, palm oil and waste oil from food industries. Internationally, there are lots of debate and controversy on generating oil using food crops and also the issues of competition for land. Hence, Nigeria is currently not in support for using food crops for production of bio fuels. The feed stock considered for bio diesel for bio ethanol is the waste from sugar cane and cassava or stem of the sweet sorghum while jatropha seed and sunflower have been identified as the preferable feed stock for bio diesel. Jatropha curcus is a drought-resistant perennial, growing well in marginal / poor soil. It is easy to establish, grows relatively quickly and producing seed for 50 years. Jatropha the wonder plant produces seeds with an oil content of 37%. The oil can be combusted as fuel without being refined. It burns with clear smoke-free flame, tested successfully as fuel for simple diesel engine. The by products are press cake-a good organic fertilizer.
i. This vegetable oil can be used as it is busted ie unrefined in the engine of cars.
ii. This vegetable oil can be blended with normal diesel and used in cars.
iii. This vegetable oil can be refined and sild as pure diesel.
iv. Refined oil can be exported as a clean fuel to anywhere in the world.
Wind energy is the by product of solar energy, available in the Form of the kinetic energy of air. Wind has been known to man as a natural source of mechanical power for long. The technology of wind power has evolved over this long period. Of the various renewable energy sources, wind energy has emerged as the most viable source of electrical power and is economically competitive with the conventional sources (Amin,2015)
The global electrical energy is rising and there is steady rise of the demand on power generation, transmission, distribution and utilization. The maximum extractable energy from the 0-100m layer of air has been estimated to be the order of 1012KWh/annum same order as hydroelectric potential (. Humada,2014).
This chapter deals with wind turbine and wind generation system. It also investigates a close loop control of wind generation system using fuzzy logic control.
A vertical (or horizontal) wind turbine is coupled to the shaft of a squirrel cage induction generator through a speed up gear ratio The variable frequency variable voltage power from the generator is rectified by a PWM IGBT rectifier (Ismai,2015). The rectifier also supplies the excitation need of the machine. Salient advantages of the converter system include the following.
i. Line side power factor is unity with no harmonic current injection
ii. The cage type induction machine is extremely rugged, reliable, economical, and universally popular.
iii. Machine current is sinusoidal and no harmonic copper loss.
iv. Rectifier can generate programmable excitation for the machine.
v. Continuous power generation from zero to highest turbine speed is possible.
vi. Power can flow in either director permitting the generator to run as a motor to startup.
vii. Autonomous operation of the system is possible with either a start-up capacitor or with a battery on the dc link.
viii. Extremely fast transient response is possible.
ix. Multiple generators or multiple systems can be operated in parallel.
x. The inverter can be operated as a VAR/harmonic compensator when spare capacity is available.
Fig. 2.2: A voltage fed double PWM converter wind generation system
Both horizontal and vertical axis wind turbines are used in wind generation systems. The vertical Darrieus type has the advantages of being located on the ground and accepting wind from any direction without any special yaw mechanism. It is, therefore, preferred for high power output. The disadvantages are that the turbine is not self-starting and there is a large pulsating torque which depends on wind velocity, turbine speed, and other factors related to the design of the turbine. ( HU,2014). The aerodynamic power of a vertical turbine is given by the equation:
The power coefficient is the figure-of-merit and is defined as the ratio of actual poor delivered to the free stream power flowing through a similar but uninterrupted area, and tip speed ratio (TSR) is the ratio of turbine speed at the tip of a blade to the free stream wind speed. The parameter is a nonlinear function of ? (. Laudani,2014). The oscillatory torque of the turbine is more dominant at the first, second, and fourth harmonics of fundamental turbine angular velocity and is given by the expression:
TOSC = Tm (ACOS (wmt) + BCos(2wmt) + CCos(4wmt) (2.4)
Where, A.B,C are the constants.
Fig.2.3 :Model of wind turbine with oscillatory torque
The turbine torque as a function of angular wind velocity is shown in result fig. 5.8.
The machine and inverter output currents are sinusoidal, as shown in fig.2.3. The machine absorbs lagging reactive current, but it is always zero on the line side: i.e., the line power factor is unity. The rectifier uses indirect vector control in the inner current control loop, whereas the direct vector control method is used for the inverter current controller. Vector control permits fast transient response of the system . (Rajasekar,2015). The generator speed is controlled by indirect vector control with torque control and synchronous control in the inner loop. Since an increase of Po causes a decrease of DC link voltage, the voltage polarity loop has been reversed. For a particular wind velocity Vw, there will be an optimum setting of generator speed wr*. The speed loop will generate the torque component of machine current so as to balance the developed torque with the load torque. The variable voltage variable frequency power from the super-synchronous induction generator will be rectified and pumped to the dc link. The dc link voltage controller ill regulate the line power Po so that the link voltage always remains constant. A feed forward power signal from the machine output to the dc voltage loop prevents transient fluctuation of link voltage.
2.6 Theory of work
To design a membership function that analysis the faults in power generation. There is a lot of faults in power companies like overcurrent, distortion, harmonic to mention a few. This can be overcome by designing a membership function that analysis the faults and provides a solution to it.
Fig. 2.4: Fuzzy control FLC-1 and FCL 2 operation showing maximization of line power.
“Optimization” comes from the same root as “optimal”, which means best. When you optimize something, you are “making it best”.
But “best” can vary. If you’re a football player, you might want to maximize your running yards, and also minimize your fumbles. Both maximizing and minimizing are types of optimization problems.
Mathematical Optimization is a branch of applied mathematics which is useful in many different fields. Here are a few examples:
The basic optimization problem consists of…
•The objective function, f(x), which is the output you’re trying to maximize or minimize.
•Variables, x1x2x3and so on, which are the inputs –things you can control. They are abbreviated xnto refer to individuals or x to refer to them as a group.
•Constraints, which are equations that place limits on how big or small some variables can get. Equality constraints are usually noted hn(x)and inequality constraints are noted gn(x).
2.7 Research Gap
Lastly, following the above Research procedures and recommendations, I noticed that there was a gap left to be filled during the impact of integrating renewable energy sources for rural electrification using an intelligent agent. That was the reason I had to use an optimized intelligent agent other than ordinaryintelligent agent or with PI controller which are not flexible as its inputs once given can’t be changed. The optimized intelligent agent introduced in this report is part of the energy power generation for rural electrification ; works better than the PI controller in terms of flexibility, speed and reliability for reduction of voltage fluctuations, harmonic distortions and low power factor to its lowest minimum value thereby enhancing stable power supply in the rural areas.