Cameroon is one of the African countries, particularly in Central Africa, with a significant renewable energy potential. Natural resources such as sunshine, wind, water and vegetable materials can be exploited to produce electricity locally. The use of renewable energy has now become a way to circumvent environmental pollution by greenhouse gases responsible for the destruction of the ozone layer [1] . This is why several countries have opted for the installation of solar power plants, hydraulic power plants, biomass power plants, wind power plants, and hydrogen power plants in order to have energy autonomy. Cameroon in particular and Africa in general have a significant amount of renewable energy. The most abundant renewable resources in Cameroon are: sunshine, wind, water and biomass [2] . However, some renewable natural resources cannot be exploited in such a way as to raise the level of power necessary to supply a large population in urban areas. In Cameroon, the use of photovoltaic solar energy is made by small localities isolated from electrical distribution lines. This is how, for example, we have a solar power plant in Banjo to supply this city. In Guider, a photovoltaic generator is injected into the northern interconnected networks with a view to strengthening it and supplying the city of Guider and its surroundings. But the problem that arises is that as the number of inhabitants increases, the need for energy also increases, which means that the existing installations are no longer sufficient to supply the locality concerned. This is why some thermal power plants are installed in regions such as Garoua, Maroua, Ngaoundere to be able to relay renewable energy sources or electrical distribution networks. However, it is true that the use of thermal power plants exposes the environment to carbon dioxide pollution responsible for the destruction of the ozone layer or the environment.

Although renewable resources exist in Cameroon and particularly in the northern part of Cameroon, knowledge of the stages of shaping electrical energy is important on the one hand and mastery of technology, design, installation or implementation is necessary in order to have operational safety or continuity of service. The advantage of using photovoltaic energy is that it is simple to implement, with fewer accessories [3] . Unlike wind energy, the impact of which is noted on birds and urban areas because wind farms are visual pollution and an obstacle for migratory birds. The use of hydraulic energy is also important, but rivers are not found everywhere in all localities in the Far North region. This is why it is important to identify areas where rivers or streams can easily be found at the same time as a significant deposit of photovoltaic solar energy. This will allow a fusion of two renewable energy sources, namely photovoltaic solar energy and hydraulic energy.

There are several techniques for setting up renewable energy plants. We have algorithms that allow the extraction of maximum power from generators. Several software such as MATLAB/Simulink, Homer Pro, PVsyst are used for the technical-economic study [4] . These softwares allow to evaluate the LCOE and the NPC which are necessary indicators in decision-making. These softwares also allow to have the pollution rate of the resources used. The same is true for the quality of the energy supplied when using certain standard tests such as the IEEE 33 bus, 69 bus, 118 bus standard, as well as other buses depending on the architecture or configuration of the network on which we are working [5] . This work uses the IEEE 33 bus standard test for the evaluation of the power losses of the proposed system as well as the voltage profile to see the behavior of the system on the one hand and the evaluation of the size of the entire system in order to meet the energy demand of the isolated localities of the Far North, Cameroon where there is a high population density living in the dark while the natural resources are available to be able to set up the renewable energy plants. This work consists of making an evaluation of education in some regions of the far north and the evaluation or identification of the different natural resources to be able to implement a multi-source plant made up of renewable energies. In order to have an organization of the work, the first part of this work is devoted to the evaluation of the available resources, the second part is devoted to the comparison of the results as well as the feasibility study in the Homer Pro software [6] . The last part is devoted to the analysis of the results and a conclusion followed by the perspectives concerning the implementation of this system in the locality of the far north.

The configuration of the proposed system is given in Figure 1 and consists of a photovoltaic generator source and the hydropower plant. An energy storage tank

is installed to boost the power level of the DC bus. DC loads can be connected to this DC bus. A DC/AC converter is used to process signals in order to supply AC loads to an AC bus. At this common coupling point, the electrical grids can be connected, as well as the AC loads. At this connection point, the hydraulic power plant is connected to raise the power level at the common point of coupling. The configuration of such a system makes it possible to have the scenario that offers an affordable NPC and LCOE when evaluating the technical-economic study in the Homer Pro software.

The configuration of the proposed system is depicted in Figure 2 , using the Homer Pro software interface for the techno-economic study to obtain the values of performance indicators such as the LCOE and the NPC. These parameters give us an idea of the feasibility of the system on the one hand, and the evaluation of the size of the system in general, as well as the performance related to the stability and robustness of the system on the other [7] . The Homer Pro software can be used to study and evaluate renewable energy systems using meteorological data from NASA data collections, which provide sunshine, temperature and wind speed values at 10 m height [8] . Unfortunately, in this study, carried out using the Homer software, the focus is only on assessing photovoltaic solar potential and hydraulic potential.

The energy generated by a photovoltaic generator is produced by the total number of modules in parallel and in series, where the modules are made up of a certain number of solar cells [16] . The photo-generated current is a function of the amount of sunshine and the ambient temperature under standard conditions. This energy is defined in Equation (10) [17] .

$P_{SP}=P_{S{P}_{\nu }}\varsigma \times \left[1+{\varsigma }_{\nu }\times \left(T_{\nu }-T_{STC}\right)\right]\times \frac{G_{\nu }}{1000},\varsigma \in N_{SP},\alpha \in \xi$ (10)

Hydraulic power stations obey a law of conservation of energy according to the capacity of the power station [18] . This condition is formulated in Equation (13) [19] :

$P{z}_{\varsigma \alpha }=C_{1\varsigma }V{z}_{\varsigma \alpha }^2+C_{2\varsigma }Q{z}_{\varsigma \alpha }^2+C_{3\varsigma }V{z}_{\varsigma \alpha }Q{z}_{\varsigma \alpha }+C_{4\varsigma }V{z}_{\varsigma \alpha }+C_{5\varsigma }Q{z}_{\varsigma \alpha }+C_{6\varsigma },\varsigma \in {\varpi }_z,\alpha \in \xi$(11)

The constraints on the correct operation of hydroelectric power stations are ensured by the conditions defined such that the water level in the tanks is within the admissible margin for fear of creating a malfunction [20] . These constraints define the range of minimum and maximum voltages and powers [21] .

$V{z}_{\varsigma }^{\min }\le V{z}_{\varsigma \alpha }\le V{z}_{\varsigma }^{\max },\varsigma \in {\varpi }_z,\alpha \in \xi$ (12)

$Q{z}_{\varsigma }^{\min }\le Q{z}_{\varsigma \alpha }\le Q{z}_{\varsigma }^{\max },\varsigma \in {\varpi }_z,\alpha \in \xi$ (13)

The reliability of service on the conservation of water in a tank in a hydropower plant is ensured by the equation defined by [22] :

$V{z}_{\varsigma \left(\alpha +1\right)}=V{z}_{\varsigma \alpha }+I{z}_{\varsigma \alpha }-Q{z}_{\varsigma \alpha }-S{z}_{\varsigma \alpha },\varsigma \in {\varpi }_z,\alpha \in \xi$ (14)

The IEEE 33 bus standard test is used in Figure 3 . This method makes it possible to highlight power profiles, voltage profiles and active and reactive power losses. In this topology of the system configuration, bus 1 represents the main source and bus 31 represents the secondary source, made up of the photovoltaic generator and the hydro plant respectively. The alternative loads are connected to bus 7 to ensure the continuity of the energy in the photovoltaic source. The configuration is divided into four scenarios. Scenario 1, which represents the photovoltaic source, scenario 2, which represents the hydroelectric plant, scenario 3, which represents the photovoltaic plant with battery, and scenario 4, which represents the entire hybrid photovoltaic generator-hydroelectric plant system and the battery storage bank. This configuration defined in Figure 3 can be modified automatically by reconfiguration, due to the definition of constraints derived from the objective function and the distribution of branches and buses using the Newton Raphson method [23] . This method enables the entire system to be implemented on the basis of the IEEE standard, using advanced algorithms such as heuristics and meta-heuristics [24] .

The optimization and evaluation of the size of the whole system takes into account the NPC which is given by Equation (16) and the LCOE defined by Equation (18).

These performance indicators give an idea of the feasibility study and the cost of producing and installing the system [25] . These are the parameters to be taken into account when carrying out a technical and economic study of a renewable energy system.

$C_{Total}=CRF\left(\epsilon ,{\eta }_{Hybrid}\right)\ast C_{NPC\left(Total\right)}$ (15)

In these mathematical relationships [26] , the $C_{NPC\left(Total\right)}$ is valid for the entire time or overall duration of the project and the LCOE represents the discount rate and ${\eta }_{Hybrid}$ represents the capital payback time in relation to a given annuity. This equation is used to determine the present value of an annuity and the current cost of an installation compared with a previous cost [27] .

$NPC=\frac{C_{Total}}{CRF\left(\epsilon ,\lambda \right)}$ (16)

From its technical aspects, the CRF is equivalent to the recovery capital, whereas the NPC is equivalent to the recovery interest of a facility whose maintenance, recovery and operating costs are known in advance [28] .

$CRF\left(\epsilon ,\lambda \right)=\frac{\epsilon {\left(1+\epsilon \right)}^{\lambda }}{{\left(1+\epsilon \right)}^{\lambda }-1}$ (17)

$COE=\frac{C_{Total}}{A{C}_{load}+D{C}_{load}}$ (18)

The analysis carried out using the COE allows an estimate to be made of the overall discounted cost of an electrical energy production system that has to supply a certain number of households.

Based on the evaluation of the solar photovoltaic potential in the different areas selected in Figure 4 , it is possible to identify the most suitable location for the implementation of the hybrid system to meet demand in the Far North. The Far North is supplied by a single hydroelectric plant located in the town of Lagdo, and part of the Northern Interconnected Grid has been strengthened by the photovoltaic plant located in the town of Guider since 2022 [29] .

The data collected ( Figure 4 ) provided the power profiles depicted in Figure 5 . These results give an idea of the size and level of energy needed to supply the Far North zone and to strengthen the Northern Interconnected Network (NIN) [31] . The power profile produced by the hybrid plant highlights that an average of 170 MW of power is generated, with a surplus of 25 MW. On the other hand, energy demand is around 15 MW. This configuration corresponds to scenario 4. This demonstrates that the PV/Hydro/BESS configuration can meet the energy demand on the one hand, and on the other provides a surplus of energy that can be stored or injected into the North Interconnected Network (NIN).

After assessing the size of the overall system using three scenarios, the proposed system, based on the hydropower plant, the photovoltaic generator and the energy

storage system, achieves an active power level of 215 kW. The importance of the hydraulic source and sunshine for a temperature that varies in the best conditions allows the implementation of such a multi-source system in the Homer Pro software and the IEEE 33 standard test gives an idea of the feasibility of the system. The locality of Bongo offers the best climatic data, which favors the implementation of a multi-source system made up of photovoltaic solar energy and hydropower. Figure 6 depicts the configuration of the different scenarios that led to the choice of the proposed system.

Using the IEEE 33 bus standard as shown in Figure 7 to carry out an analysis of the system in general, automatic reconfiguration of the various nodes in the

appropriate set of branches can be carried out. These nodes and branches correspond to the best locations for raising the power level and improving the voltage profile. In the event of a disturbance or blackout, or even load shedding, the system is automatically reconfigured. Different nodes, such as node 10 with node 24, node 13 with node 23 and node 22 with node 30, are connected. This automatic process increases the power generated and reduces power losses throughout the system. The automatic reconfiguration of the system also improves the voltage profile on the 33-bus standard test, due to the operating constraints related to the power loss minimization of the fitness function [32] .

Performance indicators such as voltage and power stability lead work on renewable energies to use the IEEE 14 bus 69, IEEE 33 bus, IEEE 118 bus standard test, as well as other buses depending on the configuration and architecture of the networks that can supply the loads [33] . These performance indicators make it possible to assess power losses, the size of the system as a whole, and the stability of the system during steady state operation [34] . In this work, four configurations are presented in the form of scenarios ( Figure 8 ):

After evaluation of the performance indicators using the IEEE 33 bus, the system comprising the photovoltaic power plant, the hydroelectric power plant storage system showed the best performance. Power losses were around an average

of 20 kW and voltage fluctuations were within the voltage fluctuations are within the affordable range in terms of stability index [35] . The objective function is defined around the constraints linked to the harmonic disturbance and the uncertain nature of AC or DC loads.

The configurations of the overall hybrid system for the different scenarios are depicted in Figure 9 . The voltage profiles for the different configurations are illustrated on the IEEE 33 bus standard. Instability is observed for scenario 1, corresponding to the photovoltaic generator, where there is a significant voltage drop at nodes 9, 11, 29 and 31. Configuration 4, on the other hand, improves the voltage profile, offering stability and the possibility of injection or connection to a common point of coupling. The configuration gradually improves with the combination of two or more renewable sources. It can be seen that as we move from the configuration of scenario 1 to scenario 4, the voltage profile improves. It is therefore clear from Figure 9 that the voltage profile is approaching unity per unit [36] . This scenario corresponds to the hybrid PV/Hydro/BESS system.

According to the evaluation of the size of the whole system based on the IEEE 33 bus standard test [37] . Figure 10 , on the other hand, presents the value of the LCOE, which decreases to 0.025 USD/kWh. We also observe a good convergence speed, which matches a constant value over a long period of time.

The aim of this article is to evaluate the solar photovoltaic and hydraulic potentials with a view to implementing a hybrid photovoltaic-hydraulic system with energy

storage, with a view to integrating the thermal power plant. The evaluation of the NPC and LCOE shows the feasibility of such a system, whose production and installation costs remain affordable. Following analysis of the results, the power losses over the entire system are negligible and the voltage profiles show good forms of stability on the IEEE 33 bus standard test. A configuration of the proposed system makes it possible to assess the size of the overall system, which is flexible in terms of robustness and accuracy when the speed of convergence of the objective function is observed. The evaluation of the solar hydraulic potential in four regions of the far north shows that the Bogor locality was chosen on the basis of three other localities, namely the Maga locality, the Lokoro locality and the Yagoua locality, where power estimates were made with a view to meeting the energy demand of localities that are isolated in the northern part of Cameroon, on the one hand, and at the same time meeting and reinforcing the electrical system of the interconnected northern network, on the other. Although the far north of Cameroon is supplied by the Northern Interconnected Network (NIN), electricity is not distributed to all localities at all times. Unfortunately, in localities where there are significant deposits of solar and hydraulic energy, the electricity networks do not cover these localities on a permanent basis. However, these areas are rich in resources that could be used as renewable energy power stations; these areas can be supplied with green energy without any risk of environmental pollution and at a reasonable cost. The feasibility study of the system proposed in this article shows that the configuration of the proposed system can meet the demand of localities in the far north on the one hand, and on the other, this energy can reinforce the only source of electrical energy production at the Lagdo hydropower plant, which supplies three regions in northern Cameroon. The aim is to assess energy demand in all the isolated areas of Cameroon, from the north to the south, and from the east to the west, so that renewable energy plants can be set up and green cities created, to give households access to electricity and a minimum of comfort.