In this paper, a solar PV powered DC microgrid is proposed and designed for Umuokpo Amumara in Nigeria with 800 households and a number of community installations which include churches, schools, shops, and a water pumping system. The appropriate sizes of system components are determined to meet the all-time load demand. A Techno-economic feasibility study was carried out in Homer Pro to determine the energy needs of the community and as well the system size and configuration that best suits the community. The energy requirement of the community was obtained to be 3.16MWh/day. The battery storage system was also sized in this work and a battery system capacity of 21,944Ah was able to meet the community energy requirement for up to a day without renewable energy supply. The dynamic model of proposed the microgrid was simulated in MATLAB/SIMULINK to observe the system's dynamic response in view of the power quality, load impact, and battery storage charging. The results obtained from the simulation depicted a stand-alone DC microgrid that is capable of meeting the daily electrical energy requirements of the system with good voltage stability. The PV system used in the system could function at maximum power conditions even with variation in the weather conditions. This was achieved by employing the Incremental Conductance MPPT system.
Umuokpo Amumara is a village with an estimated population of 9,000 people and about 800 households located in the eastern region of Nigeria in West Africa. This village has no access to power grids for over a decade of existence. Umuokpo, by virtue of its location 5°27′35.9″N 7°19′60.0″E, on the average receives about 6 hours of sunlight with a daily average irradiance of 6.12 kWh/m2. The solar energy can be tapped and harnessed to generate quality electricity for this small village. Since the wind speed is low (ranging between 3.0 m/s and 3.5 m/s), the wind resource cannot be incorporated into the design. The average load demand of the village is 9.422 MWh/day with a peak load of 1.3 MW. This paper is aimed at designing a small hybrid power system that can generate sustainable electricity for the village from renewable energy sources. The design also considers a backup diesel generator and an energy storage system. The designed system consists of a 2,750 kW solar photovoltaic (PV), a 21,600 kWh battery storage, a 1,500 kW power electronic converter, and a 1,000 kW diesel generator. The simulation suggests that the proposed system can adequately meet the electricity needs of the village. A sensitivity analysis is also carried out on the system to observe its behavior with varying levels of irradiation and load.
SCADA provides real-time system monitoring by constant communication and data exchange between various system devices to achieve data visualization and logging. Presently, in industrial systems, commercial SCADA systems are being used for data monitoring and control. These systems can be expensive, and as such can only be afforded by select industries. Even at these costs, the commercial SCADA systems face some challenges, which include interoperability and scalability issues. Research has shown that these problems can be solved by the introduction of low-cost materials and open-source software to achieve data monitoring for all levels of processes. This paper proposes an open source, low-cost Internet of Things (IoT)-based SCADA system that employs the IoT architecture for SCADA functions. The proposed system is an improvement to the existing IoT solutions by eliminating cloud based IoT platforms and introducing a single machine system. This solution increases the robustness of the system while reducing costs. The proposed system prototype consists of voltage and current sensors, Arduino Uno microcontroller and Raspberry Pi. The sensors acquire data from the monitored unit. The Arduino Uno receives the data and processes them for transmission to the Raspberry Pi using the LoRa communication technology. At the Raspberry Pi, the local Chirpstack platform processes the data and displays the measured data using the Grafana dashboard for real-time data monitoring, and the data is stored in an InfluxDB database. For system validation purposes, the prototype is designed, developed, and set up to monitor the panel voltage, current and battery voltage of a solar photovoltaic system. The results obtained from the experimental set-up are compared with the test data from physical digital multimeters. The system presented in this paper is a low-cost, open source, scalable and interoperable system. This, therefore, makes the proposed SCADA system an alternative for commercial SCADA systems, especially for select applications. The system proposed in this paper can be deployed to large industrial systems with appropriate upgrades and customization. The main contribution of this research is the design and development of a SCADA system that performs all the functions of a proprietary SCADA system at a very low-cost with scalable and interoperability features which are the main limitations of the traditional SCADA systems.
This paper presents the design, simulation and fabrication of a low noise amplifier with high gain of 1.5GHz. In communication systems, there is always difficulty in distinguishing the received signal from noise at very low signal powers. A low noise amplifier (LNA) is an effective and low-cost way of enhancing this signal quality through signal amplification at the receiver. In this work, LNA simulation and a novel design was carried out using the N76038A field effect transistor (FET). To ensure it is stable over a wide range of frequencies, the input and output stability of the transistor were plotted over its operating frequencies (0.1 GHz to 18 GHz). Constant gain and noise figure circles were plotted and the source impedance properly chosen. The input network was matched to the source impedance and conjugate matching used to match the output. The schematic was converted to microstrip and produced on a printed circuit board. Testing was carried out using the vector network analyser (VNA) and matching errors then corrected by calibration process. The fabricated LNA has a gain of 13.76dB and noise figure of 1.57dB which is in close agreement with a simulation result of 14.25dB and 1.56dB respectively.
One important aspect toward proper and stable functioning of a communication-based controlled microgrid is data transmission. Consequently, an analysis of the effect of data transmission delay is of significance for any chosen communication protocol. This paper focuses on the effect of employing LoRa for data transfer at the secondary control level of a standalone DC microgrid. It analyses the effect of LoRa transmission delay on the dynamic performance of DC microgrids. This paper simulates a community DC microgrid that operates in three modes: PV mode, battery mode and generator mode. This microgrid operates as a centralized communication-based controlled microgrid, with the secondary control level operating as an event-driven level. The system incorporates a hierarchical system where data is transferred between the various distributed energy resources (DERs) local controllers and the microgrid central controller (MGCC). Simulations for three scenarios are presented. In the first scenario, the microgrid is designed and simulated without a communication delay to observe the system behavior. Then LoRa transmission delay is calculated for the various signals transferred between the MGCC and the local controllers. This delay is introduced into the simulation as transport delays and the system exhibits a level of stability degradation. Subsequently, a time delay compensation system is incorporated into the system for more robust operation. The delay compensation is applied in two simulation scenarios. In the first scenario, the system inductor (L) and capacitor (C) components are re-calculated, and the system is re-simulated to get a stable system even with the applied communication delay. In the second scenario, the proportional integrator (PI) controller in the microgrid central controller is re-designed to a more robust form to compensate for the delay caused by the LoRa transmission. The results obtained from the two modified simulations realize a stable DC microgrid. This system modification allows for system stability again, similar to the simulation when the microgrid operated without any communication delay. This, therefore, demonstrates that with proper system design and implementation, low bandwidth communication systems such as LoRa can be effectively employed for data transfer in event-driven communication-based controlled DC microgrids.
Abstract-This paper presents the design, simulation and fabrication of a low noise amplifier with high gain of 1.5GHz. In communication systems, there is always difficulty in distinguishing the received signal from noise at very low signal powers. A low noise amplifier (LNA) is an effective and low-cost way of enhancing this signal quality through signal amplification at the receiver. In this work, LNA simulation and a novel design was carried out using the N76038A field effect transistor (FET). To ensure it is stable over a wide range of frequencies, the input and output stability of the transistor were plotted over its operating frequencies (0.1 GHz to 18 GHz). Constant gain and noise figure circles were plotted and the source impedance properly chosen. The input network was matched to the source impedance and conjugate matching used to match the output. The schematic was converted to microstrip and produced on a printed circuit board. Testing was carried out using the vector network analyzer (VNA) and matching errors then corrected by calibration process. The fabricated LNA has a gain of 13.76dB and noise figure of 1.57dB which is in close agreement with a simulation result of 14.25dB and 1.56dB respectively.
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