Fluctuations in system voltage can disrupt the system possessions both at the utility and customer end. Such a problem is most prominent at a point where a renewable source is attached to feed the grid. Photovoltaic (PV) power is one of the proposing renewable resources in the twenty-one century. However, its output depends on sunlight which varies throughout the day. This varying output of grid-connected PV systems causes harmonics and variation in system voltage. This work proposes a model of Dynamic Voltage Restorer (DVR) to overcome the issues mentioned above. DVR is a three-phase voltage source inverter (VSI) fed by a DC source. Adaptive neuro-fuzzy inference system(ANFIS) controller along with synchronous reference frame theory (SRF) is used to control the switching of voltage source inverter. According to SRF theory, three-phase a–b–c stationary frames are changed into 0–d-q rotational frames. The 0–d–q rotating frame reference signals are regulated using a PI or ANFIS controller to achieve the necessary reference signals. The measured amplitudes of the reference phase voltages are used directly to calculate the PWM signal generation for the three-phase inverter. MATLAB software is used to implement the proposed model and verify the proposed controller. The DVR is attached to a grid integrated with the PV system. PV system parameters like irradiance and temperature are varied to disturb the voltage. Voltage fluctuations and harmonics generated were mitigated by DVR. The results show that the proposed device can improve the voltage profile of a PV-integrated grid.

The increased growth of Global System for Mobile Communication (GSM) networks is not without challenges such as dropped or blocked calls, poor internet access, occasional service outages, and network congestions among other poor service challenges. This paper investigated and analysed the performance of GSM networks for optimization of Quality of Service (QoS) at Malete, Kwara State. Due to the inability to make calls, poor data service, network congestions, etc., 2G, 3G and 4G drive test analyses were conducted and a questionnaire method was adopted to compare customer feedbacks with the test results. Key Performance Indicators (KPI) and parameters such as Call Setup Success Rate (CSSR), Call Completion Rate (CCR), Call Drop Rate (CDR), and Call Handover Success Rate (CHSR) were considered and investigated. The data collected through Test Mobile System (TEMS) software were analyzed using map info professional to identify the cause of these problems with a view to providing efficient and effective solutions to the problems. Destitute network and QoS performance were encountered in some parts of the research area and parametric optimization was given as a way of improving the network performance for better QoS, reception, revenue generation and economic growth.