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Research Publications (Engineering and Built Environment)

Permanent URI for this collectionhttp://ir-dev.dut.ac.za/handle/10321/215

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    Voltage rise regulation with a Grid Connected Solar Photovoltaic system
    (MDPI AG, 2021-10-25) Stephen, Akinyemi Ayodeji; Kabeya, Musasa; Davidson, Innocent E.
    Renewable Distributed Generation (RDG), when connected to a Distribution Network (DN), suffers from power quality issues because of the distorted currents drawn from the loads connected to the network over generation of active power injection at the Point of Common Coupling (PCC). This research paper presents the voltage rise regulation strategy at the PCC to enhance power quality and continuous operation of RDG, such as Photovoltaic Arrays (PVAs) connected to a DN. If the PCC voltage is not regulated, the penetration levels of the renewable energy integration to a DN will be limited or may be ultimately disconnected in the case of a voltage rise issue. The network is maintained in both unity power factor and voltage regulation mode, depending on the condition of the voltage fluctuation occurrences at the PCC. The research investigation shows that variation in the consumer’s loads (reduction) causes an increase in the power generated from the PVA, resulting in an increase in the grid current amplitude, reduction in the voltage of the feeder impedance and an increase in the phase voltage amplitude at the PCC. When the system is undergoing unity power factor mode, PCC voltage amplitude tends to rises with the loads. Its phase voltage amplitude rises above an acceptable range with no-loads which are not in agreement, as specified in the IEEE-1547 and Southern Africa grid code prerequisite. Incremental Conduction with Integral Regulator bases (IC + PI) are employed to access and regulate PVA generation, while the unwanted grid current distortions are attenuated from the network using an in-loop second order integral filtering circuit algorithm. Hence, the voltage rise at the PCC is mitigated through the generation of positive reactive power to the grid from the Distribution Static Compensator (DSTATCOM), thereby regulating the phase voltage. The simulation study is carried out in a MATLAB/Simulink environment for PVA performance.
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    Effectiveness of dynamic voltage restorer in enhancing voltage profile in low voltage electric power distribution networks under normal mode operation
    (IEEE, 2017-11) Taiwo, Ogunboyo Patrick; Tiako, Remy; Davidson, Innocent E.; Okafor, K.C.; Atimati, E.E.; Achumba, I.E.
    © 2017 IEEE. This work addresses the compensation of power quality disturbance in electric power distribution network as a result of voltage variation and voltage unbalanced using one of the most effective power electronics based custom power controller known as Dynamic Voltage Restorer (DVR). DVR usually connected between the source voltage and the customer load. The new setup of DVR has been put forward using dqo controller and proportional integral (PI) controller method. The simulations are achieved using MATLAB/Simulink Sim Power System tool box. The simulation results attest to the effectiveness of the proposed DVR configuration in compensating the power quality problems in secondary distribution system. The simulation results runs are presented with different settings of parameter used in the model in order to help the validity of the function of DVR in enhancing the quality of power supply at customer side.
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    Voltage profile enhancement in low voltage 11/0.4 kV electric power distribution network using dynamic voltage restorer under three phase balance load
    (IEEE, 2017-09) Taiwo, Ogunboyo Patrick; Tiako, Remy; Davidson, Innocent E.; Cornish, D.R.
    With the global trend of restructuring in electricity market, providing affordable, reliable and quality electric power by service providers to customers the end users of electric energy are of immerse concern. Several initiatives have been taken by utilities to improve power quality in low voltage electric power distribution network but the inadequate operation/performance of the conventional compensation devices to mitigate the poor power quality problems have prompted the use of custom power device such as the dynamic voltage restorer (DVR). Dynamic voltage restorer (DVR) is an advanced power electronics based compensation device which is series connected to the distribution network through boosting transformers. DVR aimed at improving the voltage profile, enhancing the reliability and good quality of power flows in low voltage electric power distribution networks. The DVR is a highly efficient device, the principle is based on the voltage source inverter (VSI) which injects the appropriate missing voltage in series with the system voltage to correct the voltage variations experienced in the distribution feeder lengths. The dependability, robustness and effectiveness of the DVR control and power scheme in respect of the response to voltage disturbances at normal mode operation of three phase balanced loads is presented using the MATLAB simulation results carried out in Power System Sim Tool box. The balance of the paper gives recommendations on effective methods for improving the voltage profile and reducing the voltage variation to an allowable standard.