Jianhui Wong

Energy Storage System for Mitigating Voltage Unbalance on Low-Voltage Networks With Photovoltaic Systems

The growth of building integrated photovoltaic (BIPV) systems in low-voltage (LV) networks has the potential to raise several technical issues, including voltage unbalance and distribution system efficiency. This paper proposes an energy storage system (ESS) for mitigating voltage unbalance as well as improving the efficiency of the network. In the study, a power system simulation tool, namely PSCAD, is used to model two generic LV networks, BIPV systems and an ESS in order to simulate the performance of the networks with various levels of BIPV penetrations. A control algorithm is developed and implemented in the energy storage model in order to study the ability of the ESS to mitigate network voltage unbalance and reduce losses. Experimental studies are carried out in the experimental small-scale energy zone to investigate the effectiveness of the energy storage system under various levels of PV penetration and load conditions. The simulation and experimental studies carried out clearly show the effectiveness of the ESS in reducing the voltage unbalance factor and improving the efficiency of the two networks considered.

Novel Fuzzy Controlled Energy Storage for Low-Voltage Distribution Networks with Photovoltaic Systems under Highly Cloudy Conditions

AbstractThe amount of small-scaled renewable energy sources is anticipated to increase on the low-voltage distribution networks for the improvement of energy security and reduction of greenhouse gas emission. Malaysia has a high solar irradiance level that is ideal for photovoltaic (PV) systems. However, the growth of the PV systems on the low-voltage distribution networks can create a number of technical issues such as voltage rise, voltage unbalance, and reversed power flow. Usually, these issues happen with little fluctuations. However, these issues tend to fluctuate very rapidly in Malaysia because this region has a very low clear sky index. A large amount of clouds often passes over the country, hence making the incident solar irradiance to be highly scattered and fluctuating. Therefore, the power output of the PV systems fluctuates substantially. To ensure an effective operation of the distribution networks with the PV systems, a novel fuzzy control method is developed and implemented to govern the ...

Distributed Energy Storage Systems with an Improved Fuzzy Controller for Mitigating Voltage Unbalance on Low-Voltage Networks

AbstractThe growth of photovoltaic (PV) systems on low-voltage distribution networks can create technical issues such as voltage rise, voltage unbalance, unnecessary neutral current circulation, and reverse power flow. Usually, these happen with little fluctuation. However, they tend to fluctuate seriously because of the low clear sky index in Malaysia and they become more severe when the installation and distribution of single-phase renewable energy sources are rather arbitrary and not monitored by utility companies. To ensure effective operation of distribution networks with PV systems, an improved version of a three-phase fuzzy control algorithm for distributed energy storage (ES) systems is proposed. With this algorithm, distributed energy storage systems can control individual phase voltage to mitigate the voltage unbalance factor effectively, maintaining voltage magnitude without cutting any excess renewable energy. An experimental low-voltage distribution network with two 3.6-kWp PV systems was set...

Improved performance of PMSM speed responses using a hybrid Fuzzy/ PI controller

This paper presents an improved performance of a Permanent Magnet Synchronous Motor (PMSM) using a hybrid Fuzzy/ Proportional-Integral (PI) controller. Hybrid control has an advantage of integrating a superiority of two or more control techniques for better control performances. A fuzzy controller offers better speed responses for start-up and large reference input changes (large speed error) as compared to a Proportional-Integral controller. Nevertheless, a rules-based fuzzy controller is limited to a particular operating condition. If the nature of the load torque is varied, the steady-state error of the fuzzy logic controller will be significant. The Proportional-Integral controller has good adaptability over load torque variation and can maintain high steady-state accuracy. However, the transient responses are quite poor. This study has incorporated a Fuzzy and PI into the control of PMSM to improve its dynamic speed performances. The simulation is carried out using Matlab Simulink.

Fuzzy-driven energy storage system for mitigating voltage unbalance factor on distribution network with photovoltaic system

The amount of small-scaled renewable energy sources is anticipated to increase on the low-voltage distribution networks for the improvement of energy efficiency and reduction of greenhouse gas emission. The growth of the PV systems on the low-voltage distribution networks can create voltage unbalance, voltage rise, and reverse-power flow. Usually these issues happen with little fluctuation. However, it tends to fluctuate severely as Malaysia is a region with low clear sky index. A large amount of clouds often passes over the country, hence making the solar irradiance to be highly scattered. Therefore, the PV power output fluctuates substantially. These issues can lead to the malfunction of the electronic based equipment, reduction in the network efficiency and improper operation of the power protection system. At the current practice, the amount of PV system installed on the distribution network is constraint by the utility company. As a result, this can limit the reduction of carbon footprint. Therefore,...

Review of droop-controlled bi-directional inverter in conducting islanded operation of photovoltaic systems

Global warming due to the excessive greenhouse gas emissions has led to the emergence of green technologies in Malaysia, particularly photovoltaic (PV) systems. Under the current regulatory framework, islanded operation of the PV system is not permissible. As a result, any renewable energy sources will be disconnected immediately in the event of grid outages. This practice is to ensure the safety of working personnel, as well as the customer equipment connected within the distribution networks. In addition, there is no synchronizing equipment to aid the reconnection of the islanded network to the grid. However, with the shutdown of the Distributed Generator (DG) during islanded operation, the customers are not able to utilize the available renewable energy and the number of power interruption is not improved with the renewable energy sources. Therefore, the main objective of this paper is to investigate the feasibility of the PV system in conducting islanding operation with the use of Energy Storage Syste...

Distributed Energy Storage with Real and Reactive Power Controller for Power Quality Issues Caused by Renewable Energy and Electric Vehicles

AbstractThe integration of renewable energy sources (RE) and electric vehicles (EV) into the low voltage (LV) networks can create a number of power quality issues. RE or EV can cause voltage unbalance and low power factor when it injects or absorbs real power from the network. The energy storage system can be connected to the network to manipulate the power flow from or to those devices with the use of reactive power as a complementary support, hence correcting the voltage unbalance and power factor effectively without wasting any generated energy. To be able to correct the voltage unbalance and power factor effectively under the intermittent power of RE and EV, a novel fuzzy controller is developed and implemented in the energy storage to manipulate the flow of real and reactive power between the energy storage and the network based on the network conditions. The fuzzy controller is able to reduce any voltage excursions with the use of real and reactive power from the energy storage, hence reducing the v...