GM Shafiullah

This paper presents a proposed solution for a Constant V and Q controlled Renewable Rich Grid Connected Electric Vehicle Charging Station. The proposed solution aims to address the challenges of electric vehicle charging infrastructure, which is currently facing issues of limited renewable energy sources, grid instability, and high capital and operational costs. The proposed solution offers a smart and sustainable electric vehicle charging station that integrates renewable energy sources with a Constant V and Q control system to ensure grid stability and efficient use of energy. The system incorporates solar photovoltaic panels, wind turbines, and energy storage units to generate and store renewable energy. The charging station is equipped with a bi-directional charger that allows the station to provide power to the grid during peak demand hours and draw power during off-peak hours. The proposed solution also incorporates a user-friendly mobile application that allows users to reserve charging slots and monitor their charging status. The Constant V and Q control system provides a stable voltage and frequency to ensure efficient power transfer between the grid and the charging station. The proposed solution offers a scalable and cost-effective model for EV charging infrastructure that can be replicated in other regions facing similar challenges.

Distorted line current is always a common issue of induction motor drive (IMD) driven by an 18-pulse rectifier fed multilevel inverter (MLI). The basic 18-pulse diode bridge rectifier (DBR) used in IMD does not comply with the IEEE-519 standard. A 3-level neutral point clamped (NPC) MLI operating at low switching frequency is utilized on the motor side to provide compactness and good performance. Inverter switching uses pulse width modulation (PWM) technique which is largely affected by the total harmonic distortion (THD) produced by the DBR. A new PWM scheme is proposed which utilizes the injection of different odd harmonics into the multi-carrier based sixty-degree PWM (SDPWM) modulating signal to reduce harmonic contents of the line current. The proposed modulation technique reduces line current THD to 1.85%, which satisfies the requirement of IEEE-519 standard. The performance of the proposed PWM technique with 18-pulse 3-level NPC MLI fed IMD is analyzed by simulating it in MATLAB/Simulink environment under large load varying conditions. According to the simulation results, the system features a reduced line current THD and enhanced power quality performances.

The increased penetration of renewable distributed generation (DG) such as wind power and photovoltaics (PV) in distribution networks has brought significant economic and environmental benefits to society. However, due to the intermittent nature of wind and solar, massive integration of such kinds of DG might cause severe problems, such as greater power loss, reduced power quality, and system efficiency. The integration of energy storage systems (ESS) provides an effective way to handle the above issues due to its capability of stabilizing voltage and frequency. Hence, it is necessary to optimally allocate the ESS to exert maximum support on the distribution network. This paper presents an approach for optimal allocation of ESS to improve voltage profile and reduce power losses and line loading in the unbalanced distribution system. The proposed methodology is tested on an unbalanced medium voltage IEEE-33 bus system with higher wind and PV generation. DIgSILENT PowerFactory is used for constructing and testing the system model. The simulation results demonstrate the effectiveness of the proposed approach in improving the power quality and system efficiency of unbalanced distribution systems.

An autonomous microgrid (MG) may observe overloading and renewable-based excessive generation. Such issues can lead to unacceptable deviation in the MG's voltage or frequency. These problems can be eased by load-shedding or renewable curtailment. On the other hand, forming provisional neighboring MG clusters and facilitating power exchange among them can also improve the situation more economically and effectively. The power exchange link between the MGs can be in the various forms such as a three-phase ac, a single-phase ac or a dc link. This approach requires power electronics-based converters to interlink the three-phase ac microgrid with the power exchange link and control the power-sharing amongst them. This paper has studied such structures and has proposed a decentralized approach to control the converters of the neighboring MGs to enable power-sharing amongst them. The performance of the proposed control mechanisms is evaluated through simulation studies in PSIM ® .

Variable distributed energy resources (DERs) such as solar and wind are rapidly becoming common in low-inertia microgrids (MGs) worldwide as the world explores cost-efficient and sustainable energy solutions. Additionally, the urgent need for greenhouse gas emission reductions and the availability of vast renewable energy resources serve as motivations to harvest these renewabies. Solar photovoltaic (PV) technology is one of the most utilised due to the significant drop in prices for solar PV systems. However, the variable nature of solar PV generation due to cloud movements introduces rapid ramp events thus affecting power system management. Nowcasting, which is defined as very short-term solar irradiance forecasting, together with controllable DERs, can be integrated into MGs to possibly address these ramp events and enable an increase in PV penetration levels in MGs. This study outlines the benefits and limitations of nowcasting and its applications in the control of MGs obtained from a survey. From the survey, it was evident that sky camera-based nowcasting technology is still new but has potential in MG applications. Applications of nowcasting in MGs included ramp rates control and scheduling of spinning reserves. Additionally, PV penetration levels may be increased if nowcasting tools are incorporated into the control of MGs. However, the main barrier impeding the utilisation of sky camera-based nowcasting technology is the lack of experience and lack of demonstrated reliability.

Load-shedding and curtailment of renewable sources are common mechanism to prevent temporary overloading and over-generation in autonomous microgrids (MGs). However, these problems can be addressed by interconnecting the neighbouring MGs to share power among them. In such a scheme, the interconnected MGs, termed as coupled microgrid (CMG), are controlled to supply their local loads, as well as the loads in the neighboring MGs through an interconnecting three-phase ac link with back-to-back power electronics-based converter. This paper has proposed a suitable control mechanism to realize power sharing amongst the MGs within a CMG, when operating in different conditions. The efficacy of the proposed power sharing and control mechanisms are validated through simulation studies using PSIM ® .

Large remote areas may consist of multiple microgrids (MG), each owned and operated by a different owner (operator) in standalone mode. However, they can be coupled provisionally to support each other during overloading or excessive generation by renewables. This paper proposes a technique to maintain the voltage and frequency (VF) of each MG within the desired range in such situations. To this end, a multilevel optimization approach is utilized that determines the most suitable actions to recover the troubled MG. At first, the proposed technique utilizes the local resources of an MG, such as adjusting the generation levels of the dispatchable sources, charging or discharging of existing battery energy storages, and determining the best configuration for the microgrid's network. It then proceeds to determine the required support from neighboring healthy MGs if the local supports are not adequate. In that case, the proposed technique optimally selects the MGs (and level of support) to be coupled to support the troubled MG(s). In this regard, it considers the trading cost, reliability, emission and VF of the prospective coupled MG's network while forming an MG cluster. The performance of the developed technique is evaluated through numerical analyses in MATLAB.

Battery energy storage system has become an important part of modern energy system with the growth of renewable energy and electric vehicle (EV). With the development of recent battery technologies, the improvement in overall battery charging efficiency and its cost, have become critical issues because, as the charger efficiency increases, the charging time and electricity cost decreases. Furthermore, power electronics based chargers can cause line current distortions and harmonic issues in the ac power system; and hence efficient and low-distortion smart chargers are needed to minimize power system disturbances. The aim of this paper is to study and analyze the conventional charging algorithms and the power converter topologies available in practice to design a fast, effective and efficient battery charger for EV/Microgrid/Energy storage applications. An LC Parallel Resonant Converter (PRC) can offer an effective solution for designing a fast and reliable battery charger with simple control circuits and techniques. The distinct feature of the proposed topology is that, the converter can operate in open loop while maintaining a constant charging current and hence any of the fast charging algorithms can be easily implemented without any complex controller and sensors.

Community solar consisting of rooftop photovoltaic systems (RPVs) and battery energy storage systems, when designed properly, can address and solve many of the design and adoptability challenges brought by the individual RPVs and battery energy storage. Such systems can benefit many of the remote and rural communities, that are usually supplied by diesel generators, or long traditional distribution lines, which in addition to being expensive often don't provide the reliability at desired level. These systems can also benefit most of the urban areas since the unmanaged penetration of RPVs has resulted in the undesired duck curve profile in the network. To this end, this paper proposes and verifies the appropriate design criteria for community solar projects with an aim to improve the network duck curve profile, enable peak-shaving and increase the self-sufficiency of the community.

The optimal operation of a standalone microgrid is often governed by the central controller, which optimizes the set-points of the local controllers of the distributed generators based on the available and predicted data. However, due to the uncertainty of loads and renewable generations, the optimized set-points may not be valid for long periods. This paper proposes a technique to readjust the dispatch of the suitable generation units, between the optimizations, to support load changes. To this end, the potential field concept is used by the loads to select the suitable generation units to make the decision making very quick. The decision is made based on different criteria such as cost, reliability, emission, and power loss. This process requires low computational efforts and can be done instantly. Besides, a periodic optimization is performed by the MG's central controller to retune the whole system and reconfirm the optimal operation. Numerical analysis has been carried out on a sample microgrid to validate the performance of the proposed technique.