Analysis of Fuzzy Inference Power Control Strategies for Islanding Operation of Microgrids (original) (raw)
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Power Management of AC Islanded Microgrids using Fuzzy Logic
8th IET International Conference on Power Electronics, Machines and Drives (PEMD 2016), 2016
In an islanded AC microgrid consisting of renewable energy sources, battery, and load, the battery balances the difference between power generated by renewable sources and that consumed by the load. However, battery charging capacity is limited and its state of charge needs to be maintained within the safety limits. Furthermore, battery has limited maximum charging and discharging power. This paper proposes a controller based on fuzzy logic to prevent the battery state of charge and charging/discharging power from exceeding their limits regardless of variations in load and intermittent power of renewable sources. The microgrid considered in this paper consists of PV, battery, load and auxiliary supplementary unit. The fuzzy logic controller alters the AC bus frequency which is used by the local controllers of the parallel units to curtail the power generated by PV or to supplement power from the auxiliary unit. The main merits of the proposed controller are simplicity and easiness of implementation without the need for any communication links between the parallel units. Matlab/Simulink results are presented to validate the performance of the proposed controller.
Fuzzy-PI Controllers for Grid-Connected and Islanded Operation of DG in a Microgrid
2013
Islanding describes the condition in which a microgrid or a portion of the power grid, which consists of a load and a distributed generation (DG) system, is isolated from the remainder of the utility system. In this situation, it is important for the microgrid to continue to provide adequate power to the load. To demonstrate the operation of microgrid in grid connected mode and islanded mode, a simulink model has been designed with necessary parameters by connecting with the main grid allowing the sharing of different loads with reference to grid connection and disconnection. An islanding detection algorithm has been used to act as a switch between the two controllers so that the system operates under intentional islanded mode. This paper also proposes an algorithm of synchronization for grid reconnection. In addition, fuzzy logic controller and SVPWM have been used to reduce the THD of the inverter output.
A fuzzy-based approach for microgrids islanded operation
Electric Power Systems Research, 2017
Power system blackouts harm economic activities and worsen the customers' welfare. Smart grids' selfhealing capacity is an important feature for future power systems and it should also include the ability to manage the distributed energy resources to ensure power supply for a longer time. This is required because the duration of a blackout is unknown and bulk power system blackstart is a complex task. The deployment of microgrids can overcome these challenges since they may be operated in an autonomous way. This paper proposes a methodology for microgrid management in islanded conditions aiming to maximize the duration of power supply taking into account the availability of renewable sources and stored energy. In order to accomplish this goal, some management options are considered, such as load shedding, dispatch of expensive fossil fuel sources, and demand response actions. The control actions are determined with the help of a fuzzy logic methodology. The proposed approach is validated with a modified IEEE 34 node sample system.
Frequency control of islanded microgrid using fuzzy-PI and autotuned controllers
International Journal of Advances in Applied Sciences (IJAAS) , 2019
Any mismatch between generation and demand causes frequency to deviate from nominal value which affects the microgrid operation and reliability of power flow. The load frequency changes abnormally, which is fuzzy in nature, due to low system inertia and unpredictable variation in wind and solar irradiance level. So a frequency controller is needed to solve this problem meeting generation and demand of an islanded microgrid system considering the fuzziness in frequency fluctuation. This paper presents a case study of a hybrid microgrid system consisting of PV system, wind turbine generator set, diesel generator set along with storage facility and equipped with a proposed fuzzy-PI controller for frequency control under islanded condition. This controller shows satisfactory steady-state response. Further, performance of the proposed fuzzy-PI controller is verified with that of an autotuned PI controller to get faster response. The change in frequency is found minimum in case of autotuned PI controller as compared to fuzzy-PI controller. The proposed fuzzy-PI controller is validated based on ITAE (4-7%) which is higher than that attained form autotuned-PI controller. The developed model is simulated in Matlab/Simulink environment in this case study.
Application of Neuro-Fuzzy Controller on Voltage and Frequency Stability in Islanded Microgrids
2012
This paper presents a new droop control strategy based on neuro-fuzzy technique to minimize voltage and frequency deviations in islanded microgrids (MGs) under severe changes in load. In islanded MGs, due to lack of the backup power, the imbalance between consumption and generation usually leads to violent voltage/frequency fluctuations. Therefore, designing a reliable control structure to prevent the MG instability is needed. The proposed control strategy is designed to maintain the system stability and minimize the voltage/frequency fluctuations regardless of the MG structure. The most important advantage of the proposed controller is independency from the MG structure and operating conditions. The simulation results show the appropriate operation and efficacy of the proposed controller in the presence of severe changes in load.
IEEE Transactions on Sustainable Energy
In islanded AC microgrids consisting of renewable energy sources (RES), battery-based energy storage system (BESS), and loads, the BESS balances the difference between the RES power and loads by delivering/absorbing that difference. However, the state of charge (SOC) and charging/discharging power of the battery should be kept within their design limits regardless of variations in the load demand or the intermittent power of the RES. In this paper, a supervisory controller based on fuzzy logic is proposed to assure that the battery power and energy do not exceed their design limits and maintaining a stable power flow. The microgrid considered in this paper consists of a PV, battery, load and auxiliary supplementary unit. The fuzzy logic controller alters the AC bus frequency, which is used by the local controllers of the parallel units to curtail the power generated by the PV or to supplement the power from the auxiliary unit. The proposed FLC performance is verified by simulation and experimental results.
Research on Control Strategies for Islanding Operations of AC Microgrids
Micro grid is a new concept for future energy distribution system that enables renewable energy integration. It generally consists of multiple distributed generators that are usually interfaced to the grid through power inverters. For the islanding operation of ac micro grids, two important tasks are to share the load demand among multiple parallel connected inverters proportionately, and maintain the voltage and frequency stabilities. This research reviews and categorizes various approaches of power sharing control principles. Simultaneously, the control schemes are graphically illustrated. Moreover, various control approaches are compared in terms of their respective advantages and disadvantages. Finally, this report presents the future trends.
Recently, microgrid has become popular in the electric power industry and the important performance parameters considered, particularly when it is operating in islanded mode or under the load change condition, are voltage-frequency regulation, dynamic and steady-state response. In this paper, an intelligent optimal power control strategy, based on fuzzy gain scheduling of the conventional proportional-integral controller, is proposed for voltage-frequency control in an inverter based distributed generation unit. Simulations results, of the proposed control strategy, are compared against that of the conventional PI controller under islanded mode and under load change condition. It is evident that the proposed control strategy provides improved response.
Frequency regulation by fuzzy and binary control in a hybrid islanded microgrid
Journal of Modern Power Systems and Clean Energy, 2014
Islanded microgrids must be self-sufficient in terms of frequency and voltage control due to their islanded operation. A control strategy for frequency regulation by combining the operation of a wind generator, a diesel generator, a battery energy storage system and a dump load in a microgrid is proposed in this paper. In the proposed strategy, the control task is partitioned into two subtasks: 1) choosing the appropriate element to be used for regulation, and 2) providing frequency regulation. A global controller chooses the element to operate. Then, the frequency regulation is provided by separate individual controllers. The proposed control strategy is tested on a microgrid with mixed types of generation and modeled on Simulink. By monitoring the power of individual elements and system frequency, it is shown that the proposed control strategy operates efficiently. The proposed strategy facilitates the integration of renewable energy sources and enhances frequency regulation.
IJERT-Fuzzy-PI Controllers for Grid-Connected and Islanded Operation of DG in a Microgrid
International Journal of Engineering Research and Technology (IJERT), 2013
https://www.ijert.org/fuzzy-pi-controllers-for-grid-connected-and-islanded-operation-of-dg-in-a-microgrid https://www.ijert.org/research/fuzzy-pi-controllers-for-grid-connected-and-islanded-operation-of-dg-in-a-microgrid-IJERTV2IS100110.pdf Islanding describes the condition in which a microgrid or a portion of the power grid, which consists of a load and a distributed generation (DG) system, is isolated from the remainder of the utility system. In