scholarly journals Microgrid Frequency Fluctuation Attenuation Using Improved Fuzzy Adaptive Damping-Based VSG Considering Dynamics and Allowable Deviation

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4885
Author(s):  
Yalin Liang ◽  
Yuyao He ◽  
Yun Niu
Keyword(s):  
Frequency Response ◽  
Control Method ◽  
Frequency Deviation ◽  
Droop Control ◽  
Response Dynamics ◽  
Scaling Factors ◽  
Large Power ◽  
Fixed Parameter ◽  
Power Disturbances ◽  
Fuzzy Adaptive

Recently, virtual synchronous generators (VSGS) are a hot topic in the area of microgrid control. However, the traditional fixed-parameter-based VSG control methods have an obvious disadvantage. Namely, if the damping value is set to be small, the amplitude of frequency deviations under external power disturbances is large, meaning that the frequency suppression capacity is insufficient, but if the damping value is large, the dynamics of the system will be greatly sacrificed. To solve the problem, taking the dynamic characteristics and the maximum allowable frequency deviation (MAFD) into account, in this paper an improved fuzzy adaptive damping-based VSG control strategy is proposed to simultaneously attenuate the microgrid frequency fluctuations and guarantee the system dynamics. Firstly, in order to address the necessity of using an adaptive damping-based VSG, the structure of a fixed-parameter VSG method that incorporates the f-p/Q-V droop controllers is introduced, based on which a small signal model is established to discuss the impacts of the virtual damping on the frequency response characteristics concerning the different penetration levels of power disturbances. Then, considering the dynamics and MAFD, a fuzzy adaptive controller is constructed relying on the well-designed membership functions, control rules and output scaling factors. The main feature of the improved fuzzy controller is that two alternative output scaling factors are employed to allow the system to be overdamped when the frequency deviation is large and undamped when the frequency deviation is small, balancing the frequency response dynamics and stability characteristics. To verify the effectiveness of the proposed fuzzy adaptive damping-based VSG technique, a computer simulation is conducted on a microgrid system in MATLAB/Simulink, and the obtained results are compared with the conventional droop control and fixed-parameter based VSGs. By using the proposed fuzzy adaptive damping-based VSG control method, the peak frequency deviations under the large power disturbances would become at least 8% lower compared to the traditional droop control and fixed-parameter VSG control, and meanwhile, the frequency response speed is fast when the disturbance stands at a low position. Consequently, it is valuable to promote the proposed techniques in engineering.

Droop control method based on fuzzy adaptive virtual resistance for DC microgrids

2021 ◽  
Vol 14 (2) ◽  
pp. 197
Author(s):  
Hossein Khoramikia ◽  
Seyed Mohammad Dehghan ◽  
Saeed Hasanzadeh
Keyword(s):  
Control Method ◽  
Droop Control ◽  
Dc Microgrids ◽  
Fuzzy Adaptive

scholarly journals Automatic Generation Control Considering Uncertainties of the Key Parameters in the Frequency Response Model

2021 ◽  
Author(s):  
Likai Liu ◽  
Zechun Hu ◽  
Asd Mujeeb
Keyword(s):  
Frequency Response ◽  
Control Method ◽  
Automatic Generation ◽  
Normal Operation ◽  
Automatic Generation Control ◽  
Damping Factor ◽  
Response Model ◽  
Estimation Model ◽  
Large Power ◽  
Generation Control

The highly fluctuated renewable generations and electric vehicles have undergone tremendous growth in recent years. The majority of them are connected to the grid via power electronic devices, resulting in wide variation ranges for several key parameters in the frequency response model (FRM) such as system inertia and load damping factor. In this paper, an automatic generation control (AGC) method considering the uncertainties of these key parameters is proposed. First, the historical power system operation data following large power disturbances are used to identify the FRM key parameters offline. Second, the offline identification results and the normal operation data prior to the occurrence of the disturbance are used to train the online probability estimation model of the FRM key parameters. Third, the online estimation results of the FRM key parameters are used as the input, and the model predictive-based AGC signal optimization method is developed based on distributionally robust optimization (DRO) technology. Case studies conducted on the IEEE 118-Bus System show that the proposed AGC method outperforms the widely utilized PI-based control method in terms of performance and efficiency.<br>

scholarly journals Automatic Generation Control Considering Uncertainties of the Key Parameters in the Frequency Response Model

2021 ◽  
Author(s):  
Likai Liu ◽  
Zechun Hu ◽  
Asd Mujeeb
Keyword(s):  
Frequency Response ◽  
Control Method ◽  
Automatic Generation ◽  
Normal Operation ◽  
Automatic Generation Control ◽  
Damping Factor ◽  
Response Model ◽  
Estimation Model ◽  
Large Power ◽  
Generation Control

The highly fluctuated renewable generations and electric vehicles have undergone tremendous growth in recent years. The majority of them are connected to the grid via power electronic devices, resulting in wide variation ranges for several key parameters in the frequency response model (FRM) such as system inertia and load damping factor. In this paper, an automatic generation control (AGC) method considering the uncertainties of these key parameters is proposed. First, the historical power system operation data following large power disturbances are used to identify the FRM key parameters offline. Second, the offline identification results and the normal operation data prior to the occurrence of the disturbance are used to train the online probability estimation model of the FRM key parameters. Third, the online estimation results of the FRM key parameters are used as the input, and the model predictive-based AGC signal optimization method is developed based on distributionally robust optimization (DRO) technology. Case studies conducted on the IEEE 118-Bus System show that the proposed AGC method outperforms the widely utilized PI-based control method in terms of performance and efficiency.<br>

Droop control method based on fuzzy adaptive virtual resistance for DC microgrids

2021 ◽  
Vol 14 (2) ◽  
pp. 197
Author(s):  
Saeed Hasanzadeh ◽  
Seyed Mohammad Dehghan ◽  
Hossein Khoramikia
Keyword(s):  
Control Method ◽  
Droop Control ◽  
Dc Microgrids ◽  
Fuzzy Adaptive

scholarly journals Fuzzy Adaptive Prescribed Performance Control for Uncertain Horizontal Platform System with Unknown Control Gain

2015 ◽  
Vol 2015 ◽  
pp. 1-8
Author(s):  
Wei Xiang ◽  
Yeguo Sun ◽  
Chunzhi Yang
Keyword(s):  
Control Method ◽  
Adaptive Controller ◽  
Performance Bounds ◽  
Constrained System ◽  
Prescribed Performance ◽  
Performance Technique ◽  
Control Gain ◽  
Unknown Control ◽  
Platform System ◽  
Fuzzy Adaptive

This paper proposes a fuzzy adaptive control method for uncertain horizontal platform system with unknown control gain, which is capable of guaranteeing the prescribed performance bounds. An error transformation is introduced to transform the original constrained system into an equivalent unconstrained one. Then, based on the error transformation technique and the predefined performance technique, a fuzzy adaptive controller is designed for the unconstrained system. It is shown that all the variables of the resulting closed-loop system are bounded. Finally, an illustrative example is given to demonstrate the effectiveness and usefulness of the proposed method.

scholarly journals Capacity Limitation Control of Multiple Bi-directional DC-DC Converters for Micro Grid Application

2015 ◽  
Vol 2 (1) ◽  
pp. 61 ◽  
Author(s):  
S. J. Chiang ◽  
Yu-Min Liao ◽  
Ke-Chih Liu
Keyword(s):  
Power Management ◽  
Control Method ◽  
Droop Control ◽  
Control Methods ◽  
Power Capacity ◽  
Capacity Limitation ◽  
Current Sharing ◽  
Parallel Control ◽  
Micro Grid ◽  
Bus Voltage

The micro grid system requires battery for energy storage and power management. In which, the bi-directional DC to DC converter is the key component for maintaining the DC bus voltage and controlling the charge and discharge of the battery with or without grid support. Parallel control of multiple DC to DC converters is a critical technique to enlarge the power capacity. This paper presents two capacity limitation control methods that multiple DC to DC converters can be paralleled with distributed battery banks. The first method is the capacity limitation control with cascaded load current sense needing no control interconnection. The second method is the capacity limitation control with master-slave and cascaded current command limitation. Two methods are presented to solve the limitation of droop control method and active current sharing method respectively, and can be extended without converter number limitation theoretically. Three prototype 240W bidirectional half-bridge DC to DC converters are built and paralleled in this paper. The proposed method is confirmed with some measured results.

scholarly journals New adaptive droop control with combined line impedance estimation method for parallel inverters

2016 ◽  
Vol 19 (4) ◽  
pp. 45-64
Author(s):  
Phuong Minh Le ◽  
Duy Vo Duc Hoang ◽  
Hoa Thi Xuan Pham ◽  
Huy Minh Nguyen
Keyword(s):  
Kalman Filter ◽  
Control Method ◽  
Least Squares Method ◽  
Estimation Method ◽  
Load Sharing ◽  
Phase Lock Loop ◽  
Power Sharing ◽  
Voltage Source ◽  
Droop Control ◽  
Voltage Source Inverters

This paper presents a new load sharing control between paralleled three-phase inverters in an islanded-microgrid based on the line impedance estimation online by the use of the Kalman filter. We can solve the mismatch of power sharing when the line impedance changes due to the temperature and frequency, significant differences of line parameters and requirements of Plug-and-Play mode of inverters connected to the microgrid. Moreover, the paper also presents a new Droop control method working with the line impedance which is different from the Droop traditional algorithm when the line impedance is assumed pure resistance R or pure inductance X. In the paper, the line impedance estimation for parallel inverters uses the least squares method combined with Kalman filter. In addition, secondary control loops are designed to restore the voltage amplitude and frequency of the microgrid by using a combined nominal value SOGI-PLL with generalized integral block and phase lock loop to exactly monitor the voltage magnitude and frequency phase at common PCC. Control model has been simulated in Matlab/Simulink with three voltage source inverters connected in parallel for different ratios of the power sharing. The simulation results have shown the accuracy of the proposed control method. Therefore, the proposed adaptive droop control method based on line impedance estimation can be an alternative one for load sharing control in islanded microgrids.

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