scholarly journals Virtual Inertia-Based Control Strategy of Two-Stage Photovoltaic Inverters for Frequency Support in Islanded Micro-Grid

Electronics ◽  
2018 ◽  
Vol 7 (11) ◽  
pp. 340 ◽  
Author(s):  
Xin Huang ◽  
Keyou Wang ◽  
Guojie Li ◽  
Hua Zhang
Keyword(s):  
Frequency Control ◽  
Frequency Instability ◽  
Frequency Change ◽  
Two Stage ◽  
Power Generators ◽  
Pv Inverter ◽  
Micro Grid ◽  
Virtual Inertia ◽  
System Frequency ◽  
Inertia Response

For an islanded micro-grid with a high penetration of photovoltaic (PV) power generators, the low inertia reserve and the maximum peak power tracking control may increase the difficulty of maintaining the system’s supply–demand balance, and cause frequency instability, especially when the available generation is excessive. This will require changes in the way the PV inverter is controlled. In this paper, a virtual inertia frequency control (VIFC) strategy is proposed to let the two-stage PV inverters emulate inertia and support the system frequency with a timely response (e.g., inertia response), and the required power for inertia emulation is obtained from both the DC-link capacitor and the PV reserved energy. As the rate of the system frequency change can be reduced with the inertia increase, the proposed method can mitigate the frequency contingency event before the superior-level coordination control is enabled for the frequency restoration. The simulation results demonstrate the effectiveness of the proposed method.

Study of Multi-factor Coordinated Frequency Control Strategy by DFIG Wind Turbine

2019 ◽  
Vol 12 (1) ◽  
pp. 86-93
Author(s):  
Wang Yin-Sha ◽  
Li Wen-Yi ◽  
Li Zhi-Wen
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Frequency Response ◽  
Control Strategy ◽  
Large Scale ◽  
Frequency Control ◽  
Operating Conditions ◽  
Frequency Change ◽  
System Frequency ◽  
Inertia Response

Background: With the large-scale Doubly Fed Induction Generator (DFIG) wind turbine integrated into the power system, the DFIG inertia response of the wind turbine should be provided. Also, the frequency response should be similar to the conventional generation technologies. This paper investigated the influence of frequency response term and wind speed conditions on system frequency control. Methods: The specific operating conditions of four control strategies, including inertia control, droop control, over speed control and pitch angle control were researched in this paper. Multi-factor coordinated frequency control strategy of DFIG wind turbine was established based on the above researches. The strategy was composed of wind speed ranging from low to high. Results: According to the simulation results, the DFIG wind turbine, which was based on multifactor coordinated frequency control strategy, could respond to the system’s frequency change of power grid, effectively. Conclusion: It helps system frequency return to stable states better and faster than DFIG wind turbine and also could reduce the fluctuation of system frequency.

scholarly journals Provision of Frequency Stability of an Islanded Microgrid Using a Novel Virtual Inertia Control and a Fractional Order Cascade Controller

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4152
Author(s):  
Soroush Oshnoei ◽  
Mohammadreza Aghamohammadi ◽  
Siavash Oshnoei ◽  
Arman Oshnoei ◽  
Behnam Mohammadi-Ivatloo
Keyword(s):  
Fractional Order ◽  
Degrees Of Freedom ◽  
Search Algorithm ◽  
Frequency Control ◽  
Renewable Energy Sources ◽  
Dynamic Performance ◽  
Frequency Stability ◽  
Virtual Inertia ◽  
Inertia Control ◽  
System Frequency

Nowadays, the renewable energy sources in microgrids (MGs) have high participation to supply the consumer’s demand. In such MGs, the problems such as the system frequency stability, inertia, and damping reduction are threatened. To overcome this challenge, employing the virtual inertia control (VIC) concept in the MG structure could be considered as a viable solution to improve the system frequency response. Hence, this work proposes a novel modeling for VIC in an islanded MG that provides simultaneous emulation of the primary frequency control, virtual inertia, and damping. To show the efficiency of the proposed technique, a comparison is made between the dynamic performance of the proposed VIC and conventional VIC under different scenarios. The results indicate that the proposed VIC presents superior frequency performance in comparison with conventional VIC. In addition to VIC modeling, a new cascade controller based on three-degrees of freedom and fractional-order controllers (FOCs) is proposed as an MG secondary controller. The effectiveness of the proposed controller is compared to tilt-integral-derivative and FO proportional-integral-derivative controllers. The Squirrel search algorithm is utilized to obtain the optimal coefficients of the controllers. The results demonstrate that the proposed controller improves the MG frequency performance over other controllers. Eventually, the sensitivity analysis is performed to investigate the robustness of the proposed controller in the face of the variations of the parameters.

scholarly journals Control Strategy of BESS for Providing Both Virtual Inertia and Primary Frequency Response in the Korean Power System

Energies ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 4060 ◽  
Author(s):  
Choi ◽  
Kook ◽  
Yu
Keyword(s):  
Power System ◽  
Frequency Response ◽  
Control Strategy ◽  
Frequency Control ◽  
Storage System ◽  
Renewable Energy Resources ◽  
Virtual Inertia ◽  
Primary Frequency ◽  
Primary Frequency Response ◽  
Inertia Response

As the battery energy storage system (BESS) has been considered to be a solution to the diminished performance of frequency response in the Korean power system, in which renewable energy resources (RESs) are expected to increase rapidly, this paper proposes a control strategy for providing both the virtual inertia and primary frequency response considering the MW-scale BESS installed by the Korea Electricity Power Corporation (KEPCO). The benefit of such a fast and flexible BESS can be maximized by the proposed control strategy for making it provide both the inertia and primary frequency response, which would be deficit with the increased RES. In the proposed control strategy, the state of charge (SOC) is maintained in the specific range in which the life cycle is maximized, the interference of SOC recovery by frequency control is minimized, the responding capacity for providing the virtual inertia response is maximized during the transient period, and the performance requirements for frequency response are satisfied. The effectiveness of the proposed strategy is verified by both Korean power system model-based simulation and on-site operations.

Genetically tuned fuzzy controlled flywheel powered micro-grid for improved frequency control

2020 ◽  
pp. 0309524X2093254
Author(s):  
Saira Manzoor ◽  
Mairaj-ud-Din Mufti
Keyword(s):  
Fuzzy Logic ◽  
Fuzzy Logic Controller ◽  
Frequency Control ◽  
Frequency Deviation ◽  
Electrical Machine ◽  
Membership Functions ◽  
Micro Grid ◽  
Simulation Results ◽  
Operational Constraints ◽  
System Frequency

In this article, hybrid wind-diesel system is powered with a genetically tuned fuzzy controlled flywheel for improving its frequency control. Flywheel is interfaced with the system through an electrical machine (generator/motor) and an electronic converter for synchronization. Fuzzy logic controller for the flywheel is designed in such a way that it continuously controls the system frequency and simultaneously satisfies the operational constraints of flywheel. Fuzzy logic controller is optimized by genetically tuning its membership functions. Regulated variable based on frequency deviation of system and speed characteristics of flywheel is introduced to reach out to the optimized membership functions. Necessary modeling has been done and effectiveness of the assembly has been confirmed by the simulation results.

scholarly journals Dynamic Frequency Support from a DFIG-Based Wind Turbine Generator via Virtual Inertia Control

2020 ◽  
Vol 10 (10) ◽  
pp. 3376 ◽  
Author(s):  
Dejian Yang ◽  
Enshu Jin ◽  
Jiahan You ◽  
Liang Hua
Keyword(s):  
Wind Speed ◽  
Power Systems ◽  
Wind Turbine ◽  
Control Strategy ◽  
Control Method ◽  
Frequency Stability ◽  
Virtual Inertia ◽  
Inertia Control ◽  
System Frequency ◽  
Inertia Response

As the penetrated level of wind in power grids increases, the online system inertia becomes weak. Doubly-fed induction generator (DFIG)-based wind turbine generators (WTGs) are required to provide virtual inertia response to support system frequency. The present inertia control strategy with fixed control gain is not suitable and may cause stall of the DFIG-based WTG, as the virtual inertia response potential from the DFIG-based WTG is different with various wind speed conditions. This paper addresses a virtual inertia control method for the DFIG-based WTGs to improve the system frequency stability without causing stalling of the wind turbine for various wind speed conditions. The effectiveness of the proposed virtual inertia control method is investigated in a small system embedded with the DFIG-based WTG. Results demonstrate that the proposed virtual inertia strategy improves the frequency stability without causing the rotor speed security issue. Thus, the proposed control strategy can secure the dynamic system frequency security of power systems under the scenarios of full and partial loads, and, consequently, the proposed method provides a promising solution of ancillary services to power systems.

scholarly journals Modeling the Impact of Modified Inertia Coefficient (H) due to ESS in Power System Frequency Response Analysis

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 902 ◽  
Author(s):  
Muhammad Saeed Uz Zaman ◽  
Muhammad Irfan ◽  
Muhammad Ahmad ◽  
Manuel Mazzara ◽  
Chul-Hwan Kim
Keyword(s):  
Power Systems ◽  
Power System ◽  
Frequency Response ◽  
Frequency Control ◽  
Load Frequency Control ◽  
Response Analysis ◽  
Model And Simulation ◽  
Virtual Inertia ◽  
System Frequency ◽  
The Impact

The advantages of increased penetration of distributed generation are also accompanied by several challenges, low inertia being one of them, which threatens the grid stability. An emerging approach to confront this problem is the introduction of so-called virtual inertia (VI) provided by energy storage systems (ESS). In contrast to the already available literature which considers a conventional load frequency control (LFC) model, this work concentrates on a modified LFC model as the integration of a large portion of ESS changes the inertia constant ( H ) of a power system. A sensitivity function is derived that shows the effects of changes in H on the power system’s frequency response. With the help of the developed mathematical model and simulation results, it is shown that a difference in the actual and calculated values of H can deteriorate the system performance and economy. As one of the reasons for this difference is improper modeling of ESS in the LFC model, therefore, the study signifies the accurate calculation of H in the power systems having enlarged penetration of ESS.

DFIG Virtual Inertia Frequency Control Strategy

2013 ◽  
Vol 680 ◽  
pp. 505-508
Author(s):  
Huan Wang ◽  
Lei Pan
Keyword(s):  
Tracking Control ◽  
Frequency Control ◽  
Control Process ◽  
Active Power ◽  
Virtual Inertia ◽  
Inertia Control ◽  
Turbine Speed ◽  
Rotor Side Converter ◽  
System Frequency ◽  
Dynamic Frequency

During the DFIG maximum power tracking control process, the rotor side converter is only based on the wind turbine speed to regulate the active power output; it almost no provides effective inertia. DFIG could add auxiliary virtual inertia control system, when the system frequency is reduced, releasing the rotor "hidden" kinetic energy to support the grid dynamic frequency.

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