scholarly journals Reduced-Order-VSM-Based Frequency Controller for Wind Turbines

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 528
Author(s):  
Liang Lu ◽  
Oscar Saborío-Romano ◽  
Nicolaos A. Cutululis
Keyword(s):  
Power Systems ◽  
Wind Turbines ◽  
Rate Of Change ◽  
Reduced Order ◽  
Overcurrent Protection ◽  
Virtual Inertia ◽  
Grid Side ◽  
Grid Side Converter ◽  
Frequency Controller ◽  
System Frequency

Frequency support capability is becoming an important requirement for wind turbines, as wind power is increasingly integrated into power systems. In this paper, a frequency controller is implemented and validated. Such a controller allows wind turbines to help regulate the system frequency automatically and includes virtual inertia to help limit the rate of change of frequency. Compared with other methods, the controller achieves satisfactory frequency support capability with considerable simplicity. The controller is added to the grid-side converter controls, together with cascaded inner loops, which enables wind turbines to operate in grid-forming mode with overcurrent protection. The influence of the controller parameters on the frequency response is investigated.

scholarly journals Emulating Rotational Inertia of Synchronous Machines by a New Control Technique in Grid-Interactive Converters

2020 ◽  
Vol 12 (13) ◽  
pp. 5346 ◽  
Author(s):  
Meysam Saeedian ◽  
Bahram Pournazarian ◽  
S. Sajjad Seyedalipour ◽  
Bahman Eskandari ◽  
Edris Pouresmaeil
Keyword(s):  
Power Systems ◽  
Large Scale ◽  
Renewable Energy Sources ◽  
Rate Of Change ◽  
Power Grids ◽  
Stable Region ◽  
Control Technique ◽  
Voltage Source ◽  
Rotational Inertia ◽  
Virtual Inertia

Integration of renewable energy sources (RESs) into power systems is growing due to eco-friendly concerns and ever-increasing electricity demand. Voltage source converters (VSCs) are the main interface between RESs and power grids, which have neither rotational inertia nor damping characteristics. Lack of these metrics make the power grid sensitive to frequency disturbances and thereby under frequency, to load shedding activation or even large-scale collapse. In this regard, the contribution of this paper is to develop a new control technique for VSCs that can provide virtual inertia and damping properties with the DC-link capacitors inhered in the DC-side of grid-tied VSCs. The applied VSC is controlled in the current controlled model, with the capability of injecting extra active power with the aim of frequency support during perturbations. The dynamics assessment of the proposed platform is derived in detail. It is revealed that the control scheme performs in a stable region even under weak-grid conditions. Finally, simulations are conducted in MATLAB to depict the efficacy and feasibility of the proposed method. The results show that frequency deviation is mitigated under step up/down changes in the demand, and the rate of change of frequency is improved by 47.37% compared to the case in which the synthetic inertia loop is canceled out.

scholarly journals Application of VSG technology based on flexible parameter adjustment in PV unit grid-connected inverter

2021 ◽  
Vol 2076 (1) ◽  
pp. 012118
Author(s):  
Penghui Zhao ◽  
Peng Wu ◽  
Shuai Zhang ◽  
Ning Wang ◽  
Yan Li ◽  
...  
Keyword(s):  
Energy Storage ◽  
Power Systems ◽  
Damping Coefficient ◽  
Parameter Adjustment ◽  
Grid Connection ◽  
Adjustment Strategy ◽  
Virtual Inertia ◽  
Grid Connected Inverter ◽  
System Frequency ◽  
Storage Units

Abstract As a clean and effective renewable energy source, PV has been widely used in power systems. The application of VSG technology can effectively improve the system inertia reduction problem caused by the grid connection of PV and energy storage units. The virtual inertia and damping coefficient in VSG control have the unique advantages of being flexible and controllable. This paper designs a control strategy in which the virtual inertia and damping coefficient can be flexibly adjusted according to the system frequency, which further improves the operating performance of the PV and energy storage units based on VSG control. The frequency quality of the system is maintained. Finally, the effectiveness of the proposed flexible parameter adjustment strategy was verified through the simulation platform, which played a role in popularizing the application of the proposed strategy in engineering.

scholarly journals Investigation of Inertia Response and Rate of Change of Frequency in Low Rotational Inertial Scenario of Synchronous Dominated System

Electronics ◽  
2021 ◽  
Vol 10 (18) ◽  
pp. 2288
Author(s):  
Francisco Gonzalez-Longatt ◽  
Juan Manuel Roldan-Fernandez ◽  
Harold R. Chamorro ◽  
Santiago Arnaltes ◽  
Jose Luis Rodriguez-Amenedo
Keyword(s):  
Power Systems ◽  
Large Scale ◽  
Power Converter ◽  
Rate Of Change ◽  
Rotational Inertia ◽  
Distributed Energy ◽  
Inertial Response ◽  
System Frequency ◽  
Inertia Response ◽  
System Inertia

The shift to a sustainable energy future is becoming more reliant on large-scale deployment of renewable and distributed energy resources raising concerns about frequency stability. Rate of Change of Frequency (RoCoF) is necessary as a system inertia metric in order for network operators to perform control steps to preserve system operation. This paper presents in a straightforward and illustrative way several relevant aspects of the inertia response and RoCoF calculation that could help to understand and explain the implementation and results of inertial response controllers on power converter-based technologies. Qualitative explanations based on illustrative numerical experiments are used to cover the effects on the system frequency response of reduced rotational inertia in synchronous dominated power systems. One main contribution of this paper is making evident the importance of the governor action to avoid the synchronous machine taking active power from the system during the recovering period of kinetic energy in an under frequency event.

scholarly journals Improved Virtual Inertia of PMSG-Based Wind Turbines Based on Multi-Objective Model-Predictive Control

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3612
Author(s):  
Shiyao Qin ◽  
Yuyang Chang ◽  
Zhen Xie ◽  
Shaolin Li
Keyword(s):  
Model Predictive Control ◽  
Predictive Control ◽  
Wind Turbines ◽  
Control Strategies ◽  
Weight Coefficient ◽  
Synchronous Generators ◽  
Multi Objective ◽  
Objective Model ◽  
Virtual Inertia ◽  
System Frequency

In the case of a high penetration rate of wind energy conversion systems, the conventional virtual inertia control of permanent magnet synchronous generators (PMSG) has an insufficient support capability for system frequency, leading to an unstable system frequency and a slower response. Considering the finite control set model predictive control has multi-objective regulation capabilities and efficient tracking capabilities, and an improved multi-objective model-predictive control is proposed in this paper for PMSG-based wind turbines with virtual inertia based on its mathematical model. With the prediction model, the optimal control of the current and the frequency of the PMSG-based wind turbines can be obtained. Since the shaft torque changes rapidly under high virtual inertia, shaft oscillation may occur under this scenario. To address this problem, the electromagnetic torque is set as an additional optimization objective, which effectively suppresses the oscillation. Furthermore, based on accurate short-term wind speed forecasting, a dynamic weight coefficient strategy is proposed, which can reasonably distribute the weight coefficients according to the working conditions. Finally, simulations are carried out on a 2 MW PMSG-based wind turbine platform, and the effectiveness of the proposed control strategies is verified.

scholarly journals Analytical Approach to Understanding the Effects of Implementing Fast-Frequency Response by Wind Turbines on the Short-Term Operation of Power Systems

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3660
Author(s):  
Danny Ochoa ◽  
Sergio Martinez
Keyword(s):  
Power Systems ◽  
Power System ◽  
Wind Turbines ◽  
Analytical Approach ◽  
Frequency Control ◽  
Test System ◽  
Term Operation ◽  
Inertial Response ◽  
Virtual Inertia ◽  
Grid Operators

The significant presence of variable-speed wind turbines in worldwide power systems has led to planners and grid operators requiring them to participate in frequency control tasks. To address this demand, a large number of wind frequency control proposals have been reported in the literature in recent years. Many of these solutions have been tested by specific experiments carried out in computer simulation environments. This paper proposes a methodology to evaluate the effects of enabling frequency support by wind turbines on the magnitudes that characterize the inertial response of a power system by using an analytical approach. The derived formulation and the illustrations are designed to provide a better understanding of both the mechanisms that determine the frequency stability indices and the improvement achieved by enabling the inertial response of wind turbines by implementing a virtual inertia-based method on the active power controllers of these machines. To facilitate the comprehension of the results obtained, the analytical approach is complemented with time-domain simulations in a predefined test system implemented in MATLAB/Simulink®. The proposed methodology achieves a generalization of the results and can be used for the assessment of any power system configuration.

scholarly journals Common-Mode Frequency in Inverter-Penetrated Power Systems: Definition, Analysis, and Quantitative Evaluation

2022 ◽  
Author(s):  
Huisheng Gao ◽  
Huanhai Xin ◽  
Linbin Huang ◽  
Zhiyi Li ◽  
Wei Huang ◽  
...  
Keyword(s):  
Power Systems ◽  
Power System ◽  
Test System ◽  
Mode Frequency ◽  
Rate Of Change ◽  
Synchronous Generators ◽  
Common Mode ◽  
Response Characteristics ◽  
Frequency Drop ◽  
System Frequency

<p>As synchronous generators (SGs) are extensively replaced by inverter-based generators (IBGs), modern power systems are facing complicated frequency stability problems. Conventionally, the frequency nadir and the rate of change of frequency (RoCoF) are the two main factors concerned by power system operators. However, these two factors heavily rely on simulations or experiments, especially in a power system with high-penetration IBGs, which offer limited theoretical insight into how the frequency response characteristics are affected by the devices. This paper aims at filling this gap. Firstly, we derive a formulation of the global frequency for an IBG-penetrated power system, referred to as common-mode frequency (CMF). The derived CMF is demonstrated to be more accurate than existing frequency definitions, e.g., the average system frequency (ASF). Then, a unified transfer function structure (UTFS) is proposed to approximate the frequency responses of different types of devices by focusing on three key parameters<a>, which dramatically reduces the complexity of frequency analysis. </a>On this basis, we introduce two evaluation indices, i.e., frequency drop depth coefficient (FDDC) and frequency drop slope coefficient (FDSC), to theoretically quantify the frequency nadir and the average RoCoF, respectively. Instead of relying on simulations or experiments, our method rigorously links the system’s frequency characteristics to the characteristics of heterogeneous devices, which enables an in-depth understanding regarding how devices affect the system frequency. Finally, the proposed indices are verified through simulations on a modified IEEE 39-bus test system. </p>

scholarly journals PV/Wind-Integrated Low-Inertia System Frequency Control: PSO-Optimized Fractional-Order PI-Based SMES Approach

2021 ◽  
Vol 13 (14) ◽  
pp. 7622
Author(s):  
Md Shafiul Alam ◽  
Fahad Saleh Al-Ismail ◽  
Mohammad Ali Abido
Keyword(s):  
Power Systems ◽  
Fractional Order ◽  
Magnetic Energy ◽  
Frequency Control ◽  
Rate Of Change ◽  
Integrated System ◽  
High Rate ◽  
Control Technique ◽  
Total System ◽  
Virtual Inertia

A paradigm shift in power engineering transforms conventional fossil fuel-based power systems gradually into more sustainable and environmentally friendly systems due to more renewable energy source (RES) integration. However, the control structure of high-level RES integrated system becomes complex, and the total system inertia is reduced due to the removal of conventional synchronous generators. Thus, such a system poses serious frequency instabilities due to the high rate of change of frequency (RoCoF). To handle this frequency instability issue, this work proposes an optimized fractional-order proportional integral (FOPI) controller-based superconducting magnetic energy storage (SMES) approach. The proposed FOPI-based SMES technique to support virtual inertia is superior to and more robust than the conventional technique. The FOPI parameters are optimized using the particle swarm optimization (PSO) technique. The SMES is modeled and integrated into the optimally designed FOPI to support the virtual inertia of the system. Fluctuating RESs are considered to show the effectiveness of the proposed approach. Extensive time-domain simulations were carried out in MATLAB Simulink with different load and generation mismatch levels. Systems with different inertia levels were simulated to guarantee the frequency stability of the system with the proposed FOPI-based SMES control technique. Several performance indices, such as overshoot, undershoot, and settling time, were considered in the analysis.

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