scholarly journals Obtaining Robust Performance of a Current Fed Voltage Source Inverter for Virtual Inertia Response in a Low Short Circuit Ratio Condition

Energies ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5546
Author(s):  
Clint Z. Ally ◽  
Erik C. W. de Jong
Keyword(s):  
Power Systems ◽  
Short Circuit ◽  
Pi Controller ◽  
Voltage Source ◽  
Current Loop ◽  
Virtual Inertia ◽  
Grid Connected Inverter ◽  
Nominal Performance ◽  
Inertia Response ◽  
A Current

Low inertia levels are typical in island power systems due to the relatively small rotational generation. Displacing rotational generation units with static inertia-less PV power results in a significant increase in the frequency volatility. Virtual inertia provided by inverter-storage systems can resolve this issue. However, a low short circuit ratio (SCR) at the point of common coupling together with a fast phase locked loop (PLL) will compromise the response performance of the system. To address this issue, a robust PI controller (RPI) for the inner current-loop of a current fed grid-connected inverter is proposed. The PLL disturbance and grid impedance are incorporated into a single model and recast to a generalized representation of the system, thereby allowing easy tuning of the RPI by the mixed sensitivity H∞ method. The performance of the RPI is compared with that of a PI controller (PI) tuned by the regular loop-shaping method. The results show that when the SCR is above 10, the performance of both controllers is equivalent. However, lowering of the SCR compromises the performance of the system with PI and it becomes underdamped at SCR < 2. On the contrary, the system with the RPI is capable of maintaining the nominal performance throughout the same SCR decrease.

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.

Power Quality Problems in PV Fed Grid Connected Inverter

2014 ◽  
Vol 622 ◽  
pp. 147-151
Author(s):  
Natesan Saritha ◽  
Venkatesan Jamuna ◽  
N. Nanthini
Keyword(s):  
Power Systems ◽  
Power Quality ◽  
System Performance ◽  
Short Circuit ◽  
Multilevel Inverter ◽  
Voltage Sag ◽  
Pv Inverter ◽  
Power Quality Disturbances ◽  
Grid Connected Inverter

—– In this paper, problem faced by grid connected pv inverter is presented. Inverters connected to grid are mostly affected due to short circuit problems in the power systems. Therefore it is essential to analyze power quality disturbances in order to improve the quality of the system. Performance of inverter is affected severely by voltage sag compared to other type of power quality disturbances. Also in this paper, multilevel inverter with sag condition and without sag condition is simulated using MATLAB/SIMULINK software

Current Loop High Performance Compensation Control Strategy Analysis of Active Power Filter

2012 ◽  
Vol 588-589 ◽  
pp. 928-931
Author(s):  
Qian Qian Yuan
Keyword(s):  
High Performance ◽  
Active Power Filter ◽  
Pi Controller ◽  
Active Power ◽  
Current Loop ◽  
Static Error ◽  
Harmonic Current ◽  
Strategy Analysis ◽  
Power Filter ◽  
A Current

By particular theoretical analyzing on detection error of the traditional current loop proportion-integral (PI) controller, this paper points out the limitations of detection harmonic current at load side and proposes a current feedforward compensation controller. It can track harmonic instructions with zero static error and good compensation performance. Meanwhile, it overcomes the deficiencies of traditional load side detection harmonic current PI controller, with the traditional controller’s flexibility. Even if the load harmonic current is higher than the capacity of active power filter, it can basically maintain zero static error output and has certain theoretical significance and engineering value.

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 Dual Two-Level Voltage Source Inverter Virtual Inertia Emulation: A Comparative Study

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1160
Author(s):  
Mohammad Ali Dashtaki ◽  
Hamed Nafisi ◽  
Amir Khorsandi ◽  
Mojgan Hojabri ◽  
Edris Pouresmaeil
Keyword(s):  
Harmonic Distortion ◽  
Synchronous Generator ◽  
Voltage Source ◽  
Small Signal ◽  
Voltage Source Inverter ◽  
Nonlinear Loads ◽  
Virtual Inertia ◽  
The Stability ◽  
Stability Enhancement ◽  
Oscillation Damping

In this paper, the virtual synchronous generator (VSG) concept is utilized in the controller of the grid-connected dual two-level voltage source inverter (DTL VSI). First, the topology of the VSG and the DTL VSI are presented. Then, the state-space equations of the DTL VSI and the grid-connected two-level voltage source inverter (TL VSI), regarding the presence of the phase-locked loop (PLL) and the VSG, are given. Next, the small-signal modeling of the DTL VSI and the TL VSI is realized. Eventually, the stability enhancement in the DTL VSI compared with the TL VSI is demonstrated. In the TL VSI, large values of virtual inertia could result in oscillations in the power system. However, the ability of the DTL VSI in damping oscillations is deduced. Furthermore, in the presence of nonlinear loads, the potentiality of the DTL VSI in reducing grid current Total Harmonic Distortion (THD) is evaluated. Finally, by using a proper reference current command signal, the abilities of the DTL VSI and the TL VSI in supplying nonlinear loads and providing virtual inertia are assessed simultaneously. The simulation results prove the advantages of the DTL VSI compared with the TL VSI in virtual inertia emulation and oscillation damping, which are realized by small-signal analysis.

scholarly journals Contribution of Voltage Support Function to Virtual Inertia Control Performance of Inverter-Based Resource in Frequency Stability

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4220
Author(s):  
Dai Orihara ◽  
Hiroshi Kikusato ◽  
Jun Hashimoto ◽  
Kenji Otani ◽  
Takahiro Takamatsu ◽  
...  
Keyword(s):  
Reactive Power ◽  
Control Function ◽  
Current Source ◽  
Voltage Control ◽  
Frequency Stability ◽  
Voltage Regulation ◽  
System Stability ◽  
Voltage Source ◽  
Apparent Difference ◽  
Virtual Inertia

Inertia reduction due to inverter-based resource (IBR) penetration deteriorates power system stability, which can be addressed using virtual inertia (VI) control. There are two types of implementation methods for VI control: grid-following (GFL) and grid-forming (GFM). There is an apparent difference among them for the voltage regulation capability, because the GFM controls IBR to act as a voltage source and GFL controls it to act as a current source. The difference affects the performance of the VI control function, because stable voltage conditions help the inertial response to contribute to system stability. However, GFL can provide the voltage control function with reactive power controllability, and it can be activated simultaneously with the VI control function. This study analyzes the performance of GFL-type VI control with a voltage control function for frequency stability improvement. The results show that the voltage control function decreases the voltage variation caused by the fault, improving the responsivity of the VI function. In addition, it is found that the voltage control is effective in suppressing the power swing among synchronous generators. The clarification of the contribution of the voltage control function to the performance of the VI control is novelty of this paper.

scholarly journals A Novel Methodology for Adaptive Coordination of Multiple Controllers in Electrical Grids

Mathematics ◽  
2021 ◽  
Vol 9 (13) ◽  
pp. 1474
Author(s):  
Ruben Tapia-Olvera ◽  
Francisco Beltran-Carbajal ◽  
Antonio Valderrabano-Gonzalez ◽  
Omar Aguilar-Mejia
Keyword(s):  
Power Systems ◽  
Power System ◽  
Electric Power ◽  
Large Scale ◽  
Short Circuit ◽  
Dynamic Performance ◽  
Low Frequency ◽  
Electric Power System ◽  
Design Stage ◽  
Positive Interaction

This proposal is aimed to overcome the problem that arises when diverse regulation devices and controlling strategies are involved in electric power systems regulation design. When new devices are included in electric power system after the topology and regulation goals were defined, a new design stage is generally needed to obtain the desired outputs. Moreover, if the initial design is based on a linearized model around an equilibrium point, the new conditions might degrade the whole performance of the system. Our proposal demonstrates that the power system performance can be guaranteed with one design stage when an adequate adaptive scheme is updating some critic controllers’ gains. For large-scale power systems, this feature is illustrated with the use of time domain simulations, showing the dynamic behavior of the significant variables. The transient response is enhanced in terms of maximum overshoot and settling time. This is demonstrated using the deviation between the behavior of some important variables with StatCom, but without or with PSS. A B-Spline neural networks algorithm is used to define the best controllers’ gains to efficiently attenuate low frequency oscillations when a short circuit event is presented. This strategy avoids the parameters and power system model dependency; only a dataset of typical variable measurements is required to achieve the expected behavior. The inclusion of PSS and StatCom with positive interaction, enhances the dynamic performance of the system while illustrating the ability of the strategy in adding different controllers in only one design stage.

scholarly journals Resonance Instability of Photovoltaic E-Bike Charging Stations: Control Parameters Analysis, Modeling and Experiment

2019 ◽  
Vol 9 (2) ◽  
pp. 252 ◽  
Author(s):  
Ziqian Zhang ◽  
Cihan Gercek ◽  
Herwig Renner ◽  
Angèle Reinders ◽  
Lothar Fickert
Keyword(s):  
Major Effect ◽  
Current Control ◽  
Current Loop ◽  
Control Methods ◽  
Control Parameters ◽  
Charging System ◽  
Grid Connected Inverter ◽  
The Time Domain ◽  
Charging Stations ◽  
And Control

This article presents an in-situ comparative analysis and power quality tests of a newly developed photovoltaic charging system for e-bikes. The various control methods of the inverter are modeled and a single-phase grid-connected inverter is tested under different conditions. Models are constituted for two current control methods; the proportional resonance and the synchronous rotating frames. In order to determine the influence of the control parameters, the system is analyzed analytically in the time domain as well as in the frequency domain by simulation. The tests indicated the resonance instability of the photovoltaic inverter. The passivity impedance-based stability criterion is applied in order to analyze the phenomenon of resonance instability. In conclusion, the phase-locked loop (PLL) bandwidth and control parameters of the current loop have a major effect on the output admittance of the inverter, which should be adjusted to make the system stable.

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