scholarly journals A Comparative Analysis of a Power System Stability with Virtual Inertia

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3277
Author(s):  
Lavr Vetoshkin ◽  
Zdeněk Müller

The paper investigates the stability of a power system with synchronverters. A synchronverter is a control strategy for voltage source converters that introduces virtual inertia by mimicking synchronous machines. The authors picked a commonly known IEEE 9 bus and IEEE 39 bus test case systems for the test case studies. The paper presents the power system’s modal analysis with Voltage Source Converters (VSCs) controlled as synchronverters, vector control, or Rate of Change of Frequency-based Virtual Synchronous Generator, thus comparing different approaches to VSC control. The first case study compares selected control algorithms, the IEEE 9 bus system, with one VSC in the paper. The results demonstrate the benefits of synchronverters over other control strategies. The system with synchronverters has a higher minimal damping ratio, which is proven to be the case by numerical simulations. In the second case study, the effects of virtual inertia placement were investigated. The computations showed that placement is indeed important, however, the control strategy is as important. Besides, the system with synchronverters exhibits better stability characteristics. The paper demonstrates that the application of synchronverters is feasible and can meet the demand for algorithms that bring the benefits of virtual inertia.

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4220
Author(s):  
Dai Orihara ◽  
Hiroshi Kikusato ◽  
Jun Hashimoto ◽  
Kenji Otani ◽  
Takahiro Takamatsu ◽  
...  

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.


Author(s):  
Iván Andrade ◽  
Rubén Peña ◽  
Ramón Blasco-Gimenez ◽  
Javier Riedemann ◽  
Cristian Pesce

2021 ◽  
Author(s):  
Mengfan Zhang ◽  
xiongfei wang ◽  
Qianwen Xu

The black-box impedance of the voltage source converters (VSCs) can be directly identified at the converter terminal without access to its internal control details, which greatly facilitates the converter-grid interactions. However, since the limited impedance data amount in practical industrial applications, the existing impedance identification methods cannot accurately capture characteristics of the impedance model at various operating scenarios, which is the indicators of the VSCs system stability at the changing profiles of renewables and loads. In this paper, a transfer learning based impedance identification is proposed to fill this research gap. This method can significantly reduce the required data amount used in impedance identification so that the black-box impedance-based stability method could be applied for the practical industrial application. The comparison results confirm the accuracy of the impedance model obtained by this transfer learning based impedance identification method.


2020 ◽  
Vol 12 (13) ◽  
pp. 5346 ◽  
Author(s):  
Meysam Saeedian ◽  
Bahram Pournazarian ◽  
S. Sajjad Seyedalipour ◽  
Bahman Eskandari ◽  
Edris Pouresmaeil

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.


Energies ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3440 ◽  
Author(s):  
Edgar Lucas ◽  
David Campos-Gaona ◽  
Olimpo Anaya-Lara

Synthetic inertia provision through the control of doubly-fed induction generator (DFIG) wind turbines is an effective means of providing frequency support to the wider electrical network. There are numerous control topologies to achieve this, many of which work by making modifications to the DFIG power controller and introducing additional loops to relate active power to electrical frequency. How these many controller designs compare to one-another in terms of their contribution to frequency response is a much studied topic, but perhaps less studied is their effect on the small-signal stability of the system. The concept of small-signal stability in the context of a power system is the ability to maintain synchronism when subjected to small disturbances, such as those associated with a change in load or a loss of generation. Amendments made to the control system of a large-scale wind farm will inevitably have an effect on the system as a whole, and by making a DFIG wind turbine behave more like a synchronous generator, which synthetic inertia provision does, may incur consequences relating to electromechanical oscillations between generating units. This work compares the implications of two prominent synthetic inertia controllers of varying complexity and their effect on small-signal stability. Eigenvalue analysis is conducted to highlight the key information relating to electromechanical modes between generators for the two control strategies, with a focus on how these affect the damping ratios. It is shown that as the synthetic inertia controller becomes both more complex and more effective, the damping ratio of the electromechanical modes is reduced, signifying a decreased system stability.


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