The impact research of control modes in steam turbine control system (digital electric hydraulic) to the low-frequency oscillation of grid

This paper studies the effect of the soft feedback in hydro-turbine and its governor system on power system transient stability. Low frequency oscillation phenomenon in which the hydraulic turbine sets participate occurred on power system many times this year, which with no mechanism discovered. In this paper, we first study the effect of mechanical load moment output of the prime mover system on the mechanism of low frequency oscillations, then by analysis of small-signal stability on hydro-turbine and its governor system and simulation experiments on an two-generator power system using PSASP, we come to the conclusion that: If the soft feedback output values of hydro-turbine governor systems are set small in the power system, it will come to the unstable oscillation condition.

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The impact of wind power inverse-peaking characteristics on power system low frequency oscillation

2012 China International Conference on Electricity Distribution ◽

10.1109/ciced.2012.6508635 ◽

2012 ◽

Author(s):

Shaoxiang Feng ◽

Dichen Liu ◽

Xiaoming Yang ◽

Xiaorong Xiang

Keyword(s):

Power System ◽

Wind Power ◽

Low Frequency ◽

Frequency Oscillation ◽

Low Frequency Oscillation ◽

The Impact

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Suppression Research Regarding Low-Frequency Oscillation in the Vehicle-Grid Coupling System Using Model-Based Predictive Current Control

Energies ◽

10.3390/en11071803 ◽

2018 ◽

Vol 11 (7) ◽

pp. 1803 ◽

Cited By ~ 2

Author(s):

Yaqi Wang ◽

Zhigang Liu

Keyword(s):

High Speed ◽

Low Frequency ◽

Current Control ◽

Control Voltage ◽

Continuous Control ◽

Frequency Oscillation ◽

Low Frequency Oscillation ◽

Model Based ◽

Coupling System ◽

The Impact

Recently, low-frequency oscillation (LFO) has occurred many times in high-speed railways and has led to traction blockades. Some of the literature has found that the stability of the vehicle-grid coupling system could be improved by optimizing the control strategy of the traction line-side converter (LSC) to some extent. In this paper, a model-based predictive current control (MBPCC) approach based on continuous control set in the dq reference frame for the traction LSC for electric multiple units (EMUs) is proposed. First, the mathematical predictive model of one traction LSC is deduced by discretizing the state equation on the alternating current (AC) side. Then, the optimal control variables are calculated by solving the performance function, which involves the difference between the predicted and reference value of the current, as well as the variations of the control voltage. Finally, combined with bipolar sinusoidal pulse width modulation (SPWM), the whole control algorithm based on MBPCC is formed. The simulation models of EMUs’ dual traction LSCs are built in MATLAB/SIMULINK to verify the superior dynamic and static performance, by comparing them with traditional transient direct current control (TDCC). A whole dSPACE semi-physical platform is established to demonstrate the feasibility and effectiveness of MBPCC in real applications. In addition, the simulations of multi-EMUs accessed in the vehicle-grid coupling system are carried out to verify the suppressing effect on LFO. Finally, to find the impact of external parameters (the equivalent leakage inductance of vehicle transformer, the distance to the power supply, and load resistance) on MBPCC’s performance, the sensitivity analysis of these parameters is performed. Results indicate that these three parameters have a tiny impact on the proposed method but a significant influence on the performance of TDCC. Both oscillation pattern and oscillation peak under TDCC can be easily influenced when these parameters change.

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Inertia Control Strategy of DFIG-Based Wind Turbines Considering Low-Frequency Oscillation Suppression

Energies ◽

10.3390/en15010029 ◽

2021 ◽

Vol 15 (1) ◽

pp. 29

Author(s):

Haoming Liu ◽

Suxiang Yang ◽

Xiaoling Yuan

Keyword(s):

Wind Turbines ◽

Control Strategy ◽

Low Frequency ◽

Frequency Regulation ◽

Analysis Method ◽

Frequency Oscillation ◽

Low Frequency Oscillation ◽

The Difference ◽

Inertia Control ◽

The Impact

It has become a basic requirement for wind turbines (WTs) to provide frequency regulation and inertia support. The influence of WTs on the low-frequency oscillation (LFO) of the system will change after adopting inertia control methods. This paper intends to investigate and compare in detail the IC effects on LFO characteristics in two systems with different structures. First, the mechanism of inertia control of doubly fed induction generator (DFIG)-based WTs is analyzed. Then, the small-signal analysis method and modal analysis method are used to study the influence of the inertia control on the LFO characteristics based on the two-machine infinite-bus system and the four-machine two-area system, respectively. The difference in impact rules of IC on LFO is compared in detail. Finally, considering that the inertia control might worsen the LFO in some systems, an improved inertia control strategy of DFIG-based WTs is proposed to suppress the LFO. The simulation results demonstrate that, in systems with different structures, the impact rules of the inertia control parameters on LFO are different. With the improved inertia control strategy, DFIG-based WTs can suppress the LFO of the system and provide inertia support for the system.

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The Analysis on the Effect of Speed Regulating System on Low Frequency Oscillation

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.737.220 ◽

2015 ◽

Vol 737 ◽

pp. 220-225

Author(s):

Tong Tian Deng ◽

Jia Sheng Wang ◽

Xiao Jun Li ◽

Xi Tian Wang ◽

Jin Fu Liu ◽

...

Keyword(s):

Control System ◽

Forced Oscillation ◽

Oscillation Mode ◽

Low Frequency ◽

Speed Control ◽

Regulation System ◽

Frequency Oscillation ◽

Low Frequency Oscillation ◽

Speed Regulation ◽

Speed Control System

With the strengthening of interconnected power grid connection, interval oscillation mode damping continue to improve, interval power oscillation accidents still occur, however, the negative damping mechanism of the classic cannot be satisfactorily explain these phenomena, this paper provides the researches forced oscillation mechanism of the low frequency oscillation, the speed control system is likely to form the forced oscillation source, speed regulation system and low frequency oscillation formed an adverse coupling effect. In this paper, based on the mechanism of their method, speed control system are analyzed, the effect of various parameters on the low frequency oscillation in order to avoid speed regulation system to participate in the low frequency oscillation provides technical support.

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Study of small signal stability using PSAT including DFIG based wind penetration

Journal of Innovations in Engineering Education ◽

10.3126/jiee.v2i1.36667 ◽

2019 ◽

Vol 2 (1) ◽

pp. 137-145

Author(s):

Ram Prasad Pandey

Keyword(s):

Power System ◽

Wind Power ◽

Transient Stability ◽

System Analysis ◽

Low Frequency ◽

Synchronous Generators ◽

Frequency Oscillation ◽

Low Frequency Oscillation ◽

Global Mode ◽

The Impact

In early days of power engineering, the power system consisting of synchronous generators faced different low frequency oscillation problems and they were solved by different researchers by using suitably AVR and PSS. Later, the electricity industry is turning increasingly to renewable sources of energy to generate electricity. Wind is the fastest growing and the most widely utilized emerging renewable energy technology for power generation at present. With the increasing penetration of wind power in the power system, the impact in power system performance should be fully investigated, particularly for doubly fed induction generation (DFIG) wind turbine since this type of renewable source is gaining prominence in the power system industry. Main purpose of this study is to examine the impacts of wind power integration in the low grid from low frequency oscillation perspective. The benchmarked Two Area System is considered for this analysis using Power System Analysis Toolbox (PSAT). The critical modes of oscillation are selected from eigenvalue analysis and their participation factors are studied to identify their sensitivity. Also the time domain analysis is run in every cases to study the transient stability. From TAS, concept of local and global mode oscillation can be understood clearly. Replacing synchronous generators in TAS by DFIG WTG one by one of same rating gave conclusion that low frequency stability depends on the location of DFIG penetration and operating scenario. The results show that there is both beneficial and detrimental effects due to DFIG WTGs. The installation of PSS in the critical generators greatly enhances the system damping.

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Analysis of Power System Low Frequency Oscillation Considered the Impact of Turbine Power Changing

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.543-547.751 ◽

2014 ◽

Vol 543-547 ◽

pp. 751-756

Author(s):

Pai Liu ◽

Lin Zhang ◽

Long Sheng Hu ◽

Guo Jian Yang ◽

Ye Zhou Hu

Keyword(s):

Power System ◽

Low Frequency ◽

Power Grids ◽

Sustained Oscillation ◽

Frequency Oscillation ◽

Low Frequency Oscillation ◽

Interconnected Power System ◽

Power Oscillation ◽

The Stability ◽

The Impact

In this paper, the author introduced resonance mechanism into the stability analysis of power system, established comprehensive mathematical model including units and power grids by considering the effects from generation side and line side. On this basis, the author simulated several typical disturbances to analysis by MATLAB SIMULINK. The result showed that the power oscillation will be caused when the natural frequency of the grid and the frequency of disturbances are same or similar, especially in multi-area interconnected power system. The disturbances from different units can produce a significant impact transient or sustained oscillation by superposition, endanger the stability of power system.

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Research of the Impact of Turbine Parameters on Low-Frequency Oscillation Based on Simulink

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.607.556 ◽

2014 ◽

Vol 607 ◽

pp. 556-560

Author(s):

Ya Qing Zhu ◽

Min Zhong ◽

Feng Ping Pan ◽

Jia Luo ◽

Xi Zhang ◽

...

Keyword(s):

Time Constant ◽

Power Grid ◽

Low Frequency ◽

Slide Valve ◽

Frequency Regulation ◽

Damping Factor ◽

Frequency Oscillation ◽

Low Frequency Oscillation ◽

Power Frequency ◽

The Impact

This paper analyzed the influence of various turbine parameters on the low-frequency oscillation using Simulink, including the oil motive slide valve time constant, the volume time constant, power grid damping factor, power grid power factor, self-balancing rotor coefficient etc. Meanwhile, comparing the influence of the pure speed regulator and power-frequency regulation on low-frequency oscillations, proven that power-frequency regulation will exacerbate the low frequency oscillation.

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