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Journal ArticleDOI

Dynamics analysis of the fast-slow hydro-turbine governing system with different time-scale coupling

TL;DR: The methods and results of this paper provide a perspective to multi-time scales modeling of hydro-turbine governing system and contribute to the optimization analysis and control of the system.
About: This article is published in Communications in Nonlinear Science and Numerical Simulation.The article was published on 2018-01-01. It has received 46 citations till now.
Citations
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Journal ArticleDOI
TL;DR: Different subsystem models and stability analysis approaches for HTGS along with their applicability in different operational conditions and design layouts are reviewed to stimulate further research on HTGS models and control methods to improve grid management.
Abstract: Hydropower offers highly flexible, low-carbon generation that can be used to balance electricity grids with high levels of wind and solar penetration This will become increasingly important as the energy transition unfolds However, hydropower generation faces several problems when used in a flexible, fast manner (on the order of seconds) when in part-load, overload, or transient conditions Some of these issues may be addressed by an improved understanding of how the load is measured and controlled in a hydro-turbine governing system (HTGS) This paper reviews different subsystem models and stability analysis approaches for HTGS along with their applicability in different operational conditions and design layouts The review revealed three main challenges facing the increasing flexible use of HTGS on the grid: 1) the combination of the HTGS and shaft model, 2) the control methods of HTGS with intermittent renewable energies, and 3) the uncertain nature of load on the overall performance and stability of the hydropower system This review can stimulate further research on HTGS models and control methods to improve grid management

36 citations

Journal ArticleDOI
TL;DR: The results show that, for nonlinear HTGS–PG coupling system, the emerged bifurcation is supercritical and the area at the bottom side of b ifurcation line is stable domain.

34 citations

Journal ArticleDOI
TL;DR: A novel topology based on the employment of a second generation Current Conveyor with EXtra inputs (EX-CCII), passive resistors, and fractional-order capacitors is presented, which offers the main benefit that both fractiona-order differentiator and integrator transfer functions are simultaneously available at different output terminals.
Abstract: A novel topology for implementing fractional-order differentiator and integrator transfer functions is presented in this paper. This topology is based on the employment of a second generation Current Conveyor with EXtra inputs (EX-CCII), passive resistors, and fractional-order capacitors. The main benefit offered by this implementation is that both fractional-order differentiator and integrator transfer functions are simultaneously available at different output terminals, and that their frequency characteristics can be orthogonally adjusted without disturbing each other. With only one EX-CCII device needed, the proposed design is attractive from the active component count point of view. As an application example, a fractional-order controller is designed in order to control the velocity of a small scale submersible equipped with one propeller. Evaluation of the performance of the presented topology is performed using Cadence and the Design Kit provided by the Austria Mikro Systeme (AMS) 0.35 μ m CMOS process, as well as through experimental results.

29 citations

Journal ArticleDOI
TL;DR: Time-domain simulations demonstrate the robustness and appropriate performance of the proposed decentralized control under different large disturbances.
Abstract: This paper proposes an interconnection and damping assignment passivity-based control (IDA-PBC) for multimachine power systems including hydro-turbine governing systems (HTGS) with surge tank. The main objective is to stabilize the rotor speed and regulate the terminal voltage of each synchronous machine in a power system. The proposed control is decentralized, thus avoiding challenges of communication between generators. Passivity theory is used since the open-loop of the HTGS presents a port-Hamiltonian structure. IDA-PBC allows a control law that maintains the passive structure in closed-loop, guaranteeing its asymptotic stability using Lyapunov's theory. The dynamics of each HTGS are described by an eleventh-order model, which can be reduced to a tenth-order. The proposed control is tested in a 12-bus test system and compared to a standard control, which considers a voltage regulator and exciter based on the IEEE type ST1A excitation system model and power system stabilizer IEEE-PSS1A. The governing system based on a PID control with static and transient droop is also employed. Additionally, the proposed controller is compared to a sliding mode controller. Time-domain simulations demonstrate the robustness and appropriate performance of the proposed decentralized control under different large disturbances.

28 citations

Journal ArticleDOI
TL;DR: A controller based on passivity theory with the aim of damping oscillations in a power system is proposed, which considers the complete non-linear model of the system and guarantees global asymptotic stability in the sense of Lyapunov.

26 citations

References
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Journal ArticleDOI
TL;DR: In this paper, the effect of silt erosion on the performance and efficiency of the turbine runners of a hydro turbine has been discussed, which depends upon different parameters such as silt size, hardness and concentration, velocity of water, and base material properties.
Abstract: Erosive wear of hydro turbine runners is a complex phenomenon, which depends upon different parameters such as silt size, hardness and concentration, velocity of water, and base material properties. The efficiency of the turbine decreases with the increase in the erosive wear and final breakdown of hydro turbines. Various researchers have conducted experiments to study the effect of these parameters on erosive wear, but most of these experiments are on small-size samples in different types of test rigs to simulate the flow conditions in the turbine, but actual flow conditions and the phenomenon of erosive wear are too complex to simulate. In the present paper, studies undertaken in this field by several investigators have been discussed extensively. Based on literature survey various aspects related to silt erosion in hydro turbines, different causes for the declined performance and efficiency of the hydro turbines and suitable remedial measures suggested by various investigators have been discussed.

211 citations

Journal ArticleDOI
TL;DR: In this paper, a dynamic analysis for very low frequency oscillations (VLFO) observed in the Colombian power grid in the 0.05-Hz range is presented, where the authors present guidelines for the dynamic modeling of power plants with hydro coupling and their multi-unit formulation for frequency stability studies.
Abstract: This paper presents a dynamic analysis for very low frequency oscillations (VLFO) observed in the Colombian power grid in the 0.05-Hz range. Guidelines for the dynamic modeling of power plants with hydro coupling and their multi-unit formulation for frequency stability studies are developed. Associated models are used within simulations of the Colombian power system including its major power plants to show the possible origin of the VLFO. Conclusions and recommendations for control of hydro turbines in a multi-unit environment are developed from the modeling effort and simulation studies.

111 citations

Journal ArticleDOI
TL;DR: In this paper, a fractional order mathematical model of a hydro-turbine governing system is presented to analyze the dynamic stability of the hydropower system in the process of operation.
Abstract: In this paper, a fractional order mathematical model of a hydro-turbine governing system is presented to analyze the dynamic stability of the hydro-turbine governing system in the process of operation. The fractional order hydro-turbine governing system is composed of a hydro-turbine and penstock system, a generator system and a hydraulic servo system. As a pioneering work, we proposed a universal solution about the relationship of two parameters in higher-degree equations according to the stability theorem of a fractional order system. Based on the above theorem, we presented a variable law of stable regions of the fractional-order hydro-turbine governing system and analyzed the effect of various degree of elastic water hammer on the stable regions of the parameters k d and k p with the increase of fractional order α . The nonlinear dynamic behaviors of the system are also studied in detail. Finally, all of these results supply some basic theories for the running of a hydropower plant.

84 citations

Journal ArticleDOI
TL;DR: In this paper, a mathematical model of hydraulic turbine regulating system with a straight-tube surge tank based on a few state-space equations is introduced to study the dynamic behaviors of the HTRS system, where the existence of possible unstable oscillations of this model is extensively and presented in the forms of the bifurcation diagram, time waveform plot, phase trajectories, and power spectrum.

80 citations

Journal ArticleDOI
TL;DR: In this article, a nonlinear dynamic transfer coefficients of the hydro-turbine were proposed by utilizing internal characteristics and analyzing the change laws of the characteristic parameters of the Hydro-Turbine governing system.

77 citations