An approach to the damping of local modes of oscillations resulting from large hydraulic transients

Abstract

A new method of damping of local modes of oscillations under large disturbance is presented in this paper. The digital governor controller is used. Controller operates in real time to improve the generating unit transients through the guide vane position and the runner blade position. The dcveloped digital governor controller, whose control signals are adjusted using the on-line measurements, offers better damping effects for the generator oscillations under large disturbances than the conventional controller. Digital simulations of hydroelectric power plant equipped with low-head Kaplan turbine are performed and the comparisons between the digital governor control and the conventional governor control are presented. Simulation results show that the new controller offers better performances, than the conventional controller, when the ' system is subjected to large disturbances. , -plant's net head I Z , ,~ -steady state plant's net head h=h,,-hno -waterhammer q -turbine flow T,, -watcr starting time constant w, a,, -machine speed and governor refercnce input y, -auxiliary servomotor piston position (p, (pL -runncr blade anglc and required runner blade angle n -turbine guide vane opening h,,, b, -r,,,T,, -auxiliary servomotor and dashpot time constants T,,, T,. -turbine mechanical torque, generator electrical permanent droop and temporary droop settings torque PE-1 11-EC-0-07-1998 A paper recommended and approved by the IEEE Energy Development and Power Generation Committee of the IEEE Power Engineering Society for publication in the IEEE Transactions on Energy Conversion. Manuscript submitted November 4, 1997, made available for printing July 2, 1998. R,, RT -generator armature and transformer resistance E, -exciter controller output (input to exciter) EFD -excitation output V,, I, -generator terminal voltage and current T , , , , -sampling time r s -difference between mechanical and electrical torques which indicates large disturbance All the above quantities are expressed in per units (p.~.), except time constants, given in seconds (s). INTRODUCTIONThe study of dynamic properties of closed-loop engineering systems has inspired a wide variety of theoretical developments, as well as feasible control achievements. Practical methods for nonlinear control include an open-loop inverse model of the nonlinear plant dynamics and the use of feedback loops to cancel the plant nonlinearities. The new controller, presented in this paper, uses power of waterhammer to damp generator oscillations under large disturbances. In such a control, real-time measurements of the plant inputs are used to directly modify the controller output.This paper presents the low-head hydroelectric power unit equipped with the multivariable voltage regulator, acting to the static excitation system, and transient speeddroop governor, acting to the Kaplan turbine unit, connected to an infinite bus system. A speed deviation, plant net head, guide vane opening, runner blade position and terminal voltage and current have been chosen as input signals to...

Deployment of a full‐size converter utilised hydropower plant to enhance inter‐area oscillation damping

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Implementation and Evaluation of a Complex Pumped-Storage Hydropower Plant with Four Units, Common Penstock, and Surge Tank in a Real-Time Digital Simulator

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A non-linear model based feed forward flatness control approach to speed governor systems of hydropower plants

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