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Marc Langevin, eng., Ph.D.
Marc Soullière, tech.
Jean Bélanger, eng.
*
A Real-Time Regulator, Turbine and Alternator Test Bench for Ensuring Generators Under Test Contribute
to Whole System Stability
AC Generator in Operation
Synchronous Operation; Operation in Islanded System; In both modes of operation,
Speed/Frequency control is required.
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AC Generator in Operation in Both Modes
To maintain balance and stability, mechanical power must equal electric load;
After a disturbance, system frequency should reset to its set point value as fast as possible;
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Frequency behavior of an AC generator in an islanded mode of operation
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Frequency Behavior in a Multi-Machine System
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Important Principles
Two Important Principles to Consider when Adjusting a Speed Governor:
Speed governor must be set to ensure operating stability in an islanded power system;
Speed governor must avoid contributing to natural electro-mechanical power oscillations;
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Synchronized Generator
The synchronous interconnection transfers the stabilizing energy from the stable units to the unstable units;
But does not stabilize a power system where most of the units would be unstable in an islanded system;
Conclusion: every unit should be set to be stable in islanded operation mode. That’s the speed governor job.
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P.S.S. Interference
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Real-Time Islanded Mode Simulator
MAKE THE ACTUAL GENERATOR BEHAVE AS IF OPERATING IN ISLANDED MODE WHILE REMAINING SYNCHRONIZED WITH THE MAIN GRID;
And set the speed governor accordingly
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Modern PID Speed Governor
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Servomotors Chain
Permanent Droop
IFAC 2009 – Tampere, Finland
Hydraulic Turbine Non-Linear Model
.
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Water Flow
Net Head
Head Losses
Water Starting Time
Many Uncertainties
IFAC 2009 – Tampere, Finland
Effective Opening
Efficiency
Gross Head
Test Bench Setup for Actual Test in Powerhouse
.
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RT-LAB BERTA TEST BENCH
SPEED GOVERNOR TURBINE GENERATOR
IFAC 2009 – Tampere, Finland
MECHANICAL SWITCH
Islanded System vs Test Bench Real-Time Simulator. Stable Case
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Islanded System vs Test Bench Real-Time Simulator. Unstable Case
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P.S.S. Simulation Function
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On-site Testing in Hydro-Québec Powerhouse.
Two different sets of PID gains. Frequency variation
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On-site Testing in Hydro-Québec Powerhouse
Two different sets of PID gains. Gate servomotors variation
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On-site Testing in Hydro-Québec Powerhouse
Two different sets of settings. Mechanical Power Variation
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On-Site Testing VS Classical Modelling
What if your classical model is wrong? See next slide;
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Reality vs. Classical Model Simulation
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Reality vs. Classical Model Simulation
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.
H-Q grid actual frequency
Simulator Generated Frequency
IFAC 2009 – Tampere, Finland
Islanded Operation Simulation Unstable Case
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Islanded Operation Simulation Stable Case
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On-site Testing. Boxes and Real-Time Station
RT-LAB BERTA’s real-time computer, junction and switching boxes and flat screen during on-site testing by Hydro-Québec powerhouse, November 2008
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On-site Testing. Real-Time Station Rear View
Rear view of the RT-LAB BERTA real-time computer showing the I/O connection with the speed governor during on-site testing by Hydro-Québec powerhouse, November 2008
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Conclusions & Benefits
Until now, it has been almost impossible to assess with a high degree of accuracy the behavior of a synchronous generator in an islanded power system. Characterizing such behavior is indispensable to properly set a speed governor.
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Conclusions & Benefits
To date, model and parameter identification tests have been very expensive and don’t provide an accurate and robust model of a turbine. The process is time-consuming and arduous as described by the following steps that must be performed for each machine:
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Conclusions & Benefits
The process is time-consuming and arduous as described by the following steps that must be performed for each machine:
Preliminary settings based on specifications provided by the manufacturers of the turbine and generator;
Model and parameter identification tests in the power station;
Off-line stability studies to recommend the appropriate settings, based on the models and parameters as determined by tests carried out at the power station;
Return to the power station to implement new appropriate settings on the speed governor
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Conclusions & Benefits
The proposed Test Bench allows these operations to be carried out in a single test run at the power station with the following benefits:
Accuracy of speed governor control settings ensuring that each machine has a stabilizing effect on the power system;
Validation of PSS low frequency settings ensuring that the PSS and the speed governor do not react against each other;
Accuracy of speed governor and turbine models; Stability and reduction of demand on servomotors by
applying appropriate settings; Productivity gain for model identification and control setting; Shorter tests in the power station due to ease of use of
Test Bench.
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Thank You
Questions?
Join us for a Demonstration at the Opal-RT Booth located near the Conference Coffee Break Area
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