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 IFAC 2009 – Tampere, Finland 2

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; IFAC 2009 – Tampere, Finland 3

Frequency behavior of an AC generator in an islanded mode of operation IFAC 2009 – Tampere, Finland 4

Frequency Behavior in a Multi-Machine System IFAC 2009 – Tampere, Finland

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; IFAC 2009 – Tampere, Finland 6

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 IFAC 2009 – Tampere, Finland 7

P.S.S. Interference IFAC 2009 – Tampere, Finland

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 IFAC 2009 – Tampere, Finland

Modern PID Speed Governor Servomotors Chain Permanent Droop IFAC 2009 – Tampere, Finland

Hydraulic Turbine Non-Linear Model 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 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 IFAC 2009 – Tampere, Finland

Islanded System vs Test Bench Real-Time Simulator. Unstable Case IFAC 2009 – Tampere, Finland

P.S.S. Simulation Function IFAC 2009 – Tampere, Finland

On-site Testing in Hydro-Québec Powerhouse.  Two different sets of PID gains. Frequency variation IFAC 2009 – Tampere, Finland

On-site Testing in Hydro-Québec Powerhouse  Two different sets of PID gains. Gate servomotors variation IFAC 2009 – Tampere, Finland

On-site Testing in Hydro-Québec Powerhouse  Two different sets of settings. Mechanical Power Variation IFAC 2009 – Tampere, Finland

On-Site Testing VS Classical Modelling  What if your classical model is wrong?  See next slide; IFAC 2009 – Tampere, Finland

Reality vs. Classical Model Simulation IFAC 2009 – Tampere, Finland

Reality vs. Classical Model Simulation H-Q grid actual frequency Simulator Generated Frequency IFAC 2009 – Tampere, Finland

Islanded Operation Simulation Unstable Case IFAC 2009 – Tampere, Finland

Islanded Operation Simulation Stable Case IFAC 2009 – Tampere, Finland

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 IFAC 2009 – Tampere, Finland

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 IFAC 2009 – Tampere, Finland

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 IFAC 2009 – Tampere, Finland 26

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: IFAC 2009 – Tampere, Finland 27

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 IFAC 2009 – Tampere, Finland 28

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 IFAC 2009 – Tampere, Finland 29

Thank You  Questions?  Join us for a Demonstration at the Opal-RT Booth located near the Conference Coffee Break Area IFAC 2009 – Tampere, Finland 30