Banc d’(Bench) Essais pour(Tests for) Régulateurs(Regulators) Turbines et(Turbines) Alternateurs(Alternators)

AC Generator in Operation Synchronous Operation; Operation in Islanded System; In both modes of operation, Speed/Frequency control is required.

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;

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;

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.

Frequency behavior of an AC generator in an islanded mode of operation

Frequency Behavior in a Multi-Machine System

P.S.S. Interference

WHAT’S RT-LAB BERTA FOR? Make unit under test contribute to power system stability and frequency recovery; Test many speed governor settings without threatening the grid stability; Validate speed governor and turbine dynamic models in a closed loop set-up.

RT-LAB BERTA’s Main Feature MAKE THE ACTUAL GENERATOR BEHAVE AS IF OPERATING IN ISLANDED MODE WHILE REMAINING SYNCHRONIZED WITH THE MAIN GRID; And set the speed governor consequently.

Modern PID Speed Governor Permanent Droop Servomotors Chain

Speed Governor Models Components hard to model: –Frequency meter or speed sensor; –Pilot Valve; –Gate servomotors stroke and backlash; –Mechanical regulator dash-pot (Temporary droop). The older the equipment, the more difficult to model adequately.

Hydraulic Turbine Non-Linear Model Water Discharge Net Head Head Losses Water Starting Time Many Uncertainties ????

Modeling Techniques Use RTLAB-BERTA: –Set the governor correctly according to BERTA ’s real-time islanded mode simulation; –Analyze the input/output signals and estimate an appropriate model; –Ask BERTA to compare the model behaviour with the actual behaviour; –During the same test session;

RT-LAB BERTA Test Bench Setup for Actual Test in Powerhouse BERTA TEST BENCH SPEED GOVERNOR TURBINE GENERATOR

RT-LAB BERTA Test Bench Software includes the following modules: –Digital calculators for frequency and electric power; –Modules to estimate the speed and mechanical power; –Real-time simulator of islanded power system operation, including a P.S.S. simulation function;

Islanded Operation Mode Real-time Simulator Adequate setting adjustment of the governor, considering actual system; Still considering the synchronizing effect; Allows to validate the turbine model at the actual gate servomotor frequency of oscillation; Have a look on the next 2 slides: do you see a big diffference between actual islanded operation and RT-LAB BERTA’s simulation?

Actual Islanded System VS BERTA’s Islanded System Simulator Stable Case

Actual Islanded System VS BERTA’s Islanded System Simulator Unstable Case

P.S.S. Simulation Function

On-Site Tests with Different PID Settings

Islanded Operation Mode Real-Time Simulator (next) What if your classical model is wrong? See next slide;

Reality VS Classical Model Simulation

H-Q grid actual frequency

Reality VS Classical Model Simulation H-Q grid actual frequency Simulator Generated Frequency

Islanded Operation Mode Real-Time Simulator (next) Now, modify your models; It almost fits (red curve); Black curve: turbine model modified; Red curve: speed governor and turbine models modified.

Matching Reality with Modified Speed Governor Model Turbine Model Modified Turbine and S.G. Models Modified

RT-LAB BERTA’s islanded mode simulator is well suited for all kinds of hydro and thermal AC generator; They only need to be synchronized to the main grid.

Voltage & Current Signal Panel

Connection Settings Panel

PID Controller Panel

Islanded Operation Simulation Unstable Case

Islanded Operation Simulation Stable Case

RT-LAB BERTA’s real-time computer, junction and switching boxes and flat screen during on-site testing by Hydro-Québec powerhouse, November 2008

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

On-Site Tests. Two different sets of PID gains. Frequency variation

On-Site Tests. Two different sets of PID gains. Gate servomotors variation

On-Site Tests. Two different sets of settings. Mechanical Power Variation