Berta Test Bench

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BERTA Test Bench

OPAL-RT’s BERTA test bench is a safe, reliable and portable test bench for speed governors, turbines, voltage regulators (AVR) and power system stabilizers (PSS). Equipped with a high-performance real-time simulator programmed with world-renowned RT-LAB software, the BERTA Test bench enables users to easily and comprehensively test real generating units in the power plant, synchronized and transmitting power to the main grid and/or on real controllers connected to a virtual generating unit in laboratory.

Turbine model parameters can change over time due to turbine wear and water head variation. By using test and measurement results, RT-LAB BERTA enables precise estimation adequate to turbine and speed regulator models. Increased precision also provides more accurate offline simulation and adjustment of speed regulator settings.

The RT-LAB BERTA approach increases precision with each subsequent test session, with results that are virtually identical to those expected from an actual islanded power system, but requiring only a fraction of the time required for traditional test methods.

Increase Confidence Between Power Generators and Transmission System Operators

Control engineers and technicians can rely on BERTA for their on-site tests in power plant.

Electricity producers:

  • Control engineers involved in speed governor, AVR and PSS tuning;
  • Control engineers involved in validation and certification of generating unit control system technical specifications.

Engineering staff involved in generating units commissioning and/or specific on-site tests to comply with NERC (or any other regulatory agency) requirements on verification of models and data for:

  • Turbine/governor and load control or active power/frequency control functions; (Standard MOD-027)
  • Generator excitation control system or plant volt/var control functions. (Standard MOD-026)


RT-LAB BERTA conducts real-time simulation of the unit under test, enabling users to quickly and accurately set regulator parameters, ensuring frequency stability of the unit when operating in an islanded power system. This improves the unit’s contribution to power system stability when synchronized with a large power system.

RT-LAB’s Real-Time Digital Simulator generates a speed error signal corresponding to the behavior of the generator in an islanded power system. Injecting this signal into the regulator while the unit is generating power in the system sets up a closed loop, simulating the operation in an islanded system, even though the AC generator is actually synchronized to a multi-machine power grid. The speed error signal is added to the actual frequency signal, ensuring that the regulator continues to react to actual system frequency variations.

BERTA functionalities:

    • Ensuring the tested unit's stability in an islanded power system, regardless of operating mode

    • Correctly setting AVR and PSS for damping natural electric power oscillations

    • Ensuring no interference between the speed governor and PSS, while continuing to contribute to the main grid stability

    • Certifying that the speed governor, AVR and PSS fulfill technical requirements.

BERTA provides:

  • Closed loop tests often reveal non-linear behaviors that were not anticipated through off-line simulations based on non-validated models;
  • Dynamic models are quickly available and validated on premises using real-time comparison with physical instruments;
  • Non-linear model parameter estimation.

BERTA is the best tool for complying to NERC’s MOD-026 and MOD-027 standards

NERC’s MOD-026 and MOD-027 standards require that electricity producers provide validated models of speed governors, turbines, AVRs and PSSs to the TSOs (Transmission system operators grouped in regional coordinating councils under NERC’s supervision).

Hydro Review Article

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