Turboset Drivetrain Vibration Measurement Beyond Commissioning Frequencies
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Solution Overview
Problem
Current methods for measuring the vibration behavior of a turboset in a power plant connected to an energy network are limited in frequency range, failing to accurately capture torsional eigenmodes and resonant vibrations, which can lead to unstable operation and reduced service life due to insufficient damping of subsynchronous natural frequencies.
Innovation Solution
A method that selects excitation signals with frequencies up to 147 Hz to excite mechanical vibrations in the turboset, measures the active power, and computationally determines transfer functions to describe the behavior of the power plant over a broader frequency range, enabling the identification of torsional eigenmodes and improving damping control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If excitation signals with frequencies up to 3.0 Hz are used to activate oscillation damping devices, then the generator can be controlled during balancing operations, but torsional eigenmodes and resonant vibrations in the higher frequency range cannot be accurately measured
Solution Approach 1:
The patent applies dynamics by making the excitation signal frequency spectrum adaptable and variable. Instead of using a fixed frequency range (0.2-3.0 Hz), the system dynamically extends the excitation frequency spectrum up to at least 15 Hz, advantageously up to at least 97 Hz, or even up to at least 147 Hz. This dynamic adjustment of the frequency spectrum allows accurate measurement of both low-frequency oscillation damping characteristics and high-frequency torsional eigenmodes, resolving the contradiction between measurement precision and frequency range coverage.
2Measurement precision
If the frequency range is extended beyond 3.0 Hz, then torsional eigenmodes can be captured, but harmful effects on the energy network and excessive damping by the field winding occur
Solution Approach 1:
The patent applies parameter changes by carefully controlling the amplitude and frequency distribution of excitation signals. The excitation signal spectrum is shaped such that energy is distributed across frequencies up to at least 15 Hz, advantageously up to at least 97 Hz, or up to at least 147 Hz, but with amplitude limitations that prevent harmful effects on the energy network. The amplitude of excitation signals is specifically adapted to account for the damping characteristics of the field winding, which naturally attenuates very high frequencies, thereby enabling measurement of torsional eigenmodes without causing excessive damping or network disturbances.
3Adaptability or versatility
If excitation signals with higher frequencies are used, then a broader frequency spectrum can be analyzed, but the complexity of signal generation and evaluation increases
Solution Approach 1:
The patent applies self-service by utilizing the existing control infrastructure of the power plant. The excitation signals are generated using the available voltage controller and excitation device, and the response is measured through existing sensors and measurement systems. The evaluation process uses computational algorithms to determine transfer functions from the excitation signals to measured variables, leveraging the plant's own control loop components rather than requiring entirely new specialized equipment. This self-service approach enables extended frequency spectrum analysis while minimizing additional system complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for the precise measurement of torsional eigenmodes and resonant vibrations, enhancing the reliability of power plant operation by providing detailed frequency analysis and improved damping control, thus preventing harmful resonant vibrations and extending the service life of the turboset.
Implementation Method 1
influencing the field current of the generator using the excitation signals selected in step a) in such a manner that mechanical vibrations are excited in the power plant turboset
Implementation Method 2
capturing the excited mechanical vibrations, including the resonant vibrations, by measuring at least one suitable output variable, in particular the active power
Data Source
AI summary
A method for measuring the vibration behaviour of a drivetrain of a turboset including a generator in a power plant connected to a power network, includes: a) selecting exciter signals, wherein the frequency spectrum extends significantly beyond the frequency range usual from the commissioning of pendulum damping devices, b) influencing the field current of the generator using the exciter signals such that mechanical vibrations are excited in the power plant turboset, c) measuring the excited mechanical vibrations including the resonance vibrations by measuring at least one suitable output variable, d) determining a transfer function from the exciter signal to the output variable measured, and e) determining the transfer function from the generator torque at a desired output variable using known transfer functions of the exciter signal at a desired input variable and/or of the desired output variable for the output variable measured on the basis of the transfer function determined.