Converter Active-Axis Compensation for Subsynchronous Oscillation Damping
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Solution Overview
Problem
Conventional power electronic devices lack the capability to suppress subsynchronous oscillations, leading to voltage and power fluctuations in the grid, which can cause generators to trip, threatening grid security, especially in large-scale new energy power generation systems like wind and photovoltaic power generation.
Innovation Solution
A method and device for controlling converters that acquire electric energy fluctuation parameters caused by subsynchronous oscillations and use compensation parameters to adjust current settings for the active axis, thereby suppressing these oscillations through a series of control steps and PI controllers to generate switching signals for the inverter and rectifier modules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional power electronic devices are used without subsynchronous suppression capability, then device complexity is reduced, but voltage and power fluctuations occur in the grid causing generators to trip
Solution Approach 1:
The control system is segmented into multiple functional modules: a detection module that identifies subsynchronous oscillation components, a calculation module that computes compensation parameters, and a control module that generates switching signals. This modular segmentation allows the system to address subsynchronous oscillation without requiring complete redesign of the power electronic device, thereby improving grid reliability while controlling complexity increment.
Solution Approach 2:
The control system performs preliminary detection of subsynchronous oscillation components and calculates compensation parameters before the oscillation can cause severe grid instability. By acting in advance to generate appropriate switching signals, the system prevents voltage and power fluctuations from reaching critical levels that would cause generator tripping, thus improving grid security proactively.
2Stability of the object's composition
If subsynchronous oscillation suppression is implemented, then voltage and power fluctuations are reduced, but control system complexity increases
Solution Approach 1:
The control system continuously monitors grid conditions to detect subsynchronous oscillation components and uses this feedback to dynamically adjust compensation parameters. The switching signals are generated based on real-time feedback about voltage and power fluctuations, creating a closed-loop control system that maintains grid voltage stability while managing complexity through adaptive rather than static control mechanisms.
Solution Approach 2:
The controller acts as an intermediary between the power electronic device and the grid, introducing a compensation component that mediates the interaction. This intermediary calculates and applies compensation parameters that counteract subsynchronous oscillations, effectively decoupling the instability source from the grid while keeping the controller's complexity localized and manageable.
3Ease of operation
If conventional control methods are used, then device operation is simple, but subsynchronous oscillations cannot be suppressed leading to generator tripping
Solution Approach 1:
The power electronic device's controller is enhanced to perform self-diagnosis and self-correction by automatically detecting subsynchronous oscillation components and generating appropriate compensation signals without external intervention. This self-service capability maintains ease of operation while improving generator operation reliability, as the system autonomously suppresses oscillations that would otherwise lead to tripping.
Solution Approach 2:
The control system dynamically changes operating parameters such as switching frequencies and pulse widths based on detected subsynchronous oscillation characteristics. By adjusting these parameters in real-time, the system maintains simple operational interface while internally adapting to suppress oscillations, thereby preserving ease of operation while enhancing generator reliability.
Data Source
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AI summary
A subsynchronous oscillation suppression method and an apparatus and a controller of a converter are provided in the present disclosure, the controller is for controlling the converter. The method includes: acquiring an electric energy fluctuation parameter generated by a subsynchronous oscillation of a power transmission system; acquiring a compensation parameter of a current setting for an active axis according to the electric energy fluctuation parameter; controlling the converter to suppress the subsynchronous oscillation according to the compensation parameter of the current setting for the active axis. The subsynchronous oscillation may be suppressed by acquiring the electric energy fluctuation component in the grid and damping the fluctuation component. Specifically, since the power electronic device is controlled by a switching signal which is obtained by a series of controls on the current setting for the active axis and the actual current, the compensation parameter of the current setting for the active axis may be obtained according to the electric energy fluctuation parameter. After the current setting for the active axis is compensated, the converter is controlled to suppress the subsynchronous oscillation.