Power Converter Control for Low-Frequency Oscillation Damping
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The reduction in conventional large-inertia rotary units in power systems due to increased use of new energy and power electronic devices leads to decreased inertia levels and anti-disturbance capabilities, resulting in stability issues and low-frequency oscillations when connected to the power grid.
Innovation Solution
A power converter system that includes a power conversion circuit and a controller, where the controller inputs a series of signals with progressively increasing or decreasing frequencies and constant amplitudes, and adjusts the output to reduce the amplitude of signals corresponding to local maximum values, thereby reducing low-frequency oscillations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If equivalent inertia and damping characteristics are introduced into power converters to simulate synchronous generator behavior, then system stability and active frequency support are improved, but equivalent negative damping may be introduced causing low-frequency oscillation
Solution Approach 1:
The patent applies vibration analysis principles by scanning through a range of frequencies and identifying resonant peaks where low-frequency oscillations occur. The controller measures the amplitude of oscillations at different frequencies and selectively dampens those frequencies that exhibit excessive amplitude, effectively targeting the harmful vibrations without affecting stable operation at other frequencies.
Solution Approach 2:
The patent dynamically adjusts control parameters based on the detected oscillation characteristics. By scanning frequency responses and identifying peaks, the system changes damping parameters selectively at specific frequency ranges where oscillations occur, while maintaining other control parameters unchanged, thus resolving the contradiction between stability enhancement and oscillation suppression.
2Adaptability or versatility
If power electronic devices replace conventional rotary units to increase new energy proportion, then clean energy utilization is improved, but inertia level and anti-disturbance capability are reduced
Solution Approach 1:
The patent dynamically adjusts control parameters based on grid conditions and oscillation detection. By scanning frequency responses and identifying resonant peaks, the system changes damping parameters selectively at specific frequency ranges where oscillations occur, while maintaining other control parameters unchanged, thus resolving the contradiction between stability enhancement and oscillation suppression.
Solution Approach 2:
The patent implements a feedback mechanism where the controller continuously monitors the output signals and frequency responses of the power conversion circuit. By detecting amplitude peaks that indicate low-frequency oscillations, the system adjusts its control strategy in real-time to dampen oscillations while maintaining stable power conversion, enabling power electronic devices to provide both new energy integration and system stability.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
This application provides a power converter and a power supply system. A direct current input of the power converter is configured to connect to a photovoltaic module or an energy storage battery. An alternating current output of the power converter is configured to connect to a power grid or a load. The power converter includes a power conversion circuit and a controller. The power conversion circuit is configured to convert a direct current into an alternating current. The controller inputs a plurality of first signals to a direct current input of the power conversion circuit. Frequencies of the plurality of first signals progressively increase or decrease, and amplitudes of the plurality of first signals are the same. An alternating current output of the power conversion circuit outputs a plurality of second signals. The first signals are in a one-to-one correspondence with the second signals. The second signal and the corresponding first signal have a same frequency. Amplitudes of the plurality of second signals change as frequencies of the plurality of second signals progressively increase or decrease. The controller reduces an amplitude of a target second signal, where the target second signal is a second signal whose amplitude is a local maximum value in the plurality of second signals. According to this application, low-frequency oscillation in a working process of the power converter can be reduced.