Virtual DC Bus Capacitance Control for Wind Power Stability
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Solution Overview
Problem
The integration of DC bus capacitors in wind power generation systems leads to sub-synchronous oscillations, threatening the stability of electrical power systems, and existing stability analysis methods focus on dynamic rotor speed, DC voltage, and AC current control without effectively addressing capacitance value adjustments.
Innovation Solution
A method and apparatus that adjust the DC bus current to match a virtual DC bus capacitance value, effectively changing the capacitance value of the DC bus capacitor to improve system stability and reduce oscillations, while also allowing for cost reduction by virtualizing positive capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bus capacitance is reduced to improve system stability, then the contribution to system stability increases, but the high-frequency ripple performance deteriorates
Solution Approach 1:
The patent introduces a virtual DC bus capacitance that can be dynamically adjusted through control parameters, allowing the system to adapt the effective capacitance value based on operating conditions. This dynamic adjustment enables optimization of both stability and ripple performance without being constrained by fixed physical capacitance values.
Solution Approach 2:
The patent changes the effective capacitance parameter from a fixed physical value to a controllable virtual value through the virtual capacitance module. By modifying control parameters (such as proportional gain and integral gain in the virtual capacitance controller), the system can achieve different effective capacitance values to address different operational requirements.
2Object-affected harmful factors
If a larger DC bus capacitor is used to reduce high-frequency ripple, then the ripple performance improves, but the system stability deteriorates due to sub-synchronous oscillation
Solution Approach 1:
The virtual DC bus capacitance allows dynamic adjustment of the effective capacitance value through control parameters, enabling the system to select optimal capacitance values for different operating modes. This resolves the contradiction by allowing small effective capacitance for stability while maintaining ripple filtering through active control.
Solution Approach 2:
The patent introduces a virtual capacitance module as an intermediary between the physical capacitor and the control system. This virtual module acts as a mediator that decouples the direct relationship between physical capacitance size and system behavior, allowing independent optimization of stability and ripple performance.
3Ease of manufacture
If the physical DC bus capacitor size is reduced to lower cost, then the equipment cost decreases, but the system stability deteriorates
Solution Approach 1:
The patent creates a virtual copy of the DC bus capacitance function through software control algorithms. This virtual capacitance model replicates the electrical behavior of a physical capacitor while allowing flexible parameter adjustment, eliminating the need for large physical capacitors and reducing costs.
Solution Approach 2:
The patent replaces the physical mechanical capacitor system with a virtual capacitance implementation based on control algorithms and software. This substitution transforms a hardware-dependent solution into a software-based solution, enabling cost reduction while maintaining or improving performance.
Data Source
AI summary
The present application provides a method of controlling an electrical power system and an apparatus using the same. The electrical power system includes a DC bus and a DC bus capacitor connected to the DC bus. The method includes: receiving a virtual DC bus capacitance value of the DC bus capacitor; detecting a DC bus voltage; calculating an expected value of a DC bus current based on the virtual DC bus capacitance value and the DC bus voltage; and adjusting the DC bus current, so that the DC bus current reaches the expected value and thus the DC bus capacitor is equivalent to the virtual DC bus capacitance value.