Resonance Suppression Device for Wind Power Inverters
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Solution Overview
Problem
Existing resonance suppression methods in wind power systems face challenges in effectively reducing harmonic distortion and resonance, particularly due to changes in system configuration and capacitance, requiring large compensation currents and struggling with accurate transfer function settings and adapting to varying resonance points.
Innovation Solution
A resonance suppression device that generates a current command value by multiplying frequency components, excluding the fundamental wave, using a transfer function, to supply compensation current to the power system, thereby reducing harmonic distortion and adapting to changing resonance points with appropriate gain adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If all harmonic components are suppressed using a power active filter, then the connection point voltage waveform becomes a complete sine wave, but large compensation current is needed requiring an inverter with large capacity
Solution Approach 1:
The invention extracts only the resonance frequency component from the harmonic components using a band-pass filter, rather than suppressing all harmonic components. This selective extraction allows compensation current to be generated only for the resonance frequency, significantly reducing the required compensation current magnitude while still improving voltage waveform quality by eliminating the problematic resonance distortion.
2Reliability
If a transfer function is set in advance based on capacitor capacity and impedance characteristic, then resonance suppression can be achieved, but accurate values cannot be obtained making it difficult to appropriately set the transfer function
Solution Approach 1:
The invention uses a band-pass filter with adjustable center frequency that can be tuned based on actual resonance frequency detection. Instead of relying on pre-set transfer functions based on theoretical parameters, the system adaptively adjusts the filter characteristics to match the actual resonance conditions, providing reliable resonance suppression even when accurate parameter measurements are difficult.
3Adaptability or versatility
If the configuration of the power system changes, then the resonance point changes, but the fixed transfer function becomes ineffective and resonance may occur again
Solution Approach 1:
The invention employs a band-pass filter with a movable center frequency that can be dynamically adjusted to track changing resonance frequencies. When power system configuration changes cause the resonance point to shift, the filter's center frequency is adjusted accordingly, maintaining effective resonance suppression adaptability without requiring a fixed transfer function.
4Adaptability or versatility
If capacitance of harmonic filter changes according to the number of connected wind power generators, then the resonance frequency changes, but it is difficult to use fixed transfer function methods
Solution Approach 1:
The band-pass filter's center frequency is made dynamically adjustable to track the changing resonance frequency that occurs as wind power generators are connected or disconnected. This dynamic adjustment capability allows the system to adapt to varying capacitance conditions without requiring complex reconfiguration of the control system, simply by tuning the filter's center frequency to match the current resonance condition.
Data Source
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AI summary
The present invention whose object is to reduce compensation current at the time when suppressing harmonic distortion caused by harmonic voltage, to reduce capacitance of an inverter, a resonance suppression device (1a-1d; 2; 4a-4c) configured to suppress resonance which occurs when a power facility such as a wind power generator is connected to a power system (5) includes: an inverter (17; 27; 47) configured to supply alternating current to the power system, the inverter being in parallel with the power facility; a current command value generation unit (10a-10d; 20; 40a) in which voltage at a connection point between the power facility and the power system is inputted thereto and a current command value is obtained by multiplying, by a transfer function, a harmonic component contained in the voltage at the connection point; and a current control unit configured to control the alternating current outputted from the inverter based on the current command value.