HVDC Voltage Source Converter Damping Control
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Solution Overview
Problem
HVDC transmission systems using voltage source converters face resonance issues due to higher control bandwidths, which can lead to voltage fluctuations and potential component damage, especially since the resonance frequencies often fall within the control bandwidth, unlike in systems using current source converters.
Innovation Solution
A control apparatus for voltage source converters that generates a damping signal based on measured voltage or current and impedance values to modulate the regulation signal, with a high-pass filter to target resonance frequencies, thereby reducing resonance effects without affecting steady-state operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If voltage source converters are used in HVDC transmission systems, then control bandwidth is increased and response speed is improved, but resonance occurs within the control bandwidth causing voltage fluctuations and potential component damage
Solution Approach 1:
The invention converts the harmful resonance phenomenon into a beneficial damping effect by introducing a damping control loop that generates a damping signal proportional to the derivative of the regulated parameter. This damping signal is added to the regulation signal to actively suppress resonance oscillations within the control bandwidth, transforming the problematic resonance frequency range into a controlled damping region that prevents voltage fluctuations and component damage while maintaining the high control bandwidth benefits of voltage source converters
2Reliability
If damping control is added to regulate voltage or power, then resonance is reduced, but control signal complexity increases
Solution Approach 1:
The invention merges the damping control function with the existing regulation control by combining the damping signal and regulation signal into a single composite control signal that drives the voltage source converter. This unified approach integrates resonance damping capability into the standard voltage or power regulation loop without requiring separate parallel control paths, thereby reducing control signal complexity while maintaining effective resonance suppression
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
The proposed solution effectively reduces resonance in HVDC transmission systems, minimizing voltage fluctuations and power losses, and preventing component damage by integrating damping control within the regulation loop of voltage source converters.
Implementation Method 1
resonance can occur in such a DC transmission system at frequencies such that the wavelength of the resonance correspond to factors of 4, 4/3, 4/5, 4/7, etc. of the cable length
Implementation Method 2
damping control configured to generate a damping signal for modulating said regulation signal
Implementation Method 3
with a high-pass filter to target resonance frequencies
Data Source
AI summary
This application relates to methods and apparatus for control apparatus of a voltage source converter for direct current transmission of electrical power over a transmission line. The control apparatus comprises regulation control for generating a regulation signal for the converter to regulate an electrical parameter of the voltage source converter, such as voltage or power, so as to regulate power transmission over the transmission line. The regulation signal is based on the difference between a measured value of said parameter and a reference value of said parameter, as may be supplied from a reference control block and may be derived from a demand signal indicating the voltage or power demand. The apparatus also includes damping control configured to generate a damping signal for modulating said regulation signal to reduce the effect of resonance within the bandwidth of control of the converter. The damping signal is generated as a function of a measured voltage or current of the transmission line and an impedance value for the transmission line. The damping signal may be high-pass filtered so as to have no substantial impact on steady state operation.