Dynamic Droop Control for HVDC Converter Voltage Regulation
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Solution Overview
Problem
There is a need for a converter control arrangement that can effectively regulate the output voltage of a dc source power converter to prevent conflicts and minimize damage during fault conditions in a high-voltage direct current (HVDC) power transmission network, where multiple dc sources are connected in parallel, especially due to excessive output voltage or current.
Innovation Solution
A dynamic droop control device with first and second droop controllers, each having distinct droop rates, is used to regulate the output voltage by comparing the output voltage and current values with reference values, allowing for voltage and current control adjustments to maintain a target operating point, particularly during dynamic operating conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple dc sources are connected in parallel to supply electrical power to the HVDC network, then the required amount of dc electrical power is met and stable network operation is ensured, but conflicts in electrical power generation occur during fault conditions due to uncontrolled voltage and current increases
Solution Approach 1:
The patent implements dynamic droop control that automatically adjusts the droop rate based on operating conditions. During normal operation, a first droop rate is used for standard voltage regulation. During fault conditions detected by the controller, a second droop rate (different from the first) is applied to limit excessive current and voltage increases. This dynamic adaptation resolves the contradiction by maintaining power supply capability while ensuring reliability during faults.
2Measurement precision
If voltage control regulation is used to supply electrical power at a target voltage value, then the output voltage is regulated, but excessive output voltage occurs during fault conditions that cannot be tolerated by the dc system
Solution Approach 1:
The patent changes the control parameter (droop rate) based on operating conditions. The controller switches between a first droop rate during normal operation and a second droop rate during fault conditions. This parameter change enables the system to maintain precise voltage regulation under normal conditions while preventing excessive voltage during faults, thus resolving the contradiction between measurement precision and harmful factors.
3Measurement precision
If current control regulation is used to supply electrical power at a target current value, then the output current is regulated, but excessive output current occurs during fault conditions that cannot be tolerated by the dc system
Solution Approach 1:
The dynamic droop control device adjusts the droop rate dynamically based on the operating state. During normal operation, the first droop rate maintains precise current regulation. Upon detecting fault conditions, the controller switches to a second droop rate that limits excessive current increases. This dynamic parameter adjustment resolves the contradiction between maintaining measurement precision and preventing harmful excessive currents during faults.
Data Source
AI summary
A converter control arrangement for regulating the output voltage of a dc source power converter connecting an ac system to a HVDC system to enable dc electrical power to be supplied from the ac system to the HVDC system comprises a dynamic droop control device including first and second droop controllers in which the droop rate of the second droop controller is greater than the droop rate of the first droop controller. The converter control arrangement comprises a voltage regulator for regulating the output voltage of the dc source power converter by comparing an output voltage value with a target voltage value derived by combining a reference voltage value and a droop voltage value provided by the dynamic droop control device. The reference current value is the desired output current value of the dc source power converter and defines, in combination with the reference voltage value, a target operating point.