HVDC Power Generation Control for Offshore Wind Turbines
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Solution Overview
Problem
In high voltage direct current (HVDC) transmission systems, especially for offshore wind turbines, existing methods struggle to detect incidents such as short-circuits at the point of interconnection with the electric power system, leading to voltage increases and potential device failures due to high short-circuit currents, which necessitate costly and bulky damping resistors and semiconductor switches.
Innovation Solution
An electric power generation control device and method that allows detection of incidents at the electric power system side, rather than the DC power transmission unit, by reducing the effective power set value from the synchronous generator and using event detection based on frequency and torque imbalance, thereby reducing the need for high-capacity damping components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If damping resistor and semiconductor switch are installed in the DC power transmission unit to dissipate excessive electric power, then voltage increase can be prevented, but the capacities of these components become significantly high resulting in increases in costs, weights and sizes
Solution Approach 1:
The invention introduces an intermediary detection mechanism (frequency and torque monitoring) that indirectly detects incidents at the power system side, allowing the system to respond to voltage threats without requiring direct high-capacity damping components in the DC transmission unit. The intermediary detection enables preventive action before excessive voltage develops.
Solution Approach 2:
The system performs preliminary detection of incidents (short-circuits, groundings) by monitoring frequency and torque parameters before they cause excessive voltage in the DC transmission unit. This preliminary action allows the system to prepare protective responses in advance, avoiding the need for oversized damping components that would only react after voltage problems arise.
2Reliability
If damping resistor and semiconductor switch are installed in the DC power transmission unit to dissipate excessive electric power, then voltage increase can be prevented, but costs increase significantly
Solution Approach 1:
The invention uses intermediary frequency and torque sensors as low-cost detection mechanisms that can indirectly identify incidents at the power system side. This intermediary approach replaces the need for expensive high-capacity damping resistors and semiconductor switches, significantly reducing manufacturing costs while maintaining voltage control reliability.
Solution Approach 2:
The invention substitutes mechanical/electrical damping components (damping resistors and semiconductor switches) with a control-based detection system that uses frequency and torque monitoring. This substitution eliminates the need for bulky, expensive passive damping components while achieving the same protective function through intelligent control.
3Quantity of substance
If AC voltage is decreased in an AC/DC converter to limit electric power, then the capacities of damping resistor and semiconductor switch can be decreased, but this method cannot be effectively applied when synchronous generator has high short-circuit current
Solution Approach 1:
The invention performs preliminary detection of incidents using frequency and torque parameters before they manifest as voltage problems that would require AC voltage reduction. By detecting incidents early through intermediary parameters, the system can respond appropriately without needing to rely on AC voltage reduction, which is ineffective when synchronous generators produce high short-circuit currents.
Solution Approach 2:
The invention uses frequency and torque as intermediary parameters that can reliably detect incidents at the power system side even when synchronous generators are present. These intermediary measurements provide accurate incident detection capability that is not affected by the high short-circuit current characteristics of synchronous generators, unlike direct AC voltage monitoring.
Data Source
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AI summary
This electric power generation control device is provided with: an event detecting unit which, if an electric power converter, connecting an electric power generator to a direct-current power transmission unit which transmits direct-current power, has detected a failure necessitating the cessation of the power transmission from the electric power generator by the direct-current power transmission unit, detects events attributable to a deterioration in the balance between a torque input into the electric power generator and the effective power output by the electric power generator, said deterioration caused by a reduction in a set value of the effective power accepted from the electric power generator by the electric power converter; and a torque command reducing unit which, if the event detecting unit has detected an event attributable to a deterioration in said balance, causes a reduction in a torque command to a motor which outputs the torque that is input into the electric power generator.