Wind Farm Voltage Source Converter Artificial Inertia Control
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Solution Overview
Problem
Wind farms connected to a main AC grid face instability issues due to the lack of mechanical resistance, leading to erratic frequency variations, which existing power transmission networks struggle to manage without costly and unreliable telecommunication systems.
Innovation Solution
Introducing an artificial inertia factor in the active power demand of wind farm side voltage source converters, which modifies the power-frequency slope to stabilize frequency and allows DC transmission links to act as communication mediums, enabling master-slave control relationships between wind farm and grid side converters without separate telecommunication systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wind farms are connected to the main AC grid through voltage source converters, then power transmission efficiency is improved, but instability issues arise due to lack of mechanical resistance causing erratic frequency variations
Solution Approach 1:
The patent modifies the active power demand parameter by introducing an artificial inertia factor that changes the power-frequency slope. This parameter change allows the converter to respond to frequency deviations in a manner that simulates mechanical inertia, thereby stabilizing frequency while maintaining efficient power transmission.
Solution Approach 2:
The DC transmission link is utilized as an intermediary communication medium. By monitoring DC voltage variations and translating them into active power demand adjustments, the system enables master-slave control between converters without requiring separate telecommunication infrastructure, thus stabilizing frequency while maintaining system simplicity.
2Reliability
If separate telecommunication systems are installed for master-slave control between converters, then control reliability is improved, but system cost and complexity increase
Solution Approach 1:
The DC transmission link performs dual functions: power transmission and communication. By exploiting the inherent voltage variations in the DC link as a communication medium, the system eliminates the need for separate telecommunication systems, reducing complexity while maintaining control reliability through the artificial inertia-based master-slave control mechanism.
3Stability of the object's composition
If artificial inertia factor is introduced to stabilize frequency, then frequency stability is improved, but control system complexity increases
Solution Approach 1:
The artificial inertia factor implements a feedback mechanism where the converter monitors frequency deviations and adjusts active power demand accordingly. By modifying the power-frequency slope based on detected frequency changes, the system creates a self-regulating control loop that stabilizes frequency without requiring complex external control infrastructure.
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A wind farm side voltage source converter (32; 94) comprises a DC terminal (40) for connection to a DC transmission link (38), an AC terminal (42) for connection to a wind farm (44) that includes at least one wind turbine (46), and a main controller (10; 20; 96). The main controller (10; 20; 96) is configured to modify an active power demand (Pdemand) of the voltage source converter (32; 94) which is received from a higher level controller by introducing an artificial inertia factor and/or in response to a measured DC voltage (Vdc_msr) at the DC terminal (40).