HVDC Link Control via Dynamic Virtual Admittance
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Solution Overview
Problem
Existing electrical grid control strategies, particularly those involving high-voltage DC and AC power lines, face instability issues during malfunctions, leading to transient power imbalances and potential desynchronization of nodes, with existing methods providing insufficient time to rectify faults and limiting dynamic control over AC voltage areas.
Innovation Solution
A method for controlling an electrical transmission link between AC voltage buses using a high-voltage DC line with AC/DC converters, dynamically modifying the emulated line admittance to manage active power and damping oscillations, thereby enhancing stability and synchronism between grid areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the virtual line reactance is kept fixed during malfunction, then the stability study becomes easier, but the transient stability margin decreases and the time available to eliminate malfunction is insufficient
Solution Approach 1:
The patent applies the dynamics principle by transitioning from a fixed virtual line reactance to a dynamically adjustable virtual admittance. The control system modifies the virtual admittance in real-time based on grid conditions, allowing optimization of transient stability during malfunctions while maintaining ease of control through automated adjustment.
Solution Approach 2:
The patent implements parameter changes by dynamically modifying the virtual admittance parameters (conductance and susceptance) during malfunction conditions. This allows the system to adapt the equivalent line characteristics to optimize stability margins without requiring complex physical modifications to the transmission line.
2Device complexity
If the virtual line reactance is kept fixed, then the control system is simpler, but the system cannot impose new dynamics on AC voltage areas
Solution Approach 1:
The patent applies universality by designing a control system that performs multiple functions: it maintains the virtual line reactance function for normal operation while adding the capability to dynamically adjust virtual admittance during malfunctions. This single control system thus provides both simplicity for normal operation and advanced dynamic control when needed.
Solution Approach 2:
The system transitions from static to dynamic control by implementing adjustable virtual admittance that can be modified in real-time based on grid conditions, enabling the imposition of new dynamics on AC voltage areas while maintaining a relatively simple control architecture through automated control laws.
3Reliability
If the active power on DC line is limited, then the stability is improved, but the power transmission capability is reduced
Solution Approach 1:
The patent applies parameter changes by dynamically modifying the virtual admittance parameters to optimize the trade-off between stability and power transmission. The control system adjusts conductance and susceptance values based on real-time conditions, allowing maximum power transmission while maintaining stability margins through automated parameter optimization.
Data Source
AI summary
The invention relates to a method for controlling an electrical transmission link (3) between first and second AC voltage buses (11, 21) comprising a high-voltage DC line (320), first and second AC/DC converters (321, 322) connected to the high-voltage DC line (320), comprising:retrieving a setpoint active power value (Pdc0) applied to a converter (321, 322);retrieving the instantaneous values V1 and V2 of the voltages on the first and second buses;wherein the setpoint active power of the first or of the second converter is modified by a value including a term ΔPdc, so as to impose new dynamics on the first and second areas, where:ΔPdc=ΔPdcs+ΔPdca.