Commutation Failure Management in High-Voltage Direct Current Systems

Commutation failure occurs in line-commutated converter (LCC) based high-voltage direct current (HVDC) systems when the inverter valve fails to transfer current to the next valve, typically as a result of severe AC voltage dips or system disturbances. Such events can precipitate unwanted power oscillations, stress on converter valves and transformers, and even system-wide instability. With the rapid deployment of ultra-HVDC links for long-distance power transfer and the growing penetration of renewable energy sources, robust management of commutation failure has become crucial for grid resilience. Strategies to address this challenge can be classified into three categories: preventive support through reactive power compensation, predictive monitoring via real-time estimation of extinction angles, and active suppression using dynamic control of valve firing. Hardware solutions such as thyristor-based controllable capacitors or fixed series capacitors have been proposed to eliminate failure under extreme unbalanced faults, while advanced control schemes adjust firing angles or emulate circuit resistance to mitigate successive or intermittent failures. Real-time digital simulation and multi-infeed modelling have further enabled comprehensive assessment of immunity levels and optimisation of component parameters. The integration of these approaches enhances not only the reliability of existing HVDC installations but also paves the way for more compact, efficient, and economically viable transmission networks supporting global decarbonisation efforts.

Research from Nature Portfolio

No recent Nature Portfolio content available.

Commutation Failure Management in High-Voltage Direct Current Systems publication trend

The graph below shows the total number of articles in commutation failure management in high-voltage direct current systems across all publications each year (not limited to Nature Index journals).

Technical terms

Commutation Failure: Loss of proper transfer of current from one valve to the next in an LCC, often triggered by AC voltage dips.

Extinction Angle: The electrical-degree interval during which converter valve current falls to zero, determining commutation success.

Line-Commutated Converter (LCC): An HVDC converter technology that relies on the AC system voltage to commutate thyristor valves.

Controllable Capacitor: A power-electronic device that adjusts reactive compensation dynamically to support AC voltage and prevent commutation failure.

Virtual Resistance: A control-based emulation of resistance in the DC circuit that modulates current flow and enhances stability during faults.

References

1. Commutation Failure Elimination of LCC HVDC Systems Using Thyristor-Based Controllable Capacitors. IEEE Transactions on Power Delivery (2017).
2. Reactive Power and AC Voltage Control of LCC HVDC System With Controllable Capacitors. IEEE Transactions on Power Systems (2016).
3. Commutation Failure Prediction Method Considering Commutation Voltage Distortion and DC Current Variation. IEEE Access (2019).
4. AC Filterless Flexible LCC HVDC With Reduced Voltage Rating of Controllable Capacitors. IEEE Transactions on Power Systems (2018).
5. Series Capacitor Compensated AC Filterless Flexible LCC HVDC With Enhanced Power Transfer Under Unbalanced Faults. IEEE Transactions on Power Systems (2019).
6. Variable Extinction Angle Control Strategy Based on Virtual Resistance to Mitigate Commutation Failures in HVDC System. IEEE Access (2020).
7. Efficient approach for commutation failure immunity level assessment in hybrid multi‐infeed HVDC systems. The Journal of Engineering (2017).