Mitigation of the Commutation Failure Problem in the HVDC Multi-Infeed Scenario in Brazil Using Synchronized Phasor Measurement

This paper presents the Commutation Failure (CF) problem in the HVDC-LCC (High Voltage Direct Current - Line-Commutated Converter) scenario in Brazil through the monitoring of Short-Circuit Ratio (SCR), CF indexes, Direct Current (DC) link power, and the use of simulated synchrophasor data. The analysis was performed by training a neural network using data from the year 2020, and its robustness was verified using data from the year 2021 of the Brazilian Interconnected Power System (BIPS). Additionally, an analysis of transient instability in the North-South Transmission Corridor (NSC) will be presented right after the occurrence of CF by monitoring the Lyapunov transient instability margin, with the primary objective of bringing subsidies to the control center operation area, according to the severity of the CF occurrence, avoiding the propagation of CF, mitigating it through real-time predictive actions, such as power redispatch on DC links and, thus, minimizing the occurrence of CF.

The confirmation of CF between the results obtained from the neural network were confirmed through the transient electromagnetic simulations carried out in the PSCAD tool, where the power flow scenarios in the BIPS were taken to the equivalent network in the PSCAD containing the 6 bipoles in Brazil (Itaipu, Madeira and Belo Monte), which carry about 20GW to the main load center in Brazil (South/Southeast), where several simultaneous commutation failures occur during short-circuit conditions in the power system network.

Additionally, an analysis of transient instability in the North-South Transmission Corridor (NSC) will be presented right after the occurrence of CF by monitoring the Lyapunov transient instability margin, with the main objective of bringing subsidies to the System Operator (SO) area, according to the prediction of the severity of the CF occurrence. With this, besides making it possible to verify the influence between the DC links that cause simultaneous CF, it also allows verifying the impact of the event during post-operation on the grid, providing support for decision making by the operation area of the Transmission System Operator (TSO) and the ONS (Brazilian National Grid Operator), in order to avoid the spreading of CF and/or to mitigate them, via predictive actions in real time, such as power redispatching in the DC links, minimizing the occurrence of CF.