# Fault Ride-Through Optimization Scheme for Hybrid AC/DC Transmission Systems on the Same Tower

## TL;DR

This paper proposes new fault ride-through strategies to improve the reliability of hybrid AC/DC power systems during faults.

## Contribution

The paper introduces two novel fault ride-through schemes that address power interruptions and reactive power issues in hybrid AC/DC systems.

## Key findings

- A power compensation-based FRT scheme reduces reactive power redundancy during faults.
- A protection-control cooperation FRT scheme improves AC line protection by detecting AC components on the DC side.
- Simulation results confirm the effectiveness of the proposed methods in hybrid AC/DC systems.

## Abstract

Sensors in power systems utilize the detection results of fault signals to guide subsequent fault handling procedures. However, the traditional phase-shift restart strategy exhibits limitations such as power interruptions, reactive power redundancy, and intersystem fault clearance failures when addressing faults in the hybrid AC/DC transmission system. To address these shortcomings, a power compensation-based fault ride-through (FRT) scheme and a protection-control cooperation FRT scheme are proposed, taking into account the operational characteristics of the symmetric monopole LCC-HVDC (SM-LCC-HVDC). The power compensation-based FRT scheme actively compensates for power, mitigating the impact of reactive power redundancy on the AC-side bus during faults. The protection-control cooperation FRT scheme is activated after sufficient AC components are detected on the DC side. It leverages the adjustability of the DC system to proactively activate protection for AC transmission lines. An electromagnetic transient simulation model of the hybrid AC/DC same-tower transmission system was developed in PSCAD/EMTDC. Simulation results validate the effectiveness and superiority of the proposed methods.