1. Project Overview
Project Name: 22kV Current-Limiting Reactors for Lien Tri and An Don 110kV Substations
Project Summary: In January 2020, Da Nang Power Company Limited, in coordination with PowerMore, successfully energized and commissioned 22kV current-limiting reactors at the Lien Tri and An Don 110kV substations in Da Nang City.
The reactors were installed to reduce short-circuit current on the 22kV outgoing feeders to levels within the permissible ratings of reclosers and other feeder equipment, thereby enhancing the safety and operational reliability of the overall power distribution system.
Industry / Sector: Power Distribution / Substations / Medium-Voltage Electrical Equipment
Project Type: Short-circuit current calculation, installation, and commissioning of current-limiting reactors
Voltage Level: 22kV
Location: Lien Tri 110kV Substation and An Don 110kV Substation, Da Nang City, Vietnam
Energization Date: January 2020
2. PowerMore’s Scope of Work
For this project, PowerMore coordinated and participated in the implementation of the following key activities:
- Calculating and developing a short-circuit current mitigation solution for the 22kV outgoing feeders.
- Installing a 22kV current-limiting reactor at the Lien Tri 110kV Substation.
- Installing a 22kV current-limiting reactor at the An Don 110kV Substation.
- Coordinating energization, commissioning, and putting the equipment into actual operation.
3. Project Highlights & Value
As urban economies continue to grow, electricity demand in major cities is increasing accordingly. Power systems are continuously expanded, grid configurations become more interconnected and complex, and source capacity continues to rise. One direct consequence is an increase in prospective short-circuit current across the network.
The Lien Tri and An Don 110kV substations in Da Nang are both high-capacity substations. Each station is equipped with two 110/22kV – 63 MVA transformers. However, the transformers have relatively low short-circuit impedance, typically in the range of 10–12%.
When source capacity is high, particularly when the two transformers operate in parallel, the resulting short-circuit current can increase significantly.
If the short-circuit current exceeds the withstand capability of equipment such as busbars, disconnectors, current transformers, and reclosers, severe equipment damage may occur when a fault arises. This can extend outage and fault-recovery time while increasing repair and power system operating costs.
To address this challenge, Da Nang Power Company Limited worked with PowerMore to calculate, install, and successfully commission 22kV current-limiting reactors at both the Lien Tri and An Don 110kV substations.
Actual operating results following installation showed that the short-circuit current on the 22kV outgoing feeders was reduced by more than 30%, from approximately 17kA to below 12kA.
This brought the fault current within the allowable ratings of equipment installed on the 22kV feeders, particularly the reclosers. As a result, the solution helps protect critical electrical equipment while improving the safety and reliability of the distribution system under short-circuit fault conditions.
