The substation DC system is the equipment that provides DC power for protection, control, signaling, automatic devices, emergency power supplies, and circuit breaker tripping/closing operations. In the event of a sudden interruption of external AC power, the battery pack acts as an independent backup power supply, providing reliable operating power for the station's automatic protection devices to ensure timely fault isolation and interruption.

At present, most substation battery packs are generally in a hot standby state, with charging and discharging performed only once every few months. Long-term online operation of battery packs can lead to invisible faults that are difficult to detect, such as drying and heating of individual cells, leakage, undercharging, over-discharging, and increased internal resistance. If external AC power is lost and the battery pack is required to supply energy, faults like open circuits or increased internal resistance of individual cells will cause the entire battery pack to fail to meet the power demand of the DC bus, resulting in abnormal DC bus operation and delayed relay protection action, which can trigger large-scale and major accidents. Therefore, regular inspection and online monitoring of battery packs are essential and cannot be overlooked.

△ MDC-130 Battery Pack Open-Circuit Monitoring and Undervoltage Compensation Device

Based on in-depth research on the working principle and online operation characteristics of battery packs, combined with extensive on-site operation data and practical experience, Wuhan Haomai Electric Power has adopted innovative principles and advanced technical routes to launch the MDC-130 Battery Pack Open-Circuit Monitoring and Undervoltage Compensation Device, providing a comprehensive solution for substation battery packs with real-time online open-circuit monitoring and undervoltage compensation. This device monitors the online operating status of battery packs in real time, judges whether an open circuit occurs instantly, and issues timely alarms. If one or more cells in the battery pack open circuit while external power is lost, the undervoltage compensation device can maintain the DC bus voltage to ensure timely relay protection action. This realizes immediate alarm for battery pack open-circuit faults and completely solves the problem of battery pack failure due to open circuits, greatly improving the operational reliability of the DC bus and reducing the further expansion of power accidents.

The MDC-130 Battery Pack Open-Circuit Monitoring and Undervoltage Compensation Device consists of two main parts: the open-circuit monitoring module and the undervoltage compensation module.

The open-circuit monitoring module includes real-time acquisition and monitoring, an open-circuit judgment network, and alarm output.

The undervoltage compensation module includes real-time acquisition and monitoring, control, fault recording, interactive centralized display, IRIG-B time synchronization, and alarm output. The fault recording function can record the voltage and current data curves of the DC bus during voltage/current jumps or compensation, facilitating real-time and post-event comparative analysis.

△ Schematic Diagram of Open-Circuit Monitoring and Undervoltage Compensation for Single Battery Pack

Main Functions

1. Real-time online open-circuit monitoring and alarm for battery packs
2. DC bus undervoltage compensation: When a section/segment of the battery pack fails or opens, the undervoltage compensation device feeds energy from the healthy segments to the DC bus, ensuring stable and reliable operation of the DC bus.
3. Real-time acquisition of status quantities such as voltage, current, and switch status of the DC bus, battery pack, and undervoltage compensation device; records up to 12 seconds of fault process data waveforms, which can be queried and replayed at any time or copied to a PC for further analysis.
4. Two open-circuit alarm contact outputs (normally open and normally closed), with IRIG-B time synchronization.
5. Supports IEC 60870-5-103 and IEC 61850 communication protocols, enabling communication with the background to send alarm messages and data.

The MDC-130 Battery Pack Open-Circuit Monitoring and Undervoltage Compensation Device is suitable for new 110kV and 220kV substations as well as retrofits of existing stations. It features simple installation without modifying the original station wiring and has been widely applied in substations across several provinces and cities in China. A relevant person in charge of a power company in Guangxi, China Southern Power Grid, stated: "The MDC-130A Battery Pack Open-Circuit Monitoring and Undervoltage Compensation Device has demonstrated accurate and reliable monitoring data during use. It realizes real-time open-circuit judgment and alarm for battery packs and undervoltage compensation for the DC bus, improving the operational safety and reliability of the substation DC bus and greatly reducing the workload of battery pack operation and maintenance personnel."

Thank you for the recognition and support from our users. Wuhan Haomai Electric Power will continue to strengthen its internal capabilities, continuously enhance the technological content and innovation level of its products, and create greater value for users.