Substation DC system

Power outages

LAB have a “memory effect”, which means that the battery must be completely discharged before charging

Long charging time. On average, a full charge takes 8 to 10 hours

Discharge depth without the service life reduction is less than 60% of the rated capacity

Low power characteristics. On average, LAB can produce a continuous current of about 0,5 C. That means, that LAB with capacity of 100 A * h would provide the maximum continuous current of 50 A.

The discharge curve of LAB is flat, and the battery voltage seriously depends on the charge level.

Low charge efficiency of lead-acid batteries - 65-85%

High self-discharge rate (up to 15% per month)

Providing and reserving power for in-house needs and power facilities. Instant switch to battery power when the mains voltage disappears.

LIB are capable of charging at any charge level keeping the ability to return the full capacity

Significantly shorter charging time. The standard charge mode is 1 hour, which significantly reduces the time of operational readiness after a full discharge.

LIB allows up to 80% depth of discharge. Thus, with the same rated capacity, LIB can produce more power

High power characteristics. LIB in normal mode can produce a current of 3 C. Thus, LIB with a capacity of 100 A * h would provide the maximum continuous current of 300 A. This advantage allows to significantly reduce the nominal capacity of LIB compared to LAB. Thus, when replacing the battery in a substation DC system, the initial cost of the power accumulating device on LIB is equal to the cost of a device on scab LAB, or even less.

The discharge curve of LIB in the range from 100% to 20% of the charge is almost horizontal straight line, the battery voltage is nearly constant in that range

High charge efficiency of LIB - 93-95%

Low self-discharge rate (on average, 3% per month)

A charging room is required - a hazardous production facility

Inefficient monitoring of battery condition during operation

No charging room required (decommission of a hazardous production facility is possible)

A built-in monitoring system (BMS) that monitors the status of each element's parameters and can transmit results). In case of emergency or critical situations, BMS sends a signal to the switch gear and disconnects the energy storage device from the load and network.

Low energy density in LAB ⇒ high mass and large dimensions ⇒ need for work areas

LAB require maintenance at a certain interval during operation (for example, monitoring the appearance, leveling the electrolyte level), which entails the need for maintenance personnel

Accelerated LAB degradation ⇒ frequent battery replacement

Occupied area is reduced, no need for a room with exhaust ventilation. Thus, the battery may be placed almost at any room of a substation.

LIB are sealed and do not require maintenance.

LIB does not need to be replaced during the entire service life