Operational experience and performance characteristics of a valve-regulated lead--acid battery energy-storage system for providing the customer with critical load protection and energy-management benefits at a lead-recycling plant

摘要

The Power Control Division of GNB Technologies, commissioned on May l3, l996 a new facility which houses a 5-MW battery energy--storage system (BESS) at GNB's Lead Recycling Centre in Vemon, CA. When the plant loses utility power (which typically happens two or three times a year), the BESS wil1 provide up to 5 MW of power at 4l60 VAC in support of all the plant loads. Since the critical loads are not isolated, it is necessary to carry the entire plant load (maximum of 5 MVA) for a short period immediately following an incident until non-critical loads have been automatically shed. Plant loading typically peaks at 3.5 MVA with critical loads of about 2.l MVA. The BESS also provides the manufacturing plant with customer- side of the meter energy management options to reduce its energy demand during peak periods of the day. The BESS has provided a reduction in monthly electric bills through daily peak-shaving. By design, the battery can provide up to 2.5 MWh of energy and still retain 2.5 MWh of capacity in reserve to handle the possibility of a power outage in protecting the critical loads for up to l h. By storing energy from the utility during off peak hours of the night in the batteries when the cost is low (US4.5φ per kWh), GNB can then discharge this energy during high demand periods of the day (US$l4.50 per kW). For example, by reducing its peak demand by 300 kW, the lead-recycling centre can save over US$4000 per month in its electric bills. The BESS at Vernon represents a first large-scale use of valve-regulated lead--acid batteries in such a demanding application. This paper presents a summary of the operational experience and performance characteristics of the BESS over the past 2