The first Power Quality/Peak Shaving (PQ/PS) Battery System to utilize sodium sulfur battery technology in North America also utilizes ABB Power Electronics' PCS/Power Conditioning System (Voltage Source Inverters) and officially debuted in September as a 2-year demonstration at American Electric Power's suburban Columbus, OH, office park location in Gahanna.
In addition to ABB, AEP has brought together as vendors and project partners NGK Insulators, Ltd (NGK), which developed the stationary sodium sulfur (NAS®) battery technology; Tokyo Electric Power Co (TEPCO), the utility demonstrating the NAS battery modules throughout Japan; the U.S. Department of Energy/Sandia National Laboratories; and EPRI.
"This is the front lines of power generation for the 21st century," noted Chuck Clark, senior vice president of ABB Inc, at the ribbon cutting. "And we are pleased to join this fellow group of partners with whom we share a global vision for what customers now require to meet their energy needs." ABB's PCS, custom engineered and designed for AEP, features extremely compact inverters that are built with ABB's high-performance ACS 600 platform and utilize new ACS 800 IndustrialIT Controller technology to convert the DC current generated from the NAS batteries into AC current the office park can use.
First Ever in North America
AEP built this first-ever PQ/PS sodium sulfur Battery Energy Storage System for North America, following extensive testing of NAS batteries in peak shaving and power quality models throughout 2001; the new system demonstrates how the combined technology can mitigate power quality in "a very real-world-real-time application," the company said. Economic models developed from the demonstration can accelerate the use of such systems across a host of industrial applications, the company noted.
System Designed To Provide Stable Power To Industrial Users
The combined battery modules in the Gahanna demonstration, which are charged at off-peak hours from the utility line, are rated at 100 kW and supply up to 500 kW for critical PQ/PS generation and power stabilization.
The primary function of this type of Battery Energy Storage System is to provide Power Quality, according to Anders G. Troedson, director of ABB Inc, Power Electronics. "PQ is protecting an industrial user's critical loads from voltage sags, outages, and voltage swells -- all and each of which may disrupt a critical manufacturing process."
AEP's system, as created with NGK and ABB, consists of high-speed control to detect line conditions, control of a static switch to disconnect the load from the line and, then, to start "instantly" the inverters to support the load. "From actual test results, this complete process takes approx. 3 ms (.003 seconds)," Troedson said, which meets the criteria for protecting critical loads. ABB developed and built these critical controls into the firmware and software of the PCS utilized in the storage system. AEP's demo system delivers up to 500 kW for short-term power quality mitigation, the companies said.
Peak Shaving Saves Industrial Customers Energy Dollars, Too
Using the Battery Energy Storage System in the PS mode, industrial users could program the level of power to be provided (from the batteries) to the load, in order to reduce the load demand from the utility grid.
"For both industrial and commercial utility-grid customers, high-usage conditions almost always occur at the same time," notes Tor-Evind Moen, business development manager for ABB PCS systems. "Everyone has peak operating loads, for example, from 11:00 AM to 4:00 PM.". Since peak power usage/time is used in determining the electric bill, battery storage systems deliver energy to reduce the electric bill during these hours when the per-kW price of electricity is highest. "Batteries provide that advantage, provide uninterrupted power, and then recharge themselves at night when power is available at a cheaper rate," Moen noted. AEP's demo system is rated at 100 kW for peak shaving or load leveling for approximately seven hours.
The combination of the PQ and PS functions makes the system attractive to both large industrial users and to the utility market, according to AEP and ABB. Systems developed in the past have consisted of both of these functions, but never combined them into a single unit. AEP expects such systems will become part of distributed power resources capable of both storing energy and mitigating disruptive power quality events.
ABB Power Electronics, which also supplied to AEP the enclosures integrating the NAS batteries and PCS controls, continues to manufacture their state-of-the art PCS Power Conditioning Systems for a variety of power generation customers -- both OEMs and utilities (including fuel cell and static var applications). From ABB's standard-product family, the PCS 600, with its small footprint, modular hardware, and advanced software features, enables ABB to engineer and produce "customized packaging solutions in record time at very cost-competitive rates," according to Troedson. "Advanced technology and extremely reliable electrical components are built in."
The PCS 600 covers the power range from 50 kVA up to a maximum of 4000 kVA per unit. Multiple units are paralleled for system ratings greater than 4000 kVA. PCS product lines are optimized for 220, 480, 575, 600, and 690 V low-voltage applications; for medium-voltage applications up to 69 kV, step-up transformers are used. ABB's global presence as a technology leader also makes it easy to provide local service and maintenance support throughout the world, Troedson said.
