Midwest Paper Group, Power House No. 10, Unit No. 1
Combined Locks, WI
Midwest Paper Group
540 Prospect Street
Combined Locks, WI 54113
The L&S Advanced Excitation System (AES) Automatic Voltage Regulator was selected to replace the existing Electric Machine Voltage Regulator at the Midwest Paper Group, Combined Locks Powerhouse No. 10 Unit #1 synchronous generator. Midwest Paper Group choose the AES for its advanced monitoring and control features, the comfort they felt in L&S Electric’s excitation engineering expertise, the L&S Electric provided 24/7 product support, the two (2) year warranty, the AES’s competitive price, and the commercially available spare parts.
The Unit #1 synchronous generator’s rated output is 7.5 MW at 12.0 kV with a main field rating of 240 DC amps at 125 DC volts. The generators main field is fed from the unit’s brushless rotating exciter with field requirements of 18 DC amperes at 32.5 DC volts at rated load and 0.9 power factor. The input power to the AES AVR was provided from the 120 volt, 1-phase AC station service bus.
The Midwest Paper Group AVR is a LS-AES-VR-EXC-PB-30 Voltage Regulator System. The voltage regulator included the AES’s standard features; a digital excitation controller with Ethernet IP communications, a 30-amp, full wave rectifier bridge assembly, an AC input breaker, AC field flashing, rotating exciter diode monitoring, an MOV for over excitation protection, an AC filter, a DC filter, and a holding resistor all on a custom subpanel for installation in to the customer’s existing voltage regulator cabinet. The AES’s 15-inch color touchscreen (OIT) was supplied loose for remote installation in the customer’s control room.
The L&S Electric project provided services including the design and supply of the AES excitation elementary diagrams, the wiring diagrams, the assembly diagrams, operation & maintenance manual, installation engineering (cut-ins), installation supervision services, and the AES commissioning with onsite AES training.
Additionally, redundant protection relays were provided as part of the project. The redundant protective relays provided the IEEE functions 25A (auto synchronizer), 32 (reverse power), 46 (reverse current), 50/51V (AC Inverse Time Overcurrent), 59G (neutral overvoltage), 67 (AC Directional Overcurrent), 81OU (over/under frequency), and 87 (differential). The protection upgrade also included the supply of a protective relay add on RTD module for monitoring the unit RTDs thru the new protection relay’s front screen and providing an alarm indication via a contact output indicating an RTD over temperature condition for the monitored RTDs. The redundant protective relays with test switches were provided on a face plate and installed in the existing protection cabinet.
The unit was installed June 2017.