Solutions Intelligent Motor Control • Allen-Bradley PowerFlex ® 700 AC drives from Rockwell Automation were DirectCoupled ® with Nextek Power Systems’ own Power Gateway to deliver precise motor torque and speed when powering the HVAC system. Results Energy Savings • By using the PowerFlex 700 AC drives with the exposed DC bus, energy savings were increased by 10 percent since the DC power from the solar panels avoided the DC to AC excursion usually imposed by inverter-based systems. • The drives allow the motors to become a DC load for the Nextek system, seamlessly transitioning between the grid and solar PV. • The system can be throttled back to idle to match the energy needs of the HVAC system. In full sun, the drives are 100 percent solar-powered. Background Home to more than 750,000 residents, the town of Hempstead, N.Y., is setting an example for money- and energy-saving “green” innovation in local government. Answering a challenge from Town Supervisor Kate Murray to find alternative energy solutions that create savings for taxpayers, the town hired Hauppauge, NY based Nextek Power Systems to bring its advanced grid-connected smart power platform to the installation of a 40 –KW solar photovoltaic system on the southern face of the Hempstead Town Hall. The solar PV system will power part of the building’s HVAC system. Challenge As energy prices continue to increase, individuals and organizations alike are identifying different ways to control energy costs. The Town of Hempstead officials recognized the opportunity to innovatively work with Nextek Power Systems to set a green precedent locally and nationally. The solar transition also gave the town an opportunity to better match the HVAC system motors with adjustable frequency drives improving operational efficiencies. Answering Murray’s challenge, town officials chose the town hall site for its central role in community affairs and its ability to showcase solar power use to power not just the return air fans for the building, but also the DC lighting in the supervisor’s office and a conference room. Ron Masters, commissioner of conservation and waterways for the town, was familiar and confident with Brown to Green: Town of Hempstead Uses Solar Energy to Power Town Hall HVAC System The Town of Hempstead, Nextek Power Systems and Rockwell Automation Use Clean Air Act Settlement to Set National ‘Green’ Precedent The Town of Hempstead is setting a “green” precedent by using solar energy to power the Town Hall HVAC system. At full sun, the HVAC system is 100% solar-powered.
Transcript
Solutions Intelligent Motor Control
• Allen-Bradley PowerFlex® 700 AC drives from Rockwell Automation were DirectCoupled® with Nextek Power Systems’ own Power Gateway to deliver precise motor torque and speed when powering the HVAC system.
ResultsEnergy Savings
• By using the PowerFlex 700 AC drives with the exposed DC bus, energy savings were increased by 10 percent since the DC power from the solar panels avoided the DC to AC excursion usually imposed by inverter-based systems.
• The drives allow the motors to become a DC load for the Nextek system, seamlessly transitioning between the grid and solar PV.
• The system can be throttled back to idle to match the energy needs of the HVAC system. In full sun, the drives are 100 percent solar-powered.
BackgroundHome to more than 750,000 residents, the town of Hempstead, N.Y., is setting an example for money- and energy-saving “green” innovation in local government.Answering a challenge from Town Supervisor Kate Murray to find alternativeenergy solutions that create savings for taxpayers, the town hired Hauppauge, NYbased Nextek Power Systems to bring its advanced grid-connected smart powerplatform to the installation of a 40 –KW solar photovoltaic system on thesouthern face of the Hempstead Town Hall. The solar PV system will power part of the building’s HVAC system.
ChallengeAs energy prices continue to increase, individuals and organizations alike areidentifying different ways to control energy costs. The Town of Hempsteadofficials recognized the opportunity to innovatively work with Nextek PowerSystems to set a green precedent locally and nationally. The solar transition alsogave the town an opportunity to better match the HVAC system motors withadjustable frequency drives improving operational efficiencies.
Answering Murray’s challenge, town officials chose the town hall site for itscentral role in community affairs and its ability to showcase solar power use topower not just the return air fans for the building, but also the DC lighting in the supervisor’s office and a conference room. Ron Masters, commissioner ofconservation and waterways for the town, was familiar and confident with
Brown to Green: Town of Hempstead Uses SolarEnergy to Power Town Hall HVAC System
The Town of Hempstead, Nextek Power Systems andRockwell Automation Use Clean Air Act Settlement to Set National ‘Green’ Precedent
The Town of Hempstead is setting a “green” precedent by using solar energy to power the Town Hall HVAC system. At full sun,the HVAC system is 100% solar-powered.
Nextek Power Systems, a leader in DCpower networks and experienced infacilitating alternative energy projects.
SolutionsNextek Power Systems worked with thelocal Allen-Bradley® distributor, Mid-Island Electrical Supply of Commack, NY,to integrate the Nextek Power Gatewayand 40-kW of PV photovoltaic (PV)panels on the southern face of the townhall. The Power Gateway is also DirectCoupled® to two Allen-Bradley PowerFlex®AC drives from Rockwell Automation,creating a direct pathway for the clean DC power generated at the panels into the building’s HVAC system. Nextek’sPower Gateway eliminates the need for aninverter and bypasses the rectifier on thefront end of the drives, improving energycapacity by approximately 10 percent.
“We wanted reassurance in this newapplication that the technology used washigh quality and trusted,” said Paul Savage,president, Nextek Power Systems.“Rockwell Automation was a natural firstchoice, and the results were great.”
At night or during periods of low solaroutput, the Nextek Power Gatewayseamlessly reverts back to grid power untilthe renewable source is available again.Because the system is Direct Coupled®, it is not subject to anti-islanding regulationswhich require conventional grid-tied solarsystems to shut down in the event of a gridfailure. The Power Gateway also enablesload shaping and peak mitigating with itsadvanced metering, monitoring, andcontrols capabilities. During daytime peakusage, the HVAC system will be poweredprimarily by the solar PV array, reducingthe burden on the local utility.
ResultsThe solar energy system was funded through$260,000 from the settlement of a clean airlawsuit against a power company in 2003.Under the settlement, the power companywas required to pay $2.1 million for airpollution mitigation projects in New YorkState. The $2.1 million is being administeredby the New York State Energy Researchand Development Authority (NYSERDA)to install solar energy equipment ongovernment-owned buildings in the state.
“Many people aren’t aware of commercialHVAC operations and the energy-savingopportunities with these motor-drivenapplications,” said Masters. “Demonstratingthe value of these types of installations is important to furthering publicunderstanding, and we see many other flat-roofed buildings that could be usingand benefiting from this technology.”
AC drives, which act as controllers to protect motors and improve motorperformance, have long benefited HVAC fan and pump applications, butHempstead’s solar-power supply is unique.Rockwell Automation has a 100-yearlegacy in controlling motors in virtuallyevery conceivable application, includingHVAC, but pulling DC power off solarpanels was a first. Masters is convinced thatthe three-phase Allen-Bradley PowerFlexAC drive with the DC source gave thetown the ability to win the NYSERDAaward. In addition, the accessibility of theDC bus made it simple to Direct Couplethe drive to Nextek’s equipment.
“The success we’ve had with Allen-BradleyPowerFlex drives is an efficiency we didn’tanticipate when we started the project,”said Masters. “With the variable frequencydrives, we can set and throttle back to idlethe system to match our energy needs, andthe exposed front end of the drive addsadditional economy to the system.”
Townspeople and officials are pleased withthe new system and it is setting an exampleacross Long Island.
“To date, it has been a tremendous success,”said Masters. “It has performed beautifully.”
With the success of the town hallinstallation, Masters anticipates futuresuccesses in upcoming “green” applications.
Forty-kW of solar photovoltaic panels on the southern side of Town Hall collect solar energy.
The results mentioned above are specific to Nextek’s use of Rockwell Automation products in conjunction with other products. Specific results may vary for other customers.Allen-Bradley, PowerFlex and Rockwell Automation are trademarks of Rockwell Automation Inc. DirectCoupled is a trademark of Nextek Power Systems.
