Effects of Daylight Harvesting on Electronic Lighting Control Copyright © 2004 Joshua Scot Lester - Calvin College Engineering 315 Control SystemsTriac DimmingDaylight Harvesting SystemPhotosensor vs. PhotocellSpectral and Spatial ResponseInput characterization Spatial responseInput characterization Spectral responseOpen-loop Proportional ControlClosed-loop Proportional ControlControl Algorithm Closed-loop proportional controlSample of Daylight Harvest ControlPersonal controlsSlide 13ReferencesEffects of Daylight Harvesting onElectronic Lighting Control Copyright © 2004 Joshua Scot Lester - Calvin College Engineering 315 Control Systems© 2004, Joshua S. Lester 2Triac DimmingVbVmsin eCRsin1 2C2 R2where tan1CR Vcis the capacitor voltageVbis the breakover voltageZero-crossingA dimmer controls the power to the load through a solid state switch or triac. The triac is synchronized to the AC line through signals obtained at zero crossingsTriac-firingThe zero crossing signals are then used to fire the triac to give the correct dimmed waveform© 2004, Joshua S. Lester 3Daylight Harvesting System[10] Closed-Loop Lighting Control System Diagram© 2004, Joshua S. Lester 4Photosensor vs. Photocellphotocell the light sensitive component inside the photosensor. Photosensoran entire product including the housing, optics, electronics, and the photocell.© 2004, Joshua S. Lester 5Spectral and Spatial Response[1] Closed-loop lighting control block diagram© 2004, Joshua S. Lester 6Input characterization Spatial responseThe input to a photosensor is optical radiation infrared (IR)ultraviolet (UV) radiation For lighting control it is measuring the distribution of luminaire intensity[2] Photosensor Spatial Response Spectrum[2] Photosensor Spatial Response Spectrum© 2004, Joshua S. Lester 7Input characterization Spectral responsesensitivity to optical radiation of different wavelengths [3] Spectral Response Chart[4] Optical Radiation Chart© 2004, Joshua S. Lester 8Open-loop Proportional ControlOpen-loop control has one adjustable parameterthe constant of proportion between the control voltage and the optical signal [5] Savings in the Spotlight [7] Open-loop control© 2004, Joshua S. Lester 9Closed-loop Proportional Control2 ADJUSTABLE PARAMETERS:1. SLOPE ( open-loop response curve )2. OFFSET ( commissioning )Closed-loop control algorithma.k.a "sliding set point control"[5] Savings in the Spotlight [8] Closed-loop control© 2004, Joshua S. Lester 10Control AlgorithmClosed-loop proportional controlThe ceiling illuminance is 100 lux with no daylight present (from the 5:1 work-plane: ceiling ratio)Desired work-plane illuminance 500 luxDaylight enters the room and adds 250 luxRate of dimming was set to -0.25% per lux0.25% per lux X 250 lux = 62.5% This sets the luminaire light output to: 100 lux - (62.5% X 100 lux) = 37.5 lux. The total ceiling illuminance is now 37.5 lux + 250 lux = 287.5 lux. [9] CL Example© 2004, Joshua S. Lester 11Sample of Daylight Harvest Control[6] Simulation of lighting levels in modeled room.© 2004, Joshua S. Lester 12Personal controlshttp://www.vantagecontrols.com/© 2004, Joshua S. Lester 13Big Picture© 2004, Joshua S. Lester 14ReferencesI. http://www.lrc.rpi.edu/programs/nlpip/tutorials/photosensors/img/controlMostImportantGraphic.jpgRensselaer Polytechnic Institute, Troy, NY 12180 USAII. http://www.lrc.rpi.edu/programs/nlpip/tutorials/photosensors/polar.aspRensselaer Polytechnic Institute, Troy, NY 12180 USAIII. http://www.lrc.rpi.edu/programs/nlpip/tutorials/photosensors/img/spectralgraph.jpgRensselaer Polytechnic Institute, Troy, NY 12180 USAIV. http://www.lrc.rpi.edu/programs/nlpip/tutorials/photosensors/img/small5.jpg Rensselaer Polytechnic Institute, Troy, NY 12180 USAV. Savings in the Spotlight By John L. Fetters, published June ’02 VI. http://eetd.lbl.gov/btp/pub/designguide/section8.pdf VII. http://www.lrc.rpi.edu/programs/nlpip/tutorials/photosensors/img/openLoopProp.jpg Rensselaer Polytechnic Institute, Troy, NY 12180 USAVIII. http://www.lrc.rpi.edu/programs/nlpip/tutorials/photosensors/img/closedLoopProp.jpg Rensselaer Polytechnic Institute, Troy, NY 12180 USAIX. http://www.lrc.rpi.edu/programs/nlpip/tutorials/photosensors/img/closedLoopExample.jpg Rensselaer Polytechnic Institute, Troy, NY 12180 USAX. http://www.lrc.rpi.edu/programs/nlpip/tutorials/photosensors/img/photosensors%20fig.jpg Rensselaer Polytechnic Institute, Troy, NY 12180
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