PFC Lite. How it works OMNIVERTER. OMNIVERTER November 14, 2015 Slide 1

Transcription

1 How it works OMNVERTER November 14, 2015 Slide 1 OMNVERTER

2 How it works PFC Utility Displacement Power Factor correction -By injecting reactive current at the fundamental frequency either leading or lagging power factor problems can be corrected. Low order Harmonics - njecting harmonic current equal but opposite to the load harmonic currents allows harmonics to be corrected. Load mbalance - njecting negative sequence current equal but opposite to the negative sequence current in the load current allows imbalance to be corrected. Voltage control when voltage threshold is exceeded reactive current is injected to boost the voltage or absorbed to reduce the voltage. OMNVERTER November 14, 2015 Slide 1 OMNVERTER

3 How it works nverter operation The PFC inverter creates an AC voltage internally via its 6 GBT switches using Pulse Width Modulation (PWM) This AC voltage can be adjusted in phase and amplitude with respect to the utility. PWM Waveform generated by the rectifier GBT s Red Waveform Blue Waveform nverter PWM choke + Utility DC bus OMNVERTER November 14, 2015 Slide 1 OMNVERTER -

4 How it works Reactive current control The PFC Lite controls the current output from the inverter bridge by adjusting the voltage at the point of connection to the utility The images below are an example only as the PFC voltage will be only slightly above or below the utility voltage PFC voltage > Utility voltage PFC voltage = Utility voltage PFC voltage < Utility voltage Capacitive current flow No current flow nductive current flow OMNVERTER November 14, 2015 Slide 1 OMNVERTER

5 How it works Transducer connection PFC Lite operates in closed loop and needs voltage and current feedback Voltage feedback is internal to the PFC Current feedback must be supplied from point of correction The PFC has a 5A CT input (1A optional) Low Voltage PFC Lite Point of common coupling (PCC) Current Feedback (CT) Loads OMNVERTER November 14, 2015 Slide 1 OMNVERTER

6 How it works nstallation: Power & CT terminals CT inputs OMNVERTER November 14, 2015 Slide 1 OMNVERTER

7 How it works Control Modes Two primary control modes Power Factor - This is the most common mode used for true power factor or dynamic power factor correction applications and in data center applications. Voltage Control For specialty applications where the voltage is controlled by injecting or absorbing reactive power. Used for Motor Starting and nrush Voltage Dip applications. Additional Functions (work at the same time as one of the primary control modes) Harmonic filtering mbalance Voltage clamping OMNVERTER November 14, 2015 Slide 1 OMNVERTER

8 How it works - Power Factor Mode Power Factor Band A lower and upper limit for power factor is set. 1.0 PF 0.9 PF PFC Lite in standby PFC provides inductive current Upper PF limit PFC provides capacitive current Power Factor Set point Leading (capacitive) Lagging (inductive) Power factor is corrected to the target value. User controls: OMNVERTER November 14, 2015 Slide 1 Mode configuration User Controls Example Power Factor Band Upper PF limit Lower PF limit 1.0 (unity) 0.9 (lagging) Power Factor Setpoint Desired PF 0.95 (lagging) OMNVERTER

9 How it works Voltage Control Mode Voltage Control The PFC Lite receives a voltage reference. The internal controller compares the measured voltage. f the voltage is below the reference, capacitive reactive power is injected. f the voltage is above the reference, inductive reactive power is absorbed. User controls: Mode Configuration User Controls Example Voltage control Voltage setpoint 1.0pu (1.0 x the system voltage) OMNVERTER November 14, 2015 Slide 1 OMNVERTER

10 How it works Harmonic Filtering Function Harmonic Filtering Cancels two harmonic frequencies, 5 th and 7 th harmonic. User controls: Mode configuration User control Example Harmonic Filtering Filter 1 5 (5 th harmonic) Filter 1 current limit 0.5 (50% of PFC current) Filter 2 7 (7 th harmonic) Filter 2 current limit 0.2 (20% of PFC current) OMNVERTER November 14, 2015 Slide 1 OMNVERTER

11 How it works mbalance Function mbalance (Negative sequence) Correction Cancels negative sequence (imbalance) voltage or current User controls: Mode configuration User control Example mbalance Current Limit 0.3 (default allows 30% of inverter current) OMNVERTER November 14, 2015 Slide 1 OMNVERTER

12 How it works Voltage Clamping Function Voltage clamping Boost or absorb reactive current when voltage thresholds are breached User controls: Mode configuration User control Example Voltage clamping (over rides other modes) Over voltage limit 1.2 (default allows 120% voltage) Under voltage limit 0.8 (default allows 80% voltage) OMNVERTER November 14, 2015 Slide 1 OMNVERTER

13 How it works Power module redundancy (Power rating: 1.5 MVAr) Traditional Converter Filter nverter Filter nverter Avaliable power 0 kvar / 0 % MTTR many hours Modular PFC Lite without reduncancy Avaliable power 0 kvar / 0 % (fault with one module stops the whole system) MTTR 30min PFC Lite advanced redundancy Avaliable power kvar KVA / / 92.9% 94% 15 Mins (Fault MTTR in 30min one module or stops continue only operation affected module until scheduled pair) maintinance OMNVERTER November 14, 2015 Slide 1 OMNVERTER

14 How it works - Power Factor, Harmonics and mbalance demo 35 kw resistive, 80 kvar inductive, 5 th harmonic, mbalanced load PF = 0.96 PFC Lite OFF PFC Lite ON (PF 0.98) OMNVERTER ABB 23/10/2013 November Slide 14, 2015 Slide 1 OMNVERTER