PSCAD Simula,on of Grid- Tied Photovoltaic Systems and Total Harmonic Distor,on Analysis Abdulrahman Kalbat Columbia University in the City of New York (Teaching Assistant at UAE University currently on leave ) October th, 0
Paper Structure Abdulrahman Kalbat Columbia University 0/0/0 / PSCAD Model of Grid- Tied Photovoltaic System Detailed descripmon of all model components and the control blocks Total Harmonic Distor,on (THD) Analysis IEEE Std 99-000 IEEE Recommended PracMce for UMlity Interface of Photovoltaic (PV) Systems THD analysis using PSCAD Effects of solar irradiamon on both current and voltage THD
PSCAD Model Of Grid- Tied Photovoltaic System
Pscad Model Of Grid- Tied Photovoltaic System Abdulrahman Kalbat Columbia University 0/0/0 / Model provided by PSCAD support team SolRad CellTemp PV Array Output Capacitor G Tcell V V- Ipv 0000 Vpv T Icon 0.0 [H] 80000 R=0 Icharge dcvltg Idc gt gt gt gt gt Ia_motor gt Ec Eb Ea Timed Breaker Logic Closed@t0 Eab Ebc e- AC Filter Transformer 0V/kV # # P = 0.7 Q = -0.0008 V =.0 A V UMlity Grid kv Solar RadiaMon Cell Temperature Data DC- DC Converter for MPP Tracking - phase Inverter Bridge
Pscad Model Of Grid- Tied Photovoltaic System minimizes the ripple of the PV source current PV Array Output Capacitor Transformer 0V/kV Ipv Icon Idc SolRad CellTemp G Tcell V V- 0000 Vpv T 0.0 [H] 80000 R=0 Icharge dcvltg gt gt gt gt gt Ia_motor gt Ec Eb Ea Timed Breaker Logic Closed@t0 Eab Ebc e- AC Filter # # P = 0.7 Q = -0.0008 V =.0 A V UMlity Grid kv Solar RadiaMon Cell Temperature Data DC- DC Converter for MPP Tracking - phase Inverter Bridge Abdulrahman Kalbat Columbia University 0/0/0 /
Pscad Model Of Grid- Tied Photovoltaic System Opera,ng at Maximum Power Point Incremental Conductance Tracking Algorithm 8 >< >: I/ V = I/V, at MPP I/ V > I/V, left of MPP I/ V < I/V, right of MPP PV Array Output Capacitor! Transformer 0V/kV Ipv Icon Idc SolRad CellTemp G Tcell V V- 0000 Vpv T 0.0 [H] 80000 R=0 Icharge dcvltg gt gt gt gt gt Ia_motor gt Ec Eb Ea Timed Breaker Logic Closed@t0 Eab Ebc e- AC Filter # # P = 0.7 Q = -0.0008 V =.0 A V UMlity Grid kv Solar RadiaMon Cell Temperature Data DC- DC Converter for MPP Tracking - phase Inverter Bridge Abdulrahman Kalbat Columbia University 0/0/0 /
Pscad Model Of Grid- Tied Photovoltaic System Crea,ng MPPT voltage reference PV Array Output Capacitor! Transformer 0V/kV Ipv Icon Idc SolRad CellTemp G Tcell V V- 0000 Vpv T 0.0 [H] 80000 R=0 Icharge dcvltg gt gt gt gt gt Ia_motor gt Ec Eb Ea Timed Breaker Logic Closed@t0 Eab Ebc e- AC Filter # # P = 0.7 Q = -0.0008 V =.0 A V UMlity Grid kv Solar RadiaMon Cell Temperature Data DC- DC Converter for MPP Tracking - phase Inverter Bridge Abdulrahman Kalbat Columbia University 0/0/0 7 /
Pscad Model Of Grid- Tied Photovoltaic System Connect DC system to AC system PV Array Output Capacitor! Transformer 0V/kV Ipv Icon Idc SolRad CellTemp G Tcell V V- 0000 Vpv T 0.0 [H] 80000 R=0 Icharge dcvltg gt gt gt gt gt Ia_motor gt Ec Eb Ea Timed Breaker Logic Closed@t0 Eab Ebc e- AC Filter # # P = 0.7 Q = -0.0008 V =.0 A V UMlity Grid kv Solar RadiaMon Cell Temperature Data DC- DC Converter for MPP Tracking - phase Inverter Bridge Abdulrahman Kalbat Columbia University 0/0/0 8 /
Pscad Model Of Grid- Tied Photovoltaic System Smoothing the inverter output PV Array Output Capacitor! Transformer 0V/kV Ipv Icon Idc SolRad CellTemp G Tcell V V- 0000 Vpv T 0.0 [H] 80000 R=0 Icharge dcvltg gt gt gt gt gt Ia_motor gt Ec Eb Ea Timed Breaker Logic Closed@t0 Eab Ebc e- AC Filter # # P = 0.7 Q = -0.0008 V =.0 A V UMlity Grid kv Solar RadiaMon Cell Temperature Data DC- DC Converter for MPP Tracking - phase Inverter Bridge Abdulrahman Kalbat Columbia University 0/0/0 9 /
Pscad Model Of Grid- Tied Photovoltaic System Voltage adjustment (step up or down) Galvanic insola,on PV Array Output Capacitor Transformer 0V/kV Ipv Icon Idc SolRad CellTemp G Tcell V V- 0000 Vpv T 0.0 [H] 80000 R=0 Icharge dcvltg gt gt gt gt gt Ia_motor gt Ec Eb Ea Timed Breaker Logic Closed@t0 Eab Ebc e- AC Filter # # P = 0.7 Q = -0.0008 V =.0 A V UMlity Grid kv Solar RadiaMon Cell Temperature Data DC- DC Converter for MPP Tracking - phase Inverter Bridge Abdulrahman Kalbat Columbia University 0/0/0 0 /
Total Harmonic Distor,on (THD) Analysis
Total Harmonic Distor,on (THD) Analysis Abdulrahman Kalbat Columbia University 0/0/0 / Harmonics: are sinusoidal components of a periodic wave having a frequency that is at mulmples of the fundamental frequency Generated in PV systems by the converters that are using switching techniques that generate signals that are not perfect sinusoidal. UMlity grid is already being injected with harmonics by the non- linear load ConnecMng PV systems will add a stress on the power quality of the grid.
IEEE Std 99-000 Abdulrahman Kalbat Columbia University 0/0/0 / IEEE Recommended PracMce for UMlity Interface of Photovoltaic (PV) Systems. Total harmonic current distormon shall be less than % of the fundamental frequency current at rated inverter output.. Each individual harmonic shall be limited as follows If odd harmonic à limits in the table If even harmonic à less than % of the odd harmonic limits listed Odd Harmonic Distortion Limit rd 9 th <.0 % th th <.0 % 7 th st <. % rd rd < 0. % Above the rd < 0. %
IEEE Std 99-000 Abdulrahman Kalbat Columbia University 0/0/0 / This standard is valid for medium and high voltage level electric umlity Simulated grid is kv 0 Hz system (medium) Voltage Class Low Voltage Medium Voltage 00 V 9 kv High Voltage 9 kv 0 kv Nominal Line-Line RMS Voltage < 00 V Extra High Voltage 0 kv 00 kv Ultra High Voltage > 00 kv
THD Analysis using PSCAD Abdulrahman Kalbat Columbia University 0/0/0 / CalculaMon of Total Harmonic DistorMon. Fast Fourier Transform (FFT) à Harmonic frequency components magnitude (each index). Using harmonic frequency components Total Harmonic DistorMon (%) Individual Harmonic DistorMon (%) Total Harmonic Distortion Individual Total Harmonic Distortion Individual I_pcc Total Mag Mag Mag Harmonic () () () Distortion X Ph Individual () F F T X Ph () X Ph F = 0.0 [Hz] () dc dc dc
THD Analysis using PSCAD IEEE Std 99-000 Total harmonic current distormon shall be less than % of the fundamental frequency current at rated inverter output.! Abdulrahman Kalbat Columbia University 0/0/0 /
THD Analysis using PSCAD Abdulrahman Kalbat Columbia University 0/0/0 7 / IEEE Std 99-000 Each individual harmonic shall be limited as follows If odd harmonic à limits in the table If even harmonic à less than % of the odd harmonic limits listed
THD Analysis using PSCAD! Abdulrahman Kalbat Columbia University 0/0/0 8 / Expanding the harmonic index to The harmonics with indices from 8 to are violamng the distormon limits, which is 0.%
Solar Irradia,on Effects on Current and Voltage THD Abdulrahman Kalbat Columbia University 0/0/0 9 / IEEE Std 99-000 Limits were established for THD of the current at PCC It is a common pracmce, especially in the case of grid- Med PVs, to pay more ahenmon to current THD analysis. WHY?
Solar Irradia,on Effects on Current and Voltage THD Abdulrahman Kalbat Columbia University 0/0/0 0 / Current THD Vs. Solar IrradiaMon Current THD decreases as the Solar IrradiaMon increases
Solar Irradia,on Effects on Current and Voltage THD Abdulrahman Kalbat Columbia University 0/0/0 / Voltage THD Vs. Solar IrradiaMon Voltage THD is not affected by the varying Solar IrradiaMon
Solar Irradia,on Effects on Current and Voltage THD Abdulrahman Kalbat Columbia University 0/0/0 / Current THD Vs. Solar IrradiaMon PV systems operamng under low solar irradiamon values inject more current harmonics into the umlity grid than at high irradiamon values.
Solar Irradia,on Effects on Current and Voltage THD Abdulrahman Kalbat Columbia University 0/0/0 / This problem might force PV system operators to Disconnect the PV system from the grid to avoid paying the high THD levels penalty specified by the umlity operator. Use beher filtering techniques Passive filters (RLC) Shunt AcMve Power Filters (used for harmonic compensamon)
Thank You Contact Informa,on Abdulrahman Kalbat ak9@columbia.edu akalbat@uaeu.ac.ae