Abstract
Solar photovoltaic (SPV) energy is one of the promising and dominant renewable energy sources for clean and sustainable electricity production. Typically, a power conditioning unit (PCU) along with a low-frequency transformer on the AC side is utilized to integrate the photovoltaic (PV) source with the grid. However, they offer low efficiency, high cost, and low power density. Transformerless inverters gained more attention in grid-connected PV systems due to demands of power density, high efficiency, reliability, and low cost. However, leakage current is produced through the stray capacitances between the PV array and the ground. It is generated due to the fluctuation of common-mode voltages between PV neutral and grid. Also, it enhances DC injection into the grid due to the absence of galvanic isolation. Consequently, it causes fundamental safety problems and the degradation of the system’s performance. This chapter aims to study and compare leakage current minimization approaches through converter topology modifications and pulse width modulation schemes in transformerless PV systems. The key performance of each inverter topology in terms of leakage current is holistically evaluated through simulation studies in MATLAB software. Finally, the merits and demerits of each power converter topology for transformerless solar systems are summarized in this chapter.
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Abbreviations
- P :
-
Power (W)
- D :
-
Diode
- S :
-
Switching device
- L :
-
Inductor (mH)
- I PV :
-
PV array output current (A)
- V PV :
-
PV array output voltage (V)
- C pv :
-
Stray capacitance of PV panel (μF)
- V dc :
-
Input DC voltage (V)
- Van, Vbn, Vcn:
-
Phase voltages of converter (V)
- n :
-
Neutral point
- a, b, c :
-
Terminals of a 3-phase system
- V 0 to V 7 :
-
State vectors
- I leakage :
-
Leakage current (A)
- V CM :
-
Common-mode voltage (V)
- R g :
-
Ground resistance (Ω
- PV:
-
Photovoltaic
- PCU:
-
Power conditioning unit
- PVS:
-
Photovoltaic systems
- IEA:
-
International Energy Agency
- PVES:
-
Photovoltaic energy systems
- Hz:
-
Hertz
- LFT:
-
Low-frequency transformer
- HFT:
-
High-frequency transformer
- kWh:
-
Kilowatt hour
- THDs:
-
Total harmonic distortions
- EMI:
-
Electromagnetic interference
- CMV:
-
Common-mode voltage
- DC:
-
Direct current
- MPPT:
-
Maximum power point tracking
- CI:
-
Central inverter
- SI:
-
String inverter
- PWM:
-
Pulse width modulation
- UPS:
-
Uninterrupted power supply
- RMS:
-
Root mean square
- AC:
-
Alternating current
- kHz:
-
Kilo Hertz
- IGBTs:
-
Insulated gate bipolar transistors
- V:
-
Volt
- kW:
-
Kilo watt
- GW:
-
Giga watt
- VSI:
-
Voltage source inverter
- CSI:
-
Current source inverter
- MPPT:
-
Maximum power point tracker
- MPP:
-
Maximum power point
- I-V:
-
Current versus voltage
- P-V:
-
Power versus voltage
- A:
-
Ampere
- s:
-
Seconds
- MOSFET:
-
Metal oxide semiconductor field-effect transistor
- W:
-
Watt
- LC:
-
Inductor-capacitor
- SPWM:
-
Sine pulse width modulation
- SVM:
-
Space vector modulation
- NSPWM:
-
Near-state PWM
- AZPWM:
-
Active zero state PWM
- RSPWM:
-
Remote state PWM
- MSVPWM:
-
Multilevel space vector pulse width modulation
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Ronanki, D., Karneddi, H. (2022). Transformerless Three-Phase Solar Photovoltaic Power Conversion Systems . In: Das, S.K., Islam, M.R., Xu, W. (eds) Advances in Control Techniques for Smart Grid Applications. Springer, Singapore. https://doi.org/10.1007/978-981-16-9856-9_9
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