VSC Flashcards
Is VSC bidirectional? And what can it potentially operate as?
Yes. It can potentially work as rectifiers or inverters
What converters are mainly used in renewable generation?
Three-phase AC-DC(or DC-AC)
What can VSC independently control?
Active and reactive exchanges with the AC system
What does MPPT stand for?
Maximum power point tracking
What does MPPT measure in
- PV systems
- Wind systems
PV systems:
Optimal DC voltage and current are defined for the PV modules for a specific irradiance
Wind systems:
Optimal rotor speed and torque of the wind turbine are defined generator for a specific wind speed
What three phase converter is mainly used in PV systems?
AC-DC converters, or PV inverters as they are usually called
Which configuration is mainly used in wind applications?
Back-to-back configuration = 2 three-phase VSC AC-DC converters connected at the DC side
What does the power converters control when achieving the optimal operations points?
- in PV modules
- in WT generators
PV: applied DC voltage
WT generators: currents & frequencies of the WT generators
Active power
P
Reactive power
Q
PLL
Phase Locked Loop
It is the “eyes of the system”, the tracking. Allows us to obtain the angle of the grid voltage. Obtaining its orientation is basic to establish an adequate converter control
Inner Current loop
Permita the current regulation flowing through the AC-side of the converter.
Allows for tracking current references defined by the outer control layers, and limit current flowing through the converter
Outer control loop
Defines control mode of the converter. Four modes:
- active & reactive power control (open control references)
- active & reactive /voltage power control (closed loop control)
- DC voltage & reactive /voltage control (closed loop control)
- modulation voltage application through converter transistors (SPWM, SVPWM)
