6-4
Engineering Guide CDA3000
6 Selection of supplementary components
Procedure in practise
In order to establish whether your application conforms to the
EN61800-3/ IEC1800-3 standard or another standard, you must ascertain
the equivalent inverter referred to your line transformer. Based on the
equivalent inverter and the line impedance, you then calculate the voltage
distortion THD. You need to weight the result relative to the overall system
ratios.
Theoretical calculation of the system ratios can only serve as a guide. If
the theoretical calculation reveals that you are at the limits specified in the
standards, you should always carry out a system analysis by means of
systems analysts (measurement duration typically seven days). Only in
this way is a practise-oriented assessment of your power supply system
possible.
6.1.2 Operation with
reactive current
compensation
system
Estimation of the resonance point
Capacitors in systems with inverters cause oscillations which additionally
distort the mains voltage. The frequency of those oscillations depends on
a number of different system parameters. Reactive current compensation
systems may under certain circumstances impair the quality of the volt-
age waveform.
The compensation system forms an anti-resonant circuit together with the
transformer inductance, which in the worst case may enter into resonance
with a harmonic frequency generated by the inverter. As a result the
capacitor battery draws the corresponding harmonic from the system,
possibly leading to overloading of the capacitor battery.
.
Figure 6.1 Anti-resonant circuit
To Next Page
Loading...
