Hello, and welcome to this video
about how photovoltaic self-consumption
impacts the power quality of electrical installations.
Photovoltaic systems can generate three different types of disturbances
on the AC side of the electrical installation:
DC residual current, harmonics, and unbalance.
In this video, I will explain their origins, potential impact,
and provide recommendations on measures that can be taken.
Let’s start with DC residual current.
Photovoltaic inverters may generate DC residual current in the AC circuit,
depending on their technology.
There are two types of photovoltaic inverters:
Inverters with insulation transformer,
which cannot inject DC residual current on the AC side,
and inverters without galvanic isolation,
which inject DC residual current on the AC side,
unless measures to prevent this are taken by the inverter manufacturer.
DC residual current has an impact on the choice of protection equipment.
In particular, as stated by international standards,
residual current devices installed on the AC side of the photovoltaic system
must be type B, unless:
there is an isolation between the AC side and the DC side
or, inverter manufacturer’s instructions indicate that type B are not required.
Another potential disturbance is harmonic distortion.
Like all electronic equipment, photovoltaic inverters
inject harmonics into the electrical installation.
Photovoltaic inverters convert DC power into AC
by using Pulse Width Modulation switching.
This method allows control of the magnitude and frequency of the inverter output,
but generates high frequency harmonics.
This harmonic disturbance generally remains within an acceptable range,
because photovoltaic inverters have integrated harmonic filters.
However, the overall harmonic distortion
in the electrical installation can be higher,
because the harmonics injected by the photovoltaic inverters
are combined with those generated by the loads.
Therefore, it is recommended to supervise the harmonics
in the electrical installation.
And if the overall harmonic level is over the acceptable limits,
harmonic mitigation measures
such as active or passive filters can be added.
A third potential disturbance is unbalance.
Unbalance can be generated if single phase photovoltaic inverters
are connected to a three-phase electrical installation.
To avoid unbalance,
it is recommended to connect the photovoltaic inverters
evenly across the three phases, as shown here.
In summary, photovoltaic inverters may generate power quality disturbance.
Although inverter manufacturers have made significant efforts
to limit these disturbances, be sure to:
supervise the power quality of the electrical installation
choose type B residual current devices in the presence of DC residual current,
and, connect single phase inverters across the three phases.
I hope this video was helpful for you.
Thank you for your attention!
And see you in one of our next videos!