Electricity demand on high voltage net does not add up

[kaskranenburgQ]

In a blank nl 2019 scenario the 'HV demand' curve does not add up to the data in the graph. See screenshot below:

While reviewing the underlying queries I could not figure out how this graph was set up. Some rather confusing queries where used.
For instance, the query used for the 'HV demand' curve is the following

network_hv_demand_curve

and describes the following:

- query = V(GRAPH(electricity_network), demand_curve(hv))
- unit = curve

I looked into this and found it hard to check where the difference comes from. @mabijkerk do you have a way to check this?