eqGrid is set to improve voltage quality in a demanding IT network in Råde.
Elvia is carrying out the project with support from Enova. Using eqGrid has already
provided valuable measurement data on how power electronics and battery storage perform
in practical grid operation. The results from the installation in Råde show that the
eqGrid hybrid system — a compact «LV OLTC» unit combined with a battery system — delivers
a documented improvement in voltage quality in demanding IT networks, and that the unit can
be commissioned with minimal time in the field compared with traditional grid reinforcement.
Jan Holth, quality inspector at Elvia, checks the eqGrid system.
Background and problem statement
A growing share of asymmetric loads and unregulated solar generation is putting voltage
quality in the low-voltage grid under pressure.
Pressure on the low-voltage grid is rising
More customers charge their EVs single-phase, and solar installations feed in power
without regulation. Both make it harder to maintain good voltage quality in the
low-voltage grid. As a result, grid operators increasingly experience voltage deviations,
flicker and unbalanced phase voltages. This must be handled in line with the requirements
of the Norwegian Power Quality Regulations (FoL). Traditional measures, such as replacing
cables or building new transformer stations, require large investments and take a long time.
The «eFlow and OLTC» pilot project
Elvia is therefore carrying out the «eFlow and OLTC» pilot project, with support from
Enova through the «Flexibility in the energy system» programme. The goal is to find
solutions that are more flexible and more cost-effective for society. The solution builds
on ten years of development work at the technology company Energea — much of it in close
collaboration with Elvia. Since it began in 2014, development has taken place in strategic
and technical partnership with the Swiss power-electronics pioneer Studer Innotec.
The supplier eqGrid has been established as a separate company to bring the technology to
the Nordic and international markets.
The unit fully installed and connected in Råde.
Efficient logistics and installation in Råde
Elvia installed an eqGrid hybrid system in a weak grid segment in the municipality of Råde
to test the solution in real operation. The grid is a 230V IT network — a topology common
in Norway, but particularly vulnerable to voltage drop and phase imbalance in long radials
with low short-circuit capacity.
The pilot demonstrated a streamlined process from production to full operation, led by
Elvia's project manager Kjell Anders Tutvedt:
1
Prefabrication and testing
The system itself was built, configured and quality-tested in controlled conditions at
the switchboard manufacturer Stevid Elektro. This minimised the risk of technical faults
during assembly in the field.
2
On-site preparations
Before delivery, a local contractor prepared the installation site for Elvia. A short
cable trench was dug for the connection to the pole, and local earthing was laid. A
prefabricated concrete slab — with a cable feed-through and ready-made mounts for the
cabinet — was then placed on a layer of compacted gravel.
3
Fast commissioning and installation
SpedTrans transported the fully tested system to Råde, where Elvia's fault engineer
Tommy Olsen and Jan Holth were ready and waiting for installation. The crane truck
lifted the module into place on the concrete slab, and the cables were connected.
From the crane truck's arrival to the hybrid system being fully operational: 2.5 hours.
A prefabricated concrete slab serves as the foundation.The crane truck lifts the eqGrid module into place.Tommy Olsen from Elvia connects eqGrid to the power grid.
Technical functionality in grid operation
The system Elvia commissioned in Råde uses advanced power electronics and inverter
technology from Studer Innotec. At the core of the solution are two regulating mechanisms
that work together.
On-load tap changer («LV OLTC»)
An on-load (no-break) tap changer handles the slow voltage variations (§ 3-3) by adjusting
the base voltage according to trends in the daily load. Tap changes typically occur a few
times a day and relieve the battery.
Control system (energiScada™)
The control system monitors the installation and gives users access to real-time analysis
and visualisation. Its main function is to control the tap changer and the power-electronics
parameters so that the system improves voltage quality as effectively as possible.
Battery system
The fast-acting battery system smooths out voltage changes by injecting or absorbing
current. This happens almost instantaneously, and fast enough to dampen rapid voltage
variations (§ 3-4) and flicker (§ 3-5).
Active phase balancing and load relief in the IT network
The Råde pilot examined in particular how well the system evens out unbalanced load between
the phases (voltage unbalance, § 3-6). In an IT network, unbalanced load causes significant
voltage losses and shifts the neutral point. This increases technical losses (I²R) and
reduces how much power the grid can carry.
Studer Innotec's power electronics shift active power between the phases in real time, so the
load is distributed evenly. Measurements from Elvia's grid confirm that this reduces the peak
current in the most heavily loaded phase. The result is less strain on the upstream
transformer station and freed-up capacity in the existing cable network — with little need
for the battery.
Impact on harmonic voltage distortion (THD)
Magnetic voltage boosters are a common option for voltage support in distribution grids. The
challenge is that they regulate by means of magnetic saturation, which creates non-linear
currents. This can introduce harmonic voltages and increase total harmonic distortion (THD)
— something that is strictly regulated under FoL § 3-7.
The pilot measurements show that eqGrid corrects the voltage level in Elvia's IT network
without adding THD beyond the FoL limits. The system delivers a clean sine wave to the grid.
In Råde, a voltage booster was located about 600 metres downstream from the substation. It
was switched off after eqGrid was installed.
Conclusion and the way forward
The experience from Råde and the «eFlow and OLTC» project shows that on-load tap changing
combined with fast-acting power electronics meets the FoL power-quality requirements, even
in challenging IT networks.
Together with Energea and Studer Innotec, Elvia has developed an effective tool for
dynamic voltage support and phase balancing over many years of collaboration. The short
installation time and the minimal impact on the terrain in Råde demonstrate the result in
practice. The technology gives grid operators the option to defer or replace traditional,
time-consuming grid investments in areas with capacity constraints.
Tommy Olsen from Elvia and Per Dypvik from eqGrid in front of the fully installed system in Råde.
Documented improvement of voltage quality in a demanding 230V IT network
Commissioned in 2.5 hours on site
Active phase balancing reduces peak current in the most loaded phase
No harmonic voltages (THD) added beyond FoL requirements
An alternative to time-consuming and costly traditional grid reinforcement
