Integration of residential distributed generators and heat pumps into the low voltage grid from a voltage level perspective
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Date
2016
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Abstract
In context of combating climate change, carbon saving goals are defined on European
level. One effect of this is the increased installation of photovoltaic, heat pump and combined
heat and power systems on low voltage distribution grids. As the distribution grid
was not designed to handle this quantity of distributed generators and large loads, there
are undesirable influences. The voltage level is identified as the main issue in low voltage
grids. From the point of view of a manufacturer of such devices the influence on possible
connections to the low voltage grid and necessary measures are of interest. The characteristic
voltage influence of combined-heat-and-power, heat pump and photovoltaic systems is
evaluated. In order to quantify the influence, a 2020 penetration scenario of these devices
is developed using market expectation data. It is shown that different grids show violations
of the voltage limits according to EN 50160 and measures for voltage control are therefore
necessary in order to integrate the anticipated number of appliances. A range of measures
are evaluated regarding effectiveness, system operator and end-user economics, comfort
and environmental influence. The measures are based on grid operator equipment or enduser
appliances.
Battery storage based measures are identified as effective but very expensive compared
to other solutions. The most cost efficient measure is the installation of on-load
tap-changers at the low voltage transformers. Demand side management of heat pumps
can be effective under certain circumstances but end-user comfort is endangered here.
Considering the total economics, demand side management is more expensive than the
use of on-load tap changers. From a manufacturer perspective there are no additional
requirements for end-user appliances identified for voltage control on low voltage grids.
Connection restrictions and the grid planning process have to be reviewed in order to enable
cost efficient integration of the anticipated number of appliances in 2020. The results
are validated for increased generator penetrations in a ’maximum PV’ scenario.
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Keywords
distributed generator, heat pump, low voltage grid, voltage level