DC-bus energy management of a converter-interfaced renewable energy source comprising an energy storage system

The increasing penetration of renewable energy
sources is strongly linked to the development of voltage source
converters used in their connection to the grid. As a result, in
the near future of an inverter-dominated power system it will
be a requirement for renewable generation to provide ancillary
services in order to compensate for the absence of synchronous
generation. In this scenario, the use of energy storage systems
along with advanced control algorithms mimicking the dynamic
behaviour of the traditional generators will be of utmost importance.
This paper deals with a renewable energy source interfaced
with a voltage source converter and comprising an energy storage
system in the DC bus. Particularly, a new energy management
algorithm for the DC-bus based on a three levels hierarchical
control is proposed, which is able to simultaneously provide
ancillary services, maintain the state of charge of the storage
system within the permissible limits and use it to control the
DC bus voltage. The control strategy is validated experimentally
using a prototype with results evidencing a reliable and stable
operation.