General Introduction
Targets for future sustainable electrical networks
The electricity is suffering from a constraint irrefutable: At any moment, electrical systems
must ensure a balance between production and consumption, while maintaining a satisfactory
voltage. Historically, grid reliability was mainly assured by having excess capacity in the
system with unidirectional flow to dispersed consumers from centrally dispatched large power
plants. To combat climate change and increase the EU’s energy security while strengthening
its competitiveness, the EU Heads of State and Government have set a series of demanding
climate and energy targets to be met by 2020, known as the "20-20-20" targets:
• A reduction in EU greenhouse gas emissions of at least 20% below 1990 levels,
• A 20% reduction in primary energy use compared with projected levels, to be
achieved by improving energy efficiency,
• 20% of EU energy consumption coming from renewable resources.
Current limitation of the PV resource
Today, renewable energies are considered as a potential solution for greenhouse gases
emissions reduction and energy safety. Fueled by economic, environmental and social drivers,
the penetration of photovoltaic generators rises in distribution networks. Thanks to its
operation without noise and gas emission, it can be easily installed outdoor and on roofs. But
the development of grid-connected PV generation is limited by the intermittent power
generation and time-lag between the PV electrical production and the real consumption. A
massive deployment of PV systems complicate the balancing between production and
consumption, that may cause blackouts if it is disturbed
A new concept: the PV based active generator
Because of the intermittency of PV power generation, PV panels can not be used as a
stable, reliable and controllable power source and can not provide ancillary services like
conventional generators. The topic of this thesis is the transformation of a PV generator into
an active generator by using an embedded energy storage system and a local energy
management system for the coordination of inner sources. Long-term energy storage batteries
are used to shave the midday PV power peak and provide a complementary power supply
during the night. Fast dynamic ultracapacitors storage can smooth the generated PV power,
compensate the power gap and absorb the instantaneous high power peaks.
Local controller for a dispatched management
Three sources with different characteristics must be coordinated inside the PV active
generator. So for ensuring an optimal operation, a local energy management system of the PV
based active generator has to be developed to enable:
• the management of the renewable energy intermittency and resources,
• the quality of power supply,
• the energy level management,
• the power system protection,
• the provision of grid ancillary services.
This PV based active generator is then an additional controllable dispersed generation,
which have to be dispatched. In the context of a large scale development of PV based active
generators, the operation mode of the electric network will have to be changed.
LINK
https://tel.archives-ouvertes.fr/tel-00586393/file/Lu_Di_DLE.pdf
