Analysis and Management of the Impacts of
20
Photovoltaics
in
a
Distribution
Network
10
Author: Simon Lewis Supervisor: Iain MacGill Industry Supervisor: Kevin Nuner (Integral Energy) Assessor: Jayashri
Ravishankar
PV System Performance Challenges
Abstract
The prevalence of grid connected Photovoltaics (PV) throughout
the electricity network is increasing due to initiatives such as
generous feed in tariffs and the Blacktown solar cities program.
In fact in the Integral Energy area approximately 150 new
applications for solar panels occur every day. It is the aim of this
thesis to get a practical idea of the impacts that these numerous
PV systems are currently having on the network, investigate the
effect the predicted increased penetration will have via modelling
and to provide recommendations to network service providers
(NSP) on how to best tackle this issue. Results indicate that
current impacts are minimal but future penetrations could cause
problems
A surprising result is the actual generated output from the PV
systems. The generation data analysed suggests that the
average generation is approximately 64% of the rated value.
This limited output was also examined by taking field surveys of
streets with high PV penetrations. This result highlights the
challenges faced by installing a large number of PV systems in
a real scenario, such as orientation and shading issues.
Background
There is growing international concern
over the impacts of the increasing number of
PV systems. In Australia much of the research
has used modelling not practical data. Thus
amongst NSP’s knowledge about the practical integration a large
number of these systems is unknown. Integration issues tend to
occur because PV power production times in residential systems
is at the times of lowest load. This mismatch provides the
challenge of greater load variability in the network.
Current research suggests that this can cause the following
major integration issues: impacts on voltage levels, power factor,
harmonic distortion and protection [1,2,3]. Furthermore it is
suggested that the major concern for NSP’s are the impacts on
voltage levels being why customer supply standards will not be
met with increased penetration.
Implications for Network Service Providers
The data analysis uncovered that the current penetration of PV
systems were impacting the power factor of the systems, as
shown above, as well as the current harmonic distortion. The
impact wasn’t significant enough to mean supply standards are
not being met but are possibly introducing losses into the
network via harmonic and power factor issues impacting the
efficiency of equipment like transformers. Surprisingly voltage
problems weren’t visible at current penetrations but have been
seen in special cases (such as high impedance rural lines).
Simulation results indicate that with increased penetration
comes significant load voltage increases. Additionally in the
event of all PV systems shutting off due to protection, current
swings of up to 100A will eventuate, creating current surge
problems on the network. Overvoltage is one possible trigger
for this.
Research Methodology
Case Study Area Identification
• Identify areas with high PV penetration
• Charictersise these areas (site surveys, geographically,
etc)
Data Collection and Cleanup
• Collect PV system performance data and data for
relevant network parameters
• Cleanup data via data logic check, filtering of incorrect
data, etc.
PV System Performance Analysis
• Gather information on numerous PV systems of different
sizes
• Use statisical analysis to appraise average PV system
performance
Analysis of Current Integration Issues
• Compile network data on voltage, current , harmonics
and power levels
• Use statistical tools to show the effect of PV systems on
these network parameters.
Analysis of Future Integration Issues
• Creation of scenario prediction tools to see the potential
shape of PV integration in the future
• Creation of simulations to model future of increased PV
penetrations
Conclusions And Recommendations
For areas analysed the current penetration levels coupled with
non ideal photovoltaic outputs meant that there are issues
currently occurring on the network but supply standards are not
being exceeded.
This work has highlighted the value of for NSP’s to considering
the following management options in order to circumvent future
problems:
• Implement a data centre and monitoring program
• Consider policy to limit penetration on LV feeders
• Look into storage options such as batteries to shift the PV
production to peak times
Acknowledgements
I would like to acknowledge the assistance of Integral Energy in
their guidance and provision of the data behind this thesis.
References
UNSW
1. Intelligent Energy Europe PV Upscale. (2006). Publications review on the impacts of PV Distributed
Generation and Electricity networks. Intelligent Energy Europe.
2. Srinivasan, D. (2008). Field Experiences with Utility Scale PV System Grid Interconnection. AIRE
Workshop.
3. CSIRO. (2009). Intelligent Grid A Value Proposition for Distributed Energy in Australia. Sydney: CSIRO.
ENGINEERING @ UNSW