There are a number of potential issues that can be encountered when connecting an embedded generator to the grid, and they depend largely upon the particular location and set up of the proposed project. If you suspect that any of the issues below may apply to your project you may want to get in contact with us for technical support during the planning and design phases.
Power export into the electricity network
Found in All areas
If a generation project is planning on exporting energy into the distribution network it may make the grid connection more complicated, and the DNSP (Aka Supply Authority) may require a higher standard of compliance. This is because of the impact that the export of extra power can have on the network.
Generator stability while connected to the network
This issue can generally be overcome with the installation of a pole slip protection relay which disconnects the generator from the network if the power generator is unstable.
Fault level problems
Built Up Areas/CBD
In built up areas there are problems with the very high levels of fault current that can occur under fault conditions. This is due to the specific network configurations. The preferred method to overcome fault level issues is the installation of a fault current limiting breaker in the systems setup, though this can become an expensive addition for some projects.
Steady state voltage levels
The connection of an embedded generator can impact on the voltage levels of the connected network. HV distribution networks have a degree of dynamic voltage control, however, low voltage networks are unable to regulate this dynamically. This means that changes to the high voltage network can impact the low voltage network and studies may be reuired to make sure that the low voltage customers are not affected.
Voltage control schemes can be technically challenging, especially in rural distribution networks. These networks are generally considered to be less robust and can involve a complex voltage control scheme. Therefore this can turn out to be a significant barrier to rural embedded generation connections if not appropriately managed.
Communication methods for intertripping
For some industrial-scale solar farms the DNSPs may require the installation has a dedicated intertrip signal from the embedded generator to their control centre. Occasionally the DNSP may require a dedicated fibre optic cable for instant communication. If there is a requirement for intertripping communication for your project it is best to determine the method as early as possible. It can cost a great deal and can often be overlooked and create an unexpected expense for your project.
There is no simple correction for voltage fluctuation at the end of long regional powerlines.
Normally this will require modeling to ensure the generator can sustain its output as the network voltage fluctuates. Voltage fluctuations also often occur in the event of the generating facility tripping off supply, or if the generator’s output fluctuates sharply.