Constraint Management & G100 Export Limitation in Practise
/When undertaking G100 constraint management or active network management (ANM), one of the critical elements is how understand what an export limitation or constraint management system is doing to ensure that you stay within the regulated limits.
I thought I’d write a short piece to try and explain, using images from our Asset Management Platform called GridLENZ.
In brief, an export limit interacts with your real demand on-site and your renewable generation to create what we call a “Power Point Limit” (PPL) – essentially a maximum limit above which your generation cannot go. This works at an inverter / control interface level and aggregates up across all generation assets to a whole system limit.
The image below shows a number of interesting data points for a solar generation site:
The orange line shows the 15-minute timestamps for the PPL for a specific site for each solar inverter in Kilowatts (kW)., although, in reality, this is updated every 100 mS in our system
The blue line shows the production of an unrestricted solar inverter that is being used to provide a baseline for constraint management at the site – in other words, it is not limited by the orange line to enable the client to determine losses from G100 export limitation
The red line, however, is the production of a solar inverter that is limited by the system’s PPL. You can see that it cannot go above the PPL set by the system
This gives rise to a number of interesting elements:
G100 Export Limitation Loss Calculation
If you could have an untethered inverter then this provides a great way to determine the performance of a G100 constrained site
However, for zero-export sites this is impossible because you can’t have an unlimited inverter that could generate and export if real demand went below its generation level
Irradiance / Wind Sensors as Standard
As a result of the above, embedding an irradiance / wind sensor (dependent upon the asset) in a system as standard for at least every zero-export limited system should be a valid investment
Also, in addition, even if you have an unlimited inverter / asset, how do you know that it is performing as it should? Are you comparing limited assets with under-performing assets?
Without a Benchmark there’s No Confidence
A final point is to look at the volatility of production of the unlimited inverter for this one example day
Without some form of benchmark there is no real way of intuiting the loss of production from constraint management / G100 export limitation
The requirement for an irradiance sensor (for PV) is a valid recommendation
The same goes for wind data for a wind turbine
The upshot is that dependent upon the asset being managed under the specific constraint management regulation (G100 etc) a serious asset owner would insist on the installation of a sensor to support the vigorous assessment of performance.
Argand Solutions can embed any sensor required within our constraint management solutions and can also provide the required performance analysis for stakeholders as required.
Give us a call to discuss in more detail.