2017-05 / Management of an hybrid micro-grid system with CHP (cogeneration) and storage


May 18th, 2017

Management of an hybrid micro-grid system with CHP (cogeneration) and storage

In Germany, a solar PV plant hybridized with a cogeneration unit and, both electrical and thermal, storage facilities uses the solar production forecasts over several time horizons to optimize the operations of the micro-grid.

The company’s management system receives day- ahead forecasts and hours ahead forecasts every 15 minutes.
These hour-ahead forecasts are critical to adjust the system management to weather changes.
As an example, the day of May 18, 2017 is quite illustrative:

 

 

 

Figure 1: Actual (in blue) vs SteadyMet forecasts of the day before

 

The production drop which occurs at 11.20 am and continues the whole afternoon was not forecast on the day before.

In contrast, the hour-ahead satellite based forecasts are well predicting this event between 30 to 60 minutes in advance. This leaves enough time to adjust the power instructions to the other components of the micro-grid (CHP, programmable load, storage) and to maintain an optimal system operation.

On the contrary, the very short duration and smaller event in the morning at 100.00 am is not forecast. It is resulting from a cloud which is nearly not seen on the satellite images due to its small size. The solution would be to have a sky imager on site as proposed with our SteadyEye solution (cf. http://steady-sun.com/technology/steadyeye/ ).

 

 

Figure 2: actual (in blue) vs intraday forecasts (in red/orange for percentiles) – 60 minutes in advance