TA Success Story: TIPI-GRID
Optimising PV Inverter and Distribution Transformer Operation

Topic: Transient stability of interference of photovoltaic inverters reactive power control by the grid voltage and medium voltage transformer

Hosting facility: SmartEST Lab of AIT

Duration: 30.04.2018-27.07.2018

Outcomes: factsheet, publication 1, publication 2, publication 3

Photovoltaic (PV) inverters increase the line voltage in Distribution Grids (DG) by active power feed in. Today, modern PV inverters are also able to feed in reactive power to mitigate such a voltage rise. The favoured, cost effective implementation is the control of reactive power feed in according to the instantaneous measured line voltage. The stability of this decentralised Q(U) PV inverter closed-loop control is mandatory. The DG operator must guarantee the voltage limits given in the regulatory framework. This is challenging due to fast changing solar irradiance, load flows and the interaction of an overlying automatic voltage control-loop of a connected substation. Therefore, the TIPI-GRID user group conducted and evaluated experimental tests of the stability of the PV inverters Q(U) control with different time constraints in the AIT SmartEST lab. Their experimental research included transformers equipped with an On-Load Tap Changer (OLTC) to control with supply voltage from the higher voltage level of the grid.


As a result of their TA experimental research, the TIPI-GRID team came up with a number of practical recommendations for grid operators underpinning the results from pure simulation studies for the optimised PV inverters Q(U) operation, all of which can be found in the factsheet, the report and corresponding publications.

Before ERIGrid TA, my research group back home at the University in Switzerland didn't have the equipment to control the hardware in the lab, such as grid and load emulation conducted by a precise detailed measurement monitoring. The formulation of the ERIGrid TA target and detailed planning during the first days of the stay, including support of the lab tests by AIT experts, was pivotal to measure the transient reactive power control of PV inverters under defined conditions. Additionally, the accompanying discussion of related technical and further research topics was highly beneficial.

My personal experience in R&D collaboration over the last three decade shows me that the most efficient method of personal exchange among experts is a regular face-to-face meeting, rather than several standard web-based cyber meetings. Our ERIGrid TA stay at the AIT lab again clearly confirmed that.
Prof. Dr. Franz Baumgartner
Leader of the TA user group TIPI-GRID
TIPI-GRID Success Story