Information-quality based LV-grid-monitoring framework and its application to power-quality control

Abstract

The integration of unpredictable renewable energy sources into the low voltage (LV) power grid results in new challenges when it comes to ensuring power quality in the electrical grid. Addressing this problem requires control of not only the secondary substation but also control of flexible assets inside the LV grid. In this paper we investigate how the flexibility information of such assets can be accessed by the controller using heterogeneous off-the-shelf communication networks. To achieve this we develop an adaptive monitoring framework, through which the controller can subscribe to the assets’ flexibility information through an API. We define an information quality metric making the monitoring framework able to adapt information access strategies to ensure the information is made available to the controller with the highest possible information quality. To evaluate the monitoring framework, an event-driven voltage controller is simulated in an LV grid. This controller utilizes the flexibility of photovoltaic (PV) panels to get the voltages into acceptable ranges when the limit is exceeded. This is done by controlling the grid periodically during the time interval that starts when a voltage limit is exceeded and ends when an acceptable voltage level is reestablished. We show how the volatile behaviour of the PV panels causes overvoltages in a baseline scenario. We then show the controller’s ability to keep the voltages within their limits. Lastly, we show how control performance can be increased by optimizing information access strategies.