State identification and automatic control of smart low voltage grids

Abstract

Due to the increasing installation of decentralized generation units and the increasing demand of electrical power on distribution level the low voltage grids in Europe are facing different problems, e.g. deviations of the permitted voltage range or local inner overloads of the grid equipment. To overcome these problems a self-sustaining monitoring and control system for low voltage grids has been developed, which monitors the actual power flow situation and controls individual decentralized generation units and consumer loads if necessary. In this context new approaches for power flow calculation and control intelligence are inevitable. This paper describes a newly developed power flow algorithm to be used for online-monitoring of the grid state. In case of critical grid states identified by this power flow algorithm a control intelligence determines and executes possible strategies for elimination of the critical grid state. The developed algorithms have been tested and validated in comprehensive scenarios in consideration of plausibility, calculation speed and reliability of the results.

LV-grid automation system — A technology review

“…However, a grid state identification algorithm meeting these requirements has been developed [1]. The algorithm permits online calculation of the grid state, i.e.…”

“…Within the linear allocation method each consumption node receives an equal part of the summed power flow of the load area. This method is characterized by minimal calculation errors but the estimated results can lead to a more or less critical grid state compared to the real grid state [1]. Additionally, a worst-case method was developed.…”

“…A decentralized system for LV-grid automation has been developed and tested in several LV-grids within Germany [1], [2]. The concept of the system is shown in Fig.…”

“…The present paper is an in-depth technology review of a decentralized, autonomously operating LV-grid automation system that has been developed in recent work [1]. The system is part of a distribution grid automation system for monitoring and coordinated control of MV-and LV-grids.…”

Integrating Renewables in Distribution Grids : Storage, regulation and the interaction of different stakeholders in future grids

“…Hereby, the ratio between primary and secondary equipment is adjusted dynamically depending on the actual, local consumption and generation profiles. Neusel-Lange et al (2012) propose a method to first adjust the on-load tap changer on the transformer to influence the bus bar voltage. In case the first step is not sufficient, a second possibility is to change the power factor of the local generators to regulate reactive power and moderate the voltage increase.…”