Ensuring Power Quality and Stability in Industrial and Medium Voltage Public Grids

2018, IEEE

 ABSTRACT: Until recently, most of the power system equipment in industrial grids has been operating with deviations from the nominal voltage and frequency supplied by the utility. However, power electronics based equipment is vulnerable to such deviations and might get damaged in case of possible grid faults. This paper addresses this issue by proposing a stabilizing device that can be connected between the public grid and the industrial grid which provides not only power quality and security of supply during fault for the industrial grid but also ensuring the power quality for the public grid.


  1. Public grid
  2. Industrial grid
  3. Power quality
  4. Security of supply
  5. Grid stability




 Fig. 1. Device representation



 Fig. 2. Harmonic current injection and compensation


Fig. 3. Individual harmonic distortion voltage for different Sk’’

Fig. 4. THDu for different Sk’’

Fig. 5. Voltage behavior during load switching with and without Netz-Patron unit

Fig. 6. Voltage behavior during motor starting with and without Netz-Patron unit

Fig. 7. Voltage behavior during three phase fault with and without Netz-Patron unit


The paper presents the different functionalities of the Netz-Patron unit that is designed to provide different support functionalities like harmonic compensation and voltage support in case of disturbed grid operation. In order to analyze the effectiveness of the Netz-Patron unit, a simulation model has been developed within the DIgSILENT PowerFactory software environment. The different scenarios and their simulation results are shown in this paper and the behavior of different functionalities has been analyzed. A brief summary of the main findings is given in the following. A 900 kVA active filter has been considered to provide harmonic compensation from the AC/DC converter for Sk ’’ greater than 50 MVA.

In this paper, the study has been carried out by considering a class 2 type of load with injected harmonics of 10 minutes average value (long term). The harmonic values considered for the study are not measured values, but typical values observed in practice. Real laboratory tests are planned to be performed to check the harmonics injected by th

load before designing the Netz-Patron unit to provide harmonic compensation. The effectiveness of the voltage support function provided by the Netz-Patron unit in case of any disturbance registered at the PCC has also been analyzed in this paper.

Future work is planned to focus on a multimaster      concept which implies the analysis of the parallel operation of several Netz-Patron units connected at the PCC of different industrial grids or same industrial grid in the medium voltage network.


[1] EPRI PEAC Corporation, “C. E. Commission:, Power Quality Solutions for Industrial Customers,” August 2000.

[2] R.C.Dugan, M.F.McGranaghan, S.Santoso and H.W.Beaty, Electrical Power Systems Quality, second edition, McGraw- Hill, 2004.

[3] W. Reid, “Power Quality Issues – Standards and Guidelines,” in IEEE Transactions of Industry Applications Vol.32,No.3, 1996.

[4] DIN EN 61000-2-4: Electromagnetic compatibility (EMC) Part 2-4: Environment – Compatibility levels in industrial plants for low-frequency conducted disturbances, VDEVerlag GmbH, 2002-06.

[5] DIN EN 61000-4-11: Electromagnetic compatibility (EMC) Part 4-11: Environment – Testing and measurement techniques – Voltage dips, short interruptions and voltage variations immunity tests for equipment with input current less than 16 A per phase, February 2005.

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