What is the grid impedance?

In the world of electricity and electrical engineering, grid impedance is a term that is frequently used but often misunderstood. In this comprehensive article, we will explain this complex term in detail and show its importance in various areas such as the operation of power grids, the application of power quality analyzers and decentralised energy supply. We will also discuss the role of resonances and resonance detection as well as the effects of the frequency dependence of the grid impedance. 

What is grid impedance?

Grid impedance is a fundamental concept in electrical engineering and refers to the resistance of an electrical grid to the flow of electric current. It is a complex quantity and is determined by the resistance (R), capacitance (C) and inductance (L) of the network. The frequency-dependent mains impedance is a particularly important aspect, as it determines how the mains reacts to different frequencies.

Role of resonances and resonance detection

Resonances play a crucial role in determining the grid impedance. They occur when the frequency of the AC current matches the natural frequency of the grid, resulting in an increase in impedance. Resonance detection, i.e. the identification of these conditions, is therefore an important step in identifying potential problems and taking appropriate countermeasures.

Application in power grids

Mains impedance has a direct influence on the performance and stability of power grids. For example, high grid impedance can lead to voltage fluctuations that affect the quality of the power supply. To identify such problems, power quality analysers are used to monitor and analyse the quality of electrical power in a network.

Significance for decentralised power supply

Grid impedance is also of crucial importance for decentralised energy supply. In this model of energy supply, power generation plants are installed close to consumers in order to minimise transport and distribution losses. Correct measurement and control of grid impedance is essential here to ensure the efficiency and reliability of the system.

Analysis of the networks

Network analysis is necessary to understand the behaviour of network impedance under different conditions and to take appropriate measures to improve network performance. A deeper understanding of grid impedance enables grid operators to make better decisions and proactively respond to potential problems.

morEnergy’s ONIS and grid impedance

To effectively measure and analyse grid impedance, advanced technologies and equipment are required. morEnergy’s ONIS is one such device, specifically designed to measure frequency-dependent grid impedance up to 500 kHz 3-phase. This enables precise analysis of the grid impedance and helps grid operators to identify and rectify potential problems at an early stage.


Mains impedance is a complex but central concept in electrical engineering. Its understanding is essential for the effective operation and management of power grids and for the implementation of distributed power systems. By using advanced technologies such as morEnergy’s ONIS and conducting thorough grid analyses, grid operators can effectively control and optimise grid impedance to ensure a stable and high-quality power supply.