Smart Grid - Role of Power Electronics in Grid Following to Grid Forming

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Written by Chao Wu, Subham Sahoo, and Frede Blaabjerg

To achieve the goal of carbon free energy infrastructure as soon as possible, an extensive development and installation of renewable energy such as wind and solar is imperative. The way that renewable energy is converted into electrical energy is different than traditional thermal power generation. It is not based on synchronous generators, but has transitioned to a system dominated with power electronic converters. Thus, these renewable energy resources are generally called inverter-based resources (IBRs). The large-scale development of wind and solar power will inevitably lead to significant changes in the power system, that is, a transition from a synchronous generator-based power system to a power electronic converter-based system as shown in Fig. 1. This transition will also bring a series of emerging problems, such as the decrease in grid strength and low inertia of the grid, which will make it difficult to maintain the voltage and frequency stability. One of the important questions of such a modern power system is how to achieve a robust synchronization of multiple distributed IBRs. Different from the conventional synchronous generator, which is based on the inherent 'swing equation' guaranteeing the synchronization with the grid, IBRs’ synchronization is based on the implemented control strategies for maintaining the synchronization. The general control structure of IBRs is shown in Fig. 2. The effect of different control levels on the synchronization performance will be discussed.

Written by Zibo Chen, Houshang Salimian Rizi, and Alex Q. Huang

Today's power grids are designed based on synchronous generator (SG)-based power plants such as coal, naturel gas, hydro, and nuclear. These power plants operate as grid forming (GFM) voltage sources that set the voltage and frequency of the grid. In an SG, the kinetic energy stored in the rotor serves as inertia against frequency deviation and provides time to balance the power demand and power generation. Additionally, GFM power plants can black start the grid, which is important to recover the grid from a blackout. As inverter-based resources (IBR) such as solar and wind replace SG power plants, the safe operation of the grid is becoming a challenge. This is because today’s IBRs are all designed as grid following (GFL) units. They follow the SG power plants and do not provide inertia and frequency support. For example, in some worst-case scenarios, the system inertia has dropped to 130% of the critical inertia in the ERCOT grid [1].

Written by Paranagamage Shirosh Ayeshmantha Peiris and Shaahin Filizadeh

Conventional grids have relied chiefly on synchronous machines to carry out the crucial task of forming the grid, which includes, but is not limited to, black starting the grid, maintaining the grid voltage and frequency, power sharing, and fault ride-through and recovery. The operating nature and configuration of a synchronous machine provides such features. This further enables complex power electronic equipment, such as HVDC and FACTS devices, to lock onto the grid voltage as grid-following devices and carry out their defined tasks. Grid-following devices rely on a stiff grid with minimal voltage and frequency variations (see Figure 1).


Written by Sudhir Routray

Now the Internet of things (IoT) has ubiquitous applications. In power systems and power grids IoT plays important roles. IoT provides a lot of advantages in the measurement, control, and monitoring of the physical parameters in the power grids. In order to make the grid management better and to reduce the energy consumption in the grids the power electronic components can take the assistance of IoT. Several IoT sensors can be deployed at the appropriate locations of the power electronic components to track their performances. Based on these IoT sensors’ information, IoT actuators can take appropriate actions to make the outcome optimal. Similarly, the IoT sensors’ information can be sent to the central servers in regular intervals to keep the track of the performances of the power electronic components. In addition to the above mentioned applications, several other uses of IoT in power electronics include the monitoring of the critical parameters such as temperature, current, voltage and vibration at different key locations in the power grids. In this article, we show how IoT can assist the power electronic components in the power grids to improve overall performances.


Written by Ramon Gallart Fernandez and Miriam Peñarroya Esteve

Clearly, the Electrical Power and Energy Systems (EPES) are strategical to the economy, as many other essential domains rely on electricity in a nearly completely electrified society. The European consortium SDN-microSENSE, enables the programming of network behaviour in a centrally controlled manner through software applications.

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IEEE Smart Grid Bulletin Compendium

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