Grid-Forming Converters for Stability Issues in Future Power Grids

Abstract

Historically, the power system has relied on synchronous generators (SGs) to provide inertia and maintain grid stability. However, because of the increased integration of power-electronics-interfaced renewable energy sources, the grid’s stability has been challenged in the last decade due to a lack of inertia. Currently, the system predominantly uses grid-following (GFL) converters, built on the assumption that inertial sources regulate the system stability. Such an assumption does not hold for the low-inertia grids of the future. Grid-forming (GFM) converters, which mimic the traditional synchronous machinery’s functionalities, have been identified as a potential solution to support the low-inertia grids. The performance analysis of GFM converters for small-signal instability can be found in the literature, but large-signal instability is still an open research question. Moreover, various topologies and configurations of GFM converters have been proposed. Still, no comparative study combining all GFC configurations from the perspective of large-signal stability issues can be found. This paper combines and compares all the existing GFM control schemes from the perspective of large-signal stability issues to pave the way for future research and development of GFM converters for large-signal stability analysis and stabilization of the future low-inertia grids.

A Survey on IoT-Enabled Smart Grids: Emerging, Applications, Challenges, and Outlook

“…The FDI attacks have had major technological and physical consequences for IoTenabled smart grids. In the case of FDI attacks, smart grids must usually deal with steady-state stability and transient effects [107]. The impact of FDI attacks on steady-state stability on voltage control demand current/voltage/power management and energy management of smart grids is very significant [108,109].…”

Voltage dip propagation in renewable‐rich power systems utilizing grid‐forming converters

“…SGs) would regulate the system stability and would ensure the minimum requirement of system strength. This might be valid to an extent in low RESs penetration scenarios but not in future low inertia scenarios where most of the power demand would be met by RESs [8]. Although traditional GFL-based RESs have been usually controlled in such a way to provide dynamic voltage support by injecting more reactive power during faulty conditions, the response of the converter is limited to the capped overrating capability which cannot exceed a certain level around the ratings of the device.…”

“…Consequently, the voltage support task during the faults is going to deteriorate in high penetration scenarios of GFL-based RESs and therefore enhanced technologies or other mitigating solutions might be essentially required to avoid wide scale voltage dip propagation through the networks [9,10]. In this regard, Grid-Forming (GFM) converters have been recently proposed as a promising substitution for the lack of functionalities that SGs have traditionally provided as an alternative for GFL converters that fail to do so [8,11]. Such converters, which act as a controllable voltage source and produce voltage and frequency in the system, are a dependable substitute for grid following converters [11].…”

Comparative Study of the Transmission Capacity of Grid-Forming Converters and Grid-Following Converters

“…Among them, the static stability can initially be judged according to whether the converter has a stable static operating point [3,4]. However, power electronic converters have different response characteristics compared with traditional equipment, and there is still scant research on the stability of different types of converters when transmitting power and quantitative analyses of their power transmission limit, which are highly related to the power grid stability of power-angle, voltage, and frequency [5,6].…”