Grid Forming: Industry Status and Expected Developments [Industry GF Tutorial]

Lecture 1 (45 min.)
Grid Forming Inverters: Modeling, analysis, and road to performance standardization – An Update
Deepak Ramasubramanian (EPRI, USA)

With many power systems around the world rapidly going towards high percentage of inverter based resources, the concept of grid forming will be important. This tutorial will provide a detailed discussion on the notion of grid forming and what it entails. It goes beyond the aspect of voltage source behind impedance and showcases the importance of hierarchy of control within an IBR plant. Delivery of services and focus on performance is stressed. Further, the tutorial will walk through details of developing simulation models and identification of grid forming property from these models. Finally, through the use of application examples, a preliminary road to standardization will be discussed.

Discussion &  Short Break (15 min)

Lecture 2 (45 min.)
Global Landscape of Grid Forming Interconnection Requirements
Julia Matevosyan (ESIG, USA)

With grid forming controls being considered as one of the solutions for reliable integration of high shares of inverter-based resources (wind, solar, storage), there is a need to define interconnection requirements (or grid codes) and performance expectations for this technology. Around the world there is a growing number of entities that has already developed grid codes for grid forming technology, among those National Grid Electricity System Operator (NGESO) in Great Britain, Australian Energy and Markets Operator (AEMO), German system operators (e.g. TenneT), French system operator (RTE) and ENTSO-E (draft requirement awaiting approval). North American Reliability Corporation has also developed a white paper listing out grid forming capabilities and how a utility or a system operator wanting to deploy this technology today should test for grid forming capabilities through simulations and some of the independent system operators (ISO), e.g. Electric Reliability Council of Texas (ERCOT), Midcontinental ISO (MISO) have followed with requiring all future batteries to be grid forming. This part of the tutorial will cover capabilities sought from grid forming inverter-based resources by the system operators and compare various existing or proposed requirements.

Discussion &  Short Break (15 min)

Coffee Break

Lecture 3 (45 min.)
Grid-Forming Plant Controls: Bridging the Gap between Components and Grid Code Compliance
Benjamin Joseph Braun (FluenceEnergy, Germany)

Recent updates to the grid codes of key markets enabling grid-forming operation on the public network have opened a multitude of new applications. This in turn has exposed a gap between components level controls and complete code compliant solutions.

Historically, GFM applications have been largely limited to industrial black-start and isolated electrical systems. Such projects have provided countless lessons and improvements, but to date no component level standards defining GFM controls have been defined. Validation and bench-marking of manufacturer’s and integrator’s GFM capabilities is thus difficult.

This tutorial will highlight the current variations in component level GFM controls while recommending minimum technical requirements and testing regimes to allow for fair comparisons of suppliers in lieu of standards. Additionally, the required plant level integration considerations and controls needed to convert components into solutions compliant with the latest grid codes will be highlighted.“

Discussion & Short Break (15 min)

Lecture 4 (45 min.)
VISMA: Static Inverters with Grid Forming Capabilities
Cristina Bastida Molina 

As more static generators are integrated in the electric grid with the rise of renewable energies, the inertia that is inherent to synchronous generators is lost. In lack of a flying wheel or mass, static inverters must generate the inertia by means of software. Several methods can be used to achieve this, with VISMA (Virtual Synchronous Machine) being one of the most popular ones.
VISMA methodology is based on the integration of the inertia mathematical formula directly on the software of the inverter. It does not rely on external controllers in order to achieve faster responses, approaching that of an instantaneous reaction (< 5 ms). The control mode of the inverter changes from current source (more appropriate for a Grid Following behaviour) to a voltage source, with the ability to take voltage and frequency references. With that, the focus of the generator shifts to maintaining grid conditions stable, which can look like peaks or deeps in the generated current. VISMA allows to perform grid support and grid forming capabilities, such as virtual inertia, damping or black start.

Discussion (15 min)

LUNCH