Grid-Forming Techniques for Smart Grid Integration

Grid-Forming Inverters: A Comparative Study of Different Control Strategies ----------------------------------------------------------------------------------- As grid-forming inverters (GFMIs) are anticipated to play a leading role in future power systems, comprehensive understanding of their dynamics and control strategies becomes essential. Our recent article delves deep into this, offering a comparative study including: 1)      Detailing the control structures and tuning of four different control strategies for GFMIs (Droop, VSG, Compensated Generalized VSG, and Adaptive VSG). 2)      Conducting extensive frequency domain analysis employing impedance-based stability analysis, exploring various scenarios (SCR variations, Xg/Rg variations, operating point variations, dynamics of virtual impedance, and dynamics of inner current and voltage loops). 3)      Validating the frequency domain analysis through EMT simulations. 4)      Testing against external grid disturbances (frequency deviations, phase shifts, and voltage sags) in both strong and weak grid connections.   For more information: Article Title: Grid-Forming Inverters: A Comparative Study of Different Control Strategies in Frequency and Time Domains. Authors: Nabil Mohammed, Harith Udawatte, Weihua Zhou, Professor David Hill, Behrooz Bahrani. Journal: IEEE Open Journal of the Industrial Electronics Society. Links [Open Access]: https://lnkd.in/gE_fgJ6F ; https://lnkd.in/gMz-S4KE .   Special thanks to the Australian Renewable Energy Agency (ARENA) and the Australian Research Council for funding this work.   #powerelectronics #forminginverters #renewableenergy #gridintegration #sustainability #energytransition

If you are an early-stage researcher who wants to dive into the grid-forming (#GFM) inverter world, we have created a step-by-step tutorial based on #UNIFI’s GFM reference design— as part of UNIFI’s educational initiative. ⚙️Written in easy-to-follow language, this tutorial walks you through: ✅ The control architecture of GFM inverters ✅ How to pick control gains for outer voltage and inner current loops ✅ LCL filter design basics ✅ How current limiters work and why they matter ⚙️This tutorial also comes with hands-on guidance for navigating UNIFI’s open-source GitHub repository, which contains everything you need to build your first GFM inverter: ✅ Simulation models (both average and EMT models) ✅ PCB design files ✅ Embedded control code for running hardware ✅ Detailed documentation for single-phase and three-phase GFM hardware—covering all the bits and pieces: component selection, thermal considerations, sensing-circuit design, and more! Starting from scratch, building a working GFM inverter setup can take years. With this tutorial and the resources in UNIFI’s repository, you can skip most of the setup headaches—saving 1–2 years of work! 🔗If you’re ready to get started, check out the tutorial and explore the repository—links in the first comment. Rahul Mallik Weiqian Cai Kamakshi Tatkare Jakob Triemstra Cuauhtemoc Macias

Grid-forming control to achieve a 100% power electronics interfaced power transmission systems by Taoufik Qoria -”Nouvelles lois de contrˆole pour former des r´eseaux de transport avec 100% d’´electronique de puissance” ´ECOLE DOCTORALE SCIENCES ET M´ETIERS DE L’ING´ENIEUR L2EP - Campus de Lille  Abstract: The rapid development of intermittent renewable generation and HVDC links yields an important increase of the penetration rate of power electronic converters in the transmission systems. Today, power converters have the main function of injecting power into the main grid, while relying on synchronous machines that guaranty all system needs. This operation mode of power converters is called "Grid-following". Grid-following converters have several limitations: their inability to operate in a standalone mode, their stability issues under weak-grids and faulty conditions and their negative side effect on the system inertia.To meet these challenges, the grid-forming control is a good solution to respond to the system needs and allow a stable and safe operation of power system with high penetration rate of power electronic converters, up to a 100%. Firstly, three grid-forming control strategies are proposed to guarantee four main features: voltage control, power control, inertia emulation and frequency support. The system dynamics and robustness based on each control have been analyzed and discussed. Then, depending on the converter topology, the connection with the AC grid may require additional filters and control loops. In this thesis, two converter topologies have been considered (2-Level VSC and VSC-MMC) and the implementation associated with each one has been discussed. Finally, the questions of the grid-forming converters protection against overcurrent and their post-fault synchronization have been investigated, and then a hybrid current limitation and resynchronization algorithms have been proposed to enhance the transient stability of the system. At the end, an experimental test bench has been developed to confirm the theoretical approach.  VIEW FULL THESIS: https://lnkd.in/dcTJU-9v

Grid-Forming PV Integration for Enhanced Grid Stability ------------------------------------------------------------- As renewable penetration increases, maintaining grid stability without relying on synchronous generators has become a critical challenge. To address this, I designed and validated a grid-forming inverter system directly integrated with a photovoltaic (PV) source, controlled using droop control, and implemented in MATLAB Simulink. Unlike conventional grid-following PV systems, this architecture allows the PV inverter to form and regulate the grid actively, enabling stable operation even in weak or low-inertia grids. System Architecture & Key Design Parameters - Photovoltaic Source (DC Side) - PV Maximum Power (Pmp): 10.675 kW - PV Voltage at MPP (Vmp): 290 V - PV Current at MPP (Imp): 36.75 A The PV array is interfaced with a DC-link and grid-forming inverter, enabling seamless power conversion while maintaining dynamic control over voltage and frequency. - Grid-Forming Inverter (AC Side) - Injected Active Power: ≈ 10 kW - Grid Voltage: 400 V RMS - Nominal Grid Frequency: 50 Hz This setup reflects a realistic grid-connected PV scenario, where the inverter must operate under off-nominal frequency and voltage conditions while ensuring grid support. Why Grid-Forming Droop Control? By embedding droop control into the PV inverter, the system mimics the behavior of conventional synchronous generators, allowing the PV system to become an active grid asset rather than a passive energy source. ✔ Frequency Support: Active power modulation in response to frequency deviations ✔ Voltage Regulation: Reactive power sharing for voltage stability ✔ Black-Start Capability: Grid formation without an external voltage reference ✔ Scalability: Stable parallel operation of multiple PV inverters without communication - Effective Voltage Control: Reactive power droop ensured stable voltage profiles, even during transient conditions. - High Grid Resilience: The system maintained synchronism and stability during disturbances, demonstrating strong suitability for weak and low-inertia grids. Key Insights & Impact The simulation confirms that PV-based grid-forming inverters can: - Replace traditional synchronous generation roles - Enable higher renewable penetration without compromising stability - Support future power systems dominated by inverter-based resources This work demonstrates how PV systems can evolve from grid-following to grid-forming, transforming renewables into stability-providing elements of modern power systems. Feel free to reach out if you’d like to collaborate on similar projects.  #MATLAB #SIMULINK #GridForming #PVIntegration #DroopControl #PowerElectronics #RenewableEnergy #InverterBasedResources #SmartGrids

⚖️🔧⚡ Transitioning from Grid-Following (GFL) to Grid-Forming (GFM) in Solar + BESS Projects As more renewable projects move toward grid-forming capabilities, it’s critical to understand that success depends on two distinct but equally important layers: 👉 Power Electronics (device level) 👉 GPM – Grid Performance Management (plant/system level) They solve different parts of the problem — and both must evolve together. 🔌 1. Power Electronics – The Foundation Before (GFL): -Inverters follow grid voltage & frequency (PLL-based) -Require a strong grid -Limited stability support (no inertia, -weak voltage control) After (GFM): -Inverters create voltage & frequency -Act like synchronous machines (virtual inertia, droop control) -Operate in weak grids or islanded mode 🔧 Key Changes: Control shift: PLL → Droop / Virtual Synchronous Machine (VSM) Add: Frequency droop (P–f) Voltage droop (Q–V) Synthetic inertia OEM firmware & protection updates (e.g., Sungrow, Tesla, SMA) Integration of BESS for fast dynamic support Enhanced fault response & ride-through capability 🧠 2. GPM – The System-Level Brain GPM coordinates the entire plant: Inverters BESS Plant Power Controller (PPC) Interfaces with utilities (e.g., Oncor) and ISOs (e.g., ERCOT) 🔧 What Changes with GFM: ✔ PPC Upgrades Grid-forming dispatch Multi-unit coordination Voltage & frequency reference control Black start capability ✔ EMS Enhancements BESS dispatch optimization SOC management (maintain headroom for grid support) ✔ Grid Compliance Meet requirements like NOGRR272 Fast frequency response Voltage ride-through Disturbance support ✔ Protection Updates Adaptive protection schemes Revised relay coordination Anti-islanding updates ✔ Operational Modes Grid-connected ↔ Grid-forming Grid-forming ↔ Islanded Black start sequences ⚖️ Power Electronics vs GPM – Key Difference Power Electronics: Creates voltage & frequency (device-level stability) GPM: Coordinates and sustains plant-wide performance ⚡ Real Example: 40 MW Solar + 10 MW / 20 MWh BESS Without GFM: PV becomes unstable in weak grids No meaningful frequency support With GFM: BESS + inverter form the grid Stabilize voltage & frequency GPM ensures: SOC ~50–70% (bidirectional support) Dynamic dispatch Alignment with ERCOT signals 🚧 Key Risks if Not Done Right Control instability (oscillations) BESS depletion → loss of support Protection miscoordination Non-compliance (e.g., NOGRR272) Interconnection delays ✅ Bottom Line ⚡ Power Electronics = “Can we form the grid?” 🧠 GPM = “Can we control it reliably at scale?” 👉 You need both: Power electronics enables the capability GPM ensures it works in real-world grid conditions #SolarEnergy #RenewableEnergy #EnergyStorage #BESS #GridForming #GridFollowing #PowerElectronics #EnergyTransition #ERCOT #GridStability #CleanEnergy #Inverters #Engineering #PowerSystems #EnergyManagement #UtilityScale #SolarProjects #Transmission #Infrastructure

🔋 Typically, the grid-connected inverters are split into two types: Grid-Following (GFL) inverters and Grid-Forming (GFM) inverters. GFL inverters are conventionally controlled as current sources, relying on a Phase-Locked Loop (PLL) to achieve synchronisation to the external grid voltage. This configuration means GFL inherently lacks both voltage-forming (VFM) and frequency-supporting capabilities. Conversely, GFM inverters operate as voltage sources, achieving self-synchronisation through their active power output, and can form both grid frequency and voltage. A recently investigated extension of GFM control, the Frequency-Following Voltage-Forming (FFL-VFM) inverter, strategically decouples these capabilities. The FFL-VFM inverter forms the voltage but sacrifices frequency support, instead enabling the inverter to stably and quickly follow outer grid frequency variations (FFL) while enhancing grid voltage stiffness (VFM). This structure achieves a faster frequency response than conventional GFM and still supports the voltage control in the grid. 🔦 The FFL-VFM controller is based on GFM matching control, with a virtual amortisseur (red R) and virtual pole-pair number (red N) managing grid synchronisation and dc-link voltage regulation. The structure, integrated with the dc-link capacitor, achieves stable and quick responses to grid frequency changes. The synchronisation loop uses fast PI control, rather than the slower Low-Pass Filter (LPF) in GFM. This control damps the slip frequency between the inverter and grid via the power-angle relationship, ensuring the inverter tracks the grid frequency until synchronisation. 💡 VFM capability appears in the inverter's port admittance. Near the fundamental frequency, FFL-VFM's port admittance is 10x that of GFL. High FFL-VFM admittance lets it provide voltage support, unlike GFL inverters. #gridforming #battery #energystorage #gridmodernization #powerelectronics #renewables #cleanenergy

I’m pleased to share that my latest research paper has been published in the IEEE Xplore Digital Library. Paper link: https://lnkd.in/d8nHQktB As power systems continue to evolve toward renewable-dominated architectures, maintaining stability under dynamic operating conditions becomes increasingly challenging especially in Solar–HVDC configurations. In this work, I explore the role of grid-forming Battery Energy Storage Systems (BESS) in addressing one of the critical issues: PV curtailment events and their impact on DC-link stability. The paper proposes an enhanced grid-forming control strategy that enables BESS to operate with voltage-source behavior, ensuring fast and reliable system response during abrupt solar power reductions. A detailed dynamic model was developed and validated in MATLAB/Simulink. Key findings: - BESS compensates a 40% PV curtailment within 100 ms - DC voltage deviations are limited to within ±2% - Achieves ~60% reduction in voltage transients compared to grid-following control These results highlight the importance of grid-forming BESS not just as a storage element, but as an active stabilizing component in future HVDC-based renewable grids. Looking forward to engaging discussions with colleagues working on grid-forming technologies, HVDC systems, and energy storage integration. #IEEE #HVDC #BESS #GridForming #PowerSystems #EnergyTransition #Renewables

🔋 Powering the Future: Grid-Forming Inverters for Stable Renewable Integration 🌍⚡ As the energy landscape rapidly evolves with increasing contributions from renewable sources like solar and wind, maintaining grid stability has become more challenging. Enter Grid-Forming Inverters—the game-changers in modern power systems. A grid-forming inverter is a power electronic device that plays a crucial role in the operation and stability of electrical power grids What Makes Grid-Forming Inverters Essential? Unlike traditional grid-following inverters that merely follow grid voltage and frequency, Grid-Forming Inverters actively control voltage and frequency, making them vital in microgrids and regions with unreliable access to main power grids. They continuously monitor grid conditions and adjust their output to maintain stability and synchronization, addressing the lack of rotational inertia in inverter-based resources. 💡 Key Control Techniques in Grid-Forming Inverters: 📍 Voltage and Frequency Droop Control: Regulates voltage and frequency in multi-generating setups, ensuring smooth operation. 📍 Virtual Inertia & Frequency Support: Mimics traditional rotating masses by controlling the rate of change of output power, enhancing grid stability. 📍 Phase-Locked Loop (PLL): Ensures precise synchronization by accurately detecting grid frequency and phase. 📍 Fault Ride-Through: Keeps inverters connected during grid faults, ensuring uninterrupted power and system reliability. 📌 Why It Matters: Grid-forming inverters are not just about integrating renewables; they are about redefining grid reliability and stability. By actively managing power quality and ensuring synchronization, they play a critical role in the clean energy transition. 📈 Why Now? With 94% of new U.S. electric-generating capacity in 2024 expected to come from inverter-based resources like solar and wind, the shift to grid-forming technology is not just beneficial—it's essential for a sustainable energy future. 📖 Reference: For a comprehensive dive into the critical role of grid-forming inverters, check out the Introduction to Grid Forming Inverters by Ben Kroposki, Director at the Power Systems Engineering Center, National Renewable Energy Laboratory (NREL). This document outlines why GFM inverters are vital in today's evolving energy landscape. #GridFormingInverters #RenewableEnergy #PowerGridStability #InverterTechnology #EnergyTransition

Grid-Forming vs. Grid-Following Inverters ⚡🤖 The key difference between grid-forming (GFM) and grid-following (GFL) inverters lies in how they interact with the grid. Their control strategies define whether they merely follow an existing voltage or actively establish it. 🔄 Grid-Following Inverter Control: Synchronized but Dependent Grid-following inverters behave like current sources, injecting power into an existing grid but not influencing its voltage or frequency. Their control is based on: ✅ Phase-Locked Loop (PLL) Tracking: The inverter continuously locks onto the grid voltage phase using a PLL. This ensures synchronization, but in weak grids or during faults, PLL tracking can become unstable. ✅ Current Control Mode: Since the grid voltage is already set by other sources (such as synchronous machines), the inverter adjusts its active power (P) and reactive power (Q) based on reference commands. This is achieved through current controllers, typically implemented using a proportional-integral (PI) regulator in a synchronous reference frame (d-q control). ✅ Reactive Power Support (Optional): Some GFL inverters participate in grid support by adjusting their reactive power output based on voltage deviations, but they don’t inherently stabilize the grid. 🔹 Weakness? When the grid voltage weakens or disappears (e.g., blackouts or islanding), GFL inverters become ineffective since they depend entirely on an external voltage reference. 🏗️ Grid-Forming Inverter Control: Autonomous & Stable Grid-forming inverters act as voltage sources, creating their own reference for the grid, similar to how synchronous generators operate. Their control strategy includes: ✅ Voltage and Frequency Regulation: Instead of tracking an external signal, GFMs generate a stable voltage and frequency reference. They can operate even without a grid, making them essential for islanded microgrids and black-start capabilities. ✅ Droop Control Mechanism: Inspired by synchronous machines, GFM inverters use P-f and Q-V droop characteristics to naturally adjust their power output based on system conditions. If grid frequency decreases due to a power imbalance, the inverter increases active power output (P-f droop). If voltage drops, the inverter supplies more reactive power (Q-V droop). ✅ Virtual Inertia and Grid Support: GFMs can provide synthetic inertia by modulating power output in response to frequency changes, mimicking the rotational inertia of conventional generators. This stabilizes the grid against sudden disturbances. 🔹 Weakness? Implementing grid-forming controls is complex, requiring fast dynamic response, robust communication, and careful tuning to ensure system-wide stability. As power systems transition toward high renewable energy penetration 🌍⚡, a combination of GFL and GFM inverters will be used strategically. GFLs remain cost-effective for bulk energy injection, while GFMs are needed for stability and grid resilience.

☀ Grid-Forming Inverter Dynamics During Fault Conditions Inverter-Based Resources (IBR) with Grid-Forming (GFM) control have become essential for enhancing stability and resilience in modern power systems. One popular approach is the Virtual Synchronous Machine (VSM) method, which emulates the dynamic behavior of traditional synchronous generators. Here’s an interesting observation from my recent simulation in PSCAD, which highlights how the system reacts to a specific fault. 🖥️ Simulation Results: In the plot above, I analyzed the voltage and power response of a GFM inverter operating under normal conditions and during a BC fault with a 10-ohm fault resistance: Voltage Response (Top Plot): Before the fault (at around 0.7 seconds), the three-phase voltages (Va, Vb, Vc) are balanced and stable. Once the BC fault occurs, we observe a severe dip in the voltages, particularly in phases B and C, indicating a substantial drop in voltage at the connection point. Active and Reactive Power Behavior (P, Q) (Bottom Plot): In normal conditions, the inverter delivers constant active power (P) and minimal reactive power (Q) to the grid. Upon the fault, P decreases sharply, while Q shows oscillatory behavior and increases. This behavior aligns with the design of VSMs, where the control prioritizes reactive power injection to support the grid voltage during faults. ⚙️ Why Does This Happen? During the BC fault, the control system of the VSM reduces active power output to limit current and protect the inverter. Simultaneously, reactive power injection increases to counteract voltage drops, helping stabilize the grid voltage. This power redistribution is crucial for maintaining system stability, particularly in systems with high penetration of IBRs. This simulation illustrates the effectiveness of GFM inverters with VSM control in handling grid disturbances, providing stability akin to traditional synchronous machines. With more renewable integration, such systems are vital for the future of reliable and resilient power systems. #PowerSystems #InverterControl #GFM #VSM #PSCAD #RenewableEnergy #PowerStability #GridIntegration #Simulation #PowerQuality