Power Electronics in Power Systems

🔌 The dynamic behaviour of bulk power systems was mainly influenced by synchronous generators, their controls, and load dynamics. The timescales that required analysis were determined by electromechanical phenomena occurring over several milliseconds to minutes. However, the increasing integration of power electronic converters, such as due to the penetration of wind, photovoltaic, and energy storage systems, has shifted power system dynamics towards rapid responses driven by power electronic converters. This change extends the relevant timescales down to microseconds and several milliseconds, requiring the inclusion of faster electromagnetic dynamics in stability assessments. 🔋 Microgrids further accentuate these shifts because of their smaller size and (typically) higher penetration of intermittent Renewable Energy Sources (RES), resulting in lower system inertia, limited short-circuit capacity, and higher feeder R/X ratios, which make their dynamics inherently faster and less predictable than bulk systems. Consequently, there is a strong coupling between voltage and frequency, meaning control actions and disturbances reflect almost instantly across the system. 🔦 In traditional systems, stability was categorised into three types: rotor angle, voltage, and frequency. While the core definitions of these remain unchanged, new stability classes have emerged: Resonance Stability and Converter-driven Stability. Resonance stability includes issues such as subsynchronous resonance, like torsional interactions between series compensation and turbine-generator shafts, and electrical resonance in DFIGs, often referred to as subsynchronous control interaction due to the dominant converter control actions. Converter-driven stability, influenced by rapid dynamic interactions of power electronic controls, is further divided into fast-interaction (high-frequency harmonic instability caused by inner current loops or switching) and slow-interaction (low-frequency oscillations from outer control loops and PLLs, particularly in weak grids). 🔋 For microgrids, instabilities often manifest as fluctuations across all system variables due to the strong voltage-frequency coupling, making root-cause classification more relevant than traditional voltage or frequency distinctions. Additionally, intentional load shedding to sustain operation (beyond fault isolation or voluntary demand response) is generally regarded as causing microgrid instability. Principal challenges in microgrid stability include rapid frequency excursions caused by low inertia, issues with reactive power sharing and voltage regulation among DERs, and other problems resulting from inadequate control schemes or poorly tuned equipment controllers (e.g., Phase-Locked Loops (PLLs), which can compromise stability), introducing negative admittance). #gridmodernization #datacenter #powerelectronics #cleanenrgy #microgrids #technology

A Comprehensive HVDC Power Electronics System in Simulink: A Milestone in Innovation This project presents an advanced High Voltage Direct Current (HVDC) system modeled in Simulink, integrating diverse power electronics components and renewable energy sources into a unified setup. This unique system is a pioneering effort in simulation and modeling, designed to highlight cutting-edge energy transmission and integration techniques. Below is a detailed breakdown of the system and its components. 1. HVDC System Overview Voltage and Distance: The system operates at 230 kV DC and spans a transmission distance of 100 km, enabling high-efficiency long-distance power transfer. Power Transmission: It is designed to transfer a total of 50 MW of power between two Voltage Source Converter (VSC) stations. Grid Integration: The system is connected to an AC grid operating at 220 kV, 50 Hz, with a transformer rated at 220/110 kV to match the transmission voltage. 2. Photovoltaic (PV) Arrays Capacity: The system integrates two 1 MW PV arrays, contributing clean solar energy to the grid. Control Strategy: Each PV array is equipped with Maximum Power Point Tracking (MPPT) controllers to optimize energy harvesting under varying solar irradiance conditions. 3. Wind Energy Integration Wind Turbine: A wind turbine rated at 10 kW is included to supplement the system’s renewable energy input. Boost Converter with MPPT: A boost converter is employed alongside MPPT algorithms to ensure maximum power extraction from the wind turbine under fluctuating wind speeds. 4. Energy Storage System Z-Source Inverter: The system features a Z-source inverter integrated with storage elements, providing robust and reliable energy storage and transfer. Boost Inverter: A boost inverter is included to enhance the storage system’s performance and support the grid during peak demand or renewable energy fluctuations. 5. Key Features and Advantages Modularity: Each component is modularly designed, enabling easy expansion and testing of additional renewable sources or advanced control strategies. Efficiency: The combination of HVDC, advanced inverters, and MPPT controllers maximizes overall system efficiency. Innovation: This is the first published system of its kind to integrate such diverse components, making it a benchmark in power electronics simulation. Conclusion This comprehensive HVDC power electronics system in Simulink serves as a cutting-edge example of modern energy systems. Its ability to integrate solar, wind, and storage solutions into a unified, high-efficiency setup positions it as a vital step toward sustainable and reliable energy solutions. 💡 If you are interested in contributing to scientific publications, sharing insights, or exploring practical applications of this system, feel free to reach out directly. Let’s work together to advance the field and achieve impactful results.

Modern grids are dominated by power electronics, yet many of today’s stability problems are old physics problems we’ve forgotten how to see.   Some of the most useful intuition for today’s converter-dominated systems comes from technologies we rarely talk about anymore. A few years ago, I analysed the behaviour of fixed-speed induction generator (FSIG) wind turbines using real disturbance data and simulations. What stood out wasn’t nostalgia, it was how clearly they exposed stability mechanisms that are still relevant. Not because we should go back to FSIGs, but because they reveal physics that modern grids have to recreate through control design. ➤ FSIGs delivered inertia through physics, instant, natural, and loop-free When frequency dipped: • the rotor slowed • stored kinetic energy was released • power was injected within milliseconds • before any grid-side controller acted. In the animation below: • frequency falls (blue) • inertial power is injected in Stage I (orange) • energy is then recovered in Stage II as rotor speed returns (provided pitch allows re-acceleration) This is physical inertia in action, not synthetic inertia produced by a control loop. ➤ Why this matters for today’s engineering challenges Much of what engineers grapple with, RoCoF sensitivity, fast frequency response tuning, PLL dynamics, coordination of grid-forming controls, is an attempt to recreate, in software, behaviours that used to exist naturally in electromechanical machines. FSIGs help explain: • why historical grids were inherently more forgiving • why frequency used to decline more slowly • why inertia was once a physical property, not a procured service • why synthetic inertia is not the same physical process • why converter-dominated grids demand precise control coordination ➤ We’re not romanticising old technology, we’re extracting timeless principles FSIGs also had real limitations: poor voltage control, limited reactive capability, and constraints that ultimately pushed the industry toward modern turbines. But their inertial behaviour remains a powerful reference for: • how machines exchange torque • how energy moves in the first 200 ms • what stabilises the system before any control loop wakes up As we build a grid dominated by power electronics, we can’t lose the intuition that anchored the synchronous era. The physics hasn’t disappeared. It has moved into software, and that makes understanding it more important, not less. I’m seeing these questions surface increasingly in EMT studies, connection assessments, and early grid-forming control design decisions, not as theory, but as constraints on what actually gets approved. 👉 As we design synthetic inertia and fast frequency response, how do we ensure we’re reproducing not just the equations, but the robustness and predictability that physical inertia once gave us “for free”? #PowerSystems #RenewableEnergy #GridStability #Inertia #InverterBasedResources #GridForming #EnergyTransition

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

⚖️🔧⚡ 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

High voltage power module is the building block for our future power grid involving HVDC & MVDC, advanced transportation systems, and various types of renewable energy systems. The development of SiC technology provides more opportunities and challenges to the HV module development for future energy conversion. Silicon carbide (SiC) power modules have been demonstrated potential for improving power density and efficiency for low-voltage power electronics systems. However, designing MV/HV SiC power modules involves significant design challenges due to higher blocking voltage and exacerbation of side effects due to high switching dv/dt and di/dt of SiC devices-concerns that may not be as critical as in low-voltage module development. This article reviews the development of state-of-the-art MV/HV SiC power modules, ranging from 3.3 kV to 40 kV, from both industry and academia. In the first part of this paper, a discussion on SiC modules based on voltage level is presented. This is followed by a discussion of challenges associated with designing and testing MV/HV modules- including parasitic controls, electromagnetic interference (EMI), partial discharge, and thermal management-and the corresponding mitigation approaches from various perspectives. We conclude with a summary of major findings and future directions for the development of MV/HV modules.

System Strength and Inverter Based Resources Introduction: Modern wind and solar PV generation as well as battery energy storage systems connect to the grid using power electronics inverter-based technology and require adequate system strength for the inverters to work reliably For grid following inverters to operate, inverters must follow the grid voltage waveform seen at their terminals and inject current at an angle that follows the measured voltage which is based on process known as phase locked loop (PLL) Impact of Phase Locked Loop (PLL): 1) The inverter creates a synchronous clock driven by the voltage phase angle it senses from the grid. 2) Following the occurrence and cessation of a fault, the inverter must re-lock onto the grid quickly to ensure stable control. 3) Under low system strength conditions, the phase angle change between the pre-fault condition to fault clearance will be larger than on stronger systems, making this much more difficult. 4) If the voltage phase angle detected by an inverter is inaccurate, the current is not injected correctly, and will impact the voltage waveform to which it is connected. This further impacts the voltage that the inverter sees at its terminals which, in turn, impacts the current it injects, and so the process repeats. 5) These interactions can occur at low frequencies (below 50Hz) as well as high frequencies (above 50Hz). In an interconnected power system, these control interactions can have a cascading impact on the voltage waveform, and could result in widespread disruption if not corrected. Conclusion: Many inverter manufacturers offer different strategies for weak and strong networks and also specify a minimum SCR for which their inverter’s operation is able to operate in a stable manner. Where the SCR (calculated at the inverter terminals in this example) is above the manufacturer-specified minimum level, the operation of the inverter phase-lock-loop is more robust, which means that SCR-type measures can be used as a screening metric for likely inverter stability issues. Correct operation is still dependent on a range of other factors, however, including voltage angle changes and the stability of other IBR in the area. Managing stability in low system strength conditions often requires a combination of minimum support from the network in conjunction with coordinated tuning of power electronic control systems of existing and new equipment.  Reference: AEMO's System Strength Explained