This article presents the latest progress of the national key R&D program titled "Key Technology Development and Demonstration of DC Distribution for Photovoltaic-Storage-Direct Current-Flexible (PEDF) Buildings" under the 14th Five-Year Plan, covering the core achievements including developed key technologies, computational tools, and series of product equipment, while also reviewing the latest industry developments in relevant policies, technical standards, and industrial ecosystems within the low-voltage DC and PEDF sectors.

Hyperscale 2.0 of AIDC brings unprecedented challenges, but also unprecedented opportunities for innovation and collaboration. The transformation of compute power infrastructure is a global journey. It requires the joint efforts of the entire ecosystem: hyperscalers, data center operators, technology providers, power companies, and research institutions. VNET is committed to driving this transformation, through continuous innovation and on-theground practice. We are open to global collaboration, to build a greener, more efficient, more reliable and more intelligent compute power infrastructure for the AI era.

Focusing on the research of protection technologies for low-voltage DC distribution systems, this paper elaborates on the long-term technical exploration of Nanjing Golden Cooperate. The company has kept tackling DC fault protection technologies, developed a full range of protective equipment, and taken an active part in formulating domestic and international standards, achieving abundant technical results. Verified by research, low-voltage DC technology serves as a core solution to break the "impossible triangle" of energy security, equity and sustainability. Building low-voltage DC systems featuring high safety, high reliability, superior power quality and high penetration of new energy provides key support for the development of new power systems and low-carbon energy transition.

VSC-HVDC has been widely adopted in modern power systems, and the modular multilevel converter (MMC) has become one of its most important converter topologies. This report first analyzes the compatibility between the intrinsic characteristics of IGCTs and the application requirements of MMCs. It then introduces IGCT-Plus devices specifically developed for MMC applications, highlighting innovations in chip design and gate-driver technology. Based on the device characteristics and system requirements, iterative component design and structural optimization are conducted to develop a series of IGCT-MMC modules. Key engineering issues, including internal resonance within submodules, are also addressed. Finally, the report presents the application of IGCT-MMC technologies in several demonstration projects in China and discusses their future development trends.

AI data centers are projected to consume hundreds of terawatt-hours annually by 2035, demanding power conversion technologies that are not only energy-efficient but also cost-effective, scalable, and reliable. It is estimated that the global market for power supplies, distribution, and management systems serving AI data centers and cloud computing is expected to reach approximately $145-150 billion. Conventional line-frequency transformers and multi-stage AC-DC architectures suffer from low efficiency, bulkiness, high cost, low reliability, and limited dynamic response. To support the rapid growth of AI workloads and comply with emerging energy and environmental standards, innovative power electronics solutions are urgently needed. This presentation explores the development of a novel megawatt-scale, medium-voltage (MV) power conversion system based on a Variable Air Gap Solid-State Transformer architecture. The approach aims to reduce energy loss, footprint, and cost while enabling flexible, modular deployment, and achieving more reliable operation in large-scale AI data centers.

It is anticipated that a significant number of High Voltage Direct Current (HVDC) systems and power electronics-based Flexible AC Transmission System (FACTS) controllers will be deployed across transmission and distribution networks to support the growing integration of renewable energy resources. According to Pike Research, HVDC transmission is emerging as one of the fastest growing segments in the utility sector. Cleantech Market Intelligence reports that cumulative global investments in HVDC systems from 2012 to 2020 reached approximately US $120 billion, with spending continuing to rise rapidly throughout the 2020s. While much of this growth is concentrated in countries such as China and India, HVDC adoption is also accelerating in Europe, North America, Australia, and other regions as utilities work to enhance renewable energy integration. This presentation highlights the state of the art in HVDC and FACTS technologies and explores new applications, including AC line conversion to DC and advances in converter designs such as modular multilevel voltage source converters (VSCs).

The rapid expansion of AI data centers, EV charging infrastructure, and renewable energy integration is driving strong demand for efficient, high-power-density power conversion from medium-voltage AC (MVAC) grids to medium-voltage DC (MVDC) and low-voltage DC (LVDC) distribution buses. Conventional solutions based on line-frequency transformers combined with low-voltage rectifiers suffer from large footprint, complex manufacturing, and limited controllability. State-of-the-art modular multilevel converter (MMC) approaches provide superior performance for MVDC applications, but at the expense of significantly increased cost and footprint. Modular solid-state transformer (SST) architectures offer built-in galvanic isolation; however, they face challenges related to insulation scalability and limited application flexibility.

This talk introduces the Hybrid Modular-Multilevel Rectifier (HMMR), a new family of power converter topologies designed to bridge the gap between performance and practicality in MVDC systems. HMMR architectures combine modular, scalable cell structures with hybrid switching networks to support both step-up and step-down AC-to-DC conversion across a wide voltage range - from distribution-level inputs (e.g., 4.16 kV, 13.8 kV) to target DC bus voltages suited for hyperscale data centers, solid-state transformer (SST) front ends, and DC microgrids.

The presentation reviews the HMMR topology family, discussing key variants optimized for different application constraints. Compared to MMC and other multilevel solutions, HMMR demonstrates compelling advantages in converter size, switching loss, and component count, translating to improved efficiency and reduced capital cost. The talk further addresses modulation strategies, wide-bandgap (SiC/GaN) device integration, fault tolerance, and scalability - with design case studies anchored in AI factory power architecture, 800 V DC distribution, and fast EV charging applications.

In recent years, Medium-Voltage Direct Current (MVDC) projects have been widely implemented across the world. For the power supply of critical industrial facilities including oil fields, hydrogen production facilities, and industrial plants, MVDC offers numerous advantages, such as flexible operation, isolation from the external power grid, controllable power flow, and low harmonics. This report will introduce the application background, technical characteristics, and system design of MVDC projects applied in critical industrial facilities. Additionally, it will present an overview of real engineering projects.

In DC power systems, the current lacks natural zero-crossing points, making its interruption more challenging compared to AC, particularly in medium and high voltage applications where fault current rapid interruption is required while minimizing cost and size. It becomes a significant challenge in electrical engineering around the world. The research team at Xi'an Jiaotong University has focused on DC rapid interruption technology for long time. By regulating arcs, they developed a novel magnetic-controlled arc oscillation method for DC interruption and created medium and high voltage DC circuit breakers. It not only achieved rapid fault current interruption but also significantly reduced costs and size, providing essential support for the advancement of DC systems.

The transition toward DC-based power architectures is accelerating across modern energy systems, driven by the rapid growth of digital infrastructure, transportation electrification, and industrial decarbonization. Solid-state transformers (SSTs), as power-electronic-enabled interfaces, enable this transition by providing controllable AC/DC and DC/DC conversion, multi-port connectivity, and direct integration with DC-native sources and loads.

This paper focuses on three high-impact application domains. In hyperscale and AI-driven data centers, SST-enabled medium-voltage AC to high-voltage DC conversion supports emerging 800 VDC distribution, reducing multiple conversion stages and improving efficiency for high-density compute loads. In electric vehicle charging infrastructure, SST-based architectures directly interface medium-voltage grids with low-voltage DC outputs, enabling ultra-fast charging stations (>350 kW) with higher power density, modular scalability, and integration of on-site energy storage. In industrial electrification, SST-enabled DC microgrids provide direct coupling of distributed generation, battery storage, and high-power process loads, improving operational efficiency, reliability, and system controllability.

Across these applications, SSTs enable a common DC backbone that minimizes conversion losses, simplifies system architecture, and supports bidirectional energy flow between grid, storage, and loads. Regional deployment trends further emphasize application-driven adoption: in the United States, growth is led by data centers, EV charging hubs, and resilient microgrid solutions, while in China, large-scale development focuses on low-voltage DC distribution in buildings, industrial systems, and advanced DC power networks. Overall, SST-enabled DC architectures are emerging as foundational building blocks for next-generation power systems, particularly in applications requiring high efficiency, high power density, and seamless integration of renewable and storage resources.

The rapid growth of AI is driving data center power supply systems toward higher power density, higher efficiency, and simplified distribution architectures. Conventional AC UPS and HVDC solutions are facing increasing challenges in footprint, conversion losses, copper consumption, and system scalability. An 800 Vdc architecture based on solid-state transformers (SSTs) is becoming a practical option for next-generation AI data center power supply. This presentation discusses the industry trends behind the transition from traditional AC distribution to 800Vdc distribution. It introduces SST development and application experience from micro-grids, DC distribution to data center. Key enabling technologies are reviewed, including SiC-based power conversion, high-frequency transformers, medium-voltage insulation, modular redundancy, protection design, and coordinated control. The presentation also outlines how SSTs can support source-grid-load-storage coordination, renewable energy integration, and green power utilization in future AI data centers.

Over the last two decades over 1200 companies employing more than 60,000 people have started manufacturing supercapacitors with an annual growth rate of around 2.8%. Traditional applications are to replace or supplement batteries, based on high power density of these devices with wider operating temperature ranges. Currently there are four to five different SC families and device capacitances vary from fractional farads to over 100,000 F per single cell. Over the past several years new materials such as graphene has become a new electrode material for better performance. Supercapacitors could be used not only in energy storage applications, but also in unique families of high-performance power converters and protection systems. When you treat the SCs as very long-time-constant devices and near-lossless voltage droppers a wider application area opens. This area is now identified as supercapacitor assisted (SCA) techniques. First successful example of applications is the SCA low dropout (SCALDO) regulator for high efficiency EMC free extra low frequency DC-DC converters. Second is the SCA surge absorber (SCASA) where a SC subcircuit could be combined with a coupled inductor and a MOV for repetitive surge absorption. Third is the SCA LED technique for DC lighting based on fluctuating DC supplies from renewable energy sources. Fourth is the SCA DC refrigerator (SCARef) for renewable DC operation of refrigerators based on SC energy buffering and DC-DC conversion eliminating the need for inverters and MPPT DC-DC converters etc. There are many other applications in the SCA family such as SCA transient energy pump for DC circuit breakers to eliminate high voltage DC power supplies and cryogenic cooling systems; SCA inverter (SCAInv) for reducing the losses in DC input loop of a solar inverter; SCA lossless DC transformer (SCAL2T) for step up and step down DC-DC converters for renewable energy DC systems at the low voltage end of the AC power grid. Seminar will present a designer's view of these SCA techniques, many of which have secured patents and some commercial implementations. Presenter will also touch on innovation and commercialization aspects of these techniques at the latter part of the seminar, which is based on over hundred IEEE and other publications.

Direct Current has emerged as the key technology for meeting the extreme power demand of next-generation AI servers and racks. The necessary DC infrastructure, equipment, standards, and expertise are essential for massive deployment of AI factories. However, despite a very challenging timeline, many key aspects and the rationale for some choices remain unclear. The OCP Power Distribution project, resulting from a strategic partnership between Current/OS and ODCA, to represent the electrical industry, and OCP, to represent the data center industry, has been aimed to establish a common language and a shared consensus about basic concepts, such as architectures, voltage, earthing, protection and safety, and main components. The project has demonstrated feasibility of 800 VDC power distribution, explored various technical alternatives, analyzed their respective advantages and disadvantages, and identified remaining critical challenges. The results are reported in a whitepaper published in March 2026. The project is continuing, extending the coverage to new topics, such as EMC and control, and deep diving in certain aspects, e.g. the connection with racks. A new edition of the whitepaper is planned during the summer. The perspective is to develop technical specifications to ensure the interoperability of equipment.

The accelerating convergence of electrification, digitalization, and sustainability is reshaping the landscape of modern power electronics and energy systems. This keynote presents a forward-looking perspective on how advanced semiconductor technologies, intelligent control, and data-driven approaches are enabling the next generation of highly efficient, scalable, and resilient power conversion solutions. Focusing on key applications such as data centers, renewable energy integration, and industrial electrification, the presentation highlights the role of wide-bandgap devices, system-level optimization, and modular architectures in meeting growing performance and reliability demands. It further explores how digital technologies—including real-time sensing, edge computing, and cloud-based analytics—support predictive operation and improved lifecycle management. A central theme is the integration of artificial intelligence and digital twin technologies into power systems, enabling enhanced efficiency, fault detection, and adaptive control under dynamic operating conditions. These innovations are driving a transition from hardware-centric designs toward software-defined, service-oriented energy solutions. The keynote speech concludes with insights into future challenges and opportunities, emphasizing cross-disciplinary collaboration as a key enabler for accelerating innovation and supporting a more sustainable and electrified future.

Since 2021, when PV-Storage-DC-Flexible technology was incorporated into China's Carbon Peaking Action Plan, more than 400 related engineering projects have been implemented. The scale of application continues to expand, with new scenarios and system architectures constantly emerging. The field is currently at a critical stage, transitioning from "pilot demonstration" to "large-scale deployment." Based on the trend toward large-scale development, this paper analyzes the current status of standardization in PV-Storage-DC-Flexible systems from three perspectives: engineering construction, equipment systems, and end-use electrical devices. It further proposes directions for enhanced standardization and cross-sector coordination.

The liberalization of the energy market has significantly impacted the entire structure of the energy supply system. In addition, partially due to a strong commitment of governments to reduce CO2 emissions, vast amounts of renewable, dispersed, but volatile power generator systems are being installed. This presentation explores the potentials of DC technologies in distribution systems to realize the energy transition. The role and prospects of state-of-the-art power electronic substations and protection gear, a key enabling technology to realize a modern energy supply system, is mentioned. In particular, the saving of critical materials and control issues of solid state transformer (SST) is discussed.