What Is MVDC Technology? Benefits, Challenges & Future Trends

Medium-voltage direct current (MVDC) technology is a key innovation in power transmission, designed to overcome limitations of traditional AC systems in specific applications. By transmitting electrical energy via DC at voltages typically ranging from 1.5 kV to 50 kV, it combines the long-distance transmission advantages of high-voltage DC with the flexibility of low-voltage DC distribution. Against the backdrop of large-scale renewable integration and new power system development, MVDC is emerging as a pivotal solution for grid modernization.

The core system comprises four components: converter stations, DC cables, circuit breakers, and control/protection devices. Converter stations employ modular multilevel converter (MMC) technology, achieving high-efficiency power conversion through series-connected submodules—each equipped with independent capacitors and power semiconductors to precisely control voltage waveforms. DC cables use cross-linked polyethylene insulation with metallic shielding, significantly reducing line losses. Hybrid DC circuit breakers can isolate faults within milliseconds, ensuring system stability. The control and protection system, based on real-time digital simulation platforms, enables millisecond-level fault location and self-healing capabilities.

In practical applications, MVDC demonstrates diverse benefits. In EV charging, 1.5 kV DC chargers reduce charging time by 40% and equipment footprint by 30% compared to traditional AC chargers. Data centers using 10 kV DC power architectures achieve over 15% higher energy efficiency and approximately 8% lower distribution losses. Offshore wind integration using ±30 kV DC collection systems reduces submarine cable investment by 20% compared to AC and significantly lowers reactive power compensation needs. Urban rail transit upgrades show MVDC traction systems can reduce substation count by 50%, with regenerative braking energy recovery reaching 92%.

The technology offers three main advantages: 10–15% lower transmission losses than AC systems at the same voltage level, ideal for multi-point distributed generation integration; no need for frequency synchronization, simplifying interconnection between grids; and microsecond-level power regulation response, providing better adaptability to fluctuating power sources. However, challenges remain, including higher equipment costs and incomplete standardization—particularly, large-capacity DC breakers cost 3–5 times more than AC equivalents, and unified international certification standards are still lacking.

Standardization is accelerating. The IEC has published IEC 62897-2020 for MVDC cables, China's CEC released Q/GDW 12133-2021 for converter specifications, and the EU’s Horizon 2020-funded MVDC grid demonstration project has completed validation testing of an 18 kV/20 MW system. Domestic equipment manufacturing has made breakthroughs: Chinese manufacturers now mass-produce 2.5 kV/500 A IGBT modules with dynamic voltage balancing error within ±1.5%.

Future trends include: device miniaturization—SiC-based compact converters can reduce volume by 40%; system intelligence—digital twin technology improves equipment lifespan prediction accuracy to over 95%; and application expansion—space-based solar power microwave wireless transmission systems are beginning ground reception tests using 55 kV DC architectures. As power electronics costs continue to fall, MVDC is expected to become economically superior to traditional AC solutions in distribution grid upgrades by 2030.

Technology deployment requires cross-sector collaboration. Power design institutes are developing 3D digital design platforms for converter station layout optimization and EMI simulation. University research teams are advancing novel topologies, with dual-active-bridge converters achieving 98.7% efficiency. Utility pilot projects show that 20 kV DC microgrids in industrial parks can boost renewable penetration to over 85%. These initiatives provide valuable data for technological iteration.

Within new power systems, MVDC plays a pivotal role, bridging UHVDC backbone networks and low-voltage distributed sources to form flexible, multi-voltage DC networks. Case studies show that intelligent substations with 10 kV DC busbars can increase photovoltaic absorption by 25% and sustain critical loads for over 4 hours during main grid outages. As digital grid development progresses, MVDC systems are increasingly integrating with edge computing and blockchain to form self-regulating energy internet nodes.

Practical engineering requires attention to detail: cable installation must strictly control bend radius—minimum 25 times the cable diameter for 35 kV DC cables. Electromagnetic compatibility must meet CISPR 22 Class B standards, with converter room shielding effectiveness exceeding 60 dB. Operation and maintenance should include infrared thermography every 3 months and online partial discharge monitoring with thresholds below 20 pC, ensuring safe and stable operation.

From an energy transition perspective, MVDC is a key enabler for zero-carbon grids. It allows direct DC grid connection for wind and solar, eliminating 6–8% energy loss from AC inversion. In hydrogen production, 50 MW electrolyzers using 10 kV DC power achieve 12 percentage points higher efficiency than AC-powered systems. Cross-industry applications are expanding: maglev trains using 3 kV DC power reduce traction energy consumption by 18%. These innovations are reshaping energy utilization.

The industry faces talent shortages. There is a significant gap in professionals skilled in both power electronics and grid operations. Chinese universities have introduced specialized MVDC courses, and the National Occupational Qualification Catalog now includes a DC Distribution Engineer certification. Corporate training centers use full-scale simulation platforms to train personnel in emergency response under various fault scenarios. This talent development model is shortening technology transfer cycles and accelerating innovation deployment.