Practical Guide to Power Semiconductors for Grid Stabilization: IGBT/SiC Design for STATCOM, HVDC, and FACTS

With the massive adoption of renewable energy, demand for voltage stabilization, reactive power compensation, and long-distance power transmission infrastructure is expanding globally. STATCOM (Static Synchronous Compensator), SVC (Static Var Compensator), and HVDC (High Voltage Direct Current) are all power equipment centered on power semiconductors, and device selection according to grid scale, application, and cost requirements is key to design. In offshore wind interconnection in Europe, wide-area grid interconnection in North America, and long-distance power transmission projects in Asia, the demand for these FACTS devices is in a medium- to long-term growth trend.

Classification of FACTS Equipment and the Role of Power Semiconductors

FACTS (Flexible AC Transmission Systems) is a general term for equipment that dynamically controls the voltage, power flow, and stability of power grids. The transition from conventional SVC and LCC-HVDC using thyristors to modern STATCOM and VSC-HVDC using IGBTs is the major trend in grid modernization.

SVC is composed of a combination of thyristor-switched capacitors (TSC) and thyristor-controlled reactors (TCR). Although its control response is slower compared to STATCOM, it has a proven track record of large capacity and low cost. Mitsubishi Electric's SVCs are installed in over 30 locations worldwide and support a capacity range of 50 to over 450 MVAr.

STATCOM is a device based on VSC (Voltage Source Converter) using IGBTs or GTO thyristors. Because self-commutated operation is possible, it can control reactive power independently even in weak grid environments, and its response speed is faster than SVC. Mitsubishi Electric introduced the world's first practical grid STATCOM (±80 MVAr) in 1991 and constructed the world's largest ±450 MVAr system at that time in 2012. Mitsubishi Electric's SVC-Diamond®, which adopts the MMC topology, achieves low harmonic characteristics without filters, minimizing auxiliary equipment.

HVDC: Device Selection for LCC (Thyristor) and VSC (IGBT)

HVDC is used for long-distance, large-capacity power transmission and grid interconnection, and the selection of the converter method is the core of the design.

LCC (Line Commutated Converter) uses thyristors and features large capacity, high efficiency, and low cost, but it carries a risk of commutation failure, making it difficult to apply when the interconnection point is a weak grid. VSC (Voltage Source Converter)-HVDC uses IGBTs and enables four-quadrant control, weak grid support, and independent control of active/reactive power. The VSC method is increasingly being selected for onshore interconnection of offshore wind power and connection to isolated grids, and it has become the de facto standard method for large-scale European offshore wind projects.

Infineon's IHV series offers 4500V IGBT modules, supporting high-voltage converters for HVDC and traction applications. These modules guarantee insulation coordination characteristics with a CTI (Comparative Tracking Index) of 600 or higher and are also used for grid stabilization in STATCOM applications.

The cost of HVDC projects varies significantly depending on scope, specifications, scale, copper prices, etc., but there is a tendency for the cost per kW to decrease as transmission capacity increases (METI, Japan). Due to this economy of scale, new HVDC projects are often planned with priority given to high-capacity, long-distance routes.

Comparison with Synchronous Condensers

Synchronous condensers are equipment that compete with STATCOM. Since they are rotating machines, they have inertia and short-circuit current supply capabilities, making them effective for supplementing grid inertia, which decreases with the integration of renewable energy. Mitsubishi Electric also offers synchronous condenser systems, and cases where combined operation is being considered to address inertia shortages that cannot be handled by STATCOM alone are increasing.

Implications for Procurement and Design Personnel

In selecting power semiconductors for the grid, after determining the equipment method (SVC / STATCOM / HVDC) based on the four axes of grid strength, compensation capacity, response speed, and cost, specification confirmation of the corresponding device (thyristor or IGBT) and high-voltage modules follows.

In STATCOM and VSC-HVDC, 4500V to 6500V class IGBT modules are the main components, and Infineon, Hitachi Energy (formerly ABB), and Mitsubishi Electric are positioned as major suppliers. HVDC projects mainly involve small-volume orders for a wide variety of products, and specification determination through design discussions with OEMs is a more common procurement path than general-purpose procurement of standalone modules. With the acceleration of renewable energy integration, the demand for IGBTs for STATCOM and HVDC is a segment expected to see medium- to long-term growth, deserving prioritization in the supply chain.

Referenced FactCards