From Active Resistor to Lossless and Virtual Resistors: A Review, Insights, and Broader Applications to Energy Grids

More-electric and pure-electric ship and aircraft, and electric-grid power systems include three subsystems: generation (generators and inverter-based renewable energy sources), delivery (transmission and distribution lines and cables, transformers, capacitor banks, and inductors), and energy storage. Therefore, power systems are dominantly inductive and capacitive. Resistors are rarely used, and circuits are designed and built with minimal resistance to minimize power loss and maximize efficiency. Due to this nature, however, there have been problematic resonances, instability, and prolonged transients. To solve these problems, power converters/inverters were first presented in the 1980s as active, lossless, and virtual resistors to suppress/damp resonances, instability, and transients. In this article, we provide a comprehensive review of this innovative power converter-/inverter-based technology from the active resistor to lossless and virtual resistors. We present theoretical analysis and insights about their interrelationship and physical meanings; discuss their implementation constraints; and examine broader applications and renewed potentials to revolutionize today’s power/energy grids.