ieee power & energy magazine = - Power-Flow Control Device Used for the addition/subtraction of voltage to actively control power flow, for example, using power-electronic topology to modulate voltage insertion into each line. - + Primary Equipment for Negative Pole (Duplicate of Positive Pole) Primary Equipment for Positive Pole Used for the dissipation of energy, for example, for pole rebalancing or for using nonlinear resistor(s) controlled by power-electronic devices. Dynamic-Braking System + + - The air core inductor used to limit the rate-of-rise of fault current. Inductor Measurement Grounding Switch Applied for safety and reconfiguration of system. This is a mechanical switch with a requirement for voltage withstand and connection under voltage. Transfer Switch This is a mechanical switch with a requirement for voltage withstand, making current and current commutation. Voltage and current sensors used to enable protection and control decisions. Applied when load-current commutation is required. + + This is a mechanical switch with a requirement for interruption of residual currents and voltage withstand. A switch applied for reconfiguration of system and for safety during maintenance. Disconnector Switch figure 1. A prospective primary-equipment layout per pole for a symmetric monopolar system. Note that not all equipment is required in all substations and that the configuration is given as an example and is not indicative of an optimal system layout. ~ + Energy Dissipation Path Commutation Path Conduction Path HVdc Circuit Breaker During normal operation, current flows through the low-loss conduction path. Following the fault, additional path(s) enable current commutation into energy dissipation. DBS 58 july/august 2019