Central computer controller for multiterminal HVDC transmission systems

The operating requirements of a central digital computer controller for a multiterminal parallel connected HVdc system are developed using an ac/dc system simulator connected in real-time to a minicomputer. Control of dc system power for steady-state, faulted, dynamic and transient conditions is investigated for typical telecommunication delays with both open and closed-loop central controllers. Open-loop control is advantageous when fast change of dc power is required while closed-loop control is preferable for steady-state and dynamic control during slower disturbances. Acceptable calculation delay times can be achieved with existing minicomputers. The computer provides increased operating flexibility, data storage and calculation capability compared with hardwired controllers.