Fast local converter set point adaption after AC grid disturbances based on a priori optimization

Once having an HVDC overlay system equipment trips in the underlaid AC-grid that may cause congestions can be solved by immediate adaptation of converter power references. Such scenarios can be highly time critical. However, a coordinated set point adaptation after disturbances may be essential. This paper proposes a new redundancy concept taking AC and HVDC grid into consideration: diverse redundancy. It is based on an optimal set-point calculation for critical disturbances prior to the incident that are stored locally at each converter station. An update of that information can be made simultaneously with regular set-point changes. Continuous local measurements are used to identify disturbances. After successful identification, the converter control applies the pre-calculated new power…