Optimal use of power electronic interfaces for loads in distributed systems

This article investigates how power electronic interfaces for loads provide reactive power in case of abnormal voltage conditions. An evaluation of voltage support is done for different values of voltage sags when the power electronic interface provides with reactive current. The stability margins of the distributed system are investigated for different types of loads and it is proved that the higher the share of controlled constant power loads in the system the higher the critical clearing time of the voltage. The incremental current rating of the converter when providing additional reactive current is investigated. Comparison is made between a centralized STATCOM and distributed reactive current compensation implemented in the form of controlled constant power loads, it is observed that it is always advantageous to use distributed compensation because the amount of reactive current injected is lower for achieving the same stability margins of the system.