Current References Limitation Method Considering Voltage and Current Maximums for STATCOMs Providing Simultaneously Reactive Power and Current Harmonics

This article focuses the analysis on a static synchronous compensator (STATCOM) that operates simultaneously providing reactive power and several current harmonics of different frequencies (active power filter or active impedance functionalities). Being more specific, this article proposes a general limitation method that reduces the current references of the STATCOM whenever the current or voltage limit of the converter is exceeded. In a realistic operation scenario, the STATCOM’s operator may ask for certain reactive power and harmonic current reference signals, and depending on the actual grid voltage conditions (unbalances and harmonics), the required converter voltage and current may exceed their limit. Consequently, the proposed limitation method protects the STATCOM system from malfunctioning when the voltage limit is exceeded and from damages when the current limit is exceeded. Hence, this article first proposes a limitation method oriented to a STATCOM that operates solely exchanging reactive power. Second, the limitation method is generalized for a STATCOM that controls reactive power as well as several current harmonics. Then, simulation and experimental results are provided to validate the proposed limitation method, under a rich variety of working conditions. Finally, a conceptual analysis of the method is carried out confronting it against several possible limitation alternatives.