Inverter-less STATCOMs

Dynamic VAR support is essential for grid support, particularly to help ride-through significant faults on the system. Conventional sources of VARs, such as capacitor banks and generators, respond too slowly to have the desired impact. Static VAR compensators (SVC) are faster, responding in 1/2 to 1 cycle, but offer reduced VAR support under fault conditions. STATCOMs are even faster, allowing for dynamic control, but are seen to be expensive as they require large dc/ac inverters and significant levels of energy storage. This paper proposes a new approach to realizing STATCOM functionality without inverters, effectively using standard shunt VAR compensating capacitors to realize the needed dynamic VAR support. The technique is seen to be scalable to high voltage and high VA levels, and promises to realize lower cost through the use of existing shunt VAR resources with thin AC converter concepts (see companion paper).