Solving Motor Start Power Quality with Distribution Class STATCOMs
Distribution Substation STATCOM 101
STATCOMs are current source devices that have been used by electrical utilities to provide voltage support to the bulk transmission system during transient fault conditions. They are one of the technologies that make up the FACTs group that also includes SVCs and SSSCs. The STATCOM can inject both capacitive and inductive current and therefore is capable of providing both boost and buck to the voltage on the grid. The STATCOM can typically provide voltage support in under 1 cycle making it advantageous for transient voltage support.
The technology has been impractical for distribution applications in the past but that’s changing with recent advances and industry trends. First, the technology is becoming less expensive and reducing in physical size. More importantly, changes are occurring at a rapid pace on the distribution system. Wind and solar generation is being connected directly to the distribution system and is causing rapid voltage changes. Emphasis on reliability and system hardening is encouraging greater use of back-up ties between adjacent radial circuits that create contingency arrangements with low voltage constraints. Distribution customer loads are also trending from a constant-resistive to a constant-power characteristic which can exacerbate dynamic voltage issues. Finally, Volt/Var optimization and Conservation Voltage Reduction initiatives are leading to increased mechanical operations for equipment such as LTCs, regulators and switched capacitor banks leading to more frequent maintenance. The STATCOM requires no maintenance and has no moving parts and therefore the number of operations does not factor into the life of the product.
With this in mind the following applications will be covered
- Providing Dynamic Vars for large utility scale renewables
- Providing flicker mitigation at large industrial sites
- Providing the ability to ride through voltage sags (down to 20% nominal) so industrial and large commercial sites don’t shut down or loose their process.
- Providing voltage stability support on sub-transmission and transmission grids.