Modular FACTS devices with external fault current protection within the same impedance injection module

A power grid system, comprising:

• a plurality of impedance injection modules distributed on a power transmission line, each impedance injection module comprising:
• a plurality of modular flexible alternating current transmission systems (FACTS) based impedance injection units (IIUs), each modular FACTS based IIU comprising a plurality of FACTS based switch units and a capacitor connected in parallel with the FACTS based switch units forming a transformerless static synchronous series compensator (TL-SSSC), and each modular FACTS based IIU without fault current protection;
• and
• a fault current protection module external to the modular FACTS based IIUs, wherein the fault current protection module is coupled to the modular FACTS based IIUs to provide fault current protection to the modular FACTS based IIUs.

A method of providing fault current protection to a plurality of distributed impedance injection modules (IIMs), the method comprising:

• distributing the plurality of IIMs on a high voltage (HV) transmission line, each IIM comprising a plurality of modular flexible alternating current transmission systems (FACTS) based impedance injection units (IIUs), each modular FACTS based IIU comprising a plurality of FACTS based switch units and a capacitor connected in parallel with the FACTS based switch units forming a transformerless static synchronous series compensator (TL-SSSC), the modular FACTS based IIUs without fault current protection, and connected and coupled to a segment of the high voltage transmission line for control of power flow and disturbance at a local region of the HV transmission line;
• interconnecting, the plurality of modular FACTS based IIUs without fault current protection, in each IIM in series, parallel or series-parallel configuration;
• connecting a fault current protection module in parallel with the plurality of interconnected modular FACTS based IIUs in each IIM;
• and
• providing fault current protection to the plurality of interconnected modular FACTS based IIUs in each IIM.