Reactive power compensation by means of TCSCs can be adapted not only to brand-new installations but also be implemented in a wide range of existing systems. The TCSC provides, in addition to the conveniences of a conventional Fixed Series Compensation, some further benefits. It also controls the current and thus the load flow in parallel transmission lines, which simultaneously improves system stability. Further applications for TCSC include power oscillation damping and mitigation of subsynchronous resonance (SSR), which is a crucial issue in case of large thermal generators.