Series compensation is widely used to improve the transmission capability of long distance overhead transmission lines and the overall network efficiency. These capacitors do not only influence the operational behaviour of the power system, but also the behaviour during short circuits. Effects like voltage inversion are well known and covered in distance protection relays by determining the direction of the fault with memorized voltages. Depending on the location of the capacitor, its size, the protection level o the platform protection, and the impedance of the source current inversion is also possible. If this current inversion occurs, new problems arise for the protection scheme. High resistive earth fault protection, fault locator and also the differential protection will be affected in different ways. This was proven by RTDS real-time simulation tests. The paper explains theory and shows the different protection principles.
