HVDC links at increased voltage, CESI experience on extruded cable systems up to 525kV

The World energy consumption and the power generation to match it are set to continue to rise for the foreseeable future. Unfortunately, the bulk of the Energy resources needed to satisfy rising demands are not located near the load centers. For submarine and lengthy land cables, HVDC systems offer key advantages including higher capacity, reduced losses, no need for capacitive charging currents and better control over both load flow and reactive power transmission. A number of interconnections from mainland to islands and long undersea applications have been realized to allow different types of energy sources to connect together to boost security of supply. In EU, Projects of common interest (PCIs) were introduced as key infrastructure projects, especially cross-border projects, that link EU energy systems. Germany, with its central location in EU and increasing electricity demand, is expected to promote interconnections between neighboring countries, thereby supporting the growth of worldwide's HVDC cables market. In particular the German Transmission System Operators (GTSO), in the frame of the Energiewende, are now looking for the first set of cable manufacturers able to supply at least 3000km of 525 kVdc extruded cables systems CESI is deeply involved in this process with 4 cables lines under tests in the first third party worldwide laboratory in Mannheim, Germany. This paper highlights the experience gained during the first Long Duration Tests (PQT) performed in both lab and outdoor situations on 525kV DC cable systems.