APPLICATION OF PHASOR-BASED FUNCTIONALITY TO HVDC CONTROL IN REDUCED SYSTEM STRENGTH

The control and stability of power electronic converters are strongly related to the strength of the system to which they are connected. Traditionally, synchronous machines have provided a large share of the strength or “stiffness” of voltage control in the grid, but increasingly there are large power electronic converters in remote areas of the grid displacing this synchronous generation. At remote connection points, the network is susceptible to large changes in system strength if lines or generators trip. It is therefore challenging to design power electronic controls to remain stable over a wide range of system operating conditions. The purpose of this paper is to demonstrate capabilities to use Phasor Measurement Unit (PMU) data to derive real-time indicators of the state of the network. These indicators of AC network state can be used to select an appropriate mode of operation by the High-Voltage Direct Current (HVDC) control. This paper describes the developed phasor-based control solution and details of its functional blocks. The control approach combines direct indication of the system strength with other indicators of the outcomes of a weakening system.