Abstract: The present invention relates to apparatus 30 for determining a condition of a network section 34 comprised in an electrical power network 32. The network section 34 is configured such that electrical power flows to or from each of plural locations in the network section. The apparatus 30 is configured to receive a first quantity in respect of a first location in the network section 34 and to receive a second quantity in respect of a second location in the network section, each of the first and second quantities corresponding to a signal amplitude and a signal phase angle at its respective location. The apparatus 30 comprises a processor 42 which is operative to determine a condition quantity corresponding to a loading condition of the network section 34 between the first and second locations in dependence on the first and second quantities.

Abstract: The present invention relates to apparatus (10) for determining a contribution of at least one grid subsystem of plural grid subsystems to oscillation in angle or grid oscillation in an electrical grid (12). The apparatus (10) is configured to receive a first quantity which corresponds to oscillation in angle at a first grid subsystem (14). The apparatus (10) is also configured to receive a second quantity which corresponds to oscillation in angle at a second grid subsystem (16). The apparatus (10) comprises a processor (32) which is operative to determine a contribution of at least one of the first and second grid subsystems to oscillation in angle or grid oscillation with the contribution being determined in dependence on a phase relationship between the first and second quantities.

Abstract: A method of controlling an output of a generation plant (2) that is connected to a bulk electrical power network (4) by an electrical route (6). The method comprises determining (31) a phase angle difference between a first phase angle representing a phase angle of a voltage waveform at an output of the generation plant (2) and a second phase angle representing a phase angle of a voltage waveform at a location within the bulk electrical power network (4). The phase angle difference is compared (32) to a threshold phase angle difference that represents a constraint on the electrical route (6). The output of the generation plant (2) is controlled (33, 34) based on the comparison to prevent overloading of the electrical route (6).

Abstract: A method for determining the contribution of a grid subsystem (12) to oscillations in grid frequency experienced by an external electrical grid (14) in an electrical power network (10). A measurement of grid frequency is taken in the grid sub-system (12) and/or the external electrical grid (14). The measurement(s) of grid frequency can be used to extract oscillations in grid frequency in the grid subsystem (12) and/or the external electrical grid (14). A measurement of active power is recorded on a transmission line (16c) between the grid subsystem (12) and the external electrical grid (14). The phase relationship between the oscillations in grid frequency and the oscillations in active power allows the contribution of the grid subsystem (2) to oscillations in grid frequency in the external electrical grid (14) to be determined.

Abstract: There is described a method of monitoring high voltage electrical power system. The method involves measuring small signal power system characteristics under prevailing systems conditions and determining the power transfer limits using said measurements.