Introduction: Use of disturbance recorder information to determine harmonic levels on a rural 33kV network with a large penetration of cable connected intermittent distributed generation.

Objectives: With a growing penetration of non-linear loads, distributed generators and Flexible AC Transmission System (FACTS) devices that employ power electronic converters, harmonic voltage distortion on the distribution network are increasing.

Harmonic voltage distortion has been recognised as a cause of:

• Interference to telecommunication and control systems

• Increased losses in circuits and equipment

• Overheating of rotating plant, transformers and capacitors, the latter being particularly susceptible to harmonic damage

• Increased voltage stress on equipment

• Increased vibration and noise emissions

• Spurious tripping of control circuits and relays, and mal-operation of any equipment using zero crossing waveform technology, including digital timers

• General degradation of fuse elements.

Identifying the source of harmonic distortion is not always easy as the magnitude depends upon network parameters.