Projects:2015s1-07 Remote AVR Control for Embedded Generation

Solar panels are more annoying than you think

Project Information

Background

Project Team

William Declan Schuller

Sebastien Gray

Yiju Ma

Daniel Tang

Supervisors

Commercial

Mark Doherty

Erin Hart

Academic

Rastko Zivanovic

SA Power Networks

SA Power Networks is South Australia's privately owned but heavily regulated power distribution network operator. SA Power Networks is charged with delivering power from the transmission grid to consumers around South Australia. The company is split into a regulated monopoly and a competitive infrastructure and maintenance company.

Over the past decade South Australians have taken up rooftop solar power in a big way, recent statistics suggest that SA has at least 575 MW of installed solar capacity. As solar levels have risen SA Power Networks has begun to receive complaints of solar panels tripping off where penetration is at it's highest. The solar panels are tripping off because the voltage on their output terminals has risen above Australia's regulatory level. SA Power Networks began looking into the issue in more in late 2014 and has asked a team of Adelaide University Electrical and Electronic Engineering students to take a look at the problem from a more academic direction.

The South Australian Grid

The system of grid management in South Australia has existed in a relatively static fashion for the past decade. Power is delivered from large sites via Electranet's transmission grid to connection point substations at 275kV. These substations distribute power down to standard substations embedded in the suburbs at sub-transmission voltage 66kV. The suburban substation then sends it's power down 11kV feeders to pole top transformers at the end of the street. The mini-feeders on the 415V side of the pole top transformer then deliver power to individual premises.

Voltage Regulation Today

Dynamic voltage regulation in the form of On-load tap changing transformers exists at the substation level between 275kV/66kV and 66kV/11kV. This allows easy regulation of voltage when all the generation comes from a source at high voltage and is consumed at low voltage. In simple terms it's easy to regulate when there is an on load tap changer between the generation and consumption.

Voltage regulation at the 11kV to 415V level has always been a problem but has been easily solved with off load static tap changers on pole top transformers (a much cheaper option). With the introduction of solar we introduced a dynamic generation component to our 415V network. It appears that the static tap changing properties of pole-top transformers prevent them from being used to cope with daily fluctuations in solar output.