Premium Power has welcomed the publication of an award winning whitepaper by its Operations Director Andrew Hogan. The whitepaper Irish Large Scale Solar PV Opportunities: a Viability Analysis Prioritising the Influence of System Harmonics is being published in the SDAR Journal of Sustainable Design & Applied Research and will be officially launched in Dublin Institute of Technology in December 2016.

The whitepaper examines how high levels of voltage harmonic distortion on the Irish distribution network will lead to PV system curtailments. The whitepaper came runner up in the SDAR Awards 2016, which encourage research in sustainable design of the built environment and highlight innovative projects in this area.

As a senior electrical engineer working across the renewable, data centre and high-tech manufacturing industries, Hogan has witnessed the rise of ambitious carbon reduction policies over the past decade. The rush to deliver on such programmes has led, unwittingly, to major technical problems for the transmission/distribution system operators (TSO/DSO) in terms of availability, power system stability and power quality (PQ).

“The paper was inspired by case studies I’ve seen in the field,” said Hogan. “I thought it was important to examine this issue more closely, to see if we could highlight the issues at early design stage and address them. Solar is a relatively new industry into Ireland and we have time to get it right – to build a robust grid connection system that will deliver for both operators and the companies involved in producing the PV power. I’m hoping that this paper will help inform industry as well as Government policy.”

In the paper, Hogan asserts that PV system curtailments are unavoidable if compliance with the EN50160 standard cannot be achieved, which will ultimately lead to the failure of critical network components. These failures include the overheating of transformers, overloading of neutral conductors, nuisance tripping of circuit breakers, over-stressing of power factor correction capacitors, overheating of windings in induction motors and likely damage to converters, telecommunications and other electronic equipment.

Solar PV failures can be addressed by design and filtering solutions.

Hogan identifies the following three areas of concern when considering solar PV grid connections:

  • Feasibility studies
    Feasibility studies that not only look at resource but focus on strategies that help improve conversion efficiencies, from energy production to final consumption, are essential to accomplish a successful and attractive PV sector.
  • Site Location
    Power system transmission loss and voltage drop are major concerns for DSOs. The greater the distance generated power has to travel the greater the losses will be. Research identifies transmission and distribution network losses as the single largest use of electrical energy in any power systems. Therefore selecting a site close to where the load is consumed immediately improves system performance and contributes positively to the overall power demand of the network
  • Harmonic Distortion Levels
    There are also underlying factors that are often neglected, but are crucial to sustained PV development and growth. The DSO in Ireland, through industry standards such as EN50160, must ensure that Voltage Total Harmonic Distortion levels (VTHD) do not exceed 8% for 95% of the time. Through the Irish distribution codes, the DNO has designated an upper limit of 2% VTHD on harmonic emissions for all connected generators. The attention given to non-linear PV inverters in this paper relates to the technical issues that can arise where multiple sources of harmonic distortion are connected to any given the power system.

“In the whitepaper we highlight one example where a passive harmonic filtering solution, connected in parallel with non-linear PV inverters, reduced the overall VTHD from 9% to below 2%. These problems can be tackled at design and build stage. The time to action these future proofing methods is now,” he said.

Managing Director of Premium Power Paula O’Neill welcomed the publication of the whitepaper and congratulated Andrew on his achievements. “We invest heavily in our research and development of policies and mitigation techniques that help future-proof electrical systems, at all levels in industry. I’m delighted that Andrew’s work has been recognised and now published for policy makers to review.

For more on this issue read our previous article The Irish revolution in solar and what we need to be doing about it

For a copy of the whitepaper please email info@premium-power.com.

Premium Power’s services in grid compliance are outlined here. The below video highlights the work Premium Power carries out in the wind industry sector – many of the services highlighted can be applied to solar PV.