RENEWABLES & SUSTAINABILITY
SPECIAL FEATURE
On the whole , power is supplied at a higher voltage than is necessary .
“
VOLTAGE OPTIMISATION IS NEEDED TO CORRECT THE SUPPLY ISSUES CAUSED BY THE HIGH VOLTAGE INFRASTRUCTURE .
Any excess voltage above the VO set-point is chopped and returned back to the grid .
issues at source ( HV side optimisation ). If a company only has an LV supply then the most effective approach will be to address the issues at the LV side ( LV optimisation ).
HV side optimisation
HV side optimisation technologies offer solutions to sites that own their own distribution transformers . Many technologies exist , but there is only one system currently on the market , which provides HV , electronic variable voltage optimisation . This is a combined solution , which replaces an on-site , inefficient HV transformer with an amorphous core superlow loss HV transformer , with integrated electronic-dynamic VO technology .
The system can take up to 33,000V input and provides a fully electronically regulated 380V , or user-defined , voltage output . Technology also exists that will allow the user to alter the defined voltage locally through a Human Machine Interface ( HMI ) on site or remotely via the Internet . The HMI allows users to manage and monitor the system in real time to ensure maximum savings are being realised .
Depending on the age and type of the transformer that it replaces , an amorphous core transformer can provide between one and five per cent savings , simply due to its efficiency . In addition the integrated VO technology can be expected to provide a further saving of between 12 and 15 per cent .
Efficient transformers will provide greater return on investment over its lifespan and it is important to source transformers that exceed Eco Design 2021 efficiency specifications .
LV side optimisation
As the name suggests , LV side optimisation is connected to the low voltage infrastructure . There are two variations of LV side optimisation technology available : fixed and variable ( also known as electronic-dynamic , electronic or intelligent VO ). Fixed VO systems reduce the incoming voltage by a set amount to the optimum level for site operations . However , output varies as the input voltage varies .
Variable VO systems set the output voltage at the optimum level and maintain this by systematically managing the peaks and troughs in the power supplied – irrespective of the incoming voltage levels – to ensure that voltage is supplied at a constant , stable level .
How does voltage optimisation save energy ?
VO is a transformer based system used to optimise the characteristics of the current supplied at the source ( first current ), according to current characteristics required at the load ( second current ). The first current is typically an alternating voltage in which the resultant voltage is increased or decreased ; this transformation routinely results in excess transformed voltage .
The supply current flows from the first winding into the second winding of a VO system , wherein the magnetic flux causes the induction of a reverse current , which is
a fraction of the supply current , typically 10 per cent . The reverse current flows in the opposite direction to the supply current , where it is directed back to the electricity supply . As the reverse current is real energy , which is distinct from apparent or reactive energy , there is a direct effect on the consumption of the load . This effect is a reduction of power consumed by a load , seen by actual kWh savings .
In simple terms , any excess voltage above the VO set-point , is chopped and returned back to the grid , generating induced negative power ( back EMF ), which flows towards the supply and is subtracted from the incoming power ( the subtraction process occurs within the VO transformer ). The negative power feedback ( back EMF ) accounts for 70 to 80 per cent of VO savings with the remaining 20 to 30 per cent savings coming from equipment efficiency improvements .
Improving equipment performance
Optimising the supply voltage for a building can also prevent equipment and machinery from early burn-out , reducing maintenance costs . Operating equipment at a higher voltage than it is designed for does not improve performance ; on the contrary it has the effect of reducing its lifespan . For example a 230V rated incandescent lamp used at 240V will achieve only 55 per cent of its rated life . It will also take 4.3 per cent more current and consume almost nine per cent more energy .
If you supply a motor with more voltage than it needs , it doesn ’ t spin any faster , it just wastes the extra energy as heat . VO extends the life of motors by lowering their operating temperatures .
43