Increasing voltage headroom for the connection of distributed generation: site trials of the SuperTapp n+ AVC relay

Abstract

A common limiting factor in the connection of a generator to a distribution network is the control of the network voltage within the required statutory limits under all network operating conditions. The SuperTAPP n+, manufactured by Fundamentals Limited, is a unique voltage control relay that calculates the most appropriate transformer target voltage by estimating the output of embedded generators and adding it to that being supplied by the transformer(s) to give the 'true' load. The estimation is based on the load share between feeders with connected generation and those without. All the required measurements are made locally (within the substation) and there is no reliance on communications. The paper evaluates the relay's ability to estimate the output of embedded generators during a series of substantial group load changes. It also describes how standard network analysis tools can be used to determine the maximum generator output at a particular location dependent upon the voltage control relay used and appraises the increase in voltage headroom afforded when the SuperTAPP n+ is considered.

Programmatic smart grid trial design development and analysis methodology

“…AuRA-NMS project are similar to those proposed as part of CLNR including voltage control and EES however collaborative operation was not investigated to the extent required by CLNR [1]. In the SuperTapp N+ trials an existing commercial product was tested and trialled [2]. This project however investigated only a single voltage control component.…”

“…Therefore, the operational limits and set points need to be examined to ensure that the smart grid systems are invoked regularly in reaction to voltage events during the trial period to enable comprehensive evaluation of their characteristics and performance. A number of approaches have been identified to enable this [2]. Proxy voltage limits are to be used, within these trials, as this limits the possibility of customers' power quality being adversely affected.…”