Light & Power concerned about possible grid instability

By Marlon Madden

The Barbados Light & Power Company (BLPC) has raised alarm about the potential instability of the national grid given the increasing number of connections being made by renewable energy systems.

The issue has become so “critical” that the island’s sole electric utility company has applied for permission to build a combined total of 60 megawatts of utility-scale storage across four parishes as part of a mitigation plan.

In a notice published in the press last month, the BLPC said it had applied to the minister with responsibility for energy for permission pursuant to Section 5 (3) of the Electric
Light and Power (Amendment) Act 2019 to build 10 MW utility-scale storage projects on land situated at the Garrison Hill, St Michael; Hampton St Philip; Trents, St Lucy; Lower Estate, St Michael; Wotton, Christ Church and Whitepark, St Michael.

“This decision is driven by the results of prior studies performed to assess the impact of additional renewable energy on the grid and has been confirmed by the impacts that are currently being observed on the grid as a whole and in localised areas,” it had explained in a letter sent to stakeholders near the end of November.

“It has been exacerbated as renewable energy systems are being added to feeders without mitigation measures and some are now reaching their thermal capacity limit of 5 MW as prescribed in the BLPC Grid Code.”

Last October, then Minister of Energy Kerrie Symmonds reported that only about 11.8 per cent of the estimated 750 megawatts of renewable energy capacity required over the next eight years had been connected to the national grid.

Barbados has set an ambitious target of becoming 100 per cent reliant on renewable sources of energy by 2030.

Symmonds indicated that as of October 1, 2022, there were 65.5 megawatts of renewable energy installed on the national grid, and another 22.8 megawatts of potential capacity which was licensed but not yet connected to the grid. He stated, however, that of the 54 feeder lines across the island, only seven had been identified as approaching the peak level of 5 megawatts (MW) – Sunbury and Sam Lord’s in St Philip; Arch Hall, St Thomas; Green Hill, Grazettes and White Hall in St Michael; and Newton in Christ Church.

However, in its letter to stakeholders the following month, the BLPC informed that the penetration of renewable energy on the grid had reached a stage where the utility company “now finds it critical to implement additional mitigation measures to maintain grid stability”.

It said it had communicated the issues to the Ministry of Energy and the Fair Trading Commission (FTC) [last] year, with respect to the challenges being experienced in managing the grid. 

“Since then several megawatts have been added to the grid and the situation is becoming more critical,” the power company said.

The BLPC said that to ensure the grid remains safe and reliable for all customers and that it continues to cater to the stable growth of the renewable energy market, several mitigation strategies would be implemented.

They include a continued thermal limit of 5 MW, which will be reviewed on a feeder-by-feeder basis.

The letter, which was signed by Director of Asset Management Rohan Seale, indicated that not all feeders were at that capacity “and thus, have to be operated in such a manner as to not compromise the operability and safety of the network”.

It also outlined the need for battery storage measures which it proposed should be of a capacity that is equivalent to that of the installed renewable energy capacity and a minimum of four hours duration.

BLPC proposed that when a feeder reaches 4.5 MW of licensed and installed renewable energy capacity, systems over 10 kW “be required to provide curtailment capability or equivalent capacity of distributed four-hour battery storage until the 5 MW feeder limit is reached”.

“Any installation or installations cumulatively over 100 kW in a location on any feeder is required to include equivalent distributed four-hour battery storage or curtailment capability. Where new renewable energy capacity impacts protection coordination on a feeder, equivalent distributed four-hour battery storage will be required to be installed,” the company added.

It also indicated that volt-var optimisation – a mechanism used to adjust distribution systems to reduce system losses and demand – should be employed as a short-term mitigation measure.

This, the company said, would be required in the absence of battery storage to provide voltage support.

It further pointed to the need for cumulative capacity limits, noting that “all cumulative capacity at a location shall be connected to the grid through one point of connection/isolation with appropriate metering as determined by the BLPC”.

“Where the cumulative renewable energy capacity at a single location is greater than 1.5 MW, connection will be facilitated at 24 kW voltage through one point of connection/isolation with appropriate metering as determined by BLPC in line with section 1.7.1 of the Grid Code,” it added. 

marlonmadden@barbadostoday.bb