FEATURE RENEWABLE TECHNOLOGY
Frequency response monitoring for grid balancing services
Selling surplus energy to a transmission system operator (TSO) is an important source of income for many operators of renewable energy systems. However, as Paul McClean of eMS explains, this income can be augmented – provided monitoring requirements are met – by delivering balancing services, such as fast/firm frequency response (FFR)
T
SOs currently face a dual challenge. They must accommodate energy
from non-traditional sources, but they must also satisfy their obligations to ensure network stability and to maintain supply frequency and voltage within prescribed limits. These challenges aren’t new, but they
were easier for TSOs to meet when energy was predominantly produced by generating plant over which they had considerable control. Today the picture is different. In 2017,
renewables accounted for 29 per cent of total installed generating capacity on the island of Ireland, and in Great Britain for around 28 per cent. These percentages are growing, so relying solely on traditional generating plant to ensure grid stability is no longer possible. TSOs are therefore encouraging
operators of renewable energy sources, energy storage facilities and standby power plants to help maintain supply
16 NOVEMBER 2019 | ELECTRICAL ENGINEERING
system stability by providing ‘ancillary services’, such as responding rapidly to frequency dips by bringing additional generating capacity on line. For these services, the TSOs make a payment for the availability of the service, and a further payment when the service is actually provided. The amounts depend on how much power is offered, the time it is available for, and how quickly it can be brought on line. Providing ancillary services is an
attractive option but there are a couple of caveats. The TSOs are usually only interested in signing up larger energy suppliers, with generating capacity of 10MW or more, and they also lay down stringent requirements for the energy supplier’s monitoring systems. To satisfy the first caveat, energy suppliers can work with an aggregator that combines capacity from small suppliers to reach a TSO’s minimum. The second caveat may seem onerous, but without monitoring,
TSOs can’t confirm they are receiving the services they’re paying for! The details of monitoring requirements
differ between TSOs, but information is readily available online. Eirgrid and SONI take a slightly different approach from National Grid but, in reality, both sets of requirements have much in common. They both stipulate, for example,
that the monitoring system must provide data acquisition, data storage facilities and network connectivity. It must monitor and record parameters that include voltage, current, apparent power, real power, reactive power and frequency. It must offer high accuracy, and measurements must be precisely timed. SONI and Eirgrid, however, want data delivered in a defined layout using CSV format, whereas National Grid requires direct access to data via a webserver. Fortunately, there are now
web-enabled multifunctional monitoring
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44
