Diesel generator
Its size ranges around 50 MW and above, an open cycle gas turbine is more efficient at full load than an array of diesel engines, and far more compact, with comparable capital costs; but for regular part-loading, even at these power levels, diesel arrays are sometimes preferred to open cycle gas turbines, due to their superior efficiencies.
The packaged combination of a diesel engine, a generator, and various auxiliary devices (such as a base, canopy, sound attenuation, control systems, circuit breakers, jacket water heaters, and starting system) is referred to as a "generating set" or a "Genset" in short.
These units, referred to as power modules, are gensets on large triple axle trailers weighing 85,000 pounds (38,555 kg) or more.
The expected duty (such as emergency, prime, or continuous power), as well as environmental conditions (such as altitude, temperature, and exhaust emissions regulations), must also be considered.
Most of the larger generator set manufacturers offer software that will perform the complicated sizing calculations by simply inputting site conditions and connected electrical load characteristics.
The plant brings generator sets online and takes them offline depending on the demands of the system at a given time.
Failure to synchronize before a connection could cause a high short circuit current or wear and tear on the generator or its switchgear.
[1] This is beneficial for both parties - the diesels have already been purchased for other reasons, but to be reliable need to be fully load tested.
These diesels can in some cases be up and running in parallel as quickly as two minutes, with no impact on the site (the office or factory need not shut down).
The total capacity of reliably operable standby generation in Britain is estimated to be around 20 GW, nearly all of which is driven by diesel engines.
Most plants are for large office blocks, hospitals, supermarkets, and various installations where continuous power is important such as airports.
Although it is growing, only a very small proportion is believed to be used regularly for peak lopping, the vast majority just being only for standby generation.
The information in this paragraph is sourced from section 6.9 of the government report: "Overcoming Barriers To Scheduling Embedded Generation to Support Distribution Networks"[3] Increasing use of banks of diesel generators (known as "diesel farms") is being made in Britain to balance the fluctuating output from renewable energy sources, such as wind farms.
It is known as EJP; at times of grid stress, special tariffs can mobilize at least 5 GW of diesel-generating sets to become available.
During normal operation in synchronization with the electricity net, powerplants are governed with a five percent droop speed control.
Adjustments in power output are made by slowly raising the droop curve by increasing the spring pressure on a centrifugal governor.
Specific consumption varies, but a modern diesel plant will, at its near-optimal 65-70% loading, generate at least 3 kWh per liter (ca.
Typical application - where the generator is the sole source of power for say a remote mining or construction site, fairground, festival etc.
Many gen-set manufacturers have software programs that enable the correct choice of a set for any given load combination.
Sizing is based on site conditions and the type of appliances, equipment, and devices that will be powered by the generator set.
This is implemented by introducing gas with the intake air and using a small amount of diesel fuel for ignition.
Other possible fuels include: biodiesel, vegetable oil, animal fats and tallows, Glycerine, and coal-water slurry.
For example, engines using coal-water slurry are often modified with larger injectors to permit the higher-density fuel to be injected in the short fraction of a second time needed.
