Distributed Generation (DG)

Distributed Generation:

Nowadays, a key change is the movement from a relatively small number of large and centrally controlled power stations connected to the transmission system towards a greater number of generating plants connected to both the transmission and distribution systems.

Generation connected to the distribution network is called Distributed Generation (DG). If you install DG you can use the electricity you produce on-site, hence lowering your electricity demand and bills. You can also sell electricity to customers, suppliers or, depending on the size of the generation, on the wholesale market.

Some roles and components of the traditional power sector that you have to notice are:

- Generating plant: composed by the Generators in charge of producing electricity. Most electricity is generated between 11,000 and 33,000 volts AC by a different kind of technologies (high speed steam turbine alternator, wind turbine, wave motion, hydroelectric, oil, gas turbine, nuclear technology...).

- Transmission system: composed by the Transmission System Owners (TSOs) whose commitment is transport power from generating plants to distribution networks. Once generated, the electricity is transformed in value to 132, 275 or 400 kV and delivered to the National Grid

- Distribution network: called Distribution Network Operators (DNOs) and they distribute power from the transmission system to customers. National Grid substations provide the means to reduce the power taken from the grid by transforming it back to 11 kV again. The reduced voltage is then transmitted over short distances across country and routed to community transformers where it is further reduced for industrial, commerce and domestic voltage (400/230 V).

The transmission and distribution systems are owned and operated by regulated monopoly business.

Electricity cannot be stored and so demand has to be balanced with generation on a second by second by the System Operator. National Grid Electricity Transmission (NGET) is the System Operator in Great Britain. To match generation with demand, the System Operator could ask generators to increase the output of their plant. Conversely, some large customers on certain contracts can be asked to reduce their demand.

Until relatively recently, the design and operation of most electricity distribution networks has been based on the key assumption that power always flows from higher voltage systems to lower voltage systems. The increased penetration of DG is changing this landscape.

Benefits and impacts of Distributed Generation:

There are a variety of benefits to having Distributed Generation, on top of the financial revenue you could have from selling some or all of the electricity that you generate, others include:

- DG can be a renewable generating technology (e.g. wind, solar, CHP, tidal..). This means the DG does not rely just on fossil fuels, so it is sustainable in the long term and does not produce or reduce emissions.

- The introduction of local generation in businesses and communities can lead to greater awareness of energy issues.

- The use of CHP plants result in higher efficiencies than generating electricity and heat independently.

- There is a reduced need for the distribution and transmission infrastructure, therefore transmission and distribution losses are reduced.

As well as introducing benefits, the increase of DG in distribution networks also poses challenges:

- DG changes the current flows and shape of the load cycle and this could cause thermal ratings to be exceeded.

- DG can cause system voltage to rise beyond acceptable limits.

- DG could cause reverse power flows that means that the power flows in the opposite direction to which the system has been designed.

By taken this picture as a summary of the new energy technology challenges that the future have for us. Enjoy and share with us the creation a new community of knowledge.

Saving energy is less expensive than buying it.