Power terminology

Balance accounting

is a key comparison of planned consumption, generation and bilateral trading and actual consumption and generation for all companies trading in electricity in the wholesale market in Norway. The difference that arises between planned and actual generation and consumption is known as regulating power. The balance accounting provides buyers and sellers with access to all transmission grids and thus enables free electricity trading.
 

Balance power

is the discrepancy between planned and actual exchange of electricity between Norway and Sweden («Cross-border regulating power»).
 

Balancing service

In Sweden, the term balancing service is used to describe the same function as the regulating power system in Norway, see below for the definition of regulating power system.
 

Bilateral contracts

Electricity contracts entered into between two contractual parties.
 

Bottleneck

A bottleneck arises when the transmission grid is not capable of transmitting sufficient power, i.e. when the desired consumption in an area exceeds possible generation and import capacity, and correspondingly when the desired generation in an area exceeds consumption and export capacity. A bottleneck occurs as a consequence of too little available generation capacity in conjunction with limited possibilities for import, or as a consequence of a generation surplus in conjunction with limited export possibilities.
 

Distribution network

The distribution network is a network or grid for distributing electricity all the way to the consumers (high-voltage networks of up to 22 kV, low-voltage networks of 230 and 400 V).
 

Higher and lower revenues

are the deviation from the break-even result. The terms are used in conjunction with the services which must break even over time, such as the Main Grid Commercial Agreement and power transmission in shared regional grids. If in one year the arrangements’ revenues are higher than their costs, this surplus must be returned to customers in the form of lower prices in subsequent years. Correspondingly, a negative result (lower revenues) can be recouped by charging higher prices in subsequent years.
 

High-voltage transmission lines

are power lines carrying voltages exceeding 1 000 volt (1kV).
 

Ice load

In the winter, snow and ice accumulate on power lines. This is called the ice load, and is normally measured in the number of kilograms (kg) per metre of power line. In the Norwegian Main Grid, most power lines are designed to sustain a load of at least four kg of ice per metre, but on many stretches lines are designed for loads of up to 20-30 kg per metre.
 

Inflow

The volume of water that flows into the reservoirs from a power plant’s total catchment area.

Main Grid

is the main section of the power grid with the highest line voltages (420, 300 or 132 kV). It is part of a system that has common invoicing for transmission services, the Main Grid Commercial Agreement. The Main Grid consists of power lines and stations which are important to a single region, several regions, or the whole country.
 

Marginal losses

are changes in energy losses in the transmission grid as a result of changes in generation and/or consumption.
 

Operator

Buyers and sellers of electricity in the physical electricity markets are responsible for their own power balance. In other words, operators are financially responsible for maintaining the balance between consumption and generation when more or less electricity is used than is covered by contracts entered into. Statnett’s balance accounting (see above) uncovers this imbalance through its comparisons, while Statnett’s national control centre secures the overall power balance by ensuring that operators increase or decrease generation and consumption (regulating power system, see below).
 

Power exchange

The power exchange is the market place for organised trade in electricity.
 

Power units

  • V = volt (voltage)
  • A = ampere (current)
  • W = watt (output)
  • kV = kilovolt (1 000 volts)
  • kW = kilowatt (1 000 watts)
  • kWh = kilowatt hour (energy)
  • MW = megawatt (1 000 kW)
  • MWh = megawatt hour (1 000 kWh)
  • GW = gigawatt (1 000 000 kW)
  • GWh = gigawatt hour (1 million kWh)
  • TW = terawatt (1 000 000 000 kW)
  • TWh = terawatt hour (1 billion kWh)

 

kWh – One kilowatt hour is the amount of energy used to power a 1 000-watt fan-assisted heater. Average energy consumption in a normal house is estimated at about 25 000 kilowatt hours a year. Average consumption in flats is lower.

GWh – One gigawatt hour is one million kilowatt hours. This is sufficient energy for approximately 40 houses. In the municipality of Vang in Valdres, which has 1 700 inhabitants, approximately 33 GWh of electrical energy is used in one year. 

TWh – One terawatt hour is one billion kilowatt hours. This is approximately as much electricity as used in the town of Drammen in one year. In Oslo, nine TWh of electrical energy is consumed each year, while Norway as a whole consumed a total of 121,8 TWh in 2011.

MW – One megawatt is 1 000 kilowatt. This is a measurement of output. The maximum output for Drammen is 260 MW, whereas in Oslo it is almost 2 000 MW. In the municipality of Vang in Valdres, the equivalent figure is eight MW. The highest figure measured for Norway in total is 23 969 MW (measured on 6 January 2010).
 

Regional grids

are grids that are important to large regions, for example parts of one or more counties (as a rule, grid power lines have voltages of 132 kV and 66 kV).
 

Regulating power

The regulating power is used to regulate the power system so that electricity consumption and generation are always in balance. Operators quote a price to reduce or increase generation and/or consumption.
 

Revenue cap

The revenue cap is the revenue limit permitted by the authorities for monopolies. The Norwegian Water Resources and Energy Directorate (NVE) sets an upper limit on the revenues that grid companies can earn from their monopoly-based operations.
 

Shared grids

are common grid systems, for example at regional grid level. The owners of power lines and stations rent out their installations to a shared grid. The shared grid has a common operator and common power transmission prices for customers.
 

System-wide responsibility

is the overall responsibility for coordinating the planning and operation of the entire electricity grid. Statnett has system-wide responsibility in Norway.
 

TSO

Transmission System Operator