When faced with the option of electricity from renewable sources such as solar or wind, one of the first objections is always the erratic nature of power generation – the sun and wind can’t be controlled or depended on to generate power at all times of day. There are solutions to this, and one solution is energy storage, but a better way to stabilize the power grid may be new solar inverter technology.
Germany’s Belectric – a global provider of solar power plants – has developed new central inverters that keep the grid around the power plant stable. While Germany has a swiftly growing share of renewable power (mainly solar and wind), its main problem with keeping its grid stable is not with a dearth of power, but rather with the inability to produce reactive power on demand.
Reactive power is needed to maintain voltage — if too much real power is fed into the grid, the voltage increases. The farther the power transmission goes, the more reactive power is needed to keep voltage steady and within the grid’s operational limits. In the south of Germany, where nuclear power plants have been shut down, the amount of reactive power produced has been decreased considerably.
Keeping It Together
The new central inverters can act as phase shift oscillators, which help keep the phases of power production and transmission in sync. When the phases are in rhythm, the grid is able to take up more power and better balance real power and reactive power. However, while large-scale power plants can use these inverters effectively, the units are just too expensive to manufacture for smaller arrays.
Bernhard Beck, head of Belectric, recently spoke to Renewables International about grid expansion and the role solar power plants could – and should – play:
“All technologies that produce power irregularly are a burden on the grid. With new central inverters, power plants with a capacity of 4 to 8 megawatts can help keep the regional grid stable. For the past year, we have been using inverters that even provide reactive power at night, which provides us with completely new ways of stabilizing the grid.
“Utility-scale solar can do the job. A solar farm with hundreds of megawatts can produce enough reactive power to offset the grid-stabilizing effect of a nuclear plant. Germany is currently talking about the cost of solar, but instead of focusing on reducing feed-in tariffs for solar, PV arrays should be required to help stabilize the grid. Ground-mounted arrays larger than 30 megawatts should be required to provide reactive power regardless of how much they are producing at the time. And only then should they receive the full tariff for ground-mounted PV.”
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Source: Renewables International | Image: Wikimedia Commons