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Patent Issued for Method of providing power support to an electrical power grid (USPTO 11056885)

  • Jul 28, 2021 11:59 am GMT
  • 88 views
Source: 
Energy Business Daily

2021 JUL 27 (NewsRx) -- By a News Reporter-Staff News Editor at Energy Business Daily -- From Alexandria, Virginia, NewsRx journalists report that a patent by the inventors Hasler, Jean-Philippe (Vasteras, SE), Kheir, Jan (Vasteras, SE), Maibach, Philippe (Muhen, CH), filed on October 21, 2016, was published online on July 6, 2021.

The patent’s assignee for patent number 11056885 is Abb Power Grids Switzerland Ag (Baden, Switzerland).

News editors obtained the following quote from the background information supplied by the inventors: “Renewable energy sources such as e.g. wind or solar power generation, are substituting fossil-fuel and nuclear based energy sources for the production of electricity. For the case of wind power generation, wind turbines are often coupled to an electrical power grid through power electronic converters so that the wind turbine generator may rotate with an angular speed independent of the grid frequency. This is necessary since the wind speed varies considerably within an operating range of the wind turbine, hence causing rotor speed to vary.

“The electrical power grid may experience grid voltage transients, some of which are combatted by the inertia of the rotating masses connected to the grid. These rotating masses may, for instance, be synchronous generators connected to the electrical power grid. By definition, the inertia of these masses results in an inherent active power output response during frequency transients. The inertia thus combats these grid transient conditions and helps maintaining a power balance between the total power output of the grid (i.e. load) and the total power supplied to the grid (from e.g. power plants).

“One drawback of the renewable energy sources is that they do not or only to a very limited extent contribute to the network frequency stability as normally provided by the mechanical inertia of the electrical machines connected to the grid. The inertia may become critically small and the electrical power grid system may therefore get unstable. The current solutions for increasing the inertia are to install a synchronous condenser or energy storage such as Battery Energy Storage System (BESS), flywheel, or the like to the grid. For windfarm installations, wherein inverter-connected wind turbines as such do not provide inertia, it is proposed to use the mechanical energy stored in the blades/rotor to provide synthetic inertia. All these solutions are expensive in that additional machinery has to be purchased.”

As a supplement to the background information on this patent, NewsRx correspondents also obtained the inventors’ summary information for this patent: “An objective of the present invention is to solve or at least alleviate the above mentioned problems. A particular objective is to enable provision of inertia (in particular synthetic inertia) to an electrical power grid in a cost-efficient way. Another particular objective is to provide means for controlling e.g. a synchronous generator (e.g. speed thereof) that is used for providing the inertia. These objectives and others are achieved by the methods, devices, computer programs and computer program products according to the appended independent claims, and by the embodiments according to the dependent claims.

“The objective is according to an aspect achieved by a method of providing power support (in particular active power support) to an electrical power grid. The power support is provided by an arrangement comprising a synchronous machine connected to a converter, the converter in turn being connected to the electrical power grid. The method may be performed in a control device controlling the arrangement. The method comprises: receiving feedback from one or both of: the electrical power grid and the synchronous machine, and controlling, based on the received feedback, energy stored in a rotating mass of the synchronous machine.

“The method provides several advantages. For instance, the invention provides the possibility of using (or re-using) existing energy sources for providing synthetic inertia to the electrical power grid. This is a less costly way than e.g. purchasing and running battery systems. The method enables a stable and reliable operation of the electrical power grid, also when using renewable energy sources for the electrical power generation.

“In some embodiments, the receiving feedback comprises receiving rotational speed of a rotating mass of the synchronous machine and frequency of the electrical power grid. The controlling comprises controlling rotational speed of a rotating mass by controlling the frequency of the synchronous machine. That is, the rotational speed is controlled such as to increase or decrease the rotational speed of the rotating mass by controlling the frequency of the synchronous machine.

“In some embodiments, the controlling comprises controlling a rotational speed of a rotating mass of the synchronous machine to be within a defined interval including its nominal rotational speed.”

The claims supplied by the inventors are:

“1. A method of providing synthetic inertia for frequency support to an electrical power grid, the support being provided by an arrangement comprising a synchronous machine connected to a power electronic (PE) converter, the PE converter being connected to the electrical power grid, the method being performed in a control device controlling the arrangement, the method comprising: setting an initial rotational speed of a rotating mass of the synchronous machine in proportion to a nominal frequency of the electrical power grid; receiving feedback from the electrical power grid and the synchronous machine; and controlling, based on the received feedback, energy stored in the rotating mass such that synthetic inertia is provided to the electrical power grid via the PE converter, wherein controlling the energy stored in the rotating mass controls power provided to the electrical grid from the synchronous machine and controls power absorbed from the electrical grid to the synchronous machine.

“2. The method as claimed in claim 1, wherein receiving the feedback comprises receiving a rotational speed of the rotating mass of the synchronous machine and frequency of the electrical power grid, and wherein the controlling comprises controlling the rotational speed of the rotating mass by controlling the frequency of the synchronous machine.

“3. The method as claimed in claim 2, wherein the controlling comprises increasing or decreasing the rotational speed of the rotating mass by controlling the frequency of the synchronous machine.

“4. The method as claimed in claim 3, wherein the controlling comprises controlling the rotational speed of the rotating mass of the synchronous machine to be equal to or below a nominal rotational speed thereof.

“5. The method as claimed in claim 3, wherein the controlling comprises controlling the rotational speed of the rotating mass of the synchronous machine to be synchronized with an amplitude, a frequency and/or a phase angle of the electrical power grid.

“6. The method as claimed in claim 3, further comprising detecting a fault condition in the electrical power grid and bypassing the PE converter by a breaker device.

“7. The method as claimed in claim 2, wherein the controlling comprises controlling the rotational speed of the rotating mass of the synchronous machine to be equal to or below a nominal rotational speed thereof.

“8. The method as claimed in claim 2, wherein the controlling comprises controlling the rotational speed of the rotating mass of the synchronous machine to be synchronized with an amplitude, a frequency and/or a phase angle of the electrical power grid.

“9. The method as claimed in claim 2, further comprising detecting a fault condition in the electrical power grid and bypassing the PE converter by a breaker device.

“10. The method as claimed in claim 1, wherein the controlling comprises controlling a rotational speed of the rotating mass of the synchronous machine to be equal to or below a nominal rotational speed thereof.

“11. The method as claimed in claim 10, wherein the controlling comprises controlling the rotational speed of the rotating mass of the synchronous machine to be synchronized with an amplitude, a frequency and/or a phase angle of the electrical power grid.

“12. The method as claimed in claim 1, wherein the controlling comprises controlling a rotational speed of the rotating mass of the synchronous machine to be synchronized with an amplitude, a frequency and/or a phase angle of the electrical power grid.

“13. The method as claimed in claim 1, further comprising detecting a fault condition in the electrical power grid and bypassing the PE converter by a breaker device.

“14. The method as claimed in claim 1, further comprising detecting a fault condition in the PE converter and bypassing the PE converter by a breaker device.

“15. A non-transitory computer readable medium with a computer program thereon, the computer program comprising computer program code, which, when run on processing circuitry of the control device causes the control device to perform the method according to claim 1.

“16. A control device for controlling provision of synthetic inertia to an electrical power grid for frequency support, the synthetic inertia being provided by an arrangement comprising a synchronous machine connected to a power electronic (PE) converter, the PE converter being connected to the electrical power grid, the control device being configured to control the arrangement by: setting an initial rotational speed of a rotating mass of the synchronous machine in proportion to a nominal frequency of the electrical power grid; receiving feedback from the electrical power grid and the synchronous machine; and controlling the PE converter such that synthetic inertia is provided to the electrical power grid by the synchronous machine based on the received feedback, wherein controlling the PE converter controls power provided to the electrical grid from the synchronous machine and controls power absorbed from the electrical grid to the synchronous machine.

“17. The control device as claimed in claim 16, wherein receiving the feedback comprises receiving a rotational speed of the rotating mass of the synchronous machine and frequency of the electrical power grid, and wherein the controlling comprises controlling the rotational speed of the rotating mass by controlling the frequency of the synchronous machine.

“18. A circuit for providing power support to the electrical power grid, the circuit comprising the control device as claimed in claim 16, wherein the PE converter and the synchronous machine are connected to the control device.

“19. The circuit as claimed in claim 18, wherein receiving the feedback comprises receiving a rotational speed of the rotating mass of the synchronous machine and frequency of the electrical power grid, and wherein the controlling comprises controlling the rotational speed of the rotating mass by controlling the frequency of the synchronous machine.

“20. The circuit as claimed in claim 18, further comprising a breaker device arranged to bypass the PE converter upon detection of a fault condition.

“21. A method of providing synthetic inertia for frequency support to an electrical power grid, the support being provided by an arrangement comprising a synchronous machine connected to a converter, the converter being connected to the electrical power grid, the method being performed in a control device controlling the arrangement, the method comprising: setting an initial rotational speed of a rotating mass of the synchronous machine in proportion to a nominal frequency of the electrical power grid; receiving feedback from the electrical power grid and the synchronous machine; controlling, based on the received feedback, energy stored in the rotating mass such that synthetic inertia is provided to the electrical power grid, wherein controlling the energy stored in the rotating mass controls power provided to the electrical grid from the synchronous machine and controls power absorbed from the electrical grid to the synchronous machine; and detecting a fault condition in the electrical power grid or the converter and bypassing the converter by a breaker device in response to detecting the fault condition.”

For additional information on this patent, see: Hasler, Jean-Philippe. Method of providing power support to an electrical power grid. U.S. Patent Number 11056885, filed October 21, 2016, and published online on July 6, 2021. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=11056885.PN.&OS=PN/11056885RS=PN/11056885

 

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