July 14, 2016 - 7:22 PM EDT
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Patent Issued for Power Control System of an Electrical Generation Unit (USPTO 9382901)

By a News Reporter-Staff News Editor at Energy Weekly News -- According to news reporting originating from Alexandria, Virginia, by VerticalNews journalists, a patent by the inventors Garcia Sayes, Jose Miguel (Sarriguren, ES); Arlaban Gabeiras, Teresa (Sarriguren, ES); Ruiz Aldama, Alfonso (Sarriguren, ES); Garcia Barace, Alberto (Sarriguren, ES); Fernandez Garcia de Iturrospe, Ana (Sarriguren, ES); Otamendi Claramunt, Diego (Sarriguren, ES); Gonzalez Murua, Alejandro (Sarriguren, ES); Nunez Polo, Miguel (Sarriguren, ES), filed on July 31, 2014, was published online on July 5, 2016.

The assignee for this patent, patent number 9382901, is Acciona Windpower S.A. (Navarra, ES).

Reporters obtained the following quote from the background information supplied by the inventors: "Wind turbines today incorporate control systems whose objective is to maximise energy production by a solution of compromise, which guarantees that the loads associated to the wind are maintained within a range that can be assumed by the component design. It is for this reason that the control over the torque demanded of the generator to operate at variable speed and the control of the blade pitch angle have become conventional control systems.

"On the one hand, the control of the blade pitch angle is controlled by actuators disposed in the root of each blade, which makes the blade rotate around its longitudinal axis. Said actuation manages to vary the aerodynamic behaviour of the blade modifying the pitch of the blade to maintain the rotational speed at approximately the rated rotational speed once the rated torque has been reached.

"On the other hand, the control system over the demanded torque modulates said demanded torque to the generator from the converter in accordance with the generator speed.

"In this way, variable-speed wind turbines operate by maximizing the aerodynamic performance in a low-wind basis thanks to its capacity for working at variable rotor rotational speed, where their rotational speed is controlled by modulating the torque in the electrical generator in a determined medium and high-wind regime limit the rotational speed of the rotor in the event of gusts thanks to the control of the blade pitch angle, managing to limit the power generated in a value substantially equal to the rated power.

"Generally, the wind turbine regulation loops calculate orders in working cycles whose calculation period is less than a second, with the aim of achieving great response agility. Thus, document U.S. Pat. No. 6,420,795B2 presents a torque control system such as those described above.

"Said control system may involve an energy loss with respect to that which may be produced on many occasions due to the fact that said regulation loops incorporate limiters which, in each calculation step, prevent the power or the torque from exceeding their respective maximum value at any time.

"To resolve said problem, there are proposals which include two regulation types: a regulation such as the conventional one, with the different speed control bands typical of variable-speed wind turbines, and an alternative regulation used in certain periods of time, wherein a higher value than the rated value of the conventional regulation loop is used as power limit, as a channel for the compensation of previous energy losses which may be due to situations wherein there was no wind available to reach the rated power.

"Among the above we have document EP2336558A2 relating to control method of wind turbines comprising control means for a standard regulation tracking a power vs. generator speed curve of the generator, comprising a first sub-nominal zone wherein the generator speed is kept constant at its coupling value, a second sub-nominal zone wherein it allows that both the speed of the generator and the power increase or decrease in line with the wind speed, a third sub-nominal zone wherein the wind speed is kept constant at its nominal value and a nominal zone wherein the power is kept constant at its nominal value, where during certain periods of time an alternative regulation is used at a power higher than that determined by the standard regulation to optimise the energy production compensating for previous losses.

"Patent application US2006273595A1 is also known relating to a system and method to operate a wind farm under high wind conditions, where the method performs an intermittent increase in the rated power output of the wind turbine based on an estimate of a set of operating parameters with respect to the design conditions of said operation parameters.

"Likewise, in wind farm control loops which send rated power limitation orders, to stop below the order values, higher rated limits are applied to fast-acting or instantaneous regulation loops, with calculation cycles for the torque orders in the range of 10-100 ms and of the pitch orders in the range of 100-200 ms and the regulation loops are performed based on instantaneous measurements, so that the production can be extra-limited."

In addition to obtaining background information on this patent, VerticalNews editors also obtained the inventors' summary information for this patent: "The present invention resolves the technical problem posed, using a power control system of an electrical generation unit comprising regulation means of the instantaneous power generated P.sub.inst, means for determining a signal indicative of the instantaneous power generated and means for determining, from the signal indicative of the instantaneous power generated P.sub.inst in a time interval, an average power signal generated P.sub.avg.

"Throughout the present specification, whenever use is made of the term power, whether instantaneous or average, as a general rule reference is being made to real power. To make reference to another type of power, such as apparent or reactive, throughout the specification, the terms apparent power and reactive power shall be used respectively.

"The control system further comprises average power regulation means configured to modify an operating parameter X.sub.ref of the regulation means of the instantaneous power generated in accordance with the error between an average reference power signal P.sub.ref which may be the rated power of the generation unit, and the average power signal generated P.sub.avg, so that said error is eliminated.

"To calculate the average power P.sub.avg the historical values of the instantaneous power signal generated P.sub.inst, are considered during a time interval. Said time interval can either be configurable or predetermined, for example, equal to ten minutes.

"The average power regulation means thus configured allow that the instantaneous limits can temporarily exceed the stationary limit as long as they are not exceeded as a general rule. Due to the fact that the stationary limits are normally thermal or of loads, it guarantees that they are not exceeded nor are the components thermally or mechanically overloaded, whilst, in turn, the generation periods below the rated stationary limits, which are of shorter duration than the time interval configurable by the average power regulation means, are compensated by others also of shorter duration than the configurable time interval, wherein the power is greater than the normal stationary limits.

"In this way, the average power regulation means of the system of the present invention carry out a continuous control, where due to this compensation of the generation periods below the rated stationary limits, said compensation maximizes the energy produced by the installation whilst it guarantees the integrity of its components.

"The operating parameter of the regulation means of the instantaneous power generated which is modified by the average power regulation means of the system of the present invention may be, but is not limited to, one of the following: maximum instantaneous power P.sub.max.sub._.sub.inst, reference rotational speed, reference pitch angle, increase in power or torque over the reference power or reference torque respectively calculated in an instantaneous regulation loop.

"Optionally, the electrical generation unit is a wind turbine comprising a rotor formed by at least two blades and an electrical generator connected to said rotor and to the grid, where the regulation means of the instantaneous power comprises control means of the electrical torque of the generator and/or control means of blade pitch.

"Also optionally, the generation unit is a wind farm comprising wind turbines and where the operating parameter X.sub.ref of the regulation means of the instantaneous power generated P.sub.inst is an average power reference P.sub.ref.sub._.sub.i for the wind turbines of the wind farm.

"Optionally, the regulation means of the instantaneous power generated perform the calculation of a overall average power P.sub.avg.sub._.sub.Global based on the measurement of overall instantaneous power P.sub.inst.sub._.sub.Global, and in accordance with the error between said overall average power P.sub.avg.sub._.sub.Global and the average reference power P.sub.ref.sub._.sub.Global, which may be received from a remote control station of the customer or directly from the grid operator or be an average power reference equal to the rated power of the wind farm, calculates the parameter of average power reference P.sub.ref.sub._.sub.i for the wind turbines of the wind farm, and can perform the central control of a wind farm from a substation."

For more information, see this patent: Garcia Sayes, Jose Miguel; Arlaban Gabeiras, Teresa; Ruiz Aldama, Alfonso; Garcia Barace, Alberto; Fernandez Garcia de Iturrospe, Ana; Otamendi Claramunt, Diego; Gonzalez Murua, Alejandro; Nunez Polo, Miguel. Power Control System of an Electrical Generation Unit. U.S. Patent Number 9382901, filed July 31, 2014, and published online on July 5, 2016. 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=9382901.PN.&OS=PN/9382901RS=PN/9382901

Keywords for this news article include: Oil & Gas, Wind Energy, Acciona Windpower S.A..

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Source: Equities.com News (July 14, 2016 - 7:22 PM EDT)

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