Abstract: A variable speed wind turbine having a doubly fed induction generator (DFIG), includes an exciter machine mechanically coupled to the DFIG and a power converter placed between a rotor of the DFIG and the exciter machine. Thus, the power converter is not directly connected to the grid avoiding the introduction of undesired harmonic distortion and achieving a better power quality fed into the utility grid. Moreover, the variable speed wind turbine includes a power control and a pitch regulation.

Abstract: A variable speed wind turbine having a doubly fed induction generator (DFIG), includes an exciter machine mechanically coupled to the DFIG and a power converter placed between a rotor of the DFIG and the exciter machine. Thus, the power converter is not directly connected to the grid avoiding the introduction of undesired harmonic distortion and achieving a better power quality fed into the utility grid. Moreover, the variable speed wind turbine includes a power control and a pitch regulation.

Abstract: Electric circuit for converting direct into alternating current specially designed for photovoltaic systems connected to the electrical grid without a transformer, and enabling the earthing of one of the input terminals (2) of the photovoltaic generator, thereby working with a wide range of input voltages and having a high efficiency.

Abstract: A method and system of active power reserve regulation in a wind farm with a communication network having a plurality of wind turbines that provide an active power reserve in order to support eventual power grid contingencies and to deliver an increase of power in case it is needed.

Abstract: The object of the present invention is to provide a structure for the electrical protection of photovoltaic facilities in the event a photovoltaic generator (G1-Gp) is connected with its polarity reversed, for what it includes a protection cell that comprises two connection points (1, 2) at which the photovoltaic generator is connected (G1-Gp), at least one device (D) in charge of reducing the voltage of the photovoltaic generator (G1-Gp) in the event of polarity reversion, which is connected in parallel between the aforementioned two connection points, at least one element (M) of breakage and/or protection of the photovoltaic generator (G1-Gp) serially connected to the preceding elements, minimizing the loading on the aforementioned break and/or protection elements.

Abstract: A method and system of active power reserve regulation in a wind farm with a communication network having a plurality of wind turbines that provide an active power reserve in order to support eventual power grid contingencies and to deliver an increase of power in case it is needed.

Abstract: A method and system of active power reserve regulation in a wind farm with a communication network having a plurality of wind turbines that provide an active power reserve in order to support eventual power grid contingencies and to deliver an increase of power in case it is needed.

Abstract: A theft protection device for photovoltaic solar panels is provided. The device includes of at least one cable which is made to pass through the solar panels. The cable can be fibre optic or electrical, and a light beam or an electrical current, respectively, is made to circulate through the cable. At the ends of the cable, an electrical control circuit is connected, capable of detecting a cut in the cable caused by the interruption of the light beam in the fibre or a voltage drop at the ends of the electrical cable. Cutting of the cable for theft of the solar panels is detected by the control circuit which activates an alarm, acoustic and/or visual, which can belong to the device or be remote.

Abstract: The invention presents a structure for the conversion of direct current electric power into alternating current electric power, characterised in that it is simple, highly efficient and minimises the problem of electromagnetic compatibility. The circuit includes, in its first preferred embodiment, six switching elements governed by a command unit, four switches forming an H-bridge (T1, T2, T3, T4) and two auxiliary switches (T5D, T6D), and two auxiliary diodes (Daux1 and Daux2). The elements of the H-bridge switch at grid frequency, whereas T5D and T6D switch at high frequency by means of pulse width modulation (PWM), or other appropriate modulation techniques. The voltage of these auxiliary switching elements (T5D, T6D) is limited topologically to half the direct current input voltage (Vin), thereby reducing switching losses and resulting in a high performance converter.

Abstract: A variable speed wind turbine having a doubly fed induction generator (DFIG) includes an exciter machine mechanically coupled to the DFIG and a power converter placed between a rotor of the DFIG and the exciter machine which guarantees a stable voltage to the power converter. Thus, the power converter is not directly connected to the grid allowing the continuous operation of the system during a low voltage event in the grid.

Abstract: A system and method of reactive power regulation in a wind farm having a plurality of wind turbines that provides optimum control of the reactive power compensation in the wind farm and is able to keep a reactive power reserve in order to support eventual grid contingencies.