The present invention concerns a method of operating a wind power installation comprising an electric generator drivable by a rotor for outputting electrical power to an electrical consumer, in particular an electrical network. The invention further concerns a wind power installation comprising a rotor and an electric generator coupled to the rotor for outputting electric power to an electrical consumer, in particular an electrical network. The object of the present invention is to provide a method of operating a wind power installation, and a wind power installation, which avoid the disadvantages of the state of the art and in particular avoid voltage over-fluctuations at the consumer, in particular an electrical network, and unwanted shut-down of the wind power installation. In a method of the kind set forth in the opening part of this specification, that object is attained by the invention in that the power delivered to the network by the wind power generator is regulated in dependence on the applied network voltage of the power supply network.

Method of operating a wind power installation and a wind power installation

A cleaning sheet for cleaning and removing particles from a surface is disclosed. The sheet includes a particle retention layer including an electret material for collecting and retaining the particles. The sheet also includes an outer layer covering at least a portion of the particle retention layer. The outer layer comprises a low dust retention material and includes a surface having a plurality of apertures formed therethrough.

Particle entrapment system

A power utility system includes a generator driven by a prime mover in response to a mechanical input power and an excitation to provide an electrical output power. The excitation of the generator is controlled in response to an estimated equilibrium rotor angle. The estimation of the rotor angle is based on purely local measurements. This estimated rotor angle is used in conjunction with a feedback linearizing controller to provide field excitation control of the generator. The rotor angle reference signal is also used to provide a rotor angle error signal to a power system stabilizer which is modified to operate on the basis of an angle error rather than a speed or frequency error.

Decentralized excitation control for an electrical power utility system

Methods and apparatus for switching a load between first and second sources is shown to include first and second solid state switches connected to the load. First and second mechanical breakers are connected between the switches and the sources so that each source is connected to the load through a circuit breaker and solid state switch. A controller is connected to sense the voltage from the first and second sources. The controller is connected to the first and second switches and the first and second mechanical breakers. The controller senses the phase difference between the voltages from the first and second sources. The controller causes the first and second mechanical breakers to open and close in response to sensing the phase difference between the sources. The first and second mechanical breakers can include medium voltage vacuum breakers. In a preferred embodiment, when the controller senses that the phase difference between sources is more than 30 degrees out of phase, the controller will open the circuit breaker connected to the alternate source. In this manner voltage stress on the solid state switching devices is minimized.

Hybrid solid state switch

The present invention relates to a method of operating of a wind power plant comprising a circuit breaker and at least one wind turbine generator electrically connectable to an electrical grid through said circuit breaker, the method comprising the steps of detecting at least one condition for the circuit breaker to trip by means of a sensor; informing a control means of this detection prior to the circuit breaker disconnecting; and preparing the at least one wind turbine generator before said circuit breaker disconnects said at least one wind turbine generator from said electrical grid.

A wind power plant predictive protection circuit

A method and system for enhancing the transient stability of an intertied three-phase electric power generating system. A set of power exporting generators (10) is connected to a set of power importing generators (20). When a transient cannot be controlled by conventional stability controls, and imminent loss of synchronism is detected (such as when the equivalent rotor angle difference between the two generator sets exceeds a predetermined value, such as 150 degrees), the intertie is disconnected by circuit breakers. Then a switch (30) having a 120-degree phase rotation, or a circuit breaker having a 120-degree phase rotation is placed in the intertie. The intertie is then reconnected. This results in a 120-degree reduction in the equivalent rotor angle difference between the two generator sets, making the system more stable and allowing more time for the conventional controls to stabilize the transient.

Richard L. Cresap

Papers

Transient stability enhancement of electric power generating systems by 120-degree phase rotation