Controlling a wind turbine during a grid fault where the grid voltage drops below a nominal grid voltage. After detection of a grid fault, the total current limit for the power converter output is increased to a total maximum overload current limit. Depending on whether active or reactive current generation is prioritized, an active or reactive current reference is determined. The active current reference is determined in a way so that a reduction in active power production due to the grid voltage drop is minimized and based on the condition that the vector-sum of the active output current and the reactive output current is limited according to the total maximum overload current limit, and a maximum period of time is determined in which the power converter can be controlled based on the active/reactive current references. Afterwards the power converter is controlled based on the active and reactive current references.

A system and a method for locally controlling delivery of electrical power along the distribution feeder by measuring certain electricity parameters of a distribution feeder line using a substation phasor measurement unit (PMU) electrically coupled to a substation distribution bus at a first node on the feeder line, and at least one customer site PMU electrically coupled to a low voltage end of a transformer at a customer site, wherein the transformer is coupled by a drop line to a second node on the distribution feeder line and the customer site is coupled by another drop line to the transformer, and by controlling at least one controllable reactive power resource and optionally a real power resource connected to the second node or at the customer site. Related apparatus, systems, articles, and techniques are also described.

The present disclosure provides a harmonic suppression apparatus, method, control unit, power supply apparatus, electric appliance equipment, and storage medium, wherein the harmonic suppression apparatus includes a tuning circuit module, which is connected with a first live wire and a second live wire of a three-phase power supply and is configured to perform resonance regulation processing; a PI-type resonant filtering circuit module, which is respectively connected with the tuning circuit module and a third live wire of the three-phase power supply and is configured to perform harmonic filtering processing on the first-phase current and the second-phase current processed by the tuning circuit module and a third-phase current; and a rectification circuit module, which is connected with the PI-type resonant filtering circuit module and is configured to perform rectification progressing and a power a load.

A wind turbine system (20, 70) is connected to an electrical grid (42) by an inverter (38) that provides turbine terminal voltage (Vt) support to the grid during a grid low voltage fault that is concurrent with a lack of real power production from the generator (30) by providing reactive power to the grid. A processor (46) controls the inverter to preserve a minimum voltage on a local DC bus (34) by stopping the reactive power output when the DC bus voltage drops to a threshold value (59) that is above a low bus voltage trip setpoint (56). An energy storage device (48) such as a battery may be connected to the DC bus to provide power that supports a prolonged ride-through capability during the grid fault.

A method and system of power factor optimization and total harmonic distortion are provided under the premise of efficient power management and distribution on an electrical grid. The method and system include a novel optimization technique based on a novel current profiling methodology enabling real-time power management with power factor correction as a function of the optimization. The optimization can be performed under dynamic current constraints. When deployed on an electrical grid, the method and system can provide a new technique for power management targeting an efficiency of the electrical grid. The method and system can thus provide for reduced costs of energy production and reduced carbon emissions into the atmosphere.

A system for transmitting power and data, particularly including a half-wave control, includes a control unit connected to grid phases, the system having a phase-failure detection device which has bistable multivibrators, especially bistable multivibrators assigned to a respective grid phase. Each bistable multivibrator has an input for setting and an input for resetting, one of the inputs being connected to a digitizing device for digitizing the positive half-waves of a respective grid phase, the other of the inputs being connected to a digitizing device for digitizing the negative half-waves of a respective grid phase. The effective value of the output voltage of the bistable multivibrator is compared by a comparison device to a threshold value to detect a phase failure.

Systems and methods for controlling and methods for controlling the power factor in a generator system are provided. In some embodiments, the generator system includes one or more generators configured to supply power to a power grid, an automatic voltage regulator configured to regulate a voltage of an output of the generator to a set voltage and regulate a power factor of the output to a set power factor, and a controller. The controller is configured to detect a fault on the output and to adjust the set power factor of the automatic voltage regulator based on the fault. The controller is further configured to ramp the set power factor from the adjusted value to an initial value over a set period of time.

A method and system are provided for sourcing and sinking reactive power to an electric grid. The control system includes a terminal electrically coupled to a power source that originates from an electric utility grid. The terminal receives a grid alternating current having a real power component and a reactive power component. A power converter is electrically coupled to the terminal, the power converter includes an active rectifier that converts substantially all of the grid alternating current to a direct current and an energy storage device that stores energy supplied by the direct current. The active rectifier sources the reactive power component and the stored energy through the terminal to the electric utility grid. The power converter further includes an inverter that converts the direct current to a load alternating current having at least one of a load real power component and a load reactive power component.

A control unit of an electric motor control device includes an inverter circuit 6 that supplies power to an electric motor, a current control unit that outputs a voltage command value as a drive command of the inverter circuit, a current detecting unit that detects current flowing to each phase of the electric motor, and a failed phase identifying unit that identifies a location of a failure in the current detecting unit. The failed phase identifying unit determines whether or not a magnitude or a phase of a frequency component of the test voltage command included in a detected current value when the inverter circuit is driven with a test voltage command having a frequency higher than a rotational frequency of the electric motor as a drive command is within a predetermined range, and determines that a failure has occurred in a phase that is not within the predetermined range.

A method and a control system adapted to control a power conversion system connected to an AC power grid, wherein the control system is adapted to receive an externally provided reactive power reference and the control system includes a controller adapted to control the reactive power fed to the AC grid by the power conversion system and to produce a reactive current reference, an active current reference, a total current limiter for producing limited active and reactive current references. The total current limiter operates in reactive current priority limiting the active current reference. Further including means adapted to produce a capacity signal indicating the current capacity of the power conversion system. The control system further includes a minimum reactive power reference tracker adapted to generate an internally generated reactive power reference which is adapted to be fed to the controller adapted to control the reactive power fed by the power conversion system to the AC grid, where the minimum reactive power reference tracker is adapted to control the internally generated reactive power reference to a value with which the active current reference is not limited.