The present disclosure provides a zero-sequence parameter measurement and ground voltage control method for a resonant ground system based on a virtual ground principle. The method, based on the virtual ground principle, arbitrarily specifies a point K in a phasor plane in which three-phase voltages are located. A virtual ground control method is used to achieve virtual ground of the point K, and an accurate zero-sequence resonant parameter of a zero-sequence network under an action of the excitation {dot over (U)}.sub.KN can be obtained. When a single-phase ground fault occurs, a ground phase is specified as a target working point, and a control method is applied to cause the zero-sequence network to accurately resonate, and a voltage of this phase relative to ground is 0. At this time, both a residual voltage and a residual current of the fault phase are effectively suppressed.

The disclosure discloses a system and method for suppressing unbalanced voltage at the Point of Common Coupling (PCC) of dispersed wind farm. According to the disclosure, the wind farm comprising a STATCOM and plurality of wind turbines, dispersed wind farm controller, STATCOM controller, wind turbine controller. The dispersed wind farm controller decides that whether the STATCOM or the wind turbines inject negative-sequence current or not. Adaptive virtual negative-sequence output admittance controller is incorporated into the STATCOM controller and wind turbine controller, which can provide the negative-sequence current reference according to their participation factor. The compensation efforts of STATCOM and wind turbines can be flexibly controlled by changing their participation factor, which is related to the voltage unbalance voltage reference and the remaining capacity. The disclosure has significant advantages in cost and effectiveness to suppress the unbalanced voltage of PCC and improve the wind farm Low voltage fault recovery capability.

An electrical power system connectable to a power grid includes a cluster of electrical power subsystems, each of the electrical power subsystems including a power converter electrically coupled to a generator having a generator rotor and a generator stator. Each of the electrical power subsystems defines a stator power path and a converter power path for providing power to the power grid. Each of the electrical power subsystems further includes a transformer. The system further includes a subsystem breaker configured with each of the electrical power subsystems, and a cluster power path extending from each subsystem breaker for connecting the cluster of electrical power subsystems to the power grid. The system further includes a reactive power compensation inverter electrically coupled within the electrical power system, the reactive power compensation inverter operable to increase the reactive power level in the electrical current flowing to the power grid.

A sensor assembly system and method for providing good voltage accuracy for monitoring a three phase high voltage power line without connecting to ground. The sensor assembly system comprises three sensor assemblies having reference point ends not connected to ground. All three sensor assemblies are connected together at the reference point ends to create a neutral common reference point not connected to ground potential that is at zero volts when all of the three phases are at the same line voltage.

Disclosed techniques for power management include datacenter power management through phase balancing. Power for a datacenter is obtained across a plurality of AC power phases. A power consumption value by loads is determined within the datacenter for each of a plurality of power phases. A power consumption imbalance is calculated between a first phase and a second phase from the plurality of power phases within the datacenter. Phase power balancing is performed by transferring power from the first phase to the second phase from the plurality of power phases within the datacenter. The transferring power is accomplished using current injection. The performing phase power balancing by transferring power from the first phase to the second phase comprises a supply side transfer of power. Performing phase power balancing by transferring power from the first phase to the second phase is accomplished without transferring load power consumption between power phases.

A virtual co-phase power supply system topology suitable for an electrical sectioning device at a sectioning and paralleling post (SP) includes a step-down transformer TR.sub.1. A primary winding of the step-down transformer TR.sub.1 is electrically connected to a traction feeding section β.sub.2 in a train from a traction feeding section β.sub.1 to the traction feeding section β.sub.2. Each secondary winding is electrically connected to one rectifier separately. DC buses output from the rectifiers are connected in parallel. The other end of the DC bus is electrically connected to a plurality of parallel inverter units. An LC filter is provided on a DC bus between a rectifier unit and the inverter unit, and the LC filter is connected in parallel to an energy storage unit. After filtering through the LC filter, an output end of the inverter unit is electrically connected to a primary winding of a step-up transformer TR.sub.2.

The present invention provides methods and apparatus for producing a variable and auto regulated three phase power source from an existing three, two or single phase power supply source. Variability and regulation are achieved by producing and controlling two of the three phase nodes/phasors by their amplitude and phase angle displacement. The combination of two independent variable power source inverters, with the incoming unregulated existing power supply source, produces a variable three phase power source in a Wye configuration, that achieves a variable stable and constant regulated Delta configuration three phase power source output.

Aspects of the subject disclosure may include, for example, embodiments detecting and correcting load imbalance on power supply phases within a managed scope using a software controlled power switch matrix that is resident in each power distribution unit supplying power in the managed scope. Managed scope could include a plurality of power distribution units supplying a plurality of circuit or equipment loads in a plurality of premises. On each PDU, the software controlled switch matrix maintains and changes physical coupling of power supply phases to circuit and equipment loads. Further embodiments include correcting power supply phase load imbalances through software commands to adjust the coupling of power supply phases to circuit or equipment loads. Embodiments are intended to help power administrators maintain power supply phase load balance effectively in a managed scope. Other embodiments are disclosed.

Provided is a method for controlling a wind power installation and/or a wind farm having at least one wind power installation, particularly in the case of asymmetrical network voltages, comprising: measuring a first voltage of a first phase, a second voltage of a second phase and a third voltage of a third phase of a three-phase electrical system, calculating a symmetrical negative-sequence voltage system from the measured voltages including a first negative-sequence voltage, a second negative-sequence voltage and a third negative-sequence voltage, predefining setpoints for a negative-sequence current system depending on the calculated, symmetrical negative-sequence voltage system including a first negative-sequence current component, a second negative-sequence current component and a third negative-sequence current component, wherein the setpoints are defined such that a balancing of the measured voltages is achieved, feeding an asymmetrical three-phase AC current into a wind farm network or an electrical supply network depending on the predefined setpoints.

A control method for a power supply system includes a driving circuit conducting a switch element of a first backup transforming module of a backup supplying module corresponding to a phase of one of a plurality of power transforming modules in an abnormal operation according to a working signal corresponding to the power transforming module in the abnormal operation, when one of the plurality of power transforming modules corresponding to a three-phase voltage source is in the abnormal operation; and the driving circuit latching unconducted switch elements of at least one of undriven second backup transforming module of the backup supplying module corresponding to the phase, after a logic control circuit detects working signals corresponding to all phases of each backup transforming module, and latching unconducted switch elements corresponding to phases different with the phase of the first backup transforming module.