A phasor measurement unit (PMU) of the present disclosure measures phasor, i.e., magnitude and phase angle of voltage and current, and related data from a specific location on the electrical gird synchronized to a common time source. The time-synchronized phasor is called a synchrophasor. In a system of the present disclosure, a plurality of PMUs transmit the synchrophasors and related data to a phasor data concentrator (PDC), which aggregates and time-aligns the data for real time and post analysis. The PMU of the present disclosure further functions as a power quality meter determining at least one of symmetrical components' phasor, frequency, rate of change of frequency, high-speed digital inputs, analog fundamental power and/or displacement power factor.

Systems for determining a phase of a device coupled to an electrical distribution system. The system includes a number of gateway devices configured to transmit a synchronization signal. The gateway device receives a node response message from a first node device that includes a duration value indicating a time between a receipt of the transmitted synchronization signal and a detected zero crossing. The gateway device compares the duration value against duration values received from node devices with a known phase connection and determines a phase of the first node device based on the comparison.

This invention relates to a surface finish manufacturing system and process and more particularly, but not exclusively, to a contrast surface finish manufacturing system and process for producing boards with a wood texture finish. The surface finish manufacturing system comprises a top layer and a bottom layer where part of the top layer is removed to expose part of the bottom layer.

Waveforms in power grids typically reveal a certain pattern with specific features and peculiarities driven by the system operating conditions, internal and external uncertainties, etc. This prompts an observation of different types of waveforms at the measurement points (substations). An innovative next-generation smart sensor technology includes a measurement unit embedded with sophisticated analytics for power grid online surveillance and situational awareness. The smart sensor brings additional levels of smartness into the existing phasor measurement units (PMUs) and intelligent electronic devices (IEDs). It unlocks the full potential of advanced signal processing and machine learning for online power grid monitoring in a distributed paradigm. Within the smart sensor are several interconnected units for signal acquisition, feature extraction, machine learning-based event detection, and a suite of multiple measurement algorithms where the best-fit algorithm is selected in real-time based on the detected operating condition. Embedding such analytics within the sensors and closer to where the data is generated, the distributed intelligence mechanism mitigates the potential risks to communication failures and latencies, as well as malicious cyber threats, which would otherwise compromise the trustworthiness of the end-use applications in distant control centers. The smart sensor achieves a promising classification accuracy on multiple classes of prevailing conditions in the power grid and accordingly improves the measurement quality across the power grid.

A method for detection of a sub-synchronous oscillation in a power system includes measuring a three-phase measurement signal of an electric system value, analyzing the measurement signal to detect an oscillation component of the measurement signal having an oscillation frequency lower than a system frequency of the power system, deciding whether the detected oscillation component at the oscillation frequency qualifies as a sub-synchronous oscillation, and disconnecting a generator from the power system that might be affected by the sub-synchronous oscillation. To detect sub-synchronous oscillations with low computational effort and good accuracy, an amplitude of each phase of the oscillation component is calculated and compared against a threshold, a sub-synchronous oscillation is detected upon exceeding the threshold during a given time delay, and a fault signal is generated upon detecting a sub-synchronous oscillation. A device having a processing unit is also provided.

A method for controlling a power grid includes using a communication device to receive first data messages with first phasor measurement data from a first phasor measurement unit. A reference device is used to determine a deviation between the first phasor measurement data and reference data. The first phasor measurement data are recognized as plausible when the deviation lies below a previously defined upper threshold value and/or above a previously defined lower threshold value. A corresponding grid control arrangement is also provided.

A method for recovering missing phase measurement unit (PMU) measurements from a plurality of PMUs is provided. The method comprises: receiving a plurality of obtained PMU measurements from the plurality of PMUs; populating a PMU dataset based on the plurality of obtained PMU measurements; determining a plurality of missing entries within the PMU dataset, wherein each of the plurality of missing entries indicates a missing PMU measurement within the PMU dataset at a particular time; determining a plurality of substitute entries for the plurality of missing entries based on an optimization algorithm that determines differences associated with a missing entry, of the plurality of missing entries, and a first set of PMU measurements, of the plurality of obtained PMU measurements, that are taken immediately prior to the missing entry; and inserting the plurality of substitute entries into the PMU dataset to generate a new PMU dataset.

A power management system includes a first receiver for receiving information specifying reverse power flow from a base power meter measuring at least the reverse power flow output from a facility to a power grid, a second receiver for receiving information specifying each of individual output powers of two or more adjustment power supplies provided in the facility, and a controller for specifying each of individual reverse power flows of the two or more adjustment power supplies managed as the reverse power flow. The controller specifies individual reverse power flows of the two or more adjustment power supplies, by executing a correction process of correcting a discrepancy between a sum of the individual output powers of the two or more adjustment power supplies and the reverse power flow based on the individual output powers of the two or more adjustment power supplies.

A power management server includes a receiver for receiving, from an upper management server, an adjustment request for requesting a fluctuation adjustment of a frequency of a power grid for each fluctuation cycle of an adjustment target, a transmitter for transmitting, to an adjustment power supply, an adjustment instruction for instructing the fluctuation adjustment of the frequency of the power grid according to the fluctuation cycle of the adjustment target requested by the adjustment request, a management unit for managing a correspondence relationship between the fluctuation cycle of the adjustment target instructed by the adjustment instruction and the adjustment power supply, and a controller for determining an adjustment power supply to which the adjustment instruction is to be transmitted based on the correspondence relationship.

The present disclosure provides a system-level protection system and method for sub/super-synchronous resonance/oscillation. The system includes a centralized protection coordinator arranged in a control center and a plurality of distributed protection relays arranged in a plurality of transformer substations or wind farms. Each distributed protection relay is configured to acquire a sub/super-synchronous impedance of the wind farm. The centralized protection coordinator is configured to acquire the sub/super-synchronous impedances measured by the plurality of distributed protection relays, to obtain a sub/super-synchronous aggregate impedance of the system according to a preset circuit topology and the sub/super-synchronous impedances, and to generate a system-level protection signal when the sub/super-synchronous aggregate impedance does not meet a stable condition. Each distributed protection relay is further configured to initiate a system-level protection according to the system-level protection signal.