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.

There is provided a power system stability analysis device that analyzes stability of a power system by obtaining measurement data from a high-accuracy measurement device and existing measuring instruments installed in the power system, the apparatus including: a system state estimation unit that estimates a system state of the power system by using measurement data from the existing measuring instruments at a plurality of points in the power system; a synchronous stability analysis unit that analyzes synchronous stability in an assumed failure by using an estimation result of the system state; and a synchronous stability analysis correction unit that corrects the synchronous stability according to a difference between the estimation result of the system state and the measurement data of the high-accuracy measurement device to improve accuracy of synchronous stability analysis of the power system.

Respective phasor values are recursively computed from respective ones of a series of signal samples for a node of a power system such that each phasor value is computed from a previously computed phasor value. Frequency values are recursively computed from the phasor values for respective ones of the signal samples. Recursive computing of frequency values may include computing respective phase angle values from respective ones of the phasor values, recursively computing coefficient values for a polynomial that fits the phase angle values, and recursively computing the frequency values from the coefficient values. The samples may be generated at a sampling rate and the phasor values and the frequency values may be produced at a rate that is the same as the sampling rate. Embodiments may provide methods, apparatus and computer readable media that implement such operations.

In prior art grid systems, power-line control is done by substation based large systems that use high-voltage (HV) circuits to get injectable impedance waveforms that can create oscillations on the HV power lines. Intelligent impedance injection modules (IIMs) are currently being proposed for interactive power line control and line balancing. These IIMs distributed over the high-voltage lines or installed on mobile platforms and connected to the HV power lines locally generate and inject waveforms in an intelligent fashion to provide interactive response capability to commands from utility for power line control. These IIMs typically comprise a plurality of impedance-injection units (IIUs) that are transformer-less flexible alternating current transmission systems interconnected in a series-parallel connection and output pulses that are additive and time synchronized to generate appropriate waveforms that when injected into HV transmission lines are able to accomplish the desired response and provide interactive power flow control.

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.

In prior art grid systems, power-line control is done by substation based large systems that use high-voltage (HV) circuits to get injectable impedance waveforms that can create oscillations on the HV power lines. Intelligent impedance injection modules (IIMs) are currently being proposed for interactive power line control and line balancing. These IIMs distributed over the high-voltage lines or installed on mobile platforms and connected to the HV power lines locally generate and inject waveforms in an intelligent fashion to provide interactive response capability to commands from utility for power line control. These IIMs typically comprise a plurality of impedance-injection units (IIUs) that are transformer-less flexible alternating current transmission systems interconnected in a series-parallel connection and output pulses that are additive and time synchronized to generate appropriate waveforms that when injected into HV transmission lines are able to accomplish the desired response and an provide interactive power flow control.

Disclosed are systems and methods for utilizing a unique elastic command and control architecture to incorporate certain resiliency qualities in power grid management and outage mitigation.

The present invention relates to PMU-based control systems for dampening inter-area oscillations in large-scale interconnected power systems or grids to protect against a catastrophic blackout. The control systems receive phasor measurements from two or more locations on an AC transmission line and generates a power control command to a power resource on the grid.

The present invention relates to a method of monitoring oscillations that are liable to interact in an electrical power network, in dependence on measurement of AC waveforms in the electrical power network. The method comprises receiving first waveform data corresponding to an electrical quantity in each phase of at least two phases of three-phase AC waveforms at a location in the electrical power network. The method further comprises applying a transformation to the first waveform data to provide therefrom second waveform data corresponding to an electrical quantity at the location in a single phase representation, the second waveform data depending on the at least two phases.

This disclosure includes various systems and methods for determining an operating stage based on electrical conditions in electric power delivery systems and identifying a control strategy based upon the operating stage. The control strategy may be selected and customized to avoid or to ameliorate stresses in an electric power delivery system while maintaining the stability of electric power delivery systems. Various embodiments consistent with the present disclosure may include a distributed controller configured receive a plurality of indications of electrical conditions from a plurality of control devices in electrical communication with the electrical power delivery system. The distributed controller may determine an operating stage from among a plurality of operating stages based upon the plurality of indications of electrical conditions. The distributed controller may further identify a control strategy based upon the operating stage. The control strategy may be communicated to and implemented by the plurality of control devices.