Other

University of Alberta

Shandong University

British Columbia Hydro and Power Authority

Wilsun Xu

Xin Li

Wenpeng Luan

Yang Wang

Yu Cui

Brian Harapnuk

A method for identifying a system anomaly in a power distribution system is described herein. The system anomaly may indicate a non-technical loss or a topology error, including schematic entry errors and component modelling errors in the power distribution system. The method includes a) selecting a common coupling point in the power distribution system, wherein downstream branches are connected to the common coupling point; b) determining voltage estimates of the common coupling point according to electrical measurements from the downstream branches; and c) identifying the system anomaly by determining whether a detection criterion is satisfied using the voltage estimates.

Method for identifying a system anomaly in a power distribution system

Systems and devices that provide a shared detuning, damping, or filtering element to one or more capacitors. A number of circuit branches are coupled in parallel to each other between a first coupling point and a second coupling point. A subcircuit is coupled between the second coupling point and a third coupling point. Each branch includes at least one capacitor that provides reactive power to power systems while the subcircuit is configured to provide detuning, damping, or filtering to the multiple branches.

System using a subcircuit shared between capacitors for providing reactive power

An improved scheme to filter harmonics and damp resonance for multipulse converter systems using a single characteristic passive filter branch without a plurality of non-characteristic harmonic filters is disclosed. The filter includes a first capacitor, a first inductor and a frequency-dependent resistor block connected in series. The frequency-dependent resistor block includes a second inductor connected in parallel with a circuit which is assembled by a second capacitor in series with a resistor.

Harmonic filter for multipulse converter systems

A portable grid for creating an equipotential zone that comprises at least two portable conductive elements. Each element comprises an electrically conducting platform forming a separation barrier with a working surface such as a ground surface. The elements may be joined electrically and mechanically. By joining multiple such elements, a variable size equipotential zone can be created. The portability of the zone is ensured as the zone can be disassembled to individual elements that can be carried and stored by the workers.

Portable equipotential grid

There is a method to model large electric power consuming facilities for power system studies. A general facility model, for example a template, is created for different types of industrial or commercial facilities. A template includes all necessary and general electric system information such as the common electric network configuration of a specific type of facilities. The template, stored in a database, is then scaled and adjusted based on the power demand level of the case-specific facility to be modeled based on facility specific parameters acquired for the facility. The result is a full, case-specific model of the facility to be modeled. The case-specific model is simplified into an equivalent model with varying details according to a user's specification. The results are the case-specific facility model of interest to the user. The model is normally included into the power system model of the utility network for power system simulation studies.

Operation and construction of electric power consuming facilities using facility models

Methods and devices for establishing the relationships between the conductor currents and sensor outputs for cases where the geometric parameters of the conductors and sensors are unknown. The methodology involves a sensor calibrator. This device is connected to the conductors at a location downstream of a number of current measuring devices or current sensors. The calibrator draws specific currents from the conductors for a short period in an automated manner. The characteristics of the currents drawn by the calibrator such as the magnitude and frequency of the currents are known to the processing unit for the sensors through means such as communications. The processing unit uses these known currents to establish the relationship between the conductor currents and its sensed quantities. This process may take a few seconds. Once the relationship is established, the sensors can start to 'measure' the conductor currents by calculating them using that relationship and its sensed quantities.

Method and system for calibrating current sensors

A method and an apparatus for reducing energization transients in a three phase AC power system which includes an electrical device having legs A, B and C associated with corresponding phases of the power system. The method includes the steps of connecting the legs of the device with the power system in an order determined by an energization sequence, wherein the energization sequence is either ABC or ACB. The apparatus includes a three phase electrical device having legs A, B, and C associated with corresponding phases of a three phase AC power system and switches operable to connect the legs of the device with the power system, wherein the switches are configured to be actuated in an order determined by an energization sequence, and wherein the energization sequence is either ABC or ACB. The switches may be controlled by a switch controller. A transient-limiting impedance may be connected in series with leg A of the device, in which case the method of the invention includes the further step of bypassing the transient-limiting impedance and the energization sequence is either ABCI, ABIC, ACBI or ACIB, wherein I is the step of bypassing the transient-limiting impedance. In the apparatus of the invention, a bypass switch may be provided for bypassing the transient-limiting impedance, which bypass switch may be controlled by the switch controller.

Reduction of energization transients in a three phase power system

A signaling system for detecting power line discontinuity in a power distribution system having a local power generator in a feeder line employs a signal generator that provides a local generator control signal with a preset protocol continuously and is located in the power distribution system upstream of said local power generator. A power detector terminates the local generator control signal and a signal detector in said feeder line detects the presence of the signal and triggers the shutdown of the local generator when the signal is not detected by the signal detector for a predefined period of time.

Power signaling based technique for detecting islanding conditions in electric power distribution systems

Reduction of energization transients in a three phase Y-connected load having legs A, B and C associated with corresponding phases of a three-phase AC power system is achieved by energizing respective legs of the load in an order determined by a energization sequence dependent upon a type of the load. The energization sequence defines first, second and third legs of the legs A, B and C to be energized. A conduction path for current to flow between a neutral point of the Y-connected load to ground through a transient-limiting impedance while the first, second and third legs are being energized is employed. The transient limiting impedance has an impedance value selected such that after the first leg is energized, an energization transient produced on energizing the second leg and an energization transient produced on energizing the third leg are both approximately minimized.

Reduction of energization transients in a three phase Y-connected load

A method and apparatus provides a technique for measuring characteristics of a harmonic pollution source connected to an alternating current power distribution system. The apparatus has a harmonic current meter and a harmonic voltage meter. Also, the apparatus has a harmonic perturbation device which can produce changes in the harmonic energy present in the power distribution system. The perturbation device can be a harmonic shunt or a harmonic frequency generator. In operation, harmonic voltage and current measurements are made at the connection point between the harmonic pollution source and the rest of the power distribution system. One set of voltage and current measurements is made with the harmonic perturbation device connected and one set of measurements is made with the harmonic perturbation device disconnected. The measurements are performed at the frequencies of interest. The two sets of measurements provide enough information to solve a set of equations which reveal characteristics of the harmonic pollution source. For example, the harmonic current magnitude and impedance of the harmonic pollution source can be found.

Method and apparatus for measuring harmonic current sources in electric power distribution systems

A method of determining parameters of a harmonic pollution source connected to a power line at a connection point. The harmonic pollution source is a power customer and the power is supplied by an electric utility. The electric utility is also a source of harmonic pollution. Both the utility and customer can be modeled as a harmonic current source in parallel with an impedance. In the method of the present invention, a harmonic voltage and a harmonic current are measured at the connection point between the utility and customer. The voltage and current measurements are combined with the known reference impedances in a calculation to yield the magnitude of current produced by the customer or utility harmonic current sources. Also, the present invention provides a method for determining the relative harmonic pollution contributions from the utility and customer. Both the utility and customer can then know exactly how much harmonic pollution they are emitting into the power line to which they are connected. The pollution contribution calculation requires knowledge of both utility and customer reference impedances and the harmonic voltage and harmonic current measurements. The present invention includes a method of determining a pollution contribution from the customer where the pollution contribution measurement is not influenced by changes in utility impedance.

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Edmonton, Canada

Wilsun Xu