Structure and method for performing active injection mode filtering on an AC power system
First Claim
1. A method for injecting current onto an AC power line, wherein said power line is operated at a line voltage which exhibits a fundamental frequency component and non-fundamental frequency components, said method comprising the steps of:
- sensing said line voltage on said power line;
generating a first signal having a first component and a second component, wherein said first component is proportional to said line voltage and said second component is proportional to the rate of change of said line voltage;
filtering a fundamental frequency component from said first signal, thereby producing a second signal proportional to the non-fundamental frequency components of said first signal;
generating an electronic load current component in response to said second signal, wherein said electronic load current component is proportional to said second signal and opposite in phase to said second signal; and
providing said electronic load current component to said power line, thereby loading the non-fundamental frequency components of said line voltage.
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Accused Products
Abstract
An active current injection device is used to generate and inject fundamental and non-fundamental frequency current components onto an AC power line. A current pump control circuit receives an input signal which is representative of the line voltage of the power line. In response, the current pump control circuit generates a control signal which is used to generate a current component at the fundamental frequency which lags the line voltage by approximately 90 degrees. This fundamental frequency current component is transmitted through an impedance to the power line, thereby causing a voltage drop at the fundamental frequency across the impedance which is within a selected range about the line voltage. In one embodiment, this selected range is equal to approximately 25 to approximately 150 percent of the line voltage. Also, a damping control circuit receives an input signal which is representative of the line voltage of the power line. In response, the damping control circuit generates an output signal having a first component proportional to the line voltage and a second component proportional to the rate of change of the line voltage. This output signal is used to generate an electronic load current component which loads the non-fundamental frequency components of the line voltage. In addition, a four-wire adapter circuit allows an active current injection device to be operated from a four-conductor, three-phase AC power line using three transducers.
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Citations
11 Claims
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1. A method for injecting current onto an AC power line, wherein said power line is operated at a line voltage which exhibits a fundamental frequency component and non-fundamental frequency components, said method comprising the steps of:
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sensing said line voltage on said power line; generating a first signal having a first component and a second component, wherein said first component is proportional to said line voltage and said second component is proportional to the rate of change of said line voltage; filtering a fundamental frequency component from said first signal, thereby producing a second signal proportional to the non-fundamental frequency components of said first signal; generating an electronic load current component in response to said second signal, wherein said electronic load current component is proportional to said second signal and opposite in phase to said second signal; and providing said electronic load current component to said power line, thereby loading the non-fundamental frequency components of said line voltage. - View Dependent Claims (2, 3, 4, 5)
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6. A current injection device for injecting current onto a power line, wherein said power line is operated at a line voltage which exhibits a fundamental frequency component and non-fundamental frequency components, said current injection device comprising:
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a damping control circuit coupled to said power line, wherein said damping control circuit generates an output signal having a first component and a second component, wherein said first component is proportional to said line voltage and said second component is proportional to the rate of change of said line voltage; a filter coupled to said damping control circuit, wherein said filter removes the fundamental frequency component of said output signal, resulting in a filtered output signal proportional to the non-fundamental frequency components of said output signal; and a current generator coupled to said filter and said power line, wherein said current generator generates an electronic load current component in response to said filtered output signal and provides said electronic load current component to said power line, wherein said electronic load current component is proportional to said filtered output signal and opposite in phase to said filtered output signal, thereby loading the non-fundamental frequency components of said line voltage. - View Dependent Claims (7, 8, 9, 10, 11)
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Specification