Method and apparatus for eliminating overmodulation in a power plant
First Claim
1. A method for eliminating overmodulation in a power plant having a direct voltage network connected to at least one alternating voltage network through a station, said station being adapted to transmit power between said direct voltage network and said alternating voltage network and including at least one converter, said VSC converter being adapted to convert direct voltage into alternating voltage and the converse, said method comprising the steps of:
- calculating a reference alternating voltage;
measuring a direct voltage between two poles of a direct voltage side of a station;
dividing said reference voltage by half of said direct voltage;
comparing the quotient of the division with a pre-determined value;
sending a first signal to a means for controlling said converter when said quotient exceeds said predetermined value;
increasing consumption of reactive power on the alternating voltage side of said station in response to said first signal by control of said converter.
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Accused Products
Abstract
A method and apparatus for eliminating overmodulation in a power plant is provided. The power plant has a direct voltage network connected to at least one alternating voltage network through a station. The station is adapted to transmit power between the direct voltage network and the alternating voltage network and includes at least one converter. The converter is adapted to convert direct voltage into alternating voltage and convert alternating voltage into direct voltage. The method comprises the steps of calculating a reference alternating voltage and measuring a direct voltage between two poles of a direct voltage side of the station. The reference voltage is divided by half of the direct voltage and this quotient is compared with a predetermined value. When the quotient exceeds the predetermined value, a first signal is sent to a means for controlling the converter. In response to receiving the first signal, the converter is controlled to increase consumption of reactive power on the alternating voltage side of the station.
9 Citations
16 Claims
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1. A method for eliminating overmodulation in a power plant having a direct voltage network connected to at least one alternating voltage network through a station, said station being adapted to transmit power between said direct voltage network and said alternating voltage network and including at least one converter, said VSC converter being adapted to convert direct voltage into alternating voltage and the converse, said method comprising the steps of:
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calculating a reference alternating voltage; measuring a direct voltage between two poles of a direct voltage side of a station; dividing said reference voltage by half of said direct voltage; comparing the quotient of the division with a pre-determined value; sending a first signal to a means for controlling said converter when said quotient exceeds said predetermined value; increasing consumption of reactive power on the alternating voltage side of said station in response to said first signal by control of said converter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A plant for transmitting electric power comprising,
a direct voltage network connected through a station to at least one alternating voltage network, said station being adapted to transmit power between said direct voltage network and said alternating network, said station including at least one VSC converter, said converter being adapted to convert direct voltage into alternating voltage and the converse; -
means for calculating a pulse width modulation pattern; means for controlling said converter based on a reference alternating voltage which communicates with said means for calculating; means for comparing the quotient of (a) the reference alternating voltage and (b) half the amplitude of the direct voltage measured between the two poles of said direct voltage network to a predetermined value and for sending a signal to said means for controlling when said quotient exceeds said predetermined value, whereby said means for controlling controls said converter to increase the reactive power consumption on the alternating voltage side of said station. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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Specification