Power converters
First Claim
1. A power converter that can be used to interface a generator that provides variable voltage at variable frequency to a supply network operating at nominally fixed voltage and nominally fixed frequency, the power converter comprising:
- a first active rectifier/inverter electrically connected to the stator of the generator and including a plurality of semiconductor power switching devices;
a second active rectifier/inverter including a plurality of semiconductor power switching devices;
a dc link connected between the first active rectifier/inverter and the second active rectifier/inverter;
a filter connected between the second active rectifier/inverter and the supply network, the filter including network terminals;
a first controller for the first active rectifier/inverter; and
a second controller for the second active rectifier/inverter;
wherein the first controller uses a dc link voltage demand signal indicative of a desired dc link voltage to control the semiconductor power switching devices of the first active rectifier/inverter to achieve the desired level of dc link voltage that corresponds to the dc link voltage demand signal; and
wherein the second controller uses a power demand signal indicative of the level of power to be transferred from the dc link to the supply network through the second active rectifier/inverter, and a voltage demand signal indicative of the voltage to be achieved at the network terminals of the filter to control the semiconductor power switching devices of the second active rectifier/inverter to achieve the desired levels of power and voltage that correspond to the power and voltage demand signals.
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Accused Products
Abstract
The present invention provides a power converter that can be used to interface a generator that provides variable voltage at variable frequency to a supply network operating at nominally fixed voltage and nominally fixed frequency and including features that allow the power converter to remain connected to the supply network and retain control during supply network fault and transient conditions. The power converter includes a generator bridge electrically connected to the stator of the generator and a network bridge. A dc link is connected between the generator bridge and the network bridge. A filter having network terminals is connected between the network bridge and the supply network. A first controller is provided for controlling the operation of the semiconductor power switching devices of the generator bridge. Similarly, a second controller is provided for controlling the operation of the semiconductor power switching devices of the network bridge. The first controller uses a dc link voltage demand signal VDC_NET* indicative of a desired dc link voltage to control the semiconductor power switching devices of the network bridge to achieve the desired level of dc link voltage that corresponds to the dc link voltage demand signal VDC_NET*. The second controller uses a power demand signal P* indicative of the level of power to be transferred from the dc link to the supply network through the network bridge, and a voltage demand signal VTURB* indicative of the voltage to be achieved at the network terminals of the filter to control the semiconductor power switching devices of the network bridge to achieve the desired levels of power and voltage that correspond to the power and voltage demand signals P* and VTURB*.
98 Citations
56 Claims
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1. A power converter that can be used to interface a generator that provides variable voltage at variable frequency to a supply network operating at nominally fixed voltage and nominally fixed frequency, the power converter comprising:
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a first active rectifier/inverter electrically connected to the stator of the generator and including a plurality of semiconductor power switching devices;
a second active rectifier/inverter including a plurality of semiconductor power switching devices;
a dc link connected between the first active rectifier/inverter and the second active rectifier/inverter;
a filter connected between the second active rectifier/inverter and the supply network, the filter including network terminals;
a first controller for the first active rectifier/inverter; and
a second controller for the second active rectifier/inverter;
wherein the first controller uses a dc link voltage demand signal indicative of a desired dc link voltage to control the semiconductor power switching devices of the first active rectifier/inverter to achieve the desired level of dc link voltage that corresponds to the dc link voltage demand signal; and
wherein the second controller uses a power demand signal indicative of the level of power to be transferred from the dc link to the supply network through the second active rectifier/inverter, and a voltage demand signal indicative of the voltage to be achieved at the network terminals of the filter to control the semiconductor power switching devices of the second active rectifier/inverter to achieve the desired levels of power and voltage that correspond to the power and voltage demand signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. An arrangement comprising a plurality of power converters, each including
a first active rectifier/inverter electrically connected to the stator of the generator and including a plurality of semiconductor power switching devices; -
a second active rectifier/inverter including a plurality of semiconductor power switching devices;
a dc link connected between the first active rectifier/inverter and the second active rectifier/inverter;
a filter connected between the second active rectifier/inverter and the supply network, the filter including network terminals;
a first controller for the first active rectifier/inverter; and
a second controller for the second active rectifier/inverter;
wherein the first controller uses a dc link voltage demand signal indicative of a desired dc link voltage to control the semiconductor power switching devices of the first active rectifier/inverter to achieve the desired level of dc link voltage that corresponds to the dc link voltage demand signal; and
wherein the second controller uses a power demand signal indicative of the level of power to be transferred from the dc link to the supply network through the second active rectifier/inverter, and a voltage demand signal indicative of the voltage to be achieved at the network terminals of the filter to control the semiconductor power switching devices of the second active rectifier/inverter to achieve the desired levels of power and voltage that correspond to the power and voltage demand signals, the converters being connected together in parallel to a supply network operating at nominally fixed voltage and nominally fixed frequency by a parallel connection, wherein the voltage demand signal indicative of the voltage to be achieved at the network terminals of the filter of each power converter is derived from a comparison of a top-level voltage demand signal and a top-level voltage feedback signal that is measured at the point where the parallel connection is connected to the supply network. - View Dependent Claims (22, 23, 24, 25)
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26. A wind turbine comprising:
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a generator having a stator and a rotor;
a turbine assembly including at least one blade for rotating the rotor of the generator; and
a power converter including a first active rectifier/inverter electrically connected to the stator of the generator and including a plurality of semiconductor power switching devices;
a second active rectifier/inverter including a plurality of semiconductor power switching devices;
a dc link connected between the first active rectifier/inverter and the second active rectifier/inverter;
a filter connected between the second active rectifier/inverter and the supply network, the filter including network terminals;
a first controller for the first active rectifier/inverter; and
a second controller for the second active rectifier/inverter;
wherein the first controller uses a dc link voltage demand signal indicative of a desired dc link voltage to control the semiconductor power switching devices of the first active rectifier/inverter to achieve the desired level of dc link voltage that corresponds to the dc link voltage demand signal; and
wherein the second controller uses a power demand signal indicative of the level of power to be transferred from the dc link to the supply network through the second active rectifier/inverter, and a voltage demand signal indicative of the voltage to be achieved at the network terminals of the filter to control the semiconductor power switching devices of the second active rectifier/inverter to achieve the desired levels of power and voltage that correspond to the power and voltage demand signals.
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27. A wind farm comprising:
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a supply network operating at nominally fixed voltage and nominally fixed frequency; and
a plurality of wind turbines each including a generator having a stator and a rotor;
a turbine assembly including at least one blade for rotating the rotor of the generator; and
a power converter including a first active rectifier/inverter electrically connected to the stator of the generator and including a plurality of semiconductor power switching devices;
a second active rectifier/inverter including a plurality of semiconductor power switching devices;
a dc link connected between the first active rectifier/inverter and the second active rectifier/inverter;
a filter connected between the second active rectifier/inverter and the supply network, the filter including network terminals;
a first controller for the first active rectifier/inverter; and
a second controller for the second active rectifier/inverter;
wherein the first controller uses a dc link voltage demand signal indicative of a desired dc link voltage to control the semiconductor power switching devices of the first active rectifier/inverter to achieve the desired level of dc link voltage that corresponds to the dc link voltage demand signal; and
wherein the second controller uses a power demand signal indicative of the level of power to be transferred from the dc link to the supply network through the second active rectifier/inverter, and a voltage demand signal indicative of the voltage to be achieved at the network terminals of the filter to control the semiconductor power switching devices of the second active rectifier/inverter to achieve the desired levels of power and voltage that correspond to the power and voltage demand signals;
wherein the respective power converters of the plurality of wind turbines are connected together in parallel to the supply network by a parallel connection, and wherein the voltage demand signal indicative of the voltage to be achieved at the network terminals of the filter of each power converter is derived from a comparison of a top-level voltage demand signal and a top-level voltage feedback signal that is measured at the point where the parallel connection is connected to the supply network. - View Dependent Claims (28, 29, 30, 31)
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32. A method of operating a power converter that can be used to interface a generator that provides variable voltage at variable frequency to a supply network operating at nominally fixed voltage and nominally fixed frequency, the power converter comprising:
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a first active rectifier/inverter electrically connected to the stator of the generator and including a plurality of semiconductor power switching devices;
a second active rectifier/inverter including a plurality of semiconductor power switching devices;
a dc link connected between the first active rectifier/inverter and the second active rectifier/inverter;
a filter connected between the second active rectifier/inverter and the supply network, the filter including network terminals;
a first controller for the first active rectifier/inverter; and
a second controller for the second active rectifier/inverter;
wherein the method comprises the steps of;
the first controller using a dc link voltage demand signal indicative of a desired dc link voltage to control the semiconductor power switching devices of the first active rectifier/inverter to achieve the desired level of dc link voltage that corresponds to the dc link voltage demand signal; and
the second controller using a power demand signal indicative of the level of power to be transferred from the dc link to the supply network through the second active rectifier/inverter, and a voltage demand signal indicative of the voltage to be achieved at the network terminals of the filter to control the semiconductor power switching devices of the second active rectifier/inverter to achieve the desired levels of power and voltage that correspond to the power and voltage demand signals. - View Dependent Claims (33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53)
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54. A method of operating a plurality of power converters, each including
a first active rectifier/inverter electrically connected to the stator of the generator and including a plurality of semiconductor power switching devices; -
a second active rectifier/inverter including a plurality of semiconductor power switching devices;
a dc link connected between the first active rectifier/inverter and the second active rectifier/inverter;
a filter connected between the second active rectifier/inverter and the supply network, the filter including network terminals;
a first controller for the first active rectifier/inverter; and
a second controller for the second active rectifier/inverter;
wherein the first controller uses a dc link voltage demand signal indicative of a desired dc link voltage to control the semiconductor power switching devices of the first active rectifier/inverter to achieve the desired level of dc link voltage that corresponds to the dc link voltage demand signal; and
wherein the second controller uses a power demand signal indicative of the level of power to be transferred from the dc link to the supply network through the second active rectifier/inverter, and a voltage demand signal indicative of the voltage to be achieved at the network terminals of the filter to control the semiconductor power switching devices of the second active rectifier/inverter to achieve the desired levels of power and voltage that correspond to the power and voltage demand signals, the power converters being connected together in parallel to a supply network operating at nominally fixed voltage and nominally fixed frequency by a parallel connection, the method comprising the step of deriving the voltage demand signal indicative of the voltage to be achieved at the network terminals of the filter of each power converter from a comparison of a top-level voltage demand signal and a top-level voltage feedback signal that is measured at the point where the parallel connection is connected to the supply network. - View Dependent Claims (55, 56)
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Specification