Variable speed wind turbine having a matrix converter

• US 20020079706A1
• Filed: 05/23/2001
• Published: 06/27/2002
• Est. Priority Date: 05/23/2000
• Status: Active Grant

• Current Assignee: Vestas Wind Systems A/S
• Original Assignee: Vestas Wind Systems A/S
• Inventors: Helle, Lars, Rebsdorf, Anders V.
• Granted Patent: US 6,566,764 B2
• Time in Patent Office: Days
• US Class Current: 290/55
• CPC Class Codes: F03D 7/0284 in relation to the state of the electric grid
• CPC Class Codes: F03D 9/255 connected to electrical distribution networks; Arrangements therefor
• CPC Class Codes: F05B 2270/1016 in variable speed operation
• CPC Class Codes: H02M 1/42 Circuits or arrangements for compensating for or adjusting power factor in converters or inverters
• CPC Class Codes: H02M 5/297 for conversion of frequency
• CPC Class Codes: H02P 2101/15 for wind-driven turbines
• CPC Class Codes: H02P 9/007 Control circuits for doubly fed generators
• CPC Class Codes: H02P 9/42 to obtain desired frequency without varying speed of the generator
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
• CPC Class Codes: Y02E 10/72 Wind turbines with rotation axis in wind direction
• CPC Class Codes: Y02E 10/76 Power conversion electric or electronic aspects

Abstract

A variable speed wind turbine is disclosed comprising a turbine rotor that drives a doubly-fed induction generator, a matrix converter which converts variable frequency output into constant frequency output, and a control unit and a protection circuit for the matrix converter. Power is circulated in the system allowing for sensorless detection of rotor position and better output ratios of power from the system.

Claims

1. A variable speed wind turbine comprising:

a turbine rotor including at least one blade mounted to a rotatable turbine shaft;

a doubly-fed induction generator having a stator and a rotor coupled to the turbine shaft for rotation therewith;

a matrix converter including an array of switching elements;

a matrix converter control unit to control the switching elements; and

a voltage gradient limiting circuit located between the matrix converter and the generator rotor.

2. A turbine according to claim 1, wherein the voltage gradient limiting circuit includes an inductance.

3. A turbine according to claim 1, wherein the voltage gradient limiting circuit includes an inductance capacitor filter.

4. A turbine according to claim 1, including a transformer with at least three windings including a tertiary winding;

and

means for adjusting voltage at the tertiary winding, wherein a ratio of the input potential to the output potential is greater than 0.866.

5. A turbine according to claim 1, including a generator with a winding ratio;

and means for adjusting the winding ratio of the generator wherein a reduced matrix converter gain is overcome, wherein a ratio of the input potential to the output potential is greater than 0.866 and whereby a current rating of the switching elements is increased.

6. A turbine according to claim 1, having a protection circuit for protecting the matrix converter against over voltages.

7. A turbine according to claim 1, having a protection circuit for protecting the matrix converter against over voltages and for retaining control after a grid disruption.

8. A turbine according to claim 1, having means for position sensorless detection of the position of said turbine rotor.

9. A turbine according to claim 8, further including the measurement of the current of said rotor.

10. A turbine according to claim 8, further including the circulation of reactive power.

11. A turbine according to claim 1, having a power controller for circulating reactive energy.

12. A turbine according to claim 1, having a power controller for controlling the power factor of the turbine without impacting the circulation of reactive power.

13. A turbine according to claim 1, wherein at least one of said switching elements comprises a standard H-Bridge module.

14. A turbine according to claim 1, wherein said stator further includes a stator winding means for shifting between a Y-connection and a Δ

-connection.

15. A turbine according to claim 1, which further includes a means for the facilitating the active damping of current harmonics.

16. A turbine according to claim 1, which further includes a means for facilitating the active damping of resultant drive-train oscillations.

18. A turbine according to claim 17, having a voltage gradient limiting circuit located between the matrix converter and the generator rotor.

19. A voltage gradient limiting circuit of claim 18, wherein the voltage gradient limiting circuit includes an inductance.

20. A voltage gradient limiting circuit of claim 18, wherein the voltage gradient limiting circuit includes an inductance capacitor filter.

21. A turbine according to claim 17, including a generator with a winding ratio;

and means for adjusting the winding ratio of the generator wherein a reduced matrix converter gain is overcome, wherein a ratio of the input potential to the output potential is greater than 0.866 and whereby a current rating of the switching elements is increased.

22. A turbine according to claim 17, having a protection circuit for protecting the matrix converter against over voltages.

23. A turbine according to claim 17, having a protection circuit for protecting the matrix converter against over voltages and for retaining control after a grid disruption.

24. A turbine of claim 17, having means for position sensorless detection of the position of said turbine rotor.

25. A turbine according to claim 24, further including the measurement of the current of said rotor.

26. A turbine according to claim 24, further including the circulation of reactive power.

27. A turbine according to claim 17, having a power controller for circulating reactive energy.

28. A turbine according to claim 17, having a power controller for controlling the power factor of the turbine without impacting the circulation of reactive power.

29. A turbine according to claim 17, wherein at least one of said switching elements comprises a standard H-Bridge module.

30. A turbine according to claim 17, wherein said stator further includes a stator winding means for shifting between a Y-connection and a Δ

-connection.

31. A turbine according to claim 17, which further includes a means for the facilitating the active damping of current harmonics.

17. A variable speed wind turbine, comprising:

a turbine rotor including at least one blade mounted to a rotatable turbine shaft;

a doubly-fed induction generator having a stator and a rotor coupled to the turbine shaft for rotation therewith;

a matrix converter including an array of switching elements, the matrix converter having an input potential and an output potential;

a matrix converter control unit for controlling the switching elements;

a transformer having at least three windings including a tertiary winding; and

means for adjusting voltage at the tertiary winding, wherein a ratio of the input potential to the output potential is greater than 0.866.

32. A turbine according to 17, which further includes a means for facilitating the active damping of resultant drive-train oscillations.

33. A variable speed wind turbine, comprising:

a turbine rotor including at least one blade mounted to a rotatable turbine shaft;

a doubly-fed induction generator having a stator and a rotor coupled to the turbine shaft for rotation therewith, the generator having a winding ratio;

a matrix converter including an array of switching elements;

a matrix converter control unit to control the switching elements; and

means for adjusting the winding ratio of the generator wherein a reduced matrix converter gain is overcome, wherein a ratio of the input potential to the output potential is greater than 0.866 and whereby a current rating of the switching elements is increased.

34. A turbine according to claim 33, having a voltage gradient limiting circuit located between the matrix converter and the generator rotor.

35. A voltage gradient limiting circuit of claim 34, wherein the voltage gradient limiting circuit includes an inductance.

36. A voltage gradient limiting circuit of claim 34, wherein the voltage gradient limiting circuit includes an inductance capacitor filter.

37. A turbine according to claim 33, including a transformer with at least three windings including a tertiary winding;

and

means for adjusting voltage at the tertiary winding, wherein a ratio of the input potential to the output potential is greater than 0.866.

38. A turbine according to claim 33, having a protection circuit for protecting the matrix converter against over voltages.

39. A turbine according to claim 33, having a protection circuit for protecting the matrix converter against over voltages and for retaining control after a grid disruption.

40. A turbine of claim 33, having means for position sensorless detection of the position of said turbine rotor.

41. A turbine according to claim 40, further including the measurement of the current of said rotor.

42. A turbine according to claim 40, further including the circulation of reactive power.

43. A turbine according to claim 33, having a power controller for circulating reactive energy.

44. A turbine according to claim 33, having a power controller for controlling the power factor of the turbine without impacting the circulation of reactive power.

45. A turbine according to claim 33, wherein at least one of said switching elements comprises a standard H-Bridge module.

46. A turbine according to claim 33, wherein said stator further includes a stator winding means for shifting between a Y-connection and a Δ

-connection.

47. A turbine according to claim 33, which further includes a means for the facilitating the active damping of current harmonics.

48. A turbine according to 33, which further includes a means for facilitating the active damping of resultant drive-train oscillations.

50. A turbine according to claim 49, having a voltage gradient limiting circuit located between the matrix converter and the generator rotor.

51. A voltage gradient limiting circuit of claim 50, wherein the voltage gradient limiting circuit includes an inductance.

52. A voltage gradient limiting circuit of claim 50, wherein the voltage gradient limiting circuit includes an inductance capacitor filter.

53. A turbine according to claim 49, including a transformer with at least three windings including a tertiary winding;

and

means for adjusting voltage at the tertiary winding, wherein a ratio of the input potential to the output potential is greater than 0.866.

54. A turbine according to claim 49, including a generator with a winding ratio;

and means for adjusting the winding ratio of the generator wherein a reduced matrix converter gain is overcome, wherein a ratio of the input potential to the output potential is greater than 0.866 and whereby a current rating of the switching elements is increased.

55. A turbine according to claim 49, having a protection circuit for protecting the matrix converter against over voltages and for retaining control after a grid disruption.

56. A turbine of claim 49, having means for position sensorless detection of the position of said turbine rotor.

57. A turbine according to claim 56, further including the measurement of the current of said rotor.

58. A turbine according to claim 56, further including the circulation of reactive power.

59. A turbine according to claim 49, having a power controller for circulating reactive energy.

60. A turbine according to claim 49, having a power controller for controlling the power factor of the turbine without impacting the circulation of reactive power.

61. A turbine according to claim 49, wherein at least one of said switching elements comprises a standard H-Bridge module.

62. A turbine according to claim 49, wherein said stator further includes a stator winding means for shifting between a Y-connection and a Δ

-connection.

63. A turbine according to claim 49, which further includes a means for the facilitating the active damping of current harmonics.

49. A variable speed wind turbine, comprising:

a turbine rotor including at least one blade mounted to a rotatable turbine shaft;

a doubly-fed induction generator having a stator and a rotor coupled to the turbine shaft for rotation therewith;

a matrix converter including an array of switching elements;

a matrix converter control unit to control the switching elements; and

a protection circuit for protecting the matrix converter against over voltages.

64. A turbine according to 49, which further includes a means for facilitating the active damping of resultant drive-train oscillations.

65. A variable speed wind turbine, comprising:

a turbine rotor including at least one blade mounted to a rotatable turbine shaft;

a doubly-fed induction generator having a stator and a rotor coupled to the turbine shaft for rotation therewith;

a matrix converter including an array of switching elements;

a matrix converter control unit to control the switching elements; and

a protection circuit for protecting the matrix converter against over voltages and for retaining control after a grid disruption.

66. A turbine according to claim 65, having a voltage gradient limiting circuit located between the matrix converter and the generator rotor.

67. A voltage gradient limiting circuit of claim 66, wherein the voltage gradient limiting circuit includes an inductance.

68. A voltage gradient limiting circuit of claim 66, wherein the voltage gradient limiting circuit includes an inductance capacitor filter.

69. A turbine according to claim 65, including a transformer with at least three windings including a tertiary winding;

and

means for adjusting voltage at the tertiary winding, wherein a ratio of the input potential to the output potential is greater than 0.866.

70. A turbine according to claim 65, including a generator with a winding ratio;

and means for adjusting the winding ratio of the generator wherein a reduced matrix converter gain is overcome, wherein a ratio of the input potential to the output potential is greater than 0.866 and whereby a current rating of the switching elements is increased.

71. A turbine according to claim 65, having a protection circuit for protecting the matrix converter against over voltages.

72. A turbine of claim 65, having means for position sensorless detection of the position of said turbine rotor.

73. A turbine according to claim 72, further including the measurement of the current of said rotor.

74. A turbine according to claim 72, further including the circulation of reactive power.

75. A turbine according to claim 65, having a power controller for circulating reactive energy.

76. A turbine according to claim 65, having a power controller for controlling the power factor of the turbine without impacting the circulation of reactive power.

77. A turbine according to claim 65, wherein at least one of said switching elements comprises a standard H-Bridge module.

78. A turbine according to claim 65, wherein said stator further includes a stator winding means for shifting between a Y-connection and a Δ

-connection.

79. A turbine according to claim 65, which further includes a means for the facilitating the active damping of current harmonics.

80. A turbine according to 65, which further includes a means for facilitating the active damping of resultant drive-train oscillations.

81. A variable speed wind turbine, comprising:

a turbine rotor including at least one blade mounted to a rotatable turbine shaft;

a doubly-fed induction generator having a stator and a rotor coupled to the turbine shaft for rotation therewith;

a matrix converter including an array of switching elements;

a matrix converter control unit to control the switching elements; and

means for position sensorless detection of the position of said turbine rotor.

82. A turbine according to claim 81, further including the measurement of the current of said rotor.

83. A turbine according to claim 81, further including the circulation of reactive power.

84. A turbine according to claim 81, having a voltage gradient limiting circuit located between the matrix converter and the generator rotor.

85. A voltage gradient limiting circuit of claim 84, wherein the voltage gradient limiting circuit includes an inductance.

86. A voltage gradient limiting circuit of claim 84, wherein the voltage gradient limiting circuit includes an inductance capacitor filter.

87. A turbine according to claim 81, including a transformer with at least three windings including a tertiary winding;

and

means for adjusting voltage at the tertiary winding, wherein a ratio of the input potential to the output potential is greater than 0.866.

88. A turbine according to claim 81, including a generator with a winding ratio;

and means for adjusting the winding ratio of the generator wherein a reduced matrix converter gain is overcome, wherein a ratio of the input potential to the output potential is greater than 0.866 and whereby a current rating of the switching elements is increased.

89. A turbine according to claim 81, having a protection circuit for protecting the matrix converter against over voltages.

90. A turbine according to claim 81, having a protection circuit for protecting the matrix converter against over voltages and for retaining control after a grid disruption.

91. A turbine according to claim 81, having a power controller for circulating reactive energy.

92. A turbine according to claim 81, having a power controller for controlling the power factor of the turbine without impacting the circulation of reactive power.

93. A turbine according to claim 81, wherein at least one of said switching elements comprises a standard H-Bridge module.

94. A turbine according to claim 81, wherein said stator further includes a stator winding means for shifting between a Y-connection and a Δ

-connection.

95. A turbine according to claim 81, which further includes a means for the facilitating the active damping of current harmonics.

96. A turbine according to 81, which further includes a means for facilitating the active damping of resultant drive-train oscillations.

97. A variable speed wind turbine, comprising:

a turbine rotor including at least one blade mounted to a rotatable turbine shaft;

a doubly-fed induction generator having a stator and a rotor coupled to the turbine shaft for rotation therewith;

a matrix converter including an array of switching elements;

a matrix converter control unit to control the switching elements; and

a power controller for circulating reactive energy.

98. A turbine according to claim 97, having a voltage gradient limiting circuit located between the matrix converter and the generator rotor.

99. A voltage gradient limiting circuit of claim 98, wherein the voltage gradient limiting circuit includes an inductance.

100. A voltage gradient limiting circuit of claim 98, wherein the voltage gradient limiting circuit includes an inductance capacitor filter.

101. A turbine according to claim 97, including a transformer with at least three windings including a tertiary winding;

and

means for adjusting voltage at the tertiary winding, wherein a ratio of the input potential to the output potential is greater than 0.866.

102. A turbine according to claim 97, including a generator with a winding ratio;

and means for adjusting the winding ratio of the generator wherein a reduced matrix converter gain is overcome, wherein a ratio of the input potential to the output potential is greater than 0.866 and whereby a current rating of the switching elements is increased.

103. A turbine according to claim 97, having a protection circuit for protecting the matrix converter against over voltages.

104. A turbine according to claim 97, having a protection circuit for protecting the matrix converter against over voltages and for retaining control after a grid disruption.

105. A turbine of claim 97, having means for position sensorless detection of the position of said turbine rotor.

106. A turbine according to claim 105, further including the measurement of the current of said rotor.

107. A turbine according to claim 105, further including the circulation of reactive power.

108. A turbine according to claim 97, having a power controller for controlling the power factor of the turbine without impacting the circulation of reactive power.

109. A turbine according to claim 97, wherein at least one of said switching elements comprises a standard H-Bridge module.

110. A turbine according to claim 97, wherein said stator further includes a stator winding means for shifting between a Y-connection and a Δ

-connection.

111. A turbine according to claim 97, which further includes a means for the facilitating the active damping of current harmonics.

112. A turbine according to 97, which further includes a means for facilitating the active damping of resultant drive-train oscillations.

114. A turbine according to claim 113, having a voltage gradient limiting circuit located between the matrix converter and the generator rotor.

115. A voltage gradient limiting circuit of claim 114, wherein the voltage gradient limiting circuit includes an inductance.

116. A voltage gradient limiting circuit of claim 114, wherein the voltage gradient limiting circuit includes an inductance capacitor filter.

117. A turbine according to claim 113, including a transformer with at least three windings including a tertiary winding;

and

means for adjusting voltage at the tertiary winding, wherein a ratio of the input potential to the output potential is greater than 0.866.

118. A turbine according to claim 113, including a generator with a winding ratio;

and means for adjusting the winding ratio of the generator wherein a reduced matrix converter gain is overcome, wherein a ratio of the input potential to the output potential is greater than 0.866 and whereby a current rating of the switching elements is increased.

119. A turbine according to claim 113, having a protection circuit for protecting the matrix converter against over voltages.

120. A turbine according to claim 113, having a protection circuit for protecting the matrix converter against over voltages and for retaining control after a grid disruption.

121. A turbine of claim 113, having means for position sensorless detection of the position of said turbine rotor.

122. A turbine according to claim 121, further including the measurement of the current of said rotor.

123. A turbine according to claim 121, further including the circulation of reactive power.

124. A turbine according to claim 113, having a power controller for circulating reactive energy.

125. A turbine according to claim 113, wherein at least one of said switching elements comprises a standard H-Bridge module.

126. A turbine according to claim 113, wherein said stator further includes a stator winding means for shifting between a Y-connection and a Δ

-connection.

127. A turbine according to claim 113, which further includes a means for the facilitating the active damping of current harmonics.

130. A turbine according to claim 129, having a voltage gradient limiting circuit located between the matrix converter and the generator rotor.

131. A voltage gradient limiting circuit of claim 130, wherein the voltage gradient limiting circuit includes an inductance.

132. A voltage gradient limiting circuit of claim 130, wherein the voltage gradient limiting circuit includes an inductance capacitor filter.

133. A turbine according to claim 129, including a transformer with at least three windings including a tertiary winding;

and

means for adjusting voltage at the tertiary winding, wherein a ratio of the input potential to the output potential is greater than 0.866.

134. A turbine according to claim 129, including a generator with a winding ratio;

and means for adjusting the winding ratio of the generator wherein a reduced matrix converter gain is overcome, wherein a ratio of the input potential to the output potential is greater than 0.866 and whereby a current rating of the switching elements is increased.

135. A turbine according to claim 129, having a protection circuit for protecting the matrix converter against over voltages.

136. A turbine according to claim 129, having a protection circuit for protecting the matrix converter against over voltages and for retaining control after a grid disruption.

137. A turbine of claim 129, having means for position sensorless detection of the position of said turbine rotor.

138. A turbine according to claim 137, further including the measurement of the current of said rotor.

139. A turbine according to claim 137, further including the circulation of reactive power.

140. A turbine according to claim 129, having a power controller for circulating reactive energy.

141. A turbine according to claim 129, having a power controller for controlling the power factor of the turbine without impacting the circulation of reactive power.

142. A turbine according to claim 129, wherein said stator further includes a stator winding means for shifting between a Y-connection and a Δ

-connection.

143. A turbine according to claim 129, which further includes a means for the facilitating the active damping of current harmonics.

146. A turbine according to claim 145, having a voltage gradient limiting circuit located between the matrix converter and the generator rotor.

147. A voltage gradient limiting circuit of claim 146, wherein the voltage gradient limiting circuit includes an inductance.

148. A voltage gradient limiting circuit of claim 146, wherein the voltage gradient limiting circuit includes an inductance capacitor filter.

149. A turbine according to claim 145, including a transformer with at least three windings including a tertiary winding;

and

means for adjusting voltage at the tertiary winding, wherein a ratio of the input potential to the output potential is greater than 0.866.

150. A turbine according to claim 145, including a generator with a winding ratio;

and means for adjusting the winding ratio of the generator wherein a reduced matrix converter gain is overcome, wherein a ratio of the input potential to the output potential is greater than 0.866 and whereby a current rating of the switching elements is increased.

151. A turbine according to claim 145, having a protection circuit for protecting the matrix converter against over voltages.

152. A turbine according to claim 145, having a protection circuit for protecting the matrix converter against over voltages and for retaining control after a grid disruption.

153. A turbine of claim 145, having means for position sensorless detection of the position of said turbine rotor.

154. A turbine according to claim 153, further including the measurement of the current of said rotor.

155. A turbine according to claim 153, further including the circulation of reactive power.

156. A turbine according to claim 145, having a power controller for circulating reactive energy.

157. A turbine according to claim 145, having a power controller for controlling the power factor of the turbine without impacting the circulation of reactive power.

158. A turbine according to claim 145, wherein at least one of said switching elements comprises a standard H-Bridge module.

159. A turbine according to claim 145, which further includes a means for the facilitating the active damping of current harmonics.

162. A turbine according to claim 161, having a voltage gradient limiting circuit located between the matrix converter and the generator rotor.

163. A voltage gradient limiting circuit of claim 162, wherein the voltage gradient limiting circuit includes an inductance.

164. A voltage gradient limiting circuit of claim 162, wherein the voltage gradient limiting circuit includes an inductance capacitor filter.

165. A turbine according to claim 161, including a transformer with at least three windings including a tertiary winding;

and

means for adjusting voltage at the tertiary winding, wherein a ratio of the input potential to the output potential is greater than 0.866.

166. A turbine according to claim 161, including a generator with a winding ratio;

and means for adjusting the winding ratio of the generator wherein a reduced matrix converter gain is overcome, wherein a ratio of the input potential to the output potential is greater than 0.866 and whereby a current rating of the switching elements is increased.

167. A turbine according to claim 161, having a protection circuit for protecting the matrix converter against over voltages.

168. A turbine according to claim 161, having a protection circuit for protecting the matrix converter against over voltages and for retaining control after a grid disruption.

169. A turbine of claim 161, having means for position sensorless detection of the position of said turbine rotor.

170. A turbine according to claim 169, further including the measurement of the current of said rotor.

171. A turbine according to claim 169, further including the circulation of reactive power.

172. A turbine according to claim 161, having a power controller for circulating reactive energy.

173. A turbine according to claim 161, having a power controller for controlling the power factor of the turbine without impacting the circulation of reactive power.

174. A turbine according to claim 161, wherein at least one of said switching elements comprises a standard H-Bridge module.

175. A turbine according to claim 161, wherein said stator further includes a stator winding means for shifting between a Y-connection and a Δ

-connection.

178. A turbine according to claim 177, having a voltage gradient limiting circuit located between the matrix converter and the generator rotor.

179. A voltage gradient limiting circuit of claim 178, wherein the voltage gradient limiting circuit includes an inductance.

180. A voltage gradient limiting circuit of claim 178, wherein the voltage gradient limiting circuit includes an inductance capacitor filter.

181. A turbine according to claim 177, including a transformer with at least three windings including a tertiary winding;

and

means for adjusting voltage at the tertiary winding, wherein a ratio of the input potential to the output potential is greater than 0.866.

182. A turbine according to claim 177, including a generator with a winding ratio;

and means for adjusting the winding ratio of the generator wherein a reduced matrix converter gain is overcome, wherein a ratio of the input potential to the output potential is greater than 0.866 and whereby a current rating of the switching elements is increased.

183. A turbine according to claim 177, having a protection circuit for protecting the matrix converter against over voltages.

184. A turbine according to claim 177, having a protection circuit for protecting the matrix converter against over voltages and for retaining control after a grid disruption.

185. A turbine of claim 177, having means for position sensorless detection of the position of said turbine rotor.

186. A turbine according to claim 185, further including the measurement of the current of said rotor.

187. A turbine according to claim 185, further including the circulation of reactive power.

188. A turbine according to claim 177, having a power controller for circulating reactive energy.

189. A turbine according to claim 177, having a power controller for controlling the power factor of the turbine without impacting the circulation of reactive power.

190. A turbine according to claim 177, wherein at least one of said switching elements comprises a standard H-Bridge module.

191. A turbine according to claim 177, wherein said stator further includes a stator winding means for shifting between a Y-connection and a Δ

-connection.

192. A turbine according to claim 177, which further includes a means for the facilitating the active damping of current harmonics.

113. A variable speed wind turbine, comprising:

a turbine rotor including at least one blade mounted to a rotatable turbine shaft;

a doubly-fed induction generator having a stator and a rotor coupled to the turbine shaft for rotation therewith;

a matrix converter including an array of switching elements;

a matrix converter control unit to control the switching elements; and

a power controller for controlling the power factor of the turbine without impacting the circulation of reactive power.

128. A turbine according to 113, which further includes a means for facilitating the active damping of resultant drive-train oscillations.

129. A variable speed wind turbine, comprising:

a turbine rotor including at least one blade mounted to a rotatable turbine shaft;

a doubly-fed induction generator having a stator and a rotor coupled to the turbine shaft for rotation therewith;

a matrix converter including an array of switching elements; and

a matrix converter control unit to control the switching elements, wherein at least one of said switching elements comprises a standard H-Bridge module.

144. A turbine according to 129, which further includes a means for facilitating the active damping of resultant drive-train oscillations.

145. A variable speed wind turbine, comprising:

a turbine rotor including at least one blade mounted to a rotatable turbine shaft;

a doubly-fed induction generator having a stator and a rotor coupled to the turbine shaft for rotation therewith;

a matrix converter including an array of switching elements;

a matrix converter control unit to control the switching elements; and

wherein said stator further includes a stator winding means for shifting between a Y-connection and a Δ

-connection.

160. A turbine according to 145, which further includes a means for facilitating the active damping of resultant drive-train oscillations.

161. A variable speed wind turbine, comprising:

a turbine rotor including at least one blade mounted to a rotatable turbine shaft;

a doubly-fed induction generator having a stator and a rotor coupled to the turbine shaft for rotation therewith;

a matrix converter including an array of switching elements; and

a matrix converter control unit to control the switching elements, which further includes a means for the facilitating the active damping of current harmonics.

176. A turbine according to 161, which further includes a means for facilitating the active damping of resultant drive-train oscillations.

177. A variable speed wind turbine, comprising:

a turbine rotor including at least one blade mounted to a rotatable turbine shaft;

a doubly-fed induction generator having a stator and a rotor coupled to the turbine shaft for rotation therewith;

a matrix converter including an array of switching elements; and

a matrix converter control unit to control the switching elements;

which further includes a means for facilitating the active damping of resultant drive-train oscillations.