Method and device for preventing the disconnection of an electric power generating plant from the electrical grid

• US 7,791,223 B2
• Filed: 06/28/2005
• Issued: 09/07/2010
• Est. Priority Date: 06/30/2004
• Status: Active Grant

• Current Assignee: Gamesa Innovation and Technology SL (Siemens AG)
• Original Assignee: Gamesa Innovation and Technology SL (Siemens AG)
• Inventors: Visiers Guixot, Manuel, Llorente Gonzalez, Jose Igna'cio
• Primary Examiner(s): Paladini; Albert W
• Application Number:
  US11/630,937
• Publication Number:
  US 20090167088A1
• Time in Patent Office: 1,897 Days
• Field of Search: 307 64- 66, 307/103, 290/55, 290/44, 700/286
• US Class Current: 307/103
• CPC Class Codes: H02J 2300/28 The renewable source being wind energy wind motors F03D
• CPC Class Codes: H02J 3/1814 wherein al least one reactive element is actively controlled by a bridge converter, e.g. unified power flow controllers [UPFC]
• CPC Class Codes: H02J 3/381 Dispersed generators
• 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
• CPC Class Codes: Y02E 40/10 Flexible AC transmission systems [FACTS]
• CPC Class Codes: Y02E 70/30 Systems combining energy storage with energy generation of non-fossil origin

Abstract

Procedures to prevent the disconnection of a park of electricity generators from a network in the event of a voltage sag, through which, upon detection of the sag, the voltage travelling to the network is controlled in proportion to the magnitude of the sag; the active power produced by the park, rather than sent to the network, is thus diverted into to storage and/or energy dissipation equipment, keeping the park voltage at a nominal level.

The invention also includes a device for carrying out procedures integrating a bypass, transformer, static inverter, static converter, capacitance and dissipation resistance unit, voltage sag detection circuit and control circuit.

Claims

1. Procedure to prevent the disconnection of a park of electric generators (12) from a network (14) in the event of a voltage sag including the steps of permanent monitoring of the network (14) voltage and, in the event of a voltage sag, regulating the voltage supplied to the network (14) in proportion to the magnitude of the sag, wherein said voltage regulation is carried out at a park level comprising steps of adjusting the voltage provided by the park (12) to the network (14), dissipating and/or storing the part of the active power generated by the whole park (12) which is not provided to the network (14), and maintaining the voltage in the park (12) at a nominal level.

2. Procedure to prevent the disconnection of a park of electric generators from a network in the event of a voltage sag according to claim 1, wherein said voltage regulation includes the following steps:

i. generating, upon detection of a voltage sag, alternate voltage with appropriate size and duration which, added to that of the network, maintains a constant park voltage over all 3 phase;

ii regulating the reactive power sent to the network during the voltage sag.

3. Procedure to prevent the disconnection of a park of electric generators from a network in the event of a voltage sag according to claim 1, wherein said electric generators are wind turbines.

4. A device to prevent the disconnection of a park of electric generators from a MV (14) network in the event of a voltage sag, comprising:

a) a MV, three-phase, static bypass (1) device and an automatic switch (2) and two isolators (3) corresponding thereto;

b) a low voltage protection device;

c) a LV/MV series transformer (4);

d) a DC/AC static inverter (5);

e) a DC/DC static converter (6);

f) a capacitance (7) and dissipation resistance (8) unit;

g) a MV network voltage sag detection circuit (10);

h) a control circuit (20) connected to electronic controls (11, 15, 16) of components a) d), e) and to said detection circuit (10);

wherein said components are arranged so that in the event of a voltage sag in the MV (14) network detected by the detection circuit (10), the inverter (5) regulates the voltage sent to the MV network (14) by the transformer (4) in proportion to the magnitude of the voltage sag and the voltage sent to the MV internal network (12) for maintaining the park voltage at a nominal level, the active power generated by the park which is not directed to the MV network (14) is diverted to the capacitance (7) and resistance (8) unit, and the reactive power sent to the MV network (14) is controlled.

5. A device to prevent the disconnection of a park of electric generators from a MV (14) network in the event of a voltage sag according to claim 4, wherein the detection circuit (10) is capable of determining the size and duration of the voltage sag in a time no greater than 0.5 milliseconds using calculation algorithms implemented into the control circuit microprocessor.

6. A device to prevent the disconnection of a park of electric generators from a MV (14) network in the event of a voltage sag according to claim 4, wherein the bypass device (1) can be activated in a time less than 150 microseconds and can be deactivated in a time less than 1 millisecond.

7. A device to prevent the disconnection of a park of electric generators from a MV (14) network in the event of a voltage sag according to claim 4, wherein said electric generators are wind turbines.