CONTROL UNIT AND METHOD FOR A CONVERTER

Abstract

The present invention relates to a control unit for a converter, preferably of a power converter of a wind power installation, in particular of an active rectifier of a power converter of a wind power installation, comprising: a primary control module for specifying a setpoint value for the converter; a first secondary control module for controlling the converter, in particular a first converter module of the converter, which second secondary control module is configured to produce a first control signal according to the setpoint value; a second secondary control module for controlling the converter, in particular a second converter module of the converter, which converter module is connected in parallel with the first converter module, which second secondary control module is configured to produce a second control signal according to the first control signal.

Claims

1. A controller for an active rectifier of a power converter of a wind power installation, comprising: a primary controller for specifying a setpoint value for the power converter; a first secondary controller for controlling a first converter module of the power converter, wherein the first secondary controller is configured to produce a first control signal according to the setpoint value; and a second secondary controller for controlling a second converter module of the power converter, wherein the second converter module is connected in parallel with the first converter module, wherein the second secondary controller is configured to produce a second control signal that depends on the first control signal.

2. The controller as claimed in claim 1, wherein the primary controller is configured to produce a setpoint value for the first secondary controller according to a specified value, wherein the specified value is a setpoint power value from a wind power installation control-unit.

3. The controller as claimed in claim 1, wherein the setpoint value for the first secondary controller is a setpoint current value.

4. The controller as claimed in claim 1, wherein: the first control signal is for a first electrical system; and the second control signal is for a second electrical system.

5. The controller as claimed in claim 1, wherein first and second control signals are chosen in such a way that the first and second converter modules switch at a mutual offset.

6. The controller as claimed in claim 1, wherein: the first control signal for the first converter module comprises information about a first control angle, the second control signal for the second converter module comprises information about a second control angle, and the second control angle has a phase shift with respect to the first control angle.

7. The controller as claimed in claim 6, wherein the phase shift equals 180 degrees plus an electrical angle, wherein the electrical angle represents the phase shift between the first electrical system and the second electrical system.

8. The controller as claimed in claim 6, wherein the phase shift equals about 210 degrees.

9. The controller as claimed in claim 1, wherein the first converter module and the second converter module are functionally designed as inverters or as rectifiers.

10. The controller as claimed in claim 1, wherein a main controller is configured to be connected to a wind power installation controller to receive an installation control value for an output of the power converter.

11. A method for controlling a power converter of a wind power installation, the method comprising: specifying a setpoint value for the power converter; controlling, using a first control signal, the power converter, wherein the controlling comprises controlling a first converter module of the power converter according to the setpoint value; and controlling, using a second control signal, the power converter, wherein the controlling comprises controlling a second converter module of the power converter that corresponds to the first control signal.

12. The method as claimed in claim 11, further comprising: receiving an installation control value, and specifying the setpoint value for the power converter according to the installation control value.

13. The method as claimed in claim 11, wherein the setpoint value for the power converter is a setpoint power value.

14. The method as claimed in claim 11, wherein: the first control signal is for a first electrical system of a generator; and the second control signal is for a second electrical system of the generator.

15. The method as claimed in claim 11, wherein: the first control signal for the first converter module comprises at least information about a first control angle, the second control signal for the second converter module comprises information about a second control angle, and the second control angle has a phase shift with respect to the first control angle.

16. The method as claimed in claim 15, wherein the phase shift equals 180 degrees plus an electrical angle, wherein the electrical angle represents the phase shift between the first electrical system and the second electrical system.

17. The method as claimed in claim 16, wherein the phase shift equals about 210 degrees.

18. The method as claimed in claim 11, wherein the first control signal and the second control signal are intended for a pulse width modulation method.

19. A wind power installation, comprising: a tower, the controller as claimed in claim 1, and the power converter.

20. The wind power installation as claimed in claim 19, wherein: the power converter is a full converter and has: the first converter module for a first three-phase system, and the second converter module for a second three-phase system, wherein the second converter module is connected in parallel with the first converter module, wherein the first three-phase system and the second three-phase system are superimposed to produce a third three-phase system.

21. The wind power installation as claimed in claim 19, further comprising: a generator having a first electrical three-phase system and a second electrical three-phase system, wherein the power converter comprises: the first converter module for the first electrical three-phase system, and the second converter module for the second electrical three-phase system, wherein the first converter module has a plurality of converter submodules wherein the second converter module has a plurality of converter submodules wherein the plurality of converter submodules of the first converter module are configured to be operated in a first synchronous switching mode, wherein the plurality of converter submodules of the second converter module are configured to be operated in a second synchronous switching mode, and wherein the first synchronous switching mode is asynchronous to the second synchronous switching mode.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0078] The present invention is now explained in more detail below with reference to the accompanying figures, where the same reference signs are used for identical or similar components or assemblies.

[0079] FIG. 1 shows schematically and by way of example a perspective view of a wind power installation in one embodiment.

[0080] FIG. 2 shows schematically and by way of example a design of an electrical branch of a wind power installation in one embodiment.

[0081] FIG. 3 shows schematically and by way of example the design of an inverter.

[0082] FIG. 4 shows schematically and by way of example the design of a control unit for a converter.

[0083] FIG. 5 shows schematically and by way of example the sequence of a method for controlling a converter.

DETAILED DESCRIPTION

[0084] FIG. 1 shows a perspective view of a wind power installation 100.

[0085] The wind power installation 100 has a tower 102 and a nacelle 104.

[0086] Arranged on the nacelle 104 is an aerodynamic rotor 106 having three rotor blades 108 and a hub 110.

[0087] During operation, the wind causes the rotor 106 to rotate and thereby to drive a generator in the nacelle.

[0088] As a result, the generator produces a 6-phase current, which is rectified by an active rectifier.

[0089] FIG. 2 shows schematically and by way of example an electrical branch 100′ of a wind power installation 100, as shown preferably in FIG. 1.

[0090] The aerodynamic rotor of the wind power installation 106 is connected to the generator 120 of the wind power installation. The generator 120 is preferably in the form of a six-phase generator, for example the generator has two electrically three-phase systems 122, 124, which are mutually decoupled on the stator side and have a phase shift of 30 degrees.

[0091] The generator 120 is connected to an electrical supply grid 200, or linked to the electrical supply grid 200, via a converter 130 and by means of a transformer 150.

[0092] In order to convert the electrical power produced by the generator 120 into a current i.sub.G to be fed in, the converter 130 has one converter module 130′, 130″ for each of the electrical systems 122, 124, which converter modules 130′, 130″ are substantially identical.

[0093] The converter modules 130′, 130″ have at a converter module input an active rectifier 132′. The active rectifier 132′ is electrically connected to an inverter 137′, for example via a DC voltage line 135′ or a voltage DC link circuit. The converter 130, or the converter modules 130′, 130″, is implemented as a back-to-back converter.

[0094] FIG. 3 explains in greater detail in particular the operating principle of the active rectifiers 132′, 133″ of the converter 130.

[0095] The two electrically three-phase systems 122, 124, which are mutually decoupled on the stator side, are combined at a node 140 into a three-phase overall system 142.

[0096] In order to feed into the electrical supply grid 200 the total current i.sub.G to be fed in, also provided at the output of the wind power installation is a wind power installation transformer 150, which connects the wind power installation 100 to the electrical supply grid 200, preferably in a wye-delta connection.

[0097] The electrical supply grid 200 to which the wind power installation 100, 100′ is connected by means of the transformer 150, may be, for example, a wind farm grid or an electrical supply or distribution grid.

[0098] In addition, a wind power installation control-unit 160 is provided for controlling the wind power installation 100 or the electrical branch 100′.

[0099] Said wind power installation control-unit 160 is configured in particular to adjust a total current i.sub.G to be fed in, in particular by controlling the active rectifiers 132′, 132″ or inverters 137′, 137″.

[0100] The wind power installation control-unit 160 is preferably also configured to detect the total current i.sub.G using a current detection means 162. This is preferably done by detecting in particular the currents of every converter module 137′ in each phase.

[0101] In addition, the control unit also has voltage detection means 164, which are configured to detect a grid voltage, in particular of the electrical supply grid 200.

[0102] In a particularly preferred embodiment, the wind power installation control-unit 160 is also configured to detect the phase angle and amplitude of the current i.sub.G to be fed in.

[0103] The wind power installation control-unit 160 additionally comprises a control unit 1000, described above or below, for the converter 130.

[0104] Thus the control unit 1000 is configured in particular to use (switching) signals S to control the entire converter 130 including its two converter modules 130′, 130″ including their respective converter submodules, in particular as shown in FIG. 4.

[0105] FIG. 3 shows schematically and by way of example the design of a converter 130, in particular of the active rectifiers 132′, 132″ as shown in FIG. 2.

[0106] The converter 130 here comprises in particular two active rectifiers 132′, 132″: a first active rectifier 132′ for the first electrically three-phase system 122, and a second active rectifier 132″ for the second electrically three-phase system 124.

[0107] The active rectifiers 132′, 132″ are connected on the generator side to the respective systems 122, 124 of the generator, and connected via the DC voltage 135 to an inverter 137′, 137″, as shown in particular in FIG. 2.

[0108] The active rectifiers 132′, 132″ are each controlled by means of switching signals S1, S2 by the control unit 1000 described above or below.

[0109] FIG. 4 shows schematically and by way of example the design of a control unit (controller) 1000 of a converter 130.

[0110] The converter 130, for example in the form of a power converter of a wind power installation, comprises two converter modules 130′, 130″, where each converter module 130′, 130″ has a three-phase AC system 122, 124 having the phases u.sub.1, v.sub.1, w.sub.1 and u.sub.2, v.sub.2, w.sub.2 respectively, which are produced by the generator 120 and in particular have a phase shift of 30 degrees.

[0111] Each converter module 130′, 130″ comprises at least one active rectifier 132′, 132″, as shown in FIG. 3 for example.

[0112] The converter 130 is controlled via the control unit 1000, for example by means of a first signal S1(ϑ1) for the first active rectifier 132′, and a second signal S2(∞2) for the second active rectifier 132″.

[0113] The control unit 1000 comprises a primary control module (or primary controller) 1100, a first secondary control module (or secondary controller) 1200 and a second secondary control module (or secondary controller) 1300.

[0114] The primary control module 1100 is the main control module (master) of the control unit 1000, and is configured to receive a specified value, in particular a setpoint power value P, from the wind power installation control-unit, and to produce therefrom the setpoint value p1, for instance a setpoint current value, for the secondary control modules 1200, 1300.

[0115] The secondary control modules 1200, 1300 are thus subordinate in particular to the primary control module 1100 (slaves).

[0116] The first secondary control module 1200 is configured to receive the setpoint value p1 from the primary control module 1100 and to produce therefrom a control signal S1, for instance a pulse pattern.

[0117] Thus the control signal S1 is used to control the first converter module 130′, and is transferred to the second secondary control module 1300.

[0118] The second secondary control module 1300 is thus subordinate to the first secondary control module 1200, or is coordinated on the basis thereof.

[0119] The first secondary control module 1200 thus receives the setpoint value pl from the primary control module 1100 in order to produce the first control signal S1.

[0120] The second secondary control module 1300, on the other hand, receives the first control signal S1 in order to produce the second control signal S2, for instance a modified pulse pattern.

[0121] The control signals S1, S2 preferably comprise at least one angle ϑ, preferably a firing angle for the converter modules 130′, 130″ or converter submodules 137′, 137″, 137′″.

[0122] Said angles ϑ1, ϑ2 can also be referred to as control angles.

[0123] The control signals S1, S2, or the control angles ϑ1, ϑ2, are determined here such that the switches of the active rectifiers 132′, 132″ of the respective converter modules 130′, 130″ switch in a synchronous switching mode, but the switches of the converter modules 130′, 130″ switch at a mutual offset.

[0124] This means in particular that the converter modules 130′, 130″ are switched at an offset.

[0125] This can be achieved, for example, by the control angles ϑ1, ϑ2 having a mutual phase shift, for instance of 210°. It therefore holds that ϑ1 plus 210 degrees equals ϑ2.

[0126] FIG. 5 shows schematically and by way of example the sequence 500 of a method for controlling a converter, in particular by means of a control module described above.

[0127] In a first step 510, a current setpoint value p1 for the systems 122, 124 is determined, for example according to a setpoint power value that was received from a wind power installation control-unit.

[0128] In a next step 520, a first control signal S1 for the first active rectifier 132′ of the first system 122 is determined from this setpoint current value p1.

[0129] In a further step 530, a second control signal for the second active rectifier 132″ of the second system 124 is determined according to this first control signal S1.

[0130] In a next step 540, the control signals S1, S2 determined in this way are corrected by a correction value k, in particular if necessary.

[0131] In a further step 550, the active rectifiers 132′, 132″ are then controlled according to switching angles ϑ.sub.1, ϑ.sub.2 and by means of the switching signals S1, S2, for example by means of PWM modulation and/or a tolerance band method.

LIST OF REFERENCE SIGNS

[0132] 100 wind power installation

[0133] 100′ electrical branch, in particular of the wind power installation

[0134] 100″ segment of the electrical branch

[0135] 102 tower, in particular of the wind power installation

[0136] 104 nacelle, in particular of the wind power installation

[0137] 106 rotor, in particular of the wind power installation

[0138] 180 rotor blade, in particular of the wind power installation

[0139] 120 generator, in particular of the wind power installation

[0140] 122 first electrical system, in particular of the generator

[0141] 124 second electrical system, in particular of the generator

[0142] 130 converter, in particular of the wind power installation

[0143] 130′ converter module, in particular for the first electrical system

[0144] 130″ converter module, in particular for the second electrical system

[0145] 132 converter submodule, in particular active rectifier

[0146] 132′ converter submodule, in particular active rectifier module

[0147] 132″ converter submodule, in particular active rectifier module

[0148] 135 DC voltage

[0149] 137 converter submodule, in particular inverter

[0150] 137′ converter submodule, in particular inverter module

[0151] 137″ converter submodule, in particular inverter module

[0152] 140 node

[0153] 142 three-phase (overall) system

[0154] 150 transformer

[0155] 160 wind power installation control-unit

[0156] 200 electrical supply grid

[0157] 1000 control unit

[0158] 1100 primary control module

[0159] 1200 first secondary control module

[0160] 1300 second secondary control module

[0161] i.sub.G total current to be fed in

[0162] U.sub.DC DC voltage of a voltage DC link circuit

[0163] u voltage of a phase

[0164] i current in a phase

[0165] S (switching) signal

[0166] P setpoint (power) value, in particular from the wind power installation control-unit

[0167] p1 setpoint value

[0168] u, v, w phases, in particular of a three-phase system

[0169] ≙ switching angle

[0170] 1,2,3 indices

[0171] The various embodiments described above can be combined to provide further embodiments. These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure.