EP3911856A1 - Wind turbine for feeding electrical power into an electrical supply network - Google Patents
Wind turbine for feeding electrical power into an electrical supply networkInfo
- Publication number
- EP3911856A1 EP3911856A1 EP20700889.7A EP20700889A EP3911856A1 EP 3911856 A1 EP3911856 A1 EP 3911856A1 EP 20700889 A EP20700889 A EP 20700889A EP 3911856 A1 EP3911856 A1 EP 3911856A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- voltage
- power
- intermediate circuit
- fault
- network
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000000034 method Methods 0.000 claims abstract description 28
- 238000011084 recovery Methods 0.000 claims description 15
- 230000000630 rising effect Effects 0.000 claims description 6
- 238000001514 detection method Methods 0.000 claims description 2
- 230000036962 time dependent Effects 0.000 claims description 2
- 230000007547 defect Effects 0.000 claims 1
- 238000007599 discharging Methods 0.000 abstract 1
- 238000010586 diagram Methods 0.000 description 25
- 238000009434 installation Methods 0.000 description 17
- 230000001419 dependent effect Effects 0.000 description 4
- 230000005284 excitation Effects 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 230000007704 transition Effects 0.000 description 3
- 230000004913 activation Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 230000006641 stabilisation Effects 0.000 description 2
- 238000011105 stabilization Methods 0.000 description 2
- 230000001360 synchronised effect Effects 0.000 description 2
- 238000013459 approach Methods 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000001914 calming effect Effects 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000001934 delay Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/381—Dispersed generators
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
- F03D—WIND MOTORS
- F03D7/00—Controlling wind motors
- F03D7/02—Controlling wind motors the wind motors having rotation axis substantially parallel to the air flow entering the rotor
- F03D7/028—Controlling wind motors the wind motors having rotation axis substantially parallel to the air flow entering the rotor controlling wind motor output power
- F03D7/0284—Controlling wind motors the wind motors having rotation axis substantially parallel to the air flow entering the rotor controlling wind motor output power in relation to the state of the electric grid
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/001—Methods to deal with contingencies, e.g. abnormalities, faults or failures
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
- H02J3/48—Controlling the sharing of the in-phase component
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
- H02J2300/20—The dispersed energy generation being of renewable origin
- H02J2300/28—The renewable source being wind energy
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/70—Wind energy
- Y02E10/72—Wind turbines with rotation axis in wind direction
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/70—Wind energy
- Y02E10/76—Power conversion electric or electronic aspects
Definitions
- Wall energy system for feeding electrical power into an electrical supply network
- the present invention relates to a method for feeding electrical power into an electrical supply network having a mains voltage by means of a wind power plant.
- the present invention also relates to a corresponding wall energy system.
- the invention also relates to a corresponding wind park.
- Wind turbines are known and are usually used to feed electrical power into an electrical supply network. It has now been recognized that wind energy systems are also well suited to supporting the electrical supply network. This also means that wind turbines can react tolerantly to grid faults. In particular, in the event of a network fault, they can adapt the feed-in of electrical power to the specifications of a network operator of the electrical supply network. In particular, in the event of a grid fault in which the grid voltage drops, depending on the specification, they can reduce or interrupt the electrical power and can continue to feed in after the grid fault has ended.
- Such network faults in which the mains voltage drops briefly, are usually of very short duration and generally last less than 1 second.
- the behavior at the end and shortly after is particularly important End of network failure important.
- the electrical supply network is in a not very stable transition phase. If, during this transition phase, electrical power is fed in uncontrolled, unfavorable and / or incorrectly by many producers who feed into the same electrical supply network, this can easily lead to a renewed network fault, possibly even a more serious one than the one that has just been overcome .
- a method for controlling such a network fault is described, for example, in US Pat. No. 7,525,208 B2. There it is particularly proposed to control the feeding of the power in such a way that a higher power is fed in immediately after the grid fault than immediately before the grid fault.
- a method according to claim 1 is proposed.
- the method thus relates to feeding electrical power into an electrical supply network.
- the Feeding takes place by means of a wind power plant and this has, in particular, a so-called full converter concept in which electrical power is generated by a generator of the wind power plant, is rectified and is fed into the electrical supply network by an inverter.
- the electrical supply network is characterized by a mains voltage, ie the voltage that the electrical supply network has.
- the wind turbine therefore has an inverter for feeding the electrical power, which in turn has a DC voltage intermediate circuit.
- the inverter is also representative of several inverters or an inverter device with several inverters.
- the DC voltage intermediate circuit has an intermediate circuit voltage that can vary in its voltage level. For example, it can vary in the range from 550 V to 700 V. However, other values can also be considered. These other values can be similar, or they can be significantly higher if a correspondingly higher voltage is to be output by means of the inverter.
- a plurality of DC voltage intermediate circuits can also be provided accordingly, but a common DC voltage intermediate circuit can also be used by a plurality of inverters.
- a chopper circuit is also connected to the DC voltage intermediate circuit for removing electrical energy from the DC voltage intermediate circuit.
- the inverter naturally dissipates energy from the DC link when feeding electrical power.
- such a chopper circuit can additionally or exclusively dissipate energy from the DC voltage intermediate circuit. This is done in such a way that this removal of electrical energy is controlled via a pulse pattern. This essentially creates a pulsed current that is passed through a resistor or a resistance bank in order to be converted there into heat.
- the proposed feeding of electrical power is carried out with such a wind energy plant with a described inverter, which has a DC voltage intermediate circuit with a chopper circuit.
- Electrical power is fed into the electrical supply network by means of the inverter in normal operation if no network fault in the electrical supply network has been detected.
- the wind energy installation can particularly preferably operate in a so-called grid parallel operation, in which all of the power generated is fed into the electrical supply network.
- normal operation is understood to mean operation in which no network fault has been detected.
- this can also mean that the described network parallel operation is abandoned and, for example, the power fed in is reduced due to a frequency increase detected in the electrical supply network, to name one example.
- normal operation is understood to mean operation in which no error occurs and in which the mains voltage drops significantly.
- a line fault is thus recognized, so a line fault is assumed if the line voltage drops below a predetermined undervoltage value.
- a predetermined undervoltage value can be in particular at or below 80% of the nominal network voltage. It is therefore a question of the mains voltage falling significantly.
- the line voltage can drop, for example, to 10% of the nominal line voltage. Slight voltage fluctuations, for example in the range of a few percent, such as 1 to 3%, do not yet result in a network fault being recognized.
- the feeding of electrical power into the electrical supply network is reduced or even completely interrupted.
- the wind power installation or its inverter preferably remains connected to the electrical supply network, especially without opening a mains disconnector or even shutting down and switching off the wind power installation becomes.
- the control remains active and the wind turbine is kept ready to resume normal operation as soon as possible after the grid fault has ended.
- resuming normal operation as quickly as possible can also mean that after the end of the network fault, the power is not suddenly increased to the value of normal operation, but that, for example, a short rising edge is provided to make the amplitude of the power fed in somewhat slower than to jump to the desired final value.
- the interruption or reduction of the infeed or the reduced infeed is ended when a network fault end has been detected.
- a network fault end is recognized in particular when the network voltage has reached a normal value again, in particular when it has again reached the nominal network voltage. Slight fluctuations, such as the exemplary 1 to 3% already described above, can be tolerated. A network fault end is therefore also recognized when such small fluctuations are present.
- the power fed in is limited to a limiting power during the network fault and / or from the end of the network fault. In particular, this ensures that the electrical power fed in does not exceed this limiting power during the network fault and / or shortly thereafter.
- the limiting power can also be specified as a time course.
- the intermediate circuit voltage is limited as a function of the limiting power by means of the chopper circuit.
- the level of the intermediate circuit voltage depends in particular on how much power from the generator of the wind turbine is fed into this intermediate circuit voltage and how much power is fed by the inverter from this direct voltage intermediate circuit into the electrical supply network, which value can also be negative, since an inverter could also take power from the network, but this is not important here.
- the intermediate circuit voltage increases when more power is input into the DC intermediate circuit than is drawn and vice versa.
- This power balance can now, what is proposed here, be influenced by the chopper circuit. It is proposed here to specifically control the intermediate circuit voltage in the event of a network fault, that is to say during the network fault and / or shortly thereafter, via this chopper circuit. This can also influence the power that the inverter feeds from the DC link into the electrical supply network.
- the inverter feed electrical power into the electrical supply network depending on the intermediate circuit voltage, that is, depending on the level of the intermediate circuit voltage, into the electrical supply network.
- the feed-in power be limited to the limiting power from the end of the network fault for a predetermined recovery period.
- This recovery period is intended for the electrical supply network to have time to recover from the network fault in order to return to a stable operating point.
- the predetermined recovery period is in the range from 10 ms to 10 seconds, preferably in the range from 50 ms to 2 seconds.
- the recovery period is at least 10 ms, namely from the end of the network fault.
- the feed-in power is limited to the limiting power.
- the limiting power can also be a variable in this recovery period, especially a rising edge.
- the power fed in during this recovery period should not be higher than immediately before the network fault was detected.
- the proposed method thus prevents the power fed in from being increased beyond the value immediately before the network fault after the end of the network fault, so that a corresponding power increase is avoided.
- This is achieved in particular by the proposed limitation of the intermediate circuit voltage by means of the chopper circuit.
- the limiting power is preferably specified as a time-dependent power curve, in particular with a rising edge, so that the power fed in after the end of the fault can be attributed to a value of the power fed in immediately before the network fault. This means that the power fed in can be carried out particularly from the end of the network fault and in particular excessive power can be avoided.
- a grid fault in which the grid voltage drops is usually so short that the electrical that can be generated due to the prevailing wind conditions Wind power not changed at relevant height. In other words, an approximately constant power output can be assumed.
- the fed-in power can therefore be brought back to its value immediately before the grid fault.
- the limit of the intermediate circuit voltage qualitatively follows the limiting power.
- a rising edge of a limit of the intermediate circuit voltage is also set on a rising edge of the limiting power.
- the chopper circuit in order to limit the intermediate circuit voltage during the network fault and / or from the end of the network fault, at least one limit voltage is specified as a function of the network fault and / or as a function of the limiting power, and that the chopper circuit removes electrical energy from the DC voltage intermediate circuit as a function thereof whether the DC link voltage reaches or exceeds the limit voltage.
- the chopper circuit can thus be controlled by specifying such a limit voltage.
- the intermediate circuit voltage is recorded and compared with the limit voltage and the chopper circuit is controlled as a function thereof. To this extent, the chopper circuit regulates the intermediate circuit voltage, for which the limit voltage can be regarded as the setpoint.
- a lower limit voltage and an upper limit voltage are preferably specified as a function of the network fault and / or as a function of the limiting power.
- the limit voltage described above, depending on which the chopper circuit can be controlled, can correspond to the lower limit voltage here.
- the upper limit voltage is greater than the lower limit voltage by a variable band gap. The lower and upper limit voltage thus form a limit voltage band.
- the band gap before the network fault, that is to say in normal operation, has a pre-fault gap.
- a pre-fault distance can be regarded as comparatively large and can, for example, have a size of 2% to 5% of the intermediate circuit voltage, in particular an intermediate circuit nominal voltage, which can be, for example, 700 V.
- the band gap is reduced when the network fault is detected, in order to dissipate as much power as possible from the DC link circuit to hold the DC link voltage as soon as the DC link voltage has reached the lower limit voltage.
- the chopper circuit begins to dissipate power from the direct voltage intermediate circuit when the intermediate circuit voltage reaches the lower limit value of the chopper threshold, namely the lower limit voltage. At this moment, however, very little power is dissipated through the chopper circuit. This then increases the closer the DC link voltage comes to the upper limit voltage. If the intermediate circuit voltage reaches the upper limit voltage, the chopper circuit then delivers maximum power from the DC voltage. intermediate circuit, i.e. as much power as is possible with the chopper circuit including connected resistance bank or resistance banks and due to the intermediate circuit voltage. The amount of power dissipated is thus controlled depending on where the intermediate circuit voltage is in the limit voltage band.
- reducing the bandgap especially if it is reduced to a very low value, means that when the lower limit voltage is reached, the intermediate circuit voltage almost simultaneously reaches the upper limit voltage, and thus the chopper circuit draws maximum power from the DC intermediate circuit. It is precisely this effect that is achieved by reducing the band gap, especially by reducing it to a value close to zero. This ensures that the DC link voltage does not exceed the lower or upper limit voltage during the line fault, but does not drop below it. The DC link voltage is therefore maintained or maintained at the level of the lower or upper limit voltage. This means that the power fed in can also be managed and maintained well.
- the band gap be increased from the end of the network fault in order to reduce the power dissipated from the DC voltage intermediate circuit by means of the chopper circuit.
- the bandgap is continuously and / or continuously increased from a value of zero and thus less and less power is dissipated from the DC link by means of the chopper circuit. This is proposed for the period from the end of the network fault when the network fault has been remedied and the electrical supply network is in the process of calming down or returning to a normal, as stable as possible operating point.
- the power fed in will also rise again, so that more and more power is fed into the electrical supply network by the inverter and less and less power is dissipated through the chopper circuit.
- the DC link voltage can also be reduced again, provided that it was increased when the line fault occurred. Then it can be reduced back to its old value before the network fault.
- the wind turbine or its inverter essentially feeds back into the electrical supply network in normal operation.
- the band gap be continuously increased within the recovery period from the end of the network fault. The increase in the band gap from the end of the network fault can thus be specified over time for this recovery period.
- the band gap preferably increases from the end of the network fault to a value up to the pre-fault distance.
- the bandgap thus increases again after the end of the network fault to a value that it had before the network fault.
- the upper limit voltage before the grid fault takes on a larger value than during the grid fault.
- the upper limit voltage then increases again from the end of the network fault.
- the upper limit voltage can preferably be reduced by a value of 3 to 10% from a value before the mains fault to a value during the mains fault.
- an intermediate circuit working voltage is determined as a function of an operating point of the wind power plant for feeding in the intermediate circuit voltage in normal operation.
- the intermediate circuit voltage and thus the intermediate circuit working voltage to be determined in normal operation are dependent on the level of the mains voltage, an impedance of a mains choke and the current to be fed in, namely its phase angle and its amplitude.
- the current to be fed in, in particular the active current component to be fed in depends on the available wind power.
- a reactive current component can depend on a state of the electrical supply network and / or on the specifications of a network operator.
- the previously determined intermediate circuit working voltage is the one that was determined last, that is to say immediately before the detected network fault, that is to say the last value of the intermediate circuit working voltage. This is particularly important is based on the idea that when the network fault occurs there is neither sufficient time nor stable conditions to then independently determine an intermediate circuit fault voltage. Instead, this can be based on the last value of the DC link working voltage. It is particularly suggested that the intermediate circuit error voltage is set to a predetermined intermediate circuit error voltage if the predetermined intermediate circuit operating voltage is lower than the predetermined intermediate circuit error voltage. In this case, the value is increased, namely from the intermediate circuit working voltage to the predetermined intermediate circuit error voltage. Otherwise, the DC link error voltage is set to the previously determined DC link working voltage.
- the default value for the intermediate circuit voltage is not reduced, but is either increased if the intermediate circuit operating voltage was low, otherwise if the intermediate circuit operating voltage was high, such a high value is maintained. It was particularly recognized here that in the event of a grid fault and also with regard to an end to the grid fault, a high intermediate circuit voltage should be provided in order to provide the inverter with a sufficient working area for feeding in electrical power. Therefore, the DC link voltage should not be reduced if possible in the event of a fault. Nevertheless, the DC link error voltage then selected should also be maintained and this is also achieved as far as possible by the chopper circuit and the proposed method.
- the limit voltage or the upper limit voltage be set to the value of the intermediate circuit error voltage when the network fault is detected.
- the intermediate circuit error voltage and the limit voltage at which the chopper circuit would draw maximum power from the direct voltage intermediate circuit thus have the same value.
- the intermediate circuit error voltage is set to be minimally smaller than the limit voltage or upper limit voltage. However, this is only an option and it is not absolutely necessary.
- the intermediate circuit voltage is controlled to the value of the intermediate circuit error voltage by means of the chopper circuit. This ensures that this intermediate circuit voltage is kept at a stable value, namely the value of the DC link fault voltage. This means that the power fed in can be controlled well.
- the DC link error voltage is reduced, in particular continuously reduced, from the end of the line fault, and at the same time the limit voltage or the upper limit voltage is increased, in particular continuously increased. This is preferably done both within the recovery period. In this way, it can be achieved in particular that the fed-in power is not exceeded above a value which the fed-in power had immediately before the grid fault.
- the power fed in is fed back to a feed-in value in normal operation, in particular that it is fed back to the feed-in value in normal operation via a monotonically increasing power curve.
- overshoot of this power fed in after the end of the network fault can be avoided.
- This is achieved in particular by the limitation of the intermediate circuit voltage described.
- the wind power plant can make a contribution to ensuring that the electrical supply network returns from the network fault to stable normal operation as safely and stably as possible.
- the limitation of the intermediate circuit voltage is additionally controlled as a function of fed reactive power. It is particularly important here that this takes place as a function of a reactive power that was fed in immediately before the grid fault.
- the limitation of the intermediate circuit voltage which can be higher, for example, in the case of fed reactive power than when no or less reactive power is fed in and the operating point is otherwise the same or similar, can thus be a preparation for feed-in operation immediately after the grid fault. After the line fault, it may then also be necessary to feed in a correspondingly high reactive power as before the line fault, and the intermediate circuit voltage can then already be prepared for this.
- the limitation of the intermediate circuit voltage be increased with a predeterminable time increase from the end of the line fault. It is particularly suggested here to provide a corresponding gradient for limiting the intermediate circuit voltage.
- the resurgence of this limitation in particular the limit voltage or the upper limit voltage can go hand in hand with a drop in the intermediate circuit voltage or also a constant level in the intermediate circuit voltage, and it can go hand in hand with an increase in the power fed in.
- the power can also be increased in accordance with a predeterminable gradient and this can also be controlled by means of the described increase in the limitation of the intermediate circuit voltage, at least a control of the power can thereby be favored.
- the limitation of the intermediate circuit voltage is increased from the end of the network fault only after a predeterminable waiting time.
- This predeterminable waiting time which can be in the range from 5 to 100 ms, in particular from 5 to 50 ms, can be used to ensure that the network returns at all, i.e. has a non-zero network voltage value before power is then fed in and is increased in order to finally restore a normal operating point of the electrical supply network.
- a wind turbine is also proposed.
- Such a wind energy installation is characterized in particular by the fact that it carries out a method characterized in accordance with at least one embodiment described above or is prepared to carry it out.
- it has a control device for this purpose, which controls the at least one inverter of the wind energy installation.
- the control device can in particular be set up in such a way that corresponding control modes are preprogrammed in a process computer contained therein.
- corresponding control connections to the at least one inverter and optionally additionally to the at least one chopper circuit of the respective inverter are provided, in order thereby to carry out the control method for the execution of which the control device is prepared.
- the proposed wind turbine can have one or more inverters.
- inverter devices Several modern inverters are usually provided in modern, large wind turbines. In their entirety, these can also be referred to as inverter devices.
- Each inverter can have its own DC link or it can be a common DC link for one or several inverters can be provided.
- a chopper circuit can be provided for each individual DC voltage intermediate circuit or a common chopper circuit or a plurality of common chopper circuits for a common DC voltage intermediate circuit.
- the proposed solutions for controlling the infeed before, during and after a network fault can be implemented with all the topologies mentioned, so that at least all the topologies mentioned are preferred embodiments.
- the control of the feed can also be carried out, for example, by a common inverter or a common inverter device of a wind farm having a plurality of wind energy plants. This is also a preferred embodiment.
- a wind farm which has a plurality of wind energy installations and is characterized in that it is prepared to carry out at least one method for feeding electrical power in accordance with at least one embodiment described above.
- the wind farm has a central park control device which is prepared to carry out such a method.
- the parking control device is provided with a process computer on which such a method is preprogrammed.
- the wind farm preferably has at least one central inverter device which feeds the entire power of the wind farm into the electrical supply network at a network connection point. Such a common inverter device is preferably controlled by the central parking control device.
- Figure 1 shows a wind turbine in a perspective view.
- Figure 2 shows a wind farm in a schematic representation.
- FIG. 3 shows diagrams of voltage and power curves to illustrate a proposed method.
- Figure 4 shows some elements of a wind turbine in a schematic representation.
- FIG. 1 shows a wind energy installation 100 with a tower 102 and a nacelle 104.
- a rotor 106 with three rotor blades 108 and a spinner 110 is arranged on the nacelle 104.
- the rotor 106 is set into a rotary movement by the wind and thereby drives a generator in the nacelle 104.
- an inverter 150 is shown schematically, which has a DC voltage intermediate circuit 152 with a DC voltage intermediate circuit capacitor 154 and an inverter switching module 156 for generating a three-phase alternating current.
- the inverter switching module 156 can be followed by a choke module 158, which can also be regarded as part of the inverter 150.
- a chopper circuit 160 is provided, which is connected to the DC voltage intermediate circuit 152 and essentially has a chopper switching module 162 and a chopper resistor 164.
- This chopper circuit 160 can also be regarded as part of the inverter 150.
- a control device 166 which in particular controls the inverter switching module 156, which is indicated by a double arrow to the inverter switching module 156.
- the control device 166 also controls the chopper circuit 160, namely in particular the chopper switch module 162. This can be done indirectly via the inverter switching module 156, which is indicated by a corresponding double arrow between the inverter switching module 156 and the chopper switching module 162.
- the control of the chopper circuit 160 or of the chopper switching module 162 can depend on a detected intermediate circuit voltage UDC, which in turn is detected by the inverter switching module 156 or is also used there.
- the control device 166 can directly control the chopper switching module 162.
- the chopper switching module 162 now works in such a way that it dissipates power from the DC voltage intermediate circuit 152 via a pulse pattern. This creates a pulsed leakage current ⁇ A, which leads to heating in the chopper resistor 164, as a result of which energy is released as heat from the DC link.
- This control of the chopper circuit 160 and thus of the chopper switching module 162 can take place as a function of a mains voltage UG, an operating point of the wind power installation 100 and / or current settings of the inverter 150, in particular the inverter switching module 156.
- the control device 166 accordingly processes the information necessary for this.
- the mains voltage UG can be detected on a primary side of a mains transformer 168, via which the electrical supply network 170 is fed.
- the line voltage UG would still have to be converted in the connection shown, but could alternatively also be recorded on a secondary side of the line transformer 168.
- a voltage drop in the electrical supply network 170 can be detected by the detection of the mains voltage UG and a network fault can thus be detected.
- the control device 166 can work and then also control the chopper circuit 160 if necessary.
- Corresponding information can be obtained from the wind power plant for acquiring a working point of the wind power plant 100, which is to be indicated by the state vector x.
- This can include, for example, speed, blade angle and a set excitation power of the generator of the wind turbine, to name just a few examples.
- the inverter 150 itself is also to be understood as part of the wind energy installation 100, and its information, such as, for example, the currently emitted active power and currently emitted reactive power, can thus also be taken into account. This is indicated by a corresponding double arrow between the control device 166 and the inverter switching module 156.
- FIG. 2 shows a wind farm 112 with three wind turbines 100 by way of example, which can be the same or different.
- the three wind energy plants 100 are therefore representative of basically any number of wind energy plants of a wind farm 112.
- the wind energy plants 100 provide their power, namely in particular the electricity generated, via an electrical parking network 114.
- the currents or powers of the individual wind energy plants 100 generated in each case are added up and are usually a transformer 1 16 is provided, which transforms up the voltage in the park, in order to then feed into the supply network 120 at the entry point 1 18, which is also generally referred to as PCC.
- FIG. 2 is only a simplified illustration of a wind farm 1 12, in which, for example, the park network 1 14 can be designed differently, in which, for example, there is also a transformer at the outlet of each wind energy installation 100, to name just another embodiment.
- a central park control device 180 can be provided, which can control the individual wind turbines 100 and can also receive information from these wind turbines.
- the central parking control device 180 can detect a mains voltage UG of the electrical supply network 120.
- the electrical supply network 120 can correspond to the electrical supply network 170 of FIG. 1.
- the central park control device 180 may alternatively or additionally also receive the mains voltage UG from at least one of the wind energy plants 100.
- a common inverter device 182 is provided in FIG. 2, which can work as a central inverter for the wind farm 112. This common inverter device 182 is shown in dashed lines to clarify that this is an option.
- This common inverter device 182 can also be controlled by the central parking control device 180 and also transmit information to this central parking control device 180, which is indicated by a double arrow shown in dashed lines.
- a proposed limitation of an intermediate circuit voltage can be carried out in this common inverter device 182, so that a corresponding chopper circuit is also provided there.
- this or another common inverter device 182 it can also be provided that the inverters are carried out in the common inverter device 182, but the activation of one or more chopper circuits is carried out in the individual wind energy plants. This can be coordinated by the central parking control device 180.
- FIG. 3 shows three individual diagrams A, B and C, which are based on the same time axis. This is to illustrate and explain the connection between the functions that are shown in the diagrams.
- the uppermost diagram A shows a profile of a line voltage UG.
- This line voltage UG ideally has the value of the line voltage UN.
- the course of this line voltage UG is shown schematically as an example for an error, the solid line representing an actual, detected course of the line voltage UG.
- measurement inaccuracies, including measurement delays, are not shown in the illustrations in FIG. 3 and are therefore not discussed.
- an undervoltage value Um is also indicated by a horizontal dashed line, which the mains voltage UG should not fall below. If it falls below this value, a network fault due to a detected voltage drop is assumed.
- Such a line fault in which the line voltage UG drops below the undervoltage value Um, occurs at time ti and thus indicates a start of the line fault.
- the line voltage UG rises again above the undervoltage value U m and this marks the end of the line fault.
- diagram A also shows only one example of a possible mains fault in the event of a voltage dip, in which the mains voltage UG drops to a lower value.
- the mains voltage it is also possible for the mains voltage to drop to a very small value or even to zero.
- this also has an impact on the power that can be fed in and in this respect the following explanation of the diagram C with the curves shown there in solid and dash-dotted lines refers to the voltage drop shown in diagram A, in which the voltage does not drop to zero.
- a profile of the fed-in power is provided, as shown in diagram C.
- the course of the power P is also based on the three times ti to t3.
- diagram C shows the power P delivered to the electrical supply network by the wind energy installation or, according to another embodiment, by the wind farm.
- this has the initial power P A.
- This initial power P A is then drawn in as a dashed horizontal line for orientation.
- the power P actually fed in thus has the value P A.
- the small difference between the horizontal dashed line for P A and the solid line for P shown at the beginning of the diagram is only for clarity. In fact, as far as technically feasible, these two services should be identical, which also applies to the area after the third point in time t3.
- a limiting power PB is drawn in as a dash-dotted line and initially runs horizontally between the times ti and t 2 , namely during the duration of the network fault. From the end of the network fault at time t 2 , this course of the limiting power PB increases over a predetermined edge up to the value of the initial power PA at time t3.
- the dash-dotted line of the limiting power PB is also shown for reasons of illustration above the solid line of the power P. Ideally, these two courses should coincide.
- the power P fed in before the network fault has the value of the initial power PA, is then at the beginning of the fault at the time ti, by the specification of the limiting power PB, down to the same value of the limiting power PB ZU at the time and to this low value until Mains failure held at time t 2 .
- the output power P is then slowly controlled back to the value of the initial power before the network fault by the increasing profile of the limiting power PB.
- Diagram B thus shows the profile of an intermediate circuit voltage UDC of a direct voltage intermediate circuit of an inverter of a wind energy installation or also of a wind farm.
- the DC voltage intermediate circuit can also be coupled to a plurality of inverters.
- the solid line shows the corresponding voltage curve as the intermediate circuit voltage UDCR required or specified by the control system.
- the intermediate circuit voltage UDC actually sets itself as required by the predetermined intermediate circuit voltage UDCR.
- diagram B indicates that it is interrupted, that is, it would be significantly longer if it were actually displayed.
- the voltage variations shown in diagram B are comparatively small compared to the entire amplitude of the intermediate circuit voltage.
- an intermediate circuit voltage UDCR is specified as a function of the working point of the wind turbine. This can mean here in particular that this takes place as a function of the mains voltage, the impedance of a mains choke, such as the mains choke 158 of FIG. 1, and depending on the phase angle and the amplitude of the current to be fed.
- the intermediate circuit voltage UDC can then be controlled particularly by an upstream step-up converter, or alternatively by an active rectifier, both of which are located between a generator and the direct voltage intermediate circuit.
- it can also be controlled by feeding in, that is to say by an inverter switching module, such as the inverter switching module 156 in FIG. 1.
- the chopper circuit can also be controlled by the chopper circuit, such as chopper circuit 160 of FIG. 1.
- the chopper circuit only control the intermediate circuit voltage in exceptional cases, because when the chopper circuit responds, power is consumed, namely otherwise converted into heat unused.
- the chopper circuit intervenes there may be situations in which the chopper circuit intervenes and such a case is proposed for the network fault illustrated in FIG. 3.
- a lower limit voltage UDCU and an upper limit voltage UDCL2 are specified for controlling the chopper circuit.
- diagram B is the lower limit voltage UDCLI is drawn as a dash-dotted line and the upper limit voltage UDCL2 as a single dashed line. They have a variable band gap AUDCL from one another.
- This band gap is comparatively large before the network fault and has the following technical purpose. If the intermediate circuit voltage UDC reaches the lower limit voltage UDCLI, SO the chopper circuit begins to dissipate little power from the direct voltage intermediate circuit. The switching pattern is then such that a chopper switch which is designed as a semiconductor switch is closed for a comparatively short time and is open for a comparatively long time. So there are short current peaks in order to dissipate correspondingly little power. However, the higher the intermediate circuit voltage UDC rises, the closer it approaches the upper limit voltage UDCL2, the more power is dissipated from the DC voltage intermediate circuit by the chopper circuit. The current pulses then become ever wider and the pauses between the current pulses become narrower. If the intermediate circuit voltage reaches the upper limit voltage, the chopper circuit is then controlled so that it dissipates maximum power from the direct voltage intermediate circuit.
- the intermediate circuit voltage does not reach the lower limit voltage UDCLI or at least does not exceed it.
- the DC link voltage in this area should only be controlled by the inverter switching module, ie by the power fed in, and by the step-up converter or active rectifier mentioned.
- the chopper circuit can additionally counteract such a too high voltage value. If the intermediate circuit voltage rises further, the chopper circuit can counteract this more and more with increasing intermediate circuit voltage. If the network error now occurs at time ti, this bandgap AUDCL is immediately reduced, ideally to a very small value or even to a value close to zero.
- the active power P fed in can also be controlled to a lower value, as is shown in diagram C at the time of the network fault between times ti and t2. It should be noted that it is not essential to reduce the DC link voltage for the power reduction shown. Rather, it was recognized that a particularly stable intermediate circuit voltage, despite strongly varying further circumstances, such as the rapid change in the mains voltage UG, can also favor the stabilization of a low power input. A comparatively high DC link voltage can make the feed-in of the power more controllable.
- the predetermined intermediate circuit voltage UDCR is also raised to a higher value at time ti, that is to say at the start of the network error, namely to the value of an intermediate circuit error voltage UDCF.
- This lower value can be, for example, 550 V or 630 V, which is then raised to a value of 680 V as an intermediate circuit fault voltage in the event of a mains fault.
- the specified intermediate circuit voltage was comparatively high due to the operating point before the error, for example, it was 700 V, such a high value is maintained and is not reduced to the value of the intermediate circuit error voltage UDCF of 680 V mentioned as an example.
- the specified value for the DC link voltage is thus either raised at the beginning of the network fault if it was previously comparatively low, or its level is maintained.
- the DC link voltage UDC is controlled from the end of the line fault, ie from the time slowly increase the bandgap AUDCL.
- the lower voltage limit UDCLI can gradually decrease with an edge up to time t3, while the upper voltage limit UDCL2 also increases gradually and simultaneously up to time t3. This goes hand in hand with the fact that the specified intermediate circuit voltage UDCR gradually falls from the end of the line fault to the time t3 to its old value before the line fault. Then, at time t3, it is assumed that the electrical supply network has essentially recovered from the network fault.
- the recovery period TD the period between the end of the network fault at time t2 and the later time t3 is referred to as the recovery period TD.
- the recovery period TD at the latest from time t3, it is then assumed that the chopper circuit hardly works anymore, if at all, dissipates little power from the intermediate circuit, ideally no longer dissipates any power from the intermediate circuit.
- the power P fed in has then again reached its initial value PA.
- the upper limit voltage UDCL2, the lower limit voltage UDCLI and the predetermined intermediate circuit voltage UDCR are close to one another during the network fault, that is to say between times ti and t2.
- the upper limit voltage UDCL2 and the lower limit voltage UDCLI differ more clearly. There is also a small company in these areas Difference between the lower limit voltage UDCU and the predetermined limit voltage UDCR shown. According to one embodiment, however, these two profiles can coincide and the specified limit voltage UDCR can optionally be specified in this case via the lower limit voltage UDCU.
- UDCU is preferably somewhat higher than UDCR.
- a power curve with P * is shown as a further alternative, which drops to zero at the beginning of the network fault, but is also controlled back to the value of the initial power at the end of the network fault at time t2.
- This course is marked with x symbols.
- the course of a reactive power Q * is also shown for this variant.
- the reactive power also drops to zero at the beginning of the network fault ti, but then rises again from the end of the network fault at the time t2 to the time t3 to the old reactive power value.
- This variant can also be implemented with an intermediate circuit control, as illustrated in diagram B.
- FIG. 4 shows a rotor 406 for a wind energy installation 400 with rotor blades 408 that can be adjusted in their blade angle.
- the rotor 406 is coupled to a generator 430, which is designed here as a six-phase synchronous generator with external excitation.
- the generator 430 thus generates a six-phase stator current at its generator output 432, which is rectified by means of a rectifier 434 and applied to a lower DC voltage intermediate circuit 436.
- An excitation controller 438 can also be supplied from this lower DC voltage intermediate circuit 436 in order to provide an excitation current for the externally excited synchronous generator 430.
- a step-up converter 440 is connected to the lower DC voltage intermediate circuit 436, which raises the voltage of the lower DC voltage intermediate circuit 436 to a higher voltage in a subsequent upper DC voltage intermediate circuit 442.
- the upper DC voltage intermediate circuit 442 in FIG. 4 can correspond to the DC voltage intermediate circuit 152 in FIG.
- the lower DC voltage intermediate circuit 436 can be arranged, for example, in the nacelle 104 of the wind energy installation 100 in FIG. 1.
- the upper DC voltage intermediate circuit 442 also has a chopper circuit 444, which can be constructed like the chopper circuit 160 in FIG.
- An inverter switching module 446 is provided for inverters, which outputs a three-phase alternating current or a three-phase alternating voltage and passes it through a line filter 448, which contains a corresponding line reactor.
- a network transformer 468 is provided, which can correspond to the network transformer 168 of FIG. 1 and can contain an actuating device, that is to say can be designed as an actuating transformer.
- the result is then fed into the electrical supply network 470, which can correspond to the electrical supply network 170 in FIG. 1 or 120 in FIG.
- Wind energy plants with a modular full converter concept preferably feed the power generated from the wind into the energy system, that is to say into an electrical supply network.
- An operating point-dependent rectifier DC link voltage UDI is established.
- step-up converter 440 can do this, for example.
- a need for the voltage to be applied by this step-up converter 440 arises particularly when comparatively little power can be drawn from the wind, when the wind energy installation, and thus the generator, does not operate under full load.
- the necessary intermediate circuit voltage UD2 which corresponds to the intermediate circuit voltage UDC according to FIG. 1, is particularly dependent on the mains voltage UG, the impedance of the mains choke, in particular also the impedance of the filter 448 in FIG. 4, and both the phase angle and the amplitude of the current to be fed in .
- the line choke is particularly relevant and the capacitance can be neglected, so that only the line choke 158 is shown in FIG.
- This necessary DC link voltage is calculated online on the basis of setpoints for each operating point and updated accordingly.
- the working point can thus be recorded, but here it is proposed to use the setpoints for the working point.
- any excess energy from the DC link is converted into heat in the chopper resistor.
- a current is set at the output of the inverter, which depends on the feed-in strategy and the parameterization. This current at the output of the inverter therefore does not need to feed in all the power, but only the power that is also to be fed in based on the selected or predetermined concept.
- the rest is removed from the intermediate circuit by means of the chopper circuit and converted into heat in the chopper resistor, which of course can also be implemented as a resistance bank.
- the proposed invention is particularly intended for connection to soft networks which would otherwise react with overvoltage to a power overshoot at the output of the inverter. Such an overshoot of the power and thus an overshoot of the voltage of the soft network, that is to say the electrical supply network which is fed in, is avoided.
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Abstract
Description
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Application Number | Priority Date | Filing Date | Title |
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DE102019101048.9A DE102019101048A1 (en) | 2019-01-16 | 2019-01-16 | Wind turbine for feeding electrical power into an electrical supply network |
PCT/EP2020/050865 WO2020148313A1 (en) | 2019-01-16 | 2020-01-15 | Wind turbine for feeding electrical power into an electrical supply network |
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EP3911856A1 true EP3911856A1 (en) | 2021-11-24 |
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EP20700889.7A Pending EP3911856A1 (en) | 2019-01-16 | 2020-01-15 | Wind turbine for feeding electrical power into an electrical supply network |
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US (1) | US11870265B2 (en) |
EP (1) | EP3911856A1 (en) |
CN (1) | CN113302396A (en) |
DE (1) | DE102019101048A1 (en) |
WO (1) | WO2020148313A1 (en) |
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DE102019104892A1 (en) * | 2019-02-26 | 2020-08-27 | Wobben Properties Gmbh | Method for operating a wind turbine in the event of a grid failure |
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PL1665495T3 (en) | 2003-09-23 | 2012-07-31 | Aloys Wobben | Method for operating a wind turbine during a disturbance in the grid |
WO2006069569A1 (en) * | 2004-12-28 | 2006-07-06 | Vestas Wind Systems A/S | Method of controlling a wind turbine connected to an electric utility grid |
GB0523087D0 (en) * | 2005-11-11 | 2005-12-21 | Alstom Power Conversion Ltd | Power converters |
US8198742B2 (en) * | 2007-12-28 | 2012-06-12 | Vestas Wind Systems A/S | Variable speed wind turbine with a doubly-fed induction generator and rotor and grid inverters that use scalar controls |
US20130334818A1 (en) * | 2012-06-19 | 2013-12-19 | Clipper Windpower, LLC. | Dynamic Braking on a Wind Turbine During a Fault |
DE102012212364A1 (en) * | 2012-07-13 | 2014-01-16 | Wobben Properties Gmbh | Method and device for feeding electrical energy into an electrical supply network |
DE102012212366A1 (en) * | 2012-07-13 | 2014-01-30 | Wobben Properties Gmbh | Method for controlling an electric generator |
US9941687B2 (en) * | 2013-06-04 | 2018-04-10 | General Electric Company | Methods for operating wind turbine system having dynamic brake |
US20140361624A1 (en) * | 2013-06-10 | 2014-12-11 | Active Power, Inc. | Apparatus and methods for control of load power quality in uninterruptible power systems |
US9577557B2 (en) * | 2013-10-18 | 2017-02-21 | Abb Schweiz Ag | Turbine-generator system with DC output |
US9467081B2 (en) * | 2014-09-29 | 2016-10-11 | Ingeteam Power Technology, S.A. | Protection system for a power converter connected to a doubly fed induction generator |
DE102016101469A1 (en) * | 2016-01-27 | 2017-07-27 | Wobben Properties Gmbh | Method for feeding electrical power into an electrical supply network |
EP3206286A1 (en) | 2016-02-10 | 2017-08-16 | GE Energy Power Conversion Technology Ltd | Gatespannungsübersteuerung für das schalten von stossströmen in igbt schaltern |
DE102016105662A1 (en) * | 2016-03-29 | 2017-10-05 | Wobben Properties Gmbh | Method for feeding electrical power into an electrical supply network with a wind farm and wind farm |
DE102017106436A1 (en) * | 2017-03-24 | 2018-09-27 | Wobben Properties Gmbh | Wind farm with several wind turbines |
AT519747B1 (en) * | 2017-05-23 | 2018-10-15 | Ing Gerald Hehenberger Dipl | Method and device for regulating the operation of a drive train |
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2019
- 2019-01-16 DE DE102019101048.9A patent/DE102019101048A1/en active Pending
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2020
- 2020-01-15 WO PCT/EP2020/050865 patent/WO2020148313A1/en unknown
- 2020-01-15 US US17/422,599 patent/US11870265B2/en active Active
- 2020-01-15 EP EP20700889.7A patent/EP3911856A1/en active Pending
- 2020-01-15 CN CN202080009713.8A patent/CN113302396A/en active Pending
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US11870265B2 (en) | 2024-01-09 |
DE102019101048A1 (en) | 2020-07-16 |
WO2020148313A1 (en) | 2020-07-23 |
US20220094167A1 (en) | 2022-03-24 |
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