Network construction type wind generating set and power grid voltage fault ride-through method

Abstract

The invention relates to the technical field of power electronic converter control, and discloses a network construction type wind generating set and a power grid voltage fault ride-through method, and the power grid voltage fault ride-through method comprises the steps: obtaining the network side output active power of a current source main converter and the active power output by a wind driven generator, if the active power output by the grid side of the current source main converter is smaller than the active power output by the wind driven generator, the operation states of the energy consumption crowbar and the energy storage crowbar are switched to open states; the active power output by the wind driven generator is converted into the heat of the resistor by using the energy consumption crowbar; the energy storage crowbar is used for converting active power output by the wind driven generator into energy of a battery; and reducing the active power output by the wind driven generator to the target output power until the power grid voltage fault point is removed. According to the invention, the cost per kilowatt-hour of the grid voltage fault ride-through of the grid-forming type wind generating set is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of power electronic converter control, and in particular to a grid-type wind turbine generator set and a grid voltage fault ride-through method. Background Art

[0002] The fault ride-through problem of wind turbine generator sets refers to the ability of wind turbine generator sets to ensure continuous operation without disconnection from the grid and smoothly transition to normal operation state within a certain voltage or frequency range and its duration time interval when the voltage or frequency of the grid connection point exceeds the normal operating range allowed by the standard. Grid failures will bring a series of transient processes to wind turbine generator sets and other wind farm electrical equipment, such as overcurrent, low voltage, overspeed, etc. Wind turbine generator sets need to have a certain ability to ride through faults, that is, wind turbine generator set fault ride-through. The proportion of wind power in the power grid has reached a relatively high level. If wind turbine generator sets do not have qualified grid fault resistance capabilities, they will automatically decouple when a grid fault occurs, which will increase the difficulty of recovering from local grid faults, deteriorate grid stability, and even aggravate faults and cause system collapse.

[0003] In the event of a grid voltage failure, the technical idea of ​​riding through is to first input the unit's active power into the current source main converter, and then divert it through the energy consumption unit or energy storage unit to continuously input active power. This requires the current source main converter to passively improve the response speed of processing active power, and also passively increase the weight and volume of the current source main converter, reducing the power density of the converter and increasing the unit's cost per kilowatt-hour. Summary of the invention

[0004] In view of this, the present invention provides a grid-type wind turbine generator set and a grid voltage fault ride-through method to solve the problem of high unit electricity cost in the grid voltage fault ride-through method.

[0005] In a first aspect, the present invention provides a grid-type wind turbine generator set, comprising: a current source main converter, and a wind turbine generator, an energy storage crowbar, a battery, an energy consumption crowbar and a resistor arranged on the side of the current source main converter; the wind turbine generator is connected to the current source main converter, the energy storage crowbar and the energy consumption crowbar respectively, the energy storage crowbar and the energy consumption crowbar are connected in parallel, the energy storage crowbar is connected to the battery, and the energy consumption crowbar is connected to the resistor; wherein,

[0006] The energy dissipation crowbar is used to convert the active power output by the wind turbine generator into heat of the resistor when the active power output by the grid side of the current source main converter is less than the active power output by the wind turbine generator;

[0007] The energy storage crowbar is used to convert the active power output by the wind turbine generator into the energy of the battery when the active power output by the grid side of the current source main converter is less than the active power output by the wind turbine generator;

[0008] The wind turbine generator is used to reduce the active power output by the generator to the target output power if the energy consumption crowbar and the energy storage crowbar are in the on state until the grid voltage fault point is removed.

[0009] The present embodiment provides a grid-forming wind turbine generator set, which arranges an energy storage crowbar and an energy consumption crowbar on the side of the current source main converter. In the event of a grid voltage failure, the energy consumption crowbar and the energy storage crowbar are used to shunt the surplus active power on the side of the current source main converter, thereby significantly reducing the active power output by the wind turbine to the current source main converter. At the same time, it is ensured that the current source main converter does not go off-grid in the event of a grid voltage failure and continues to form a grid, thereby improving the grid-forming reliability of the set, being able to reduce the cost per kilowatt-hour of the grid-forming wind turbine generator set, and improving the project investment return rate.

[0010] In an optional implementation, it also includes:

[0011] The AC side transformer is connected to the energy storage crowbar and the wind turbine generator respectively, and is used to adjust the battery stack voltage according to the AC outlet side transformer step-up ratio.

[0012] The grid-type wind turbine generator set provided in this embodiment can flexibly adjust the battery stack voltage according to the transformer step-up ratio at the AC outlet side, and can adapt to battery stacks of different DC voltage levels, thereby reducing energy storage costs.

[0013] In an optional implementation, the current source main converter comprises:

[0014] Inverter, DC energy storage inductor and rectifier; the DC energy storage inductor is connected to the inverter and the rectifier respectively, the inverter is connected to the power grid through the grid-side capacitor and the grid-side reactor, and the rectifier is connected to the wind turbine generator through the machine-side capacitor and the machine-side reactor.

[0015] In a grid-type wind turbine generator set provided in this embodiment, the DC energy storage inductor has a fault current limiting function, which provides multi-layer protection for the fault current limiting of the main converter.

[0016] In an optional implementation, it also includes:

[0017] The step-up transformer is connected to the power grid and is connected to the inverter through a grid-side capacitor and a grid-side reactor.

[0018] In an optional implementation, the energy storage crowbar is also used to detect the state of charge of the battery.

[0019] The grid-type wind turbine generator set provided in this embodiment manages the battery status by detecting the charge status of the battery, thereby ensuring that the energy storage crowbar can be diverted.

[0020] In an optional implementation, it also includes:

[0021] The main control device of the unit is connected to the wind turbine generator and is used to control the active power output by the wind turbine generator.

[0022] The present embodiment provides a grid-type wind turbine generator set, in which the main control device of the set significantly reduces the active power output by the wind turbine generator to the current source main converter by controlling the active power output by the wind turbine generator, and provides multi-layer protection for the fault current limiting of the current source main converter.

[0023] In a second aspect, the present invention provides a method for riding through a grid voltage fault of a grid-connected wind turbine generator set, which is applied to the method for riding through a grid-connected wind turbine generator set of the first aspect or any corresponding embodiment thereof, and the method comprises:

[0024] Obtain the grid-side output active power of the current source main converter and the active power output of the wind turbine generator. If the grid-side output active power of the current source main converter is less than the active power output of the wind turbine generator, switch the operation states of the energy consumption crowbar and the energy storage crowbar to the on state.

[0025] The active power outputted by the wind turbine is converted into heat of the resistor by using the energy-consuming crowbar;

[0026] The active power output by the wind turbine is converted into battery energy using an energy storage crowbar;

[0027] The active power output of the wind turbine is reduced to the target output power until the grid voltage fault point is removed.

[0028] The present embodiment provides a method for riding through a grid voltage fault of a grid-connected wind turbine generator set. When the grid-side output active power of a current source main converter is less than the active power output of the wind turbine generator, an energy-consuming crowbar and an energy storage crowbar are used to shunt the active power output of the wind turbine generator set. The energy-consuming crowbar fills the function of limiting the flow of active power into the current source main converter for a short time and a long time. In combination with multi-level protection measures such as the energy-consuming crowbar, the flow of active power into the main converter is limited at the source, which can improve the unit's ability to ride through a grid voltage fault without being disconnected from the grid, improve the unit's grid-connected reliability, and reduce the cost per kilowatt-hour of the grid-connected wind turbine generator set during the grid voltage fault riding process.

[0029] In an optional implementation, the active power output by the wind turbine generator is converted into battery energy using an energy storage crowbar, including:

[0030] When the energy consumption crowbar startup time period reaches the preset time period, the energy storage crowbar is started, and the energy storage crowbar is used to convert the active power output by the wind turbine into battery energy, and the operating state of the energy consumption crowbar is converted into a locked state.

[0031] The present embodiment provides a grid voltage fault ride-through method for a grid-connected wind turbine generator set, which uses an energy storage crowbar as a shunting supplementary device for an energy-consuming crowbar, thereby reducing the frequency and time of the energy-consuming crowbar being put into use and improving the reliability of the energy-consuming crowbar; secondly, the energy storage crowbar on the machine side of the current source main converter is used for shunting, which can reduce the unit's electricity cost without increasing the number of redundant power modules on the grid side of the main converter.

[0032] In an optional implementation, it also includes:

[0033] When the wind turbine stops outputting active power, the energy storage crowbar is used to establish the microgrid voltage on the AC side of the generator, and the operating voltage is provided to the current source main converter through the microgrid voltage on the AC side of the generator.

[0034] This embodiment provides a grid voltage fault ride-through method for a grid-connected wind turbine generator set. When the wind turbine stops outputting active power, the energy storage crowbar is used to establish the microgrid voltage on the AC side of the generator, which supplements the internal loss of the current source main converter, ensures that the current source main converter does not go off the grid, and improves the grid connection reliability of the unit.

[0035] In an optional implementation, it also includes:

[0036] If the grid voltage fault point is removed, the active power output by the wind turbine is increased, the current source main converter is controlled to synchronously increase the grid-side output active power, and the operating state of the energy storage crowbar is switched to standby state.

[0037] The present embodiment provides a method for riding through a grid voltage fault of a grid-connected wind turbine generator set. In the event of a grid voltage fault, surplus active power is stored on the machine side, and after the grid voltage returns to normal, the stored active power is released, thereby improving the efficiency of the unit's power generation system and increasing the unit's power generation. At the same time, the capacity of the cooling system is reduced, investment is reduced, and the cost per kilowatt-hour is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0039] Figure 1 is a schematic diagram of a topological structure of a grid-type wind turbine generator set according to an embodiment of the present invention;

[0040] Figure 2 It is a flow chart of a method for riding through a grid voltage fault of a grid-connected wind turbine generator set according to an embodiment of the present invention;

[0041] Figure 3 It is a flow chart of another method for riding through a grid voltage fault of a grid-connected wind turbine generator set according to an embodiment of the present invention. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0043] New energy stations should have the ability of primary frequency regulation, rapid voltage regulation and peak regulation, and configure energy storage at a rate of no less than 10% of installed capacity and for a duration of no less than 2 hours. The energy storage devices in new energy stations are centrally configured, mainly energy-type electrochemical energy storage batteries. Due to the shortage of land in coastal areas, the deployment of large-scale energy storage devices has reduced the project investment rate of return. Some new energy stations have carried out demonstrations of grid-type wind turbines to gradually reduce the demand for energy storage configuration and improve the project investment rate of return.

[0044] As grid connection guidelines and unit reliability requirements become increasingly stringent, it is a trend for large-capacity new energy units to adopt full-power and multi-level converters. The maximum capacity of a single wind power full-power converter based on integrated gate-commutated thyristor (IGCT) has exceeded 10MW. In theory, the hardware cost of the current source main converter of a large-capacity unit is an important part of the unit's cost per kilowatt-hour.

[0045] In the event of a grid voltage fault drop, the new power system further requires that the grid-connecting units remain connected to the grid, and continue to supply power after the fault point is removed and disconnected from the grid. The grid-connecting units remain connected to the grid due to a short-term overcurrent, which requires the voltage source converter, which currently accounts for a dominant proportion of installed capacity, to have a short-term overcurrent capability. The overcurrent time (ms level) far exceeds the design limit time of power semiconductors (e.g. 8 to 10us).

[0046] On the grid side of the grid-connected converter, three times the power semiconductor modules are connected in parallel to deal with short-term overcurrent: considering that when there is a two-phase short-circuit fault in the grid, only one phase remains normal, the three times the power module can still concentrate the active current on the normal one-phase output. One power semiconductor module includes at least one fully controlled device (such as IGBT, IGCT) and one fast reverse recovery diode; among them, IGBT (Insulate-Gate Bipolar Transistor) stands for insulated gate bipolar transistor.

[0047] If the large unit converter adopts a 3-level topology, then the redundant 3-phase 2x modules on the grid side add a total of 12 fully controlled devices and 12 fast reverse recovery diodes. These devices operate almost all under low load in normal working conditions and are only put into operation for a short time (ms). This hardware configuration method increases the unit's cost per kilowatt-hour and reduces the project investment return rate.

[0048] If the grid side of the voltage source converter does not adopt the redundant power module technology route, the number of DC bus chopper energy-consuming units will be increased. The largest energy-consuming unit is the energy-consuming resistor. Too many energy-consuming resistors also increase the weight and volume of the converter, reduce the power density of the converter, and increase the unit's cost per kilowatt-hour.

[0049] If the grid side of the voltage source converter does not adopt the redundant power module technology route, then a DC bus power storage unit is added. The ordinary power storage unit is basically close to a fully charged state under normal operation of the unit, so as to provide active output to the outside world, such as black start and other scene services. The apparent capacitance value of the fully charged energy storage unit is small, and its dynamic response speed may not keep up with the active power fluctuation under grid faults. Increasing the apparent capacitance value requires the energy storage unit to be in a low charge state, which conflicts with the requirement of the reserve active output function. The solution is to deploy more energy storage units.

[0050] In the event of a grid voltage failure, the technical idea of ​​riding through is to first input the unit's active power into the current source main converter, and then divert it through the energy consumption unit or energy storage unit to continuously input active power. This requires the current source main converter to passively improve the response speed of processing active power, and also passively increase the weight and volume of the current source main converter, reducing the power density of the converter and increasing the unit's cost per kilowatt-hour.

[0051] The embodiment of the present invention provides a grid-type wind turbine generator set, such as Figure 1 As shown, it includes: a current source main converter 101, and a wind turbine 102, an energy storage crowbar (crowbar circuit, a power protection circuit) 103, a battery 104, an energy consumption crowbar 105 and a resistor 106 arranged on the machine side of the current source main converter 101; the wind turbine 102 is connected to the current source main converter 101, the energy storage crowbar 103 and the energy consumption crowbar 105 respectively, the energy storage crowbar 103 and the energy consumption crowbar 105 are connected in parallel, the energy storage crowbar 103 is connected to the battery 104, and the energy consumption crowbar 105 is connected to the resistor 106; wherein,

[0052] The energy consumption crowbar 105 is used to convert the active power output by the wind generator 102 into heat of the resistor 106 when the active power output by the grid side of the current source main converter 101 is less than the active power output by the wind generator 102 .

[0053] Specifically, when the grid-side output active power of the current source main converter 101 is less than the active power output of the wind turbine 102, there is a fault in the grid voltage on the grid side of the current source main converter 101. The modes and types of grid voltage faults include amplitude drop, frequency drift, single-phase or multi-phase short circuit, etc.

[0054] Furthermore, the resistor 106 converts the active power output by the wind generator 102 into heat energy, that is, the converter in the energy-consuming crowbar 105 converts the AC power output by the wind generator 102 into DC power, and dissipates the energy in the resistor 106 by generating heat.

[0055] The energy storage crowbar 103 is used to convert the active power output by the wind generator 102 into energy of the battery 104 when the active power output by the grid side of the current source main converter 101 is less than the active power output by the wind generator 102 .

[0056] Specifically, the converter in the energy storage crowbar 103 converts AC power into DC power, and then stores the active power output by the wind turbine 102 as electrochemical energy through the battery 104; wherein the battery 104 can be a lead-acid battery, a lithium battery, a flow battery, a fuel cell, a flywheel, etc.

[0057] Furthermore, the number of bridge arms on the AC side of the converter of the energy storage crowbar 103 can be single-phase, two-phase, three-phase, etc., and the way in which the AC side of the converter of the energy storage crowbar 103 is connected to the machine side of the current source main converter 101 includes using transformer isolation or direct connection.

[0058] The wind turbine 102 is used to reduce the active power output by the generator to the target output power if the energy consumption crowbar 105 and the energy storage crowbar 103 are in the on state, until the grid voltage fault point is removed.

[0059] Specifically, the number of windings of the grid-type wind turbine generator set can be three-phase, six-phase, twelve-phase, etc.

[0060] The present embodiment provides a grid-forming wind turbine generator set, which arranges an energy storage crowbar and an energy consumption crowbar on the side of the current source main converter. In the event of a grid voltage failure, the energy consumption crowbar and the energy storage crowbar are used to shunt the surplus active power on the side of the current source main converter, thereby significantly reducing the active power output by the wind turbine to the current source main converter. At the same time, it is ensured that the current source main converter does not go off-grid in the event of a grid voltage failure and continues to form a grid, thereby improving the grid-forming reliability of the set, being able to reduce the cost per kilowatt-hour of the grid-forming wind turbine generator set, and improving the project investment return rate.

[0061] In some optional embodiments, the method further comprises:

[0062] The AC side transformer 107 is connected to the energy storage crowbar 103 and the wind turbine 102 respectively, and is used to adjust the stack voltage of the battery 104 according to the AC outlet side transformer step-up ratio.

[0063] Specifically, the battery stack voltage can be flexibly adjusted according to the transformer step-up ratio on the AC outlet side, and it can be applicable to various battery forms such as lead-acid, lithium, liquid flow, and fuel, thereby reducing the cost of the energy storage device.

[0064] Furthermore, the DC voltage of the battery stack of the energy storage crowbar 103 is 0.4 kV, 1.0 kV, 2.0 kV, etc.

[0065] The grid-type wind turbine generator set provided in this embodiment can flexibly adjust the battery stack voltage according to the transformer step-up ratio at the AC outlet side, and can adapt to battery stacks of different DC voltage levels, thereby reducing energy storage costs.

[0066] In some optional implementations, the current source main converter 101 includes:

[0067] Inverter 108, DC energy storage inductor 109 and rectifier 110; DC energy storage inductor 109 is connected to inverter 108 and rectifier 110 respectively, inverter 108 is connected to power grid 113 through grid-side capacitor 111 and grid-side reactor 112, and rectifier 110 is connected to wind turbine 102 through machine-side capacitor 114 and machine-side reactor 115.

[0068] Specifically, Figure 1As shown, Ca, Cb, and Cc represent grid-side capacitors 111, Cu, Cv, and Cw represent machine-side capacitors 114, La, Lb, and Lc represent grid-side reactors 112, and Lu, Lv, and Lw represent machine-side reactors 115, wherein the machine-side reactors 115 and the grid-side reactors 112 are connected to the grid side and the machine side of the current source main converter 101 to counteract voltage mutations on both sides.

[0069] Furthermore, the inverter 108 is used to convert direct current into alternating current, the rectifier 110 is used to convert alternating current into direct current, and the direct current energy storage inductor 109 has the function of limiting sudden changes in grid-side current in a very short time.

[0070] Furthermore, circuit breakers are added to the machine side and the grid side of the current source main converter 101, a circuit breaker is added to the AC side of the energy storage crowbar 103, the switching and closing actions of the circuit breakers, and the form of the filters on the machine side and the grid side of the current source main converter 101 are changed, the active and reactive power control of the current source main converter 101 during grid voltage faults, the pulse modulation of power semiconductor switching and shutdown, etc. are changed, the pulse modulation of power semiconductor switching and shutdown of the energy consumption crowbar 105, etc., the current limiting and voltage limiting protection technology of the power semiconductor driver of the current source main converter 101, the topology of the current source main converter 101 such as multi-level, DC energy storage inductor design, etc. are changed, the topology of the energy consumption crowbar 105 converter, the number of resistors, etc. are changed, without affecting the topology and fault ride-through method of the energy storage crowbar 103 configured on the machine side.

[0071] In a grid-type wind turbine generator set provided in this embodiment, the DC energy storage inductor has a fault current limiting function, which provides multi-layer protection for the fault current limiting of the main converter.

[0072] In some optional embodiments, the method further comprises:

[0073] The step-up transformer 116 is connected to the power grid 113 , and is connected to the inverter 108 via the grid-side capacitor 111 and the grid-side reactor 112 .

[0074] Specifically, the step-up transformer 116 is used for electrical isolation and voltage level conversion (stepping up or stepping down).

[0075] In some optional implementations, the energy storage crowbar 103 is also used to detect the state of charge of the battery 104 .

[0076] Specifically, the battery management system in the energy storage crowbar 103 detects the charge state of the battery 104 , and the energy storage crowbar 103 is charged or discharged to a target charge state through the voltage of the microgrid on the AC side of the generator.

[0077] Furthermore, during the normal operation of the grid-type wind turbine generator 102, the state of charge of the battery 104 is not fully charged, so as to prepare for the grid voltage fault ride-through that may occur at any time.

[0078] The grid-type wind turbine generator set provided in this embodiment manages the battery status by detecting the charge status of the battery, thereby ensuring that the energy storage crowbar can be diverted.

[0079] In some optional embodiments, the method further comprises:

[0080] The unit main control device is connected to the wind turbine 102 and is used to control the active power output by the wind turbine 102 .

[0081] Specifically, when there is a grid voltage fault, the unit main control device sends a control instruction to the wind turbine 102 to control the active power output of the wind turbine 102 to be reduced to the target power value, and after the grid voltage fault is removed, controls the wind turbine 102 to increase its output active power.

[0082] The present embodiment provides a grid-type wind turbine generator set, in which the main control device of the set significantly reduces the active power output by the wind turbine generator to the current source main converter by controlling the active power output by the wind turbine generator, and provides multi-layer protection for the fault current limiting of the current source main converter.

[0083] In this embodiment, a method for riding through a grid voltage fault of a grid-connected wind turbine generator set is also provided, which can be used for the above-mentioned grid-connected wind turbine generator set. Figure 2 is a flow chart of a method for riding through a grid voltage fault of a grid-connected wind turbine generator set according to an embodiment of the present invention. Figure 2 As shown, the process includes the following steps:

[0084] Step S201, obtaining the grid-side output active power of the current source main converter and the active power output of the wind generator. If the grid-side output active power of the current source main converter is less than the active power output of the wind generator, the energy consumption crowbar and the energy storage crowbar operating states are switched to the on state.

[0085] Specifically, the grid side of the current source main converter provides reactive power support for the grid voltage fault point, and the ability of the current source main converter to output active power on the grid side decreases, but the machine side of the current source main converter continues to input active power. The grid side output active power of the current source main converter is less than the active power output of the wind turbine. The active power accumulates in the current source main converter. The current source main converter relies on the DC energy storage inductor to suppress the rapid rise of the DC bus current value. The DC bus current value will still rise slightly, but it is within the safe working range. At the same time, the generator output power is reduced. However, due to the large inertia of the wind turbine, it takes a long time for the power to be reduced to the target value. Therefore, the energy-consuming crowbar and the energy storage crowbar are used to realize the diversion of the active power output of the wind turbine.

[0086] Step S202: using an energy-consuming crowbar to convert the active power output by the wind turbine generator into heat of a resistor.

[0087] Specifically, the active power output by the wind turbine generator is converted into heat on the resistor, and the energy-consuming crowbar prevents the wind turbine generator from continuously inputting active power to the current source main converter.

[0088] Step S203: using the energy storage crowbar to convert the active power output by the wind turbine into battery energy.

[0089] Specifically, the active power output by the wind turbine generator is converted into energy in the battery, and the energy storage crowbar prevents the wind turbine generator from continuously inputting active power to the current source main converter.

[0090] Furthermore, the energy consumption crowbar is turned on after a preset time period after the energy consumption crowbar is turned on, and the energy consumption crowbar is turned off at the same time, or the energy consumption crowbar and the energy consumption crowbar are turned on at the same time after a preset time period, and the energy consumption crowbar is turned off; wherein the preset time period may be 1 second.

[0091] Step S204, reducing the active power output by the wind turbine to the target output power until the grid voltage fault point is removed.

[0092] The present embodiment provides a method for riding through a grid voltage fault of a grid-connected wind turbine generator set. When the grid-side output active power of a current source main converter is less than the active power output of the wind turbine generator, an energy-consuming crowbar and an energy storage crowbar are used to shunt the active power output of the wind turbine generator set. The energy-consuming crowbar fills the function of limiting the flow of active power into the current source main converter for a short time and a long time. In combination with multi-level protection measures such as the energy-consuming crowbar, the flow of active power into the main converter is limited at the source, which can improve the unit's ability to ride through a grid voltage fault without being disconnected from the grid, improve the unit's grid-connected reliability, and reduce the cost per kilowatt-hour of the grid-connected wind turbine generator set during the grid voltage fault riding process.

[0093] In this embodiment, a method for riding through a grid voltage fault of a grid-connected wind turbine generator set is provided, which can be used for the above-mentioned grid-connected wind turbine generator set. Figure 3 is a flow chart of a method for riding through a grid voltage fault of a grid-connected wind turbine generator set according to an embodiment of the present invention. Figure 3 As shown, the process includes the following steps:

[0094] Step S301, obtain the grid-side output active power of the current source main converter and the active power output of the wind turbine generator. If the grid-side output active power of the current source main converter is less than the active power output of the wind turbine generator, switch the energy consumption crowbar and energy storage crowbar operation states to the on state. For details, please refer to Figure 2 Step S201 of the illustrated embodiment will not be described in detail here.

[0095] Step S302: Use the energy-consuming crowbar to convert the active power output by the wind turbine generator into heat of the resistor. Figure 2 Step S202 of the illustrated embodiment will not be described in detail here.

[0096] Step S303: using the energy storage crowbar to convert the active power output by the wind turbine into battery energy.

[0097] Specifically, when the energy consumption crowbar activation time period reaches a preset time period, the energy storage crowbar is activated, the energy storage crowbar is used to convert the active power output by the wind turbine into battery energy, and the operating state of the energy consumption crowbar is converted into a locked state.

[0098] Step S304, reducing the active power output by the wind turbine to the target output power until the grid voltage fault point is removed.

[0099] Specifically, the active power output by the wind turbine is reduced to a target output power, and the target output power is lower than the active power that the energy storage crowbar can absorb for a long time. In the process of providing reactive power support for the grid voltage fault point, only a small amount of active power is consumed inside the current source main converter, which is almost negligible. Among them, the target value of the active power output by the wind turbine can also be zero.

[0100] Furthermore, the energy storage crowbar continues to absorb the target active power output by the wind turbine. If the wind turbine has stopped outputting active power, the energy storage crowbar establishes the microgrid voltage on the AC side of the generator, and the internal loss of the current source main converter is supplemented by the microgrid voltage on the AC side of the generator. Specifically, when the wind turbine stops outputting active power (that is, the active power output by the wind turbine is zero), the energy storage crowbar is used to establish the microgrid voltage on the AC side of the generator, and the operating voltage is provided to the current source main converter by the microgrid voltage on the AC side of the generator.

[0101] Step S305: if the grid voltage fault point is removed, the active power output by the wind turbine generator is increased, the current source main converter is controlled to synchronously increase the grid-side output active power, and the operation state of the energy storage crowbar is switched to the standby state.

[0102] Specifically, after waiting for the power system to remove the grid voltage fault point, the new energy station sends a communication command, the unit main control device resumes providing active output, the energy storage crowbar stops exchanging active and reactive power with the generator AC side microgrid, its AC side power semiconductor enters a locked state, and the energy storage crowbar enters a standby state and continues to detect the wind turbine microgrid.

[0103] The present embodiment provides a method for riding through a grid voltage fault of a grid-connected wind turbine generator set. In the event of a grid voltage fault, surplus active power is stored on the machine side, and after the grid voltage returns to normal, the stored active power is released, thereby improving the efficiency of the unit's power generation system and increasing the unit's power generation. At the same time, the capacity of the cooling system is reduced, investment is reduced, and the cost per kilowatt-hour is reduced.

[0104] The following is a specific example to illustrate the specific steps of the method for performing grid voltage fault ride-through using a grid-type wind turbine generator set.

[0105] Embodiment 1:

[0106] When a grid voltage fault is detected on the AC grid side, the specific steps of the grid voltage fault ride-through method include:

[0107] In the first step, the grid side of the current source main converter provides reactive power support for the grid voltage fault point. The ability of the current source main converter to output active power on the grid side decreases, but the machine side of the current source main converter continues to input active power. The grid side output active power of the current source main converter is less than the active power output of the wind turbine. The active power accumulates in the current source main converter. The current source main converter relies on the DC energy storage inductor to suppress the rapid increase of the DC bus current value. The DC bus current value will still increase slightly, but it is within the safe working range. At the same time, the generator output power is reduced. However, due to the large inertia of the wind turbine, it takes a long time for the power to be reduced to the target value. Therefore, the energy-consuming crowbar and the energy storage crowbar are used to realize the diversion of the active power output of the wind turbine.

[0108] The second step is to put the energy-consuming crowbar on the machine side of the current source main converter into use: the active power output by the generator is converted into heat on the resistor, and the energy-consuming crowbar prevents the generator from continuously inputting active power to the current source main converter.

[0109] The third step is to put the energy storage crowbar on the machine side of the current source main converter into use: the active power output from the machine side is converted into energy in the battery, and the energy storage crowbar prevents the generator from continuously inputting active power to the current source main converter.

[0110] In the fourth step, the energy-consuming crowbar on the machine side of the current source main converter is stopped from being used.

[0111] In the fifth step, the active power output by the wind turbine is reduced to the target value, which is lower than the active power that the energy storage crowbar can absorb for a long time. In the process of providing reactive power support for the grid voltage fault point, only a small amount of active power is consumed inside the current source main converter, which is almost negligible. The target value of the active power output by the wind turbine can also be zero.

[0112] In the sixth step, the energy storage crowbar continues to absorb the target active power output by the wind turbine. If the wind turbine has stopped outputting active power, the energy storage crowbar will establish the microgrid voltage on the AC side of the generator, and the internal loss of the current source main converter will be supplemented by the microgrid voltage on the AC side of the generator.

[0113] The seventh step is to wait for the power system to remove the grid voltage fault point. After the fault point is removed, the new energy station sends a communication command and the unit resumes providing active output.

[0114] In the eighth step, the unit's main control device increases the generator output power, and the current source main converter simultaneously increases the grid-side active power output.

[0115] In the ninth step, the battery management system in the energy storage crowbar detects the charge state of the battery unit, and the energy storage crowbar is charged or discharged to the target charge state through the microgrid voltage on the AC side of the generator.

[0116] In the tenth step, the energy storage crowbar stops exchanging active and reactive power with the microgrid on the AC side of the generator, its AC side power semiconductor enters a locked state, and the energy storage crowbar enters a standby state and continues to detect the microgrid on the generator.

[0117] In the above-mentioned embodiment 1, in order to protect the current source main converter from being disconnected from the grid due to an overcurrent fault, it is necessary to limit the active power flowing into the main converter from the machine side. Compared with the method of arranging power-type energy storage on the DC bus side of the main converter and arranging energy-type energy storage on the grid side of the main converter, the energy storage crowbar fills the function of limiting the active power flowing into the main converter for a short time and a long time. It cooperates with the multi-level protection means of the DC energy storage inductor, the energy consumption crowbar, and the main control device of the unit, and is a method of limiting the active power flowing into the main converter at the source, wherein, The DC energy storage inductor has the function of limiting the sudden change of grid-side current in a very short time. The energy consumption crowbar has the function of limiting the active power flowing into the main converter in a short time. The energy storage crowbar has the function of limiting the active power flowing into the main converter for a longer time. The unit main control device has the function of limiting the active power flowing into the main converter for a longer time. By increasing the hardware improvement of the energy storage crowbar and coordinating it with the algorithm improvement of the grid voltage fault ride-through process, the cost of electricity of the grid-type units can be reduced and the project investment return rate can be improved.

[0118] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the embodiments of the present application.

[0119] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0120] In the several embodiments provided in the embodiments of the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0121] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0122] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0123] If the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the embodiment of the present application is essentially or the part that contributes to the prior art or the part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the various embodiments of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (Read-Only Memory, ROM), random access memory (Random Access Memory, RAM), disk or optical disk and other media that can store program codes.

[0124] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A grid-type wind turbine generator set, characterized in that: include: A current source main converter, and a wind turbine generator, an energy storage crowbar, a battery, an energy consumption crowbar and a resistor arranged on the machine side of the current source main converter; the wind turbine generator is connected to the current source main converter, the energy storage crowbar and the energy consumption crowbar respectively, the energy storage crowbar and the energy consumption crowbar are connected in parallel, the energy storage crowbar is connected to the battery, and the energy consumption crowbar is connected to the resistor; wherein, The energy consumption crowbar is used to convert the active power output by the wind turbine generator into heat of the resistor when the active power output by the grid side of the current source main converter is less than the active power output by the wind turbine generator; The energy storage crowbar is used to convert the active power output by the wind turbine into the energy of the battery when the active power output by the grid side of the current source main converter is less than the active power output by the wind turbine; The wind turbine generator is used to reduce the active power output by the generator to the target output power if the energy consumption crowbar and the energy storage crowbar are in the on state until the grid voltage fault point is removed.

2. The grid-type wind turbine generator set according to claim 1, characterized in that: Also includes: The AC side transformer is connected to the energy storage crowbar and the wind turbine generator respectively, and is used to adjust the stack voltage of the battery according to the step-up ratio of the AC outlet side transformer.

3. The grid-type wind turbine generator set according to claim 1, characterized in that: The current source main converter comprises: Inverter, DC energy storage inductor and rectifier; the DC energy storage inductor is connected to the inverter and the rectifier respectively, the inverter is connected to the power grid through the grid-side capacitor and the grid-side reactor, and the rectifier is connected to the wind turbine generator through the machine-side capacitor and the machine-side reactor.

4. The grid-type wind turbine generator set according to claim 3, characterized in that: Also includes: A step-up transformer is connected to the power grid and is connected to the inverter via the grid-side capacitor and the grid-side reactor.

5. The grid-type wind turbine generator set according to claim 1, characterized in that: The energy storage crowbar is also used to detect the state of charge of the battery.

6. The grid-type wind turbine generator set according to claim 1, characterized in that: Also includes: The main control device of the unit is connected to the wind turbine generator and is used to control the active power output by the wind turbine generator.

7. A method for riding through a grid voltage fault of a grid-type wind turbine generator set, characterized in that: Applied to a grid-type wind turbine generator set according to any one of claims 1 to 6, the method comprises: Obtain the grid-side output active power of the current source main converter and the active power output of the wind turbine generator. If the grid-side output active power of the current source main converter is less than the active power output of the wind turbine generator, switch the operation states of the energy consumption crowbar and the energy storage crowbar to the on state; The energy-consuming crowbar is used to convert the active power output by the wind turbine into heat of a resistor; Using the energy storage crowbar to convert the active power output by the wind turbine into battery energy; The active power output by the wind turbine generator is reduced to the target output power until the grid voltage fault point is removed.

8. The method according to claim 7, characterized in that The method of using the energy storage crowbar to convert the active power output by the wind turbine generator into battery energy includes: When the energy consumption crowbar activation time period reaches a preset time period, the energy storage crowbar is activated, the active power output by the wind turbine generator is converted into battery energy by the energy storage crowbar, and the operation state of the energy consumption crowbar is converted into a locked state.

9. The method according to claim 7, characterized in that: Also includes: When the wind turbine stops outputting active power, the energy storage crowbar is used to establish the generator AC side microgrid voltage, and the generator AC side microgrid voltage is used to provide the operating voltage for the current source main converter.

10. The method according to claim 7, characterized in that Also includes: If the grid voltage fault point is removed, the active power output by the wind turbine generator is increased, the current source main converter is controlled to synchronously increase the grid-side output active power, and the operating state of the energy storage crowbar is switched to a standby state.

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