Wind power generation and energy storage integrated system based on open winding motor and control method

Abstract

The invention discloses a wind power generation and energy storage integrated system based on an open winding motor and a control method of the wind power generation and energy storage integrated system. The system comprises an open winding permanent magnet synchronous wind driven generator, a controller, an energy storage device, a machine side converter, a network side converter, a three-phase diode rectifier bridge, a capacitor, a three-phase power grid and a filter. Compared with a traditional direct-drive type permanent magnet synchronous wind power generation system, the wind power generation system has the advantages that the structural characteristic of double-end feed of the open winding motor is utilized, the capacity of the system for absorbing wind energy can be brought into full play, and the problem of low electric energy quality caused by intermittent wind power generation and generated power fluctuation is solved. The invention can effectively reduce the cost of the open winding permanent magnet synchronous wind power generation system, improve the energy utilization rate, reduce the system control complexity and improve the power quality of the power grid.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of power electronics and power transmission, and particularly relates to a wind power generation and energy storage integrated system based on an open-winding motor and a control method. BACKGROUND

[0002] The non-renewable fossil energy consumed in large quantities due to economic development cannot meet the needs of sustainable development. Vigorously developing new energy mainly including wind power generation and photovoltaic power generation has great significance for promoting energy structure transformation and realizing the double-carbon goal.

[0003] In 2022, the wind power generation accounted for about 24.2% of the non-fossil energy power generation in China. With the increasing proportion of wind power generation in the power grid, how to solve the intermittency and volatility of wind power generation and the influence on the power grid is the key to maintaining high power quality of the power grid after large-scale wind power generation is connected to the power grid. SUMMARY

[0004] The application aims at overcoming the defects of the prior art and providing a wind power generation and energy storage integrated system based on an open-winding motor, which comprises an open-winding permanent magnet synchronous wind power generator, a controller, energy storage, a machine-side converter, a grid-side converter, a three-phase diode rectifier bridge, a capacitor, a three-phase power grid and a filter.

[0005] The machine-side converter, the open-winding permanent magnet synchronous wind power generator and the three-phase diode rectifier bridge are sequentially connected; the three-phase diode rectifier bridge is connected with the capacitor; the capacitor is connected with the grid-side converter; the machine-side converter is connected with the energy storage; the controller is connected with the grid-side converter and the machine-side converter respectively; the grid-side converter is connected with the three-phase power grid through the filter.

[0006] The control method applied to the wind power generation and energy storage integrated system based on the open-winding motor comprises the following processes.

[0007] If the output power of the open-winding permanent magnet synchronous wind power generator is less than the grid-connected power input into the three-phase power grid, the energy storage transmits the electric energy output by the open-winding permanent magnet synchronous wind power generator and the electric energy output by the machine-side converter to the capacitor through the three-phase diode rectifier bridge, and the capacitor transmits the absorbed electric energy to the three-phase power grid through the grid-side converter and the filter.

[0008] If the output power of the open-winding permanent magnet synchronous wind power generator is greater than the grid-connected power input into the three-phase power grid, the open-winding permanent magnet synchronous wind power generator transmits the electric energy to the capacitor through the three-phase diode rectifier bridge, the capacitor transmits the absorbed electric energy to the three-phase power grid through the grid-side converter and the filter, and the surplus output power of the open-winding permanent magnet synchronous wind power generator is transmitted to the energy storage through the machine-side converter, so that the absorbed surplus energy is stored.

[0009] The beneficial effects of the present application are: (1) Compared with the traditional back-to-back direct-drive permanent magnet synchronous wind power generation system using energy storage to balance power fluctuation, the number of power electronic converters experienced by the electric energy transmission process between the generator and the energy storage is reduced, and the wind power generation efficiency is improved.

[0010] (2) Compared with the scheme of balancing wind power generation fluctuation by connecting the energy storage through a DC-DC converter and a capacitor or connecting the energy storage through a DC-AC converter and a power grid in the traditional back-to-back direct-drive permanent magnet synchronous wind power generation system, the present application reduces the cost while improving the power quality.

[0011] (3) The control of the motor is changed from two levels to multi-level, and the control accuracy of the motor is improved.

[0012] (4) The utilization rate of motor voltage is high, and the motor power and speed range are improved. Through the open-winding topology system of two-side feeding, the utilization rate of motor voltage is improved under the same voltage level. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 It is a schematic diagram of the wind power energy storage integrated system based on the open-winding motor.

[0014] Figure 2 It is a schematic diagram of the voltage space vector output by the machine-side converter and the three-phase diode rectifier bridge at both ends of the open-winding permanent magnet synchronous generator.

[0015] Figure 3 It is a schematic diagram of the voltage space vector synthesis of the half-controlled open-winding permanent magnet synchronous generator.

[0016] Figure 4 It is a schematic diagram of the movement trajectory of the voltage space vector output by the machine-side converter in sector I.

[0017] Figure 5 It is a schematic diagram of the control strategy of the wind power energy storage integrated system based on the open-winding motor.

[0018] The reference signs are explained as follows: 11 is the energy storage, 12 is the machine-side converter, 13 is the open-winding permanent magnet synchronous generator, 14 is the three-phase diode rectifier bridge, 15 is the capacitor, 16 is the grid-side converter, 17 is the filter, 18 is the three-phase power grid, and 19 is the controller. DETAILED DESCRIPTION

[0019] The technical solutions of the present application will be described in further detail below in combination with the drawings, but the protection scope of the present application is not limited to the following description.

[0020] In order to make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention is further described in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only intended to explain the present invention and are not intended to limit the present invention. That is, the embodiments described herein are only some embodiments of the present invention, not all embodiments. Generally, the components of the embodiments of the present invention described and illustrated in the drawings herein can be arranged and designed in various different configurations.

[0021] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making any creative work shall fall within the scope of protection of the present invention. It should be noted that relational terms such as "first" and "second" are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations.

[0022] Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not preclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0023] The features and performance of the present invention are further described in detail below with reference to the embodiments.

[0024] like Figure 1 As shown, the integrated wind power generation and energy storage system based on the open-winding motor includes an open-winding permanent magnet synchronous wind turbine 13, a controller 19, an energy storage 11, a machine-side converter 12, a grid-side converter 16, a three-phase diode rectifier bridge 14, a capacitor 15, a three-phase grid 18, and a filter 17;

[0025] The machine-side converter 12, the open-winding permanent magnet synchronous wind turbine 13, and the three-phase diode rectifier bridge 14 are connected in sequence; the three-phase diode rectifier bridge 14 is connected to the capacitor 15; the capacitor 15 is connected to the grid-side converter 16; the machine-side converter 12 is connected to the energy storage 11; the controller 19 is respectively connected to the grid-side converter 16 and the machine-side converter 12; the grid-side converter 16 is connected to the three-phase power grid 18 via the filter 17.

[0026] The application relates to a control method for a new energy power generation and transmission electric system based on an open-winding motor, which comprises the following processes:

[0027] If the output power of the open-winding permanent magnet synchronous wind power generator 13 is less than the grid-connected power of the input three-phase power grid 18, the energy storage 11 outputs the power to make up the insufficient part through the machine-side converter 12, the output electric energy of the energy storage 11 and the output electric energy of the open-winding permanent magnet synchronous wind power generator 13 are transmitted to the capacitor 15 through the three-phase diode rectifier bridge 14, and the capacitor absorbs the electric energy and transmits the electric energy to the three-phase power grid 18 through the grid-side converter 16 and the filter 17.

[0028] If the output power of the open-winding permanent magnet synchronous wind power generator 13 is greater than the grid-connected power of the input three-phase power grid 18, the open-winding permanent magnet synchronous wind power generator 13 transmits the electric energy to the capacitor 15 through the three-phase diode rectifier bridge 14, the capacitor 15 absorbs the electric energy and transmits the electric energy to the three-phase power grid 18 through the grid-side converter 16 and the filter 17, and the surplus output power of the open-winding permanent magnet synchronous wind power generator 13 is transmitted to the energy storage 11 through the machine-side converter 12, so that the surplus energy is stored.

[0029] Specifically, the whole system can be divided into two small systems, as shown in the figure, one is a half-controlled open-winding permanent magnet synchronous generator system, and the other is a grid-connected system. Figure 1 In the half-controlled open-winding permanent magnet synchronous generator system, the open-winding permanent magnet synchronous wind power generator 13 is connected with the machine-side converter 12 and the three-phase diode rectifier bridge 14 at both ends. The core of the control is to determine the open and break state of each bridge arm of the three-phase diode rectifier bridge 14 by determining the flow direction of the three-phase current, and to calculate the voltage vector u αβ2 of the three-phase diode rectifier bridge 14 outputted according to the state, wherein the direction of the current flowing into the three-phase diode rectifier bridge 14 is positive, and the calculation result of the output voltage vector is shown in Table 1, wherein U dc2 is the capacitor voltage amplitude.

[0030] Table 1

[0031]

[0032] The calculated voltage vector and the voltage vector u αβ of the open-winding permanent magnet synchronous wind power generator 13 are synthesized to obtain the voltage vector u αβ1Then the pulse signal of the machine side converter 12 can be outputted by the SVPWM. The reference voltage vector of the open-winding permanent magnet synchronous wind generator 13 is obtained by controlling the d-q axis current of the motor. The d-axis of the motor corresponds to the reactive power, and in order to improve the power factor of the motor output, the corresponding d-axis reference value is set to 0. The q-axis of the motor corresponds to the active power, and when the d-axis current is 0, the electromagnetic torque of the motor is linearly related to the q-axis current, and the torque determines the speed of the motor, so the q-axis current reference value is generated by the difference between the reference speed and the actual speed of the motor through the PI controller, so as to achieve the purpose of controlling the speed of the motor.

[0033] Figure 2 The voltage space vector diagram outputted by the machine side converter 12 and the three-phase diode rectifier bridge 14 at both ends of the open-winding permanent magnet synchronous wind generator 13 is shown, wherein the voltage vector u αβ2 is divided into six regions by the six three-phase current combinations given in Table 1. When the A-phase and B-phase currents are negative and the C-phase current is positive, u αβ2 corresponds to OE, and the corresponding u αβ2 corresponds to OB. In the case of given parameters and stable operation of the system, the speed of the open-winding permanent magnet synchronous wind generator 13 is constant, and the amplitude of the voltage vector u αβ does not change. Therefore, the synthesis of u αβ2 can be controlled by adjusting the amplitude of u αβ1 . As shown in Figure 3 , in the same region, the direction and amplitude of the voltage vector u αβ2 change with the amplitude of u αβ1 . When u αβ · u αβ1 > 0, the power absorbed by the three-phase power grid 18 is less than the power output by the open-winding permanent magnet synchronous wind generator 13, and the energy storage 11 absorbs the excess power to charge. When u αβ · u αβ1 < 0, the power absorbed by the three-phase power grid 18 is greater than the power output by the open-winding permanent magnet synchronous wind generator 13, and the energy storage 11 discharges to make up the part of the power shortage of the grid-connected power. The direction of the voltage vector u αβ2 is determined by the three-phase current, and the amplitude is determined by the voltage U dc2 of the capacitor 15, so controlling the size of the voltage U dc2 of the capacitor 15 can control the charging and discharging of the energy storage, and further control the energy flow of the entire system to achieve power balance.

[0034] The grid-connected system adopts a control strategy of power outer loop and voltage inner loop to realize stable output of power. A reference power of the input three-phase power grid 18 is set, and a reference capacitor 15 voltage is obtained by subtracting the actual power from the reference power and passing through a PI controller. The d-axis voltage is oriented to the voltage vector of the three-phase power grid 18, so that the d-axis corresponds to active power and the q-axis corresponds to reactive power. Since the current at the input DC side of the three-phase diode rectifier bridge 14 in the half-controlled open-winding permanent magnet synchronous generator system is almost constant under given system parameters, the power of the input three-phase power grid 18 is positively correlated with the capacitor 15 voltage. Therefore, the reference capacitor 15 voltage obtained by passing through the PI controller is subtracted from the actual capacitor 15 voltage to obtain the reference current of the d-axis, and the corresponding reference current of the q-axis is set to 0.

[0035] The above description is only preferred embodiments of the present application, and it should be understood that the present application is not limited to the forms disclosed herein, and should not be considered as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concepts described herein by the above teachings or related art or knowledge. Any modification and change made by those skilled in the art without departing from the spirit and scope of the present application shall be within the protection scope of the claims of the present application.

Claims

1. A wind power generation and energy storage integrated system based on an open-winding motor, characterized in that: The invention comprises an open-winding permanent magnet synchronous wind turbine generator (13), a controller (19), an energy storage (11), a machine-side converter (12), a grid-side converter (16), a three-phase diode rectifier bridge (14), a capacitor (15), a three-phase grid (18), and a filter (17). The machine-side converter (12), the open-winding permanent magnet synchronous wind turbine (13), and the three-phase diode rectifier bridge (14) are connected in sequence; the three-phase diode rectifier bridge (14) is connected to the capacitor (15); the capacitor (15) is connected to the grid-side converter (16); the machine-side converter (12) is connected to the energy storage (11); the controller (19) is respectively connected to the grid-side converter (16) and the machine-side converter (12); and the grid-side converter (16) is connected to the three-phase power grid (18) via a filter (17).

2. The control method for the wind power generation and energy storage integrated system based on the open-winding motor according to claim 1 is characterized in that: By utilizing the structural characteristics of double-end feeding of open-winding motors, the supporting capacity of energy storage open-winding motors can be fully utilized: One side of the open-winding permanent magnet synchronous wind turbine generator (13) is connected to the energy storage (11) via the machine-side converter (12), and the other side is connected to the capacitor (15) via the three-phase diode rectifier bridge (14). The voltage vector u output by the three-phase diode rectifier bridge (14) is αβ2 It can be determined by the direction of the three-phase current. Unlike the fully controlled converter that can output eight different states of spatial voltage vectors, the three-phase diode rectifier bridge (14) outputs only six voltage vectors, as shown in Table I. The six different direction combinations of the three-phase current divide the entire space into six sectors. Each current direction combination corresponds to a sector, which determines the output spatial voltage vector u αβ2 direction, and u αβ2 The amplitude of the capacitor (15) voltage U dc2 Determine, the synthesis relationship of voltage vector is u αβ =u αβ1 -u αβ2 , then it is necessary to control the voltage vector u output by the machine-side converter (12) αβ1 OK, when u αβ ·u αβ1 >0, at this time, the power absorbed by the three-phase grid (18) is less than the power output by the open-winding permanent magnet synchronous wind turbine (13), and the energy storage (11) absorbs the surplus power for charging; and when u αβ ·u αβ1 <0, the power absorbed by the three-phase grid (18) is greater than the power output by the open-winding permanent magnet synchronous wind turbine generator (13), and the energy storage (11) releases energy to maintain the power input to the three-phase grid (18) constant, wherein the voltage vector u of the open-winding permanent magnet synchronous wind turbine generator (13) αβ The amplitude is basically determined by the speed of the generator. Furthermore, the charging and discharging of the energy storage (11) is determined by the speed of the generator and the size of the voltage of the capacitor (15), that is, the voltage U of the capacitor (15) is controlled. dc2 The size of the generator and the speed of the generator can control the charging and discharging of the energy storage (11), and then control the energy flow of the entire system to achieve power balance. When the open-winding permanent magnet synchronous wind turbine generator (13) operates stably, the voltage vector u αβ When the grid power is changed according to the demand, the voltage U of capacitor (15) is constant. dc2 The amplitude of the voltage vector u output by the three-phase diode rectifier bridge is also changing. αβ2 It is also changing; When the open-winding permanent magnet synchronous wind turbine (13) changes due to wind speed fluctuations and speed fluctuations, the voltage vector u αβ When the fluctuation changes, it is only necessary to change the PWM wave of the switch state of the control side converter (12) so that the output voltage vector u αβ1 The need for system balance is met, and the demand for stable operation and grid-connected power of the open-winding permanent magnet synchronous wind turbine (13) can be met within the modulation range of the machine-side converter (12), thereby realizing flexible energy transmission of the entire system.

3. The control method for the wind power generation and energy storage integrated system based on the open-winding motor according to claim 1 is characterized in that: The control strategy of the power outer loop and the voltage inner loop is used to stabilize the grid-connected power and the capacitance amplitude, solving the problems of intermittent wind power generation and power fluctuation. The grid-connected power can be adjusted at any time to meet the needs of the system. The process includes the following: During stable operation, the three-phase sinusoidal current of AC is converted into DC through the three-phase diode rectifier bridge. The average DC current output by the three-phase diode rectifier bridge is I r =0.955I m , where I m is the three-phase current peak value. Since the d-axis current is controlled to 0, the q-axis current I q The amplitude is equal to the peak value of the three-phase current, so I r =0.955I q , then the output power P of the three-phase diode rectifier bridge is r =0.955U dc2 I q , when the capacitor voltage is stable, the grid power P grid =P r , it can be seen that the grid power is positively correlated with the amplitude of the capacitor voltage. By increasing U dc2 The purpose of power improvement can be achieved by increasing the amplitude of the grid-connected capacitor, thereby establishing a power outer loop. The above results are based on the fact that the system is running stably and the voltage amplitude of the grid-connected capacitor is approximately constant. Therefore, the regulation of the voltage amplitude of the grid-connected capacitor is a very important part of the control strategy. The power P flowing through the grid-connected capacitor is c =P r -P grid , and the grid-connected power can be obtained by P grid =3(U gd I gd +U gq I gq ) / 2 is calculated, where U gd and U gq Represents the dq axis voltage of the power grid, I gd and I gq Represents the dq axis current of the power grid. If the d axis is oriented to the power grid voltage vector, then the d axis corresponds to active power and the q axis corresponds to reactive power. To control reactive power to 0, set I gq =0, since the voltage of the grid is basically constant, P grid The size of I gd The amplitude is positively correlated, that is, U dc2 The amplitude and I gd The amplitude is also positively correlated, so a voltage loop can be added to the traditional current loop. Combined with the above-mentioned power outer loop control, the fluctuation of wind power generation can be balanced, and the grid-connected capacitor voltage in the system can be balanced and the grid power input can be stable. If the output power of the open-winding permanent magnet synchronous wind turbine generator (13) is less than the grid-connected power input to the three-phase grid (18), the energy storage (11) outputs power to make up for the shortfall through the machine-side converter (12), and the output electric energy and the output electric energy of the open-winding permanent magnet synchronous wind turbine generator (13) are transmitted to the capacitor (15) through the three-phase diode rectifier bridge (14), and the capacitor (15) transmits the absorbed electric energy to the three-phase grid (18) through the grid-side converter (16) and the filter (17); If the output power of the open-winding permanent magnet synchronous wind turbine generator (13) is greater than the grid-connected power input to the three-phase grid (18), the open-winding permanent magnet synchronous wind turbine generator (13) transmits electric energy to the capacitor (15) through the three-phase diode rectifier bridge (14), and the capacitor (15) transmits the absorbed electric energy to the three-phase grid (18) through the grid-side converter (16) and the filter (17). The surplus output power of the open-winding permanent magnet synchronous wind turbine generator (13) is transmitted to the energy storage through the machine-side converter (12), and the absorbed surplus energy is stored. If the size of the grid-connected power changes to meet the needs of the system, it is only necessary to adjust the reference value of the grid-connected power input to the three-phase grid (18), without controlling the open-winding permanent magnet synchronous wind turbine (13) to change the generated power. The control strategy of the power outer loop and the voltage inner loop controls the grid-side converter (16) so that the power delivered by the three-phase diode rectifier bridge (14) to the capacitor (15) is unbalanced with the grid-connected power, thereby realizing the charging and discharging of the capacitor (15). The voltage amplitude of the capacitor (15) changes accordingly according to the needs of the grid-connected power, so that the actual grid-connected power quickly tracks the reference value, and the unbalanced power is borne by the energy storage (11).

4. The control method for the wind power generation and energy storage integrated system based on the open-winding motor according to claim 1 is characterized in that: Selecting an appropriate energy storage DC bus voltage amplitude can reduce device costs while meeting the needs of stable system operation: In order to enable the machine-side converter (12) to output an ideal voltage vector and to reduce the cost increase of the machine-side converter (12) due to the need to be able to withstand a higher voltage, the amplitude U of the DC bus voltage of the energy storage (11) is set. dc1 There are also certain requirements. In a system operating at unity power factor, when u αβ In the process of rotation from θ = -30° to θ = 30° in space, -u αβ2 Will always be fixed in the OA position, accordingly, can be Calculate u αβ1 The amplitude of u is as follows: when θ approaches ±30° infinitely αβ1 Has maximum amplitude u αβ1max , there are similar calculation formulas in other sectors, but the maximum amplitudes obtained are equal, where u αβ The amplitude can be determined according to the rotation speed of the open-winding permanent magnet synchronous wind turbine (13), u αβ2 The amplitude can be determined according to the voltage requirement of capacitor (15). For the full-control converter on the machine side, the maximum voltage vector that can be modulated and output is Therefore, the minimum DC bus voltage of the energy storage (11) that can meet the modulation requirements

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