A grid-constructing wind and storage integrated power generation system and a collaborative operation method thereof

Abstract

The application discloses a grid-constructing type wind and storage integrated power generation system and a coordinated operation method thereof, and belongs to the technical field of wind power generation and energy storage. The system comprises a wind wheel, a front-end speed-regulating type differential transmission system, a synchronous generator, a machine-side rectifier, a direct-current bus, a battery energy storage system and a grid-constructing type grid-side inverter. The battery energy storage system is connected to the direct-current bus through a bidirectional direct-current converter, and an electrically tightly coupled structure is formed. The speed-regulating motor in the front-end speed-regulating type differential transmission system and the battery energy storage system are coordinately controlled through a coordination controller, mechanical power regulation and rapid electric power throughput are combined, the grid-constructing type grid-side inverter simulates the operation characteristics of the synchronous generator, the grid-constructing type grid-side inverter can independently establish and stabilize the alternating voltage and frequency, and thus active inertia response, primary frequency modulation and reactive voltage support are provided for the power grid, and the problem of insufficient active support capability of the traditional wind turbine on the power grid is effectively solved.

Description

Technical Field

[0001] This invention relates to the field of wind power generation and energy storage technology, specifically to a grid-type integrated wind and energy storage power generation system and its coordinated operation method. Background Technology

[0002] With the continuous increase in the proportion of wind power connected to the grid, the problems of inertia reduction and frequency stability faced by modern power systems are becoming increasingly prominent. Currently, mainstream doubly-fed and direct-drive wind turbines all require full-power or partial-power power electronic converters for grid connection. While this grid connection method enables variable-speed operation of the wind turbine, it also completely blocks the natural frequency support path of the wind turbine rotor's huge rotational inertia to the power grid, resulting in a significant reduction in the system's equivalent inertia. Furthermore, these grid-connected converters based on current-source control cannot autonomously establish grid voltage, and their support capability during grid disturbances is limited, meaning they lack the ability to "build a grid."

[0003] To improve the grid connection performance of wind farms, integrating energy storage systems with wind farms has become an important technological approach. Existing technologies offer various wind-storage integration schemes, such as configuring energy storage modules on the DC side of the wind turbine or at the AC grid connection point of the wind farm. However, in schemes placing energy storage at the AC grid connection point (such as those disclosed in patent CN219801909U), the wind turbine and energy storage are electrically independent, resulting in a lag in coordinated response. This makes it difficult to act as a unified voltage source with strong grid-connection capabilities to provide rapid and effective active support to the grid. Some schemes that coordinate on the DC side focus primarily on allocating wind and energy storage output according to the magnitude of disturbances to maintain DC voltage or extend energy storage lifespan, without fundamentally addressing the inherent lack of grid-connection capability of the wind turbine itself. Specifically, existing grid-connection wind-storage integration technologies still rely on grid-connected wind turbines with full-power converters at the bottom layer. Their grid-connection capability is entirely generated by additional converter algorithms and energy storage simulation, rather than stemming from the inherent characteristics of the power generation unit itself.

[0004] Therefore, there is an urgent need for a comprehensive innovative solution that integrates the architecture of the power generation unit and the coordinated control of the system, so that the wind-storage combined system can not only simulate the traditional synchronous generator in terms of function, but also approach the traditional synchronous generator in terms of physical nature, providing a stable and reliable voltage source support. Summary of the Invention

[0005] This invention aims to overcome the shortcomings of the prior art and provide a grid-connected wind-storage integrated power generation system and its coordinated operation method. This invention achieves deep electrical coupling between a "front-end speed-regulating" wind turbine unit with inherent grid-friendly characteristics and battery energy storage on the DC side, combined with grid-connected control, to construct an integrated power generation system that inherently possesses synchronous machine characteristics. This system fundamentally solves the core problems of traditional wind power grid-connected systems, such as weak grid-connection capability and insufficient grid inertia and voltage support due to power electronic interfaces.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A grid-connected wind and energy storage integrated power generation system includes:

[0008] Windmill;

[0009] A front-end speed-regulating differential transmission system, whose input end is connected to the wind turbine, is used to convert the variable speed mechanical energy input to the wind turbine into constant speed mechanical energy output. The front-end speed-regulating differential transmission system includes a differential planetary gear train and a speed-regulating motor.

[0010] A synchronous generator, the input of which is connected to the constant speed output of the front-end speed-regulating differential transmission system;

[0011] A machine-side rectifier, the AC side of which is connected to the output terminal of the synchronous generator;

[0012] A DC bus connects to the DC side of the machine-side rectifier.

[0013] The battery energy storage system is connected to the DC bus via a bidirectional DC-DC converter;

[0014] A grid-side inverter with its DC side connected to the DC bus and its AC side used to connect to the power grid.

[0015] In some embodiments, a speed-increasing gearbox is also included, with its input end connected to the wind turbine and its output end connected to the planet carrier of the differential planetary gear train.

[0016] In some embodiments, the differential planetary gear train includes a sun gear, a planet carrier, and an external ring gear; the planet carrier serves as the main input terminal connected to the speed-increasing gearbox, the external ring gear serves as the speed-regulating input terminal connected to the speed-regulating motor, and the sun gear serves as the constant-speed output terminal connected to the input shaft of the synchronous generator.

[0017] In some embodiments, a coordination controller is also included, which is configured to generate and issue a first control command for the speed-regulating motor and a second control command for the bidirectional DC-DC converter based on grid status information, so as to coordinate the operation of the speed-regulating motor and the battery energy storage system.

[0018] In some implementations, the cooperative controller includes a grid support ring and a power distribution ring; the grid support ring is used to generate a total power support command based on grid frequency deviation and voltage deviation; the power distribution ring is used to dynamically distribute power regulation requirements to the first control command and the second control command based on the total power support command, the real-time power of the wind turbine, and the DC bus voltage.

[0019] In some implementations, the power distribution loop integrates an extended state observer for real-time estimation of system lumped disturbances; the first control command and the second control command include a feedforward compensation amount based on the lumped disturbance estimate.

[0020] In some implementations, the grid-side inverter employs a virtual synchronous machine control strategy, whose control algorithm simulates the rotor motion equation of a synchronous generator, and the algorithm parameters include a virtual inertia coefficient and a virtual damping coefficient.

[0021] In some implementations, when the grid-side inverter of the grid-type system is locked due to a grid fault, the battery energy storage system takes over the closed-loop voltage control of the DC bus through the bidirectional DC converter.

[0022] A collaborative operation method based on a grid-connected wind-storage integrated power generation system as described in any of the above methods includes the following steps:

[0023] The synchronous generator is maintained at a constant speed at its rated speed by the aforementioned front-end speed-regulating differential transmission system;

[0024] The AC power output from the synchronous generator is converted into DC power by the generator-side rectifier and then transmitted to the DC bus.

[0025] The battery energy storage system uses the bidirectional DC-DC converter to perform power throughput on the DC bus in order to maintain the stability of the bus voltage.

[0026] The grid-side inverter converts the electrical energy on the DC bus into AC power and connects it to the grid in a voltage source mode that autonomously establishes its voltage and frequency.

[0027] In some implementations, the power throughput command is dynamically generated based on the magnitude of grid disturbances: when the grid frequency deviation is less than a first threshold, it is mainly regulated by the speed-regulating motor; when the grid frequency deviation is greater than a second threshold, it is jointly responded by the speed-regulating motor and the battery energy storage system; wherein, the second threshold is greater than the first threshold.

[0028] Compared with the prior art, the grid-type integrated wind and energy storage power generation system and its coordinated operation method of the present invention have at least the following beneficial effects:

[0029] Network construction at the source: By combining a "front-end speed-regulating differential drive system + synchronous generator", the system achieves the unification of variable-speed operation of the wind turbine and constant-frequency output of the generator from the source of energy conversion. The synchronous generator itself has excitation regulation capability, which can provide reactive power support and short-circuit current. This provides an inherent physical network foundation for the system, which is fundamentally different from the technical path of relying entirely on converter algorithm simulation for network construction.

[0030] Deep Coupling and Rapid Response: The energy storage system is directly integrated into the DC bus of the synchronous generator outlet, forming a tight electrical coupling between wind and energy storage. The power exchange path is extremely short, avoiding the multi-stage conversion delay and coordination lag problems existing in traditional AC-side parallel energy storage solutions, enabling the energy storage's rapid power throughput capability to seamlessly connect with the power generation unit.

[0031] Generalized Inertia through Mechanical and Electrical Coordination: This invention creatively integrates the mechanical power regulation capability of a speed-regulating motor with the rapid power throughput capability of a battery through a coordinated controller. The speed-regulating motor can respond to slow, high-capacity power changes, simulating the "large inertia" of a synchronous machine rotor; the battery responds to fast, instantaneous power fluctuations, providing "damping" and "fast frequency support." The two work together, merging on the DC bus into a "generalized inertia" power source with both large inertia and fast response, which is then presented to the grid through a grid-connected inverter. Its support effect is superior to simple virtual inertia algorithms or independent frequency regulation by energy storage.

[0032] High reliability and fault ride-through capability: In the event of a severe grid fault, the grid-connected inverter can enter current-limiting mode or be temporarily locked out. At this time, the DC-side energy storage system can immediately take over the DC bus voltage control, quickly absorb the power continuously generated by the wind turbine, prevent DC voltage collapse, provide robust "fault ride-through" backup protection for the system, and improve overall reliability.

[0033] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the electrical topology of a grid-type integrated wind and energy storage power generation system provided in an embodiment of the present invention;

[0035] Figure 2 A flowchart illustrating the collaborative operation method of a grid-type integrated wind and energy storage power generation system provided in an embodiment of the present invention.

[0036] Explanation of reference numerals in the attached figures:

[0037] 1. Wind turbine; 2. Speed-increasing gearbox; 3. Sun gear; 4. Planetary carrier; 5. External gear ring; 6. Synchronous generator; 7. Machine-side rectifier; 8. DC bus; 9. Battery energy storage system; 10. Bidirectional DC converter; 11. Grid-side inverter. Detailed Implementation

[0038] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the specific embodiments, structures, features, and effects according to the present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments. In the following description, different "an embodiment" or "an embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0039] In the description of this invention, it should be clearly stated that the terms "first," "second," etc., in the specification, claims, and accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence; the terms "vertical," "lateral," "longitudinal," "front," "rear," "left," "right," "up," "down," "horizontal," etc., indicate orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, and are merely for the convenience of describing this invention, and do not mean that the device or element referred to must have a specific orientation or position, and therefore should not be construed as a limitation of this invention.

[0040] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0041] like Figure 1-2 As shown, an embodiment of the present invention provides a grid-type integrated wind and energy storage power generation system, comprising:

[0042] Windmill 1;

[0043] A front-end speed-regulating differential transmission system, whose input end is connected to the wind turbine 1, is used to convert the variable speed mechanical energy input to the wind turbine 1 into constant speed mechanical energy output. The front-end speed-regulating differential transmission system includes a differential planetary gear train and a speed-regulating motor.

[0044] Synchronous generator 6, whose input end is connected to the constant speed output end of the front-end speed-regulating differential transmission system;

[0045] The machine-side rectifier 7 is connected to the output terminal of the synchronous generator 6 on its AC side;

[0046] DC bus 8 is connected to the DC side of the machine-side rectifier 7;

[0047] The battery energy storage system 9 is connected to the DC bus 8 via a bidirectional DC-DC converter 10;

[0048] The grid-side inverter 11 is a grid-type inverter whose DC side is connected to the DC bus 8 and whose AC side is used to connect to the power grid.

[0049] In this embodiment, the core of the system lies in its unique configuration. The wind turbine 1 converts captured wind energy into mechanical energy input. A front-end speed-regulating differential transmission system receives this speed input; its integrated differential planetary gear train and speed-regulating motor work together to dynamically adjust the transmission ratio, ultimately outputting a constant mechanical speed. This constant-speed output directly drives the rotor of the synchronous generator 6, enabling it to stably generate AC power at the industrial frequency. This AC power is converted to DC power by the generator-side rectifier 7 and collected onto a common DC bus 8. A battery energy storage system 9 is connected in parallel to this DC bus 8 via a bidirectional DC-DC converter 10, thereby achieving flexible storage and release of electrical energy. Finally, all the electrical energy collected on the DC bus 8 is converted into AC power that meets grid connection requirements by a grid-connected inverter 11 and fed into the power grid. The specific connection relationships of this series of components constitute a deeply electrically coupled integrated power generation unit. Its advantage lies in the fact that it directly integrates the synchronous generator 6, which has inherent grid-friendliness, with the fast-response battery energy storage system 9 on the DC side from the source, thus building a physical hardware foundation for the system. This allows it to achieve grid connection without relying on a complex full-power converter, while retaining the potential to provide inertial support and short-circuit current.

[0050] The coordinating controller is configured to generate and issue a first control command for the speed-regulating motor 5 and a second control command for the bidirectional DC-DC converter 10 based on the grid status information, so as to coordinate the actions of the two, so that the system as a whole presents voltage source characteristics and provides inertia, primary frequency regulation and reactive voltage support to the grid.

[0051] In some embodiments, a speed-increasing gearbox 2 is also included, the input end of which is connected to the wind turbine 1, and the output end is connected to the planet carrier 4 of the differential planetary gear system.

[0052] In this embodiment, to further optimize the initial stage of energy transfer, a speed-increasing gearbox 2 is added between the wind turbine 1 and the aforementioned differential transmission system. The input end of the speed-increasing gearbox 2 is connected to the wind turbine 1, and its output end is connected to the motion input component of the differential planetary gear system. The operation of this design is as follows: the lower speed generated by the wind turbine 1 at lower wind speeds is initially boosted by the speed-increasing gearbox 2 to reach the efficient operating speed range required by the differential planetary gear system. The beneficial effect is that it allows the wind turbine 1 to be designed with better aerodynamic performance and greater torque, without directly meeting the high-speed requirements of the downstream generator 6, thereby improving the efficiency of the entire wind energy capture process and enabling subsequent differential speed control to be performed within a more reasonable and precise speed range.

[0053] In some embodiments, the differential planetary gear train includes a sun gear 3, a planet carrier 4, and an external ring gear 5; the planet carrier 4 serves as the main input terminal connected to the speed-increasing gearbox 2, the external ring gear 5 serves as the speed-regulating input terminal connected to the speed-regulating motor, and the sun gear 3 serves as the constant-speed output terminal connected to the input shaft of the synchronous generator 6.

[0054] In this embodiment, the differential planetary gear system includes a sun gear 3, a planet carrier 4, and an external gear ring 5. The planet carrier 4 serves as the main input end, fixedly connected to the output shaft of the speed-increasing gearbox 2, receiving the main mechanical power flow from the wind turbine 1. The external gear ring 5 serves as the speed-regulating input end, connected to the output shaft of the speed-regulating motor. The sun gear 3 serves as the final constant-speed output end, directly driving the rotor shaft of the synchronous generator 6. In operation, when wind speed changes cause changes in the rotational speed of the wind turbine 1 and the planet carrier 4, the torque and rotation direction of the speed-regulating motor connected to the external gear ring 5 can be precisely controlled to offset the impact of speed changes on the sun gear 3 in real time. Regardless of fluctuations in the input speed of the planet carrier 4, the output speed of the sun gear 3 can be strictly maintained at the rated value required by the synchronous generator 6 through the compensation control of the speed-regulating motor. The benefits of this design are remarkable. It creatively transfers the decoupling function of "speed change" and "constant frequency" from the back-end power electronic equipment to the front-end mechanical transmission link, enabling the synchronous generator 6 to operate at a truly constant power frequency speed and directly output high-quality electrical energy. This fundamentally avoids the harmonic problems introduced by the power electronic converter and significantly reduces the electrical complexity and cost of the system.

[0055] In some embodiments, a coordination controller is also included, which is configured to generate and issue a first control command for the speed-regulating motor and a second control command for the bidirectional DC-DC converter 10 based on grid status information, so as to coordinate the operation of the speed-regulating motor and the battery energy storage system 9.

[0056] In this embodiment, to enable intelligent coordination between the aforementioned mechanical and electrical components, a coordination controller is also configured in the system. This coordination controller continuously collects real-time status information from the power grid and generates two independent control commands based on this: one is sent to the speed-regulating motor in the front-end speed-regulating differential drive system, and the other is sent to the bidirectional DC-DC converter 10 connected to the battery energy storage system 9. Its operation is characterized by global coordination; the coordination controller acts as the system's brain, simultaneously directing the speed-regulating motor on the mechanical side and the energy storage system on the electrical side to coordinate their actions according to the needs of the power grid. The beneficial effect of this design is that it breaks the traditional independent control mode of wind turbines and energy storage in wind-storage systems, achieving unified scheduling across physical domains and laying a control foundation for the system as a whole to present stable and controllable power characteristics.

[0057] In some embodiments, the cooperative controller includes a grid support ring and a power distribution ring; the grid support ring is used to generate a total power support command based on grid frequency deviation and voltage deviation; the power distribution ring is used to dynamically distribute power regulation requirements to the first control command and the second control command based on the total power support command, the real-time power of wind turbine 1 and the voltage of DC bus 8.

[0058] In this embodiment, the internal logic of the collaborative controller can employ a hierarchical strategy to achieve more refined management. Internally, it can be divided into a grid support loop and a power distribution loop. The grid support loop is primarily responsible for sensing the deviation of the grid frequency and voltage from their rated values, and calculating the total power adjustment command required to support grid stability. The power distribution loop receives this total command and, considering factors such as the actual mechanical power captured by the wind turbine 1 and the voltage level of the DC bus 8, dynamically decomposes the total power demand into two parts: one part is converted into a precise torque command for the speed-regulating motor, and the other part is converted into a charging and discharging power command for the battery energy storage system 9. Its operation is a dynamically optimized decision-making process. For example, when the grid requires a small amount of power support, the distribution loop may prioritize calling the speed-regulating motor for slow mechanical power adjustment; when the demand is urgent, it may instruct the battery energy storage system 9 to discharge rapidly. The beneficial effect of this hierarchical structure is that it decouples control objectives, decomposes complex global support tasks into specific executable instructions, and enables the system to respond to the macro-level needs of the power grid while taking into account the operating status and constraints of its internal units, thus achieving safe, economical, and efficient multi-objective collaborative operation.

[0059] The power distribution loop integrates an extended state observer for real-time estimation of system lumped disturbances (including wind speed change disturbances, inaccurate system model parameter disturbances, and grid background harmonic disturbances); the first control command and the second control command include feedforward compensation based on the lumped disturbance estimate.

[0060] The extended state observer is designed based on an augmented system model that includes the dynamics of differential planetary gear train speed regulation, DC bus capacitor dynamics, and grid-side circuit dynamics, and is implemented in the following manner:

[0061] Establish a speed control based on the motor speed ω m The state-space equations are defined by the DC bus voltage U8c and the synchronous generator output current i7 as state variables.

[0062] Wind speed fluctuations, model parameter mismatch, and power grid background harmonics are uniformly modeled as a lumped disturbance d(t) acting on the state space equation.

[0063] Design the observer gain matrix L such that the estimated value ẑ(t) of the lumped disturbance d(t) converges within a preset time T, and the feedforward compensation is directly -K·ẑ(t), where K is the feedforward compensation coefficient matrix.

[0064] The cooperative controller is also configured to perform fault-crossing control, specifically including:

[0065] Real-time monitoring of the grid-connected contactor status and output current of the grid-side inverter 11;

[0066] When a serious grid fault is detected and the inverter (11) enters a locked state, a seamless switching process is executed:

[0067] a. Within the first time window Δt1 (1-5ms), maintain the current control mode of the bidirectional DC converter (10), and lock the DC bus voltage sampling value U8c* of the grid-type grid-side inverter (11) before the blocking moment as the initial value of the voltage loop of the bidirectional DC converter (10).

[0068] b. Within the second time window Δt2 (50-200ms), the voltage loop setpoint of the bidirectional DC-DC converter (10) is smoothly transitioned from U8c* to the rated safe voltage value U8c_rated in the form of a ramp function or a first-order inertial element.

[0069] c. During the seamless switching process, the speed-regulating motor maintains its current torque command unchanged.

[0070] In some implementations, the power distribution loop integrates an extended state observer for real-time estimation of system lumped disturbances; the first control command and the second control command include a feedforward compensation amount based on the lumped disturbance estimate.

[0071] In this embodiment, to further improve the system's stability and control accuracy when facing internal and external disturbances, an advanced algorithm called an extended state observer can be integrated into the power distribution loop. This algorithm can estimate and quantify the lumped disturbance formed by the superposition of various factors such as sudden wind speed changes, model parameter errors, and unknown loads in real time. Its operation involves the extended state observer acting as a keen observer, continuously monitoring the system's key state variables and estimating the total disturbance currently acting on the system in real time through its internal algorithm model. Subsequently, this estimate is added in advance as a feedforward compensation to the control commands sent to the speed-regulating motor and the bidirectional DC-DC converter 10. The beneficial effects are crucial, enabling the system to possess "predictive" and "anti-interference" capabilities. Through feedforward compensation, disturbances can be offset before they actually affect the output performance, greatly improving the system's robustness, dynamic response speed, and overall voltage and frequency control accuracy in complex and variable environments.

[0072] In some implementations, the grid-side inverter 11 adopts a virtual synchronous machine control strategy, whose control algorithm simulates the rotor motion equation of a synchronous generator, and the algorithm parameters include virtual inertia coefficient and virtual damping coefficient.

[0073] In this embodiment, at the grid-connected interface, the grid-side inverter 11 employs a control strategy that mimics the physical characteristics of a synchronous generator, namely, virtual synchronous machine technology. The core of this strategy is that its control algorithm completely simulates the motion equations of the synchronous generator rotor, and adjustable virtual inertia and virtual damping coefficients are set within the algorithm. In its operation, when the grid frequency changes, the virtual inertia coefficient determines the magnitude of the inverter's output power's inertia in following the frequency change; the virtual damping coefficient determines the rate of system oscillation decay. Through the setting of these two parameters, the electrical behavior of the grid-side inverter 11 at the grid connection point is highly similar to that of a traditional synchronous generator. The beneficial effect of this design is that it endows the inverter, composed of power electronic equipment, with the "soul of a synchronous generator," enabling it to autonomously establish and stabilize the grid's voltage and frequency, presenting itself externally as a stable voltage source with inertia and damping, rather than merely a current source following the grid. This is the core characteristic of achieving active grid connection functionality.

[0074] The equation of motion for the synchronous generator rotor is J(dΔω / dt)+DΔω=P_ref-P_e, where J is the virtual inertia, D is the damping coefficient, P_ref is the active power reference value, P_e is the output active power, and Δω is the frequency deviation.

[0075] In some embodiments, when the grid-side inverter 11 is locked due to a grid fault, the battery energy storage system 9 takes over the closed-loop voltage control of the DC bus 8 through the bidirectional DC-DC converter 10. The DC bus voltage is strictly controlled within a safe threshold of ±5% of the rated value.

[0076] In this embodiment, considering the possibility of severe grid faults, the system is designed with a reliable fault ride-through mechanism. When a grid fault is detected that forces the grid-side inverter 11 to lock out for self-protection, the battery energy storage system 9 immediately takes over closed-loop control of the DC bus 8 voltage via its bidirectional DC-DC converter 10. During the inverter 11 lockout period, the synchronous generator 6 continues to generate electricity due to mechanical inertia. If left unattended, electrical energy will accumulate on the DC bus 8, causing a voltage spike that could endanger equipment. At this time, the co-controller commands the bidirectional DC-DC converter 10 to switch to DC voltage regulation mode, and the battery energy storage system 9 quickly absorbs the excess power based on the voltage deviation. The beneficial effect of this design is that it provides crucial fault ride-through protection for the system. By utilizing the rapid power absorption capability of energy storage, it ensures the stability of the DC bus voltage under extreme grid conditions, protects the safety of the main power equipment, and enables the entire power generation unit to safely weather the fault period and quickly resume operation after grid restoration, significantly enhancing the system's reliability and adaptability.

[0077] A collaborative operation method based on a grid-connected wind-storage integrated power generation system as described in any of the above methods includes the following steps:

[0078] The synchronous generator 6 is maintained at a constant speed of rated speed by the aforementioned front-end speed-regulating differential transmission system; it operates at a constant speed of 1500 rpm at the rated speed.

[0079] The AC power output from the synchronous generator 6 is converted into DC power by the machine-side rectifier 7 and then transmitted to the DC bus 8.

[0080] The battery energy storage system 9 uses the bidirectional DC-DC converter 10 to perform power throughput on the DC bus 8 in order to maintain the stability of the bus voltage.

[0081] The grid-side inverter 11 converts the electrical energy on the DC bus 8 into AC power and connects it to the grid in a voltage source mode that autonomously establishes voltage and frequency.

[0082] In this embodiment, based on the above system, its collaborative operation method follows a series of steps. First, through continuous adjustment of the front-end speed-regulating differential transmission system, the synchronous generator 6 is ensured to maintain a constant speed operation at its rated speed. Next, the AC power generated by the synchronous generator 6 is efficiently converted into DC power by the machine-side rectifier 7 and delivered to the common DC bus 8. At the same time, the battery energy storage system 9 monitors the voltage of the DC bus 8 in real time through the bidirectional DC converter 10, and absorbs power through rapid charging or discharging to smooth power fluctuations and maintain the basic stability of the bus voltage. Finally, the grid-connected grid-side inverter 11 inverts the stabilized DC power on the DC bus 8 into AC power and injects the power into the grid in a voltage source mode that can autonomously establish and maintain voltage and frequency. The beneficial effect of this method is that it connects the smoothness of mechanical speed regulation, the convergence of the DC bus, the speed of energy storage regulation, and the initiative of inverter grid connection into an organic whole, forming an efficient, controllable, and intelligent energy conversion and management chain from wind power to grid support.

[0083] In some implementations, the power throughput command is dynamically generated based on the magnitude of grid disturbance: when the grid frequency deviation is less than a first threshold, it is mainly regulated by the speed-regulating motor; when the grid frequency deviation is greater than a second threshold, it is jointly responded by the speed-regulating motor and the battery energy storage system 9; wherein, the second threshold is greater than the first threshold.

[0084] In this embodiment, the generation of power throughput commands for the battery energy storage system 9 can be finely differentiated based on the degree of grid disturbance. Two different frequency deviation thresholds are set: a smaller first threshold and a larger second threshold. The operation is as follows: when the grid frequency deviates slightly and does not exceed the first threshold, the system judges it as a minor disturbance, and primarily relies on the front-end speed-regulating motor for slow mechanical power adjustment in response. When the frequency deviation intensifies and exceeds the second threshold, the system judges it as a severe disturbance. At this time, the co-controller simultaneously commands the speed-regulating motor and the battery energy storage system 9 to work together, with the battery leveraging its millisecond-level rapid response to provide crucial instantaneous power support. The beneficial effect of this differentiated design is that it achieves hierarchical and differentiated responses to different levels of grid events, optimizing resource allocation. It can economically handle daily minor fluctuations with mechanical speed regulation, extending energy storage life, and provide strong support in the event of a grid crisis by combining the rapid power of energy storage, embodying the unity of intelligent collaboration, economy, and reliability.

[0085] The specific methods for the "joint response" include:

[0086] S1: Perform a first-order high-speed filter on the total active power support command P_sup generated by the virtual synchronous machine algorithm from the grid frequency deviation Δf to separate the high-frequency component P_sup_h and the low-frequency component P_sup_l;

[0087] S2: The low-frequency component P_sup_l is mainly allocated to the first control command of the speed-regulating motor, and the allocation weight α is negatively correlated with the degree of deviation of the DC bus voltage U8c;

[0088] S3: The high-frequency component P_sup_h is mainly allocated to the second control command of the battery energy storage system 9, and the allocation weight β is positively correlated with the real-time state of charge (SOC) of the battery energy storage system 9.

[0089] The cutoff frequency f_c of the high-speed filter is determined jointly based on the maximum torque response frequency f_motor of the speed-regulating motor and the bandwidth f_batt of the bidirectional DC-DC converter 10, and satisfies f_motor <f_c<f_batt。

[0090] In step S2, the allocation weight α is calculated as follows: α = α0·(1-kᵤ·|U8c-U8c_rated|), where α0 is the base weight coefficient and kᵤ is the voltage deviation suppression coefficient; in step S3, the allocation weight β is calculated as follows: β = β0·SOC, where β0 is the base weight coefficient.

[0091] The following are specific embodiments of the present invention:

[0092] See Figure 1 The present invention provides a grid-type wind and energy storage integrated power generation system, which mainly includes a wind turbine 1, a speed-increasing gearbox 2, a front-end speed-regulating differential transmission system, a synchronous generator 6, a machine-side rectifier 7, a DC bus 8, a battery energy storage system 9, a bidirectional DC converter 10, a grid-type grid-side inverter 11, and a collaborative controller.

[0093] like Figure 1 As shown, the front-end speed-regulating differential transmission system is the core mechanical component, which includes a differential planetary gear train. The differential planetary gear train consists of a sun gear 3, a planet carrier 4, planet gears, and an external gear ring 5. The wind energy captured by the wind turbine 1 is initially accelerated by the speed-increasing gearbox 2, driving the planet carrier 4 to rotate; this is the main power path. The external gear ring 5 is connected to the speed-regulating motor (not shown in the figure, typically a permanent magnet synchronous motor or a doubly-fed asynchronous motor). The sun gear 3 serves as the output end and is rigidly connected to the rotor shaft of the synchronous generator 6.

[0094] Its core working principle is as follows: When wind speed changes cause the rotational speed of wind turbine 1 to change, by controlling the torque and speed (motor or generator mode) of the speed-regulating motor connected to the external gear ring 5, the speed and torque relationship inside the differential planetary gear train can be continuously and precisely adjusted, thereby ensuring that the rotational speed of the output shaft of the sun gear 3 remains absolutely constant (e.g., 1500 rpm). This allows the synchronous generator 6 to operate at a constant power frequency speed and directly output stable power frequency AC. This process is achieved entirely through mechanical transmission and motor speed regulation, eliminating the need for a large-capacity full-power frequency converter at the generator outlet.

[0095] The AC power output from the synchronous generator 6 is converted into DC power by the generator-side rectifier 7 and collected on the DC bus 8. The battery energy storage system 9 is connected in parallel to the DC bus 8 through the bidirectional DC converter 10, forming a deeply integrated power pool of wind turbine and energy storage on the DC side. The grid-type grid-side inverter 11 converts the electrical energy on the DC bus into AC power that meets the grid requirements.

[0096] The grid-side inverter 11 is a key device that presents itself as a voltage source to the outside world. It adopts virtual synchronous machine control technology. The core of this technology lies in simulating the second-order rotor motion equation of a synchronous generator through a control algorithm, enabling the inverter to have adjustable virtual inertia and virtual damping characteristics, thereby autonomously establishing and stabilizing AC voltage and frequency.

[0097] The cooperative controller is the core of realizing the "generalized inertia" and intelligent cooperation of this invention. It adopts a hierarchical control structure, specifically including:

[0098] Outer ring power grid support ring: Real-time monitoring of the grid frequency f_grid and voltage U_grid at the grid connection point, comparing them with their rated reference values ​​f_ref and U_ref. Based on the frequency deviation Δf and voltage deviation ΔU, the total active power command P_support and reactive power command Q_support required to support the power grid are calculated using a virtual synchronous machine algorithm or a droop control algorithm.

[0099] Inner loop power allocation and interference rejection loop: This loop receives the total power command and performs two key tasks:

[0100] Intelligent power allocation: Taking into account the mechanical power P_wind captured by the wind turbine, the DC bus voltage U_dc, and the state of charge (SOC) of the battery, P_support is dynamically decomposed. Slow-changing, long-duration power components (mainly corresponding to wind speed trends and the steady-state portion of primary frequency regulation) are allocated as the speed-regulating motor torque command T_m_ref. Rapidly changing power surge components requiring millisecond-level response (mainly corresponding to inertial response and the transient portion of primary frequency regulation) are allocated as the battery power command P_batt_ref. This allocation strategy significantly reduces the number of actions required by the energy storage unit to respond to small, frequent disturbances, thus helping to extend its service life.

[0101] Extended State Observer Feedforward Compensation: The inner loop integrates an extended state observer to observe and estimate the lumped disturbance z caused by sudden wind speed changes, inaccurate model parameters, and grid background harmonics in real time. The disturbance estimate is then fed forward to the generation loops of T_m_ref and P_batt_ref, significantly improving the system's robustness and control accuracy in the face of internal uncertainties and external disturbances.

[0102] The speed-regulating motor adjusts torque and speed according to T_m_ref, changing the transmission ratio of the differential gear train, thereby regulating the mechanical power input to the synchronous generator. The battery energy storage system 9 rapidly absorbs or releases electrical energy through the bidirectional DC-DC converter 10 by executing P_batt_ref. The power from wind and storage is combined and balanced on the DC bus 8, jointly ensuring DC voltage stability and providing a powerful and responsive DC power supply for the grid-side inverter 11.

[0103] Fault Ride-Through Example: When a severe fault such as a short circuit occurs in the power grid, the grid voltage drops sharply. Upon detecting the fault, the grid-side inverter 11 immediately switches to low-voltage ride-through mode, potentially entering current-limiting or brief pulse-lockout states to protect the devices. At this time, the synchronous generator 6 continues to generate electricity due to mechanical inertia, and the unabsorbed power causes a sharp rise in the DC bus voltage. The co-controller quickly detects this state and immediately commands the battery energy storage system 9 to switch to "DC voltage regulation mode" via the bidirectional DC-DC converter 10. The energy storage system absorbs the excess power, strictly controlling the DC bus voltage within a safe threshold until the grid fault is cleared and the inverter resumes normal operation. This mechanism ensures the system's survivability under extreme grid conditions.

[0104] Performance Verification: Through the deep integration of the aforementioned hardware architecture and collaborative control software, this system organically combines the physical grid foundation of "front-end speed-regulating synchronous power generation," the rapid flexibility of "DC-side energy storage," and the intelligent external characteristic simulation capability of "virtual synchronization algorithm," resulting in a completely new power generation unit that inherently possesses the characteristics of a synchronous machine. It not only achieves efficient wind energy capture but also serves as a reliable and dispatchable main power source in the power grid, providing inertia, damping, primary frequency regulation, and reactive power voltage support services that were previously only stably provided by traditional synchronous power sources. This provides crucial technical equipment for constructing a new power system with a high proportion of renewable energy.

[0105] This embodiment provides a method for the coordinated operation of a grid-connected speed-regulating wind power station with energy storage at the front end to support grid stability. Specifically, it involves a system and control method for integrating battery energy storage on the DC side to form a grid-connected integrated wind and energy storage system. This system deeply integrates front-end speed-regulating wind power technology with DC-side energy storage and achieves active voltage and frequency support for the grid through overall grid-connected control. The specific implementation steps are as follows:

[0106] 101: For example Figure 1 As shown, the system consists of the following core components: a wind turbine, a front-end speed-regulating differential drive system (including a planetary gear train, a sun gear, an external gear ring, and a speed-regulating motor), a synchronous generator, a generator-side rectifier, a common DC bus, a battery energy storage system (connected via a bidirectional DC / DC converter), and a grid-side inverter. The energy storage system is directly connected to the DC bus between the synchronous generator's rectified output and the grid-side inverter, forming an electrically tightly coupled wind-storage integrated structure.

[0107] 102: The mechanical power of the wind turbine is split through a differential planetary gear system. One path (the main power flow) drives the synchronous generator rotor through the planetary carrier and external gear ring; the other path (the speed-regulating power flow) is transmitted to the speed-regulating motor through the sun gear shaft and parallel shaft. By controlling the torque and speed of the speed-regulating motor (in motoring or generating mode), the transmission ratio can be continuously adjusted, thereby maintaining a constant input shaft speed of the synchronous generator during wind turbine speed-changing operation, creating conditions for its output of industrial frequency AC power.

[0108] 103: The AC power output from the synchronous generator is converted to DC power by the generator-side rectifier and delivered to the common DC bus. The battery energy storage system is also connected to this DC bus via a bidirectional DC / DC converter, enabling flexible bidirectional power dispatch. The electrical energy on the DC bus is ultimately converted to AC power by a grid-side inverter and fed into the grid. This inverter adopts a grid-based control strategy, enabling it to autonomously establish and stabilize AC voltage and frequency, and externally appears as a voltage source with inertia and damping.

[0109] 104: During grid-connected operation, the system aims to maximize wind energy capture and meet grid demand in a coordinated manner. The front-end speed control system adjusts the wind turbine to the optimal tip speed ratio to track maximum wind power. Simultaneously, the energy storage system charges or discharges in real time based on DC bus voltage fluctuations and grid dispatch instructions, smoothing out wind turbine output fluctuations and providing necessary power margin and dynamic response capabilities for grid control.

[0110] 105: To achieve proactive support for the power grid, the system adopts a hierarchical collaborative grid control system. In the inner layer control, the extended state observer estimates the lumped disturbances caused by wind speed disturbances, model uncertainties, etc., in real time and feeds forward compensation to the control commands of the speed-regulating motor and energy storage converter. The outer layer control targets the grid frequency and voltage reference values, comprehensively scheduling the power regulation capability of the speed-regulating motor and the rapid throughput capability of the energy storage, and uniformly generating the voltage and frequency setting commands for the grid-connected inverter. Through this collaborative mechanism, the wind-storage integrated unit can simulate the operating characteristics of a synchronous generator, actively providing inertial response, primary frequency regulation, and reactive voltage support, thereby enhancing grid stability.

[0111] In summary, this embodiment integrates battery energy storage deeply into the DC side of the front-end speed-regulating wind power system and implements overall grid-based collaborative control, constructing a novel wind-storage combined power station capable of actively supporting the stable operation of the power grid. This method achieves an organic combination of efficient wind energy utilization and rigid grid demands, improving the safe and stable operation level of a high-proportion renewable energy grid.

[0112] 201: Wind turbines convert varying wind energy into mechanical energy. The output power of wind turbines is analyzed using Betz theory and aerodynamics.

[0113]

[0114] In the formula: It is the output power of the wind turbine; R is the radius of the wind turbine; It is the wind turbine wind energy utilization coefficient. It is the tip speed ratio. The pitch angle of the wind turbine blades; This refers to air density.

[0115] The expression for the output torque of the wind turbine is:

[0116]

[0117] 202: The wind energy utilization coefficient represents the efficiency with which a wind turbine converts incoming natural wind into mechanical energy. According to Betz's law, the maximum wind energy utilization coefficient achievable by a wind turbine is 0.593. The magnitude of the wind energy utilization coefficient is related to the turbine pitch angle and the tip speed ratio.

[0118] This step constructs the speed-increasing gearbox model architecture. Since the wind turbine's output speed is too low to meet the speed requirements of the differential gear train, a speed-increasing gearbox is added between the wind turbine and the differential gear train. The relationship between the speed-increasing gearbox's output speed and the wind turbine's output speed is as follows:

[0119]

[0120]

[0121] In the formula: To increase the output speed of the gearbox, To increase the gearbox transmission ratio.

[0122] The relationship between the output torque of the speed-increasing gearbox and the output torque of the wind turbine is as follows:

[0123]

[0124] Output torque of the speed-increasing gearbox for:

[0125]

[0126] 203: Differential gear train structure. The planetary carrier is connected to the output shaft of the speed-increasing gearbox as the main input of the differential gear train. The gear ring is connected to the output shaft of the speed-regulating motor as the secondary input of the differential gear train. Finally, the sun gear is connected to the input shaft of the generator as the output of the differential gear train. The rotational speed of the planetary carrier... Equal to the output speed of the speed-increasing gearbox Speed ​​control motor input speed With gear speed The relationship is:

[0127]

[0128] Sun gear speed Equal to generator speed .

[0129] Next, the transmission ratio from the planet carrier to the sun gear is:

[0130]

[0131] Sun gear output speed for:

[0132]

[0133] The output torque of the sun gear is...

[0134]

[0135] The transmission ratio from the planetary carrier to the gear ring is:

[0136]

[0137] The output torque of the gear ring is:

[0138]

[0139] In the formula: Rotational speed; For torque; These are the structural parameters of the differential gear train; subscript , , These represent the gear ring, planet carrier, and sun gear, respectively. and These are the transmission ratios from the planet carrier to the ring gear and from the planet carrier to the sun gear, respectively.

[0140] 204: The speed-regulating motor is a unique device in front-end speed-regulating wind turbines. It adjusts the speed and torque of the gear ring to maintain a constant output speed and torque for the sun gear. When the wind turbine speed changes, the speed-regulating motor speed is adjusted by regulating the current frequency. Based on the rotational relationships of the components in the differential gear train, it can be concluded that if the generator speed is stabilized at a constant value... Therefore, it is necessary to control the output speed of the speed-regulating motor. :

[0141]

[0142] Control the output torque of the speed-regulating motor for:

[0143]

[0144] In the formula: This refers to the output power of the speed-regulating motor.

[0145] 205: Simplified Dynamic Model of the System (for Controller Design)

[0146] Single-mass model of the transmission chain and aerodynamic torque equation:

[0147]

[0148] These represent the moments of inertia of the wind turbine, generator, and speed-regulating motor, respectively. These represent the damping coefficients of the wind turbine, generator, and speed-regulating motor, respectively.

[0149] 206: Virtual synchronous control is used to simulate the inertia and damping characteristics of a synchronous generator. Its core feature is the simulation of the rotor motion equations of a synchronous generator.

[0150]

[0151] In the formula, J and D are the adjustable virtual inertia and damping coefficient, respectively; This represents the reference value for active power. Indicates voltage frequency reference; This indicates the rated voltage and frequency. Virtual synchronous control can simulate inertia, improve the equivalent inertia level of the system, and help improve grid frequency stability. Energy storage is configured on the DC side of the wind turbine to achieve DC-side synergy between wind and energy storage. A significant advantage of this synergy is that it can stabilize the DC voltage with the help of additional energy storage on the DC side, effectively assisting in the realization of overall voltage source-type grid control. The wind-energy storage DC-side synergy is structurally and controllably integrated, thus, in addition to meeting the active support energy requirements, it has the potential to further improve the unit's transient / steady-state control capabilities and optimize the unit's operational flexibility. This invention provides auxiliary support from the energy storage side while the grid-side converter maintains the DC voltage. In the event of a grid fault, the energy storage-side converter takes over DC voltage control in an emergency to avoid power accumulation and DC voltage exceeding limits, thereby achieving transient / steady-state coordinated control of the wind-energy storage synergy unit.

[0152] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the devices, apparatuses, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0153] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A grid-connected wind-storage integrated power generation system, characterized in that, include: Windmill (1); The front-end speed-regulating differential transmission system has its input end connected to the wind turbine (1) and is used to convert the variable speed mechanical energy input by the wind turbine (1) into constant speed mechanical energy output. The front-end speed-regulating differential transmission system includes a differential planetary gear train and a speed-regulating motor. Synchronous generator (6), whose input end is connected to the constant speed output end of the front-end speed-regulating differential transmission system; The generator-side rectifier (7) is connected to the output terminal of the synchronous generator (6) on its AC side; DC bus (8) is connected to the DC side of the machine-side rectifier (7); The battery energy storage system (9) is connected to the DC bus (8) via a bidirectional DC converter (10). The grid-side inverter (11) is connected to the DC bus (8) on its DC side and to the grid on its AC side.

2. The grid-type integrated wind and energy storage power generation system according to claim 1, characterized in that, It also includes a speed-increasing gearbox (2), the input end of which is connected to the wind turbine (1), and the output end is connected to the planet carrier (4) of the differential planetary gear system.

3. The grid-type integrated wind and energy storage power generation system according to claim 2, characterized in that, The differential planetary gear system includes a sun gear (3), a planet carrier (4), and an external gear ring (5); the planet carrier (4) is connected to the speed-increasing gearbox (2) as the main input end, the external gear ring (5) is connected to the speed-regulating motor as the speed-regulating input end, and the sun gear (3) is connected to the input shaft of the synchronous generator (6) as the constant speed output end.

4. The grid-type integrated wind and energy storage power generation system according to any one of claims 1 to 3, characterized in that, It also includes a coordination controller, which is configured to generate and issue a first control command for the speed-regulating motor and a second control command for the bidirectional DC-DC converter (10) based on grid status information, so as to coordinate the operation of the speed-regulating motor and the battery energy storage system (9).

5. The grid-type integrated wind and energy storage power generation system according to claim 4, characterized in that, The collaborative controller includes a grid support ring and a power distribution ring; the grid support ring is used to generate a total power support command based on the grid frequency deviation and voltage deviation; the power distribution ring is used to dynamically distribute the power regulation demand to the first control command and the second control command based on the total power support command, the real-time power of the wind turbine (1) and the DC bus (8) voltage.

6. The grid-type integrated wind and energy storage power generation system according to claim 5, characterized in that, The power distribution loop integrates an extended state observer for real-time estimation of system lumped disturbances; the first control command and the second control command include feedforward compensation based on the lumped disturbance estimate.

7. The grid-type integrated wind and energy storage power generation system according to claim 1, characterized in that, The grid-side inverter (11) adopts a virtual synchronous machine control strategy. Its control algorithm simulates the rotor motion equation of a synchronous generator. The algorithm parameters include virtual inertia coefficient and virtual damping coefficient.

8. The grid-type integrated wind and energy storage power generation system according to claim 1, characterized in that, When the grid-side inverter (11) is locked due to a grid fault, the battery energy storage system (9) takes over the closed-loop voltage control of the DC bus (8) through the bidirectional DC converter (10).

9. A method for the coordinated operation of a grid-type integrated wind and energy storage power generation system according to any one of claims 1 to 8, characterized in that, Includes the following steps: The synchronous generator (6) is maintained at a constant speed at the rated speed by the front-end speed-regulating differential transmission system; The power frequency AC power output by the synchronous generator (6) is converted into DC power by the machine-side rectifier (7) and then transmitted to the DC bus (8). The battery energy storage system (9) uses the bidirectional DC converter (10) to power the DC bus (8) to maintain the bus voltage stability. The grid-side inverter (11) converts the electrical energy on the DC bus (8) into AC power and connects it to the grid in a voltage source mode that autonomously establishes voltage and frequency.

10. The cooperative operation method according to claim 9, characterized in that, The power throughput command is dynamically generated based on the magnitude of the grid disturbance: when the grid frequency deviation is less than the first threshold, it is mainly regulated by the speed-regulating motor; when the grid frequency deviation is greater than the second threshold, it is jointly responded by the speed-regulating motor and the battery energy storage system (9); wherein, the second threshold is greater than the first threshold.

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