Impulse water turbine nozzle with double injection needle and small power fluctuation regulation

Abstract

This invention discloses a dual-needle, low-power fluctuation regulating impingement turbine nozzle, belonging to the field of hydropower technology. In this device, a nozzle orifice is provided at the axial front end of the nozzle housing; a main nozzle is axially movable within the nozzle housing; a main nozzle drive mechanism drives the main nozzle to move slowly axially to perform slow coarse adjustment of the annular flow area within the nozzle orifice; a small nozzle is coaxially and axially movable relative to the main nozzle within the main nozzle; a small nozzle drive mechanism drives the small nozzle to move rapidly axially to perform rapid fine adjustment of the annular flow area within the nozzle orifice. This invention enables rapid and precise fine-tuning of the unit's output power, improving the unit's frequency regulation capability and its support for the power grid.

Description

Technical Field

[0001] This invention relates to the field of hydropower technology, and in particular to an impact turbine nozzle with dual-needle low-power fluctuation regulation. Background Technology

[0002] Impulse turbines, especially large bucket turbines, are the core equipment of high-head, low-flow hydropower stations. Their output power is primarily controlled by altering the flow rate of the water jet sprayed onto the runner buckets. Traditional impulse turbine nozzles employ a single-needle adjustment method, changing the position of the needle within the nozzle to alter the annular flow area at the nozzle outlet, thereby regulating the water jet flow rate and the turbine's output.

[0003] With the increasing demands for power supply flexibility and stability in modern power grids, generator units, especially large hydropower units, are required to undertake more ancillary services such as peak shaving and frequency regulation. The single-needle jet regulation method has the following shortcomings: First, the nozzles of large impulse turbine units are large in size, heavy in mass, and have high inertia. In addition, the hydraulic cylinders of the nozzles are also large in volume. When the main nozzle is moved, a large change in oil volume is required. Oil compressibility, pipeline resistance, and servo valve flow limitation will all cause response lag, slow nozzle movement, and long response time. Furthermore, the frequent small reciprocating motion of the nozzles for frequency adjustment will increase the wear of the nozzles, seals, hydraulic cylinders, and servo valves, and may also cause pressure fluctuations in the hydraulic system.

[0004] Second, under high-load conditions, the nozzle is close to the fully open position, and the flow area corresponding to a unit displacement changes significantly, resulting in large flow rate changes and thus causing large power fluctuations. The small adjustments made by the nozzle in response to dispatch commands can lead to excessive power fluctuations, making it difficult to achieve fine regulation and affecting the stability of the power grid.

[0005] Third, the slow response speed of peak shaving and frequency regulation cannot meet the ancillary service requirements of rapid grid response. Existing impulse turbines generally use a single nozzle for flow regulation. This single nozzle handles both large-scale load regulation and small-amplitude power correction. When the unit is performing peak shaving, the traditional single nozzle can usually meet the requirements due to the large adjustment range and relatively low time requirements. However, when the unit participates in rapid grid frequency regulation, the nozzle needs to perform frequent, small-amplitude, and high-precision movements within a short period. Large impulse turbines have large main nozzles that are heavy, subjected to significant hydraulic forces, and require large-capacity hydraulic actuators. Therefore, their operating speed and control accuracy are limited, making it difficult to meet the power regulation requirements of rapid frequency regulation.

[0006] Therefore, the existing design of large-scale impulse turbine nozzles has certain shortcomings and is difficult to meet the requirements of future smart grids for rapid and flexible adjustment capabilities. Summary of the Invention

[0007] This invention aims to at least partially solve one of the technical problems in related technologies. Therefore, one objective of this invention is to propose a dual-needle, low-power fluctuation regulating nozzle for an impulse turbine, enabling rapid and precise fine-tuning of the unit's output power, improving the unit's frequency regulation capability and its support for the power grid, and solving the technical problems of slow power regulation response and weak frequency regulation performance in existing large impulse turbines due to the large inertia of the nozzle mechanism.

[0008] The impact turbine nozzle with dual-needle low-power fluctuation adjustment according to an embodiment of the present invention includes: Nozzle housing; the nozzle housing has a nozzle orifice at its axial front end; The main nozzle is axially movable and disposed within the nozzle housing; A main nozzle drive mechanism is used to drive the main nozzle to move slowly axially to slowly coarsely adjust the annular flow area inside the nozzle orifice. The small nozzle is coaxially disposed within the main nozzle and is axially movable relative to the main nozzle. The small nozzle drive mechanism is used to drive the small nozzle to move rapidly axially, so as to quickly fine-tune the annular flow area inside the nozzle orifice.

[0009] The dual-needle low-power fluctuation adjustment of the impulsive turbine nozzle in this invention has the following advantages: First, it has a fast adjustment speed: When making rapid fine adjustments to the annular flow area, because the mass and inertia of the small nozzle are smaller than those of the main nozzle, the response time of the small nozzle when the small nozzle drive mechanism drives the small nozzle to move axially can be shorter. When the impulsive turbine requires a large adjustment of the output power, the main nozzle drive mechanism is used to drive the main nozzle axis to move, while the small nozzle remains in a locked position or moves synchronously with the main nozzle but does not participate in the adjustment. In this way, the main nozzle is responsible for large-range load adjustment, and the small nozzle is responsible for small-amplitude power correction, resulting in a faster adjustment speed. Second, it has high adjustment accuracy. On the one hand, the mass and volume of the small nozzle are smaller than those of the main nozzle, so the axial movement of the small nozzle makes it easier to achieve precise positioning of the small nozzle, thereby accurately adjusting the annular flow area; on the other hand, the small nozzle is lightweight and has low inertia, so the adjustment power required for the small nozzle drive mechanism to drive the small nozzle is lower than that required for the main nozzle drive mechanism to drive the main nozzle, which is more conducive to controlling the adjustment accuracy. Third, it reduces component wear and impact. The impact turbine nozzle with dual-needle low-power fluctuation adjustment uses a small needle drive mechanism to drive the small needle to move axially quickly. This allows for rapid fine adjustment of the annular flow area inside the nozzle orifice, avoiding frequent driving of the large, heavy, and inertial main needle, thus reducing wear and impact on components.

[0010] In summary, the dual-needle low-power fluctuation adjustment of the impulsive turbine nozzle, through the main nozzle drive mechanism 3 driving the main nozzle to slowly coarsely adjust the annular flow area inside the nozzle orifice, and through the small nozzle drive mechanism 5 driving the small nozzle to quickly finely adjust the annular flow area inside the nozzle orifice, can effectively suppress grid frequency fluctuations and enhance grid stability.

[0011] In some embodiments, the front section of the main nozzle has a central cavity, and the main body of the small nozzle is disposed in the central cavity; when the small nozzle is completely retracted into the central cavity, the small nozzle is in a closed state, and the outer contour of the head of the small nozzle and the main nozzle forms a smooth and continuous streamlined flow surface.

[0012] In some embodiments, the inertia and stroke of the small nozzle drive mechanism are less than those of the main nozzle drive mechanism, and the action response frequency of the small nozzle drive mechanism is higher than that of the main nozzle drive mechanism.

[0013] In some embodiments, the small nozzle drive mechanism includes a small nozzle hydraulic cylinder, a small nozzle servo oil circuit, and a high-speed electro-hydraulic servo valve; the miniature piston in the small nozzle hydraulic cylinder is connected to the small nozzle, the small nozzle servo oil circuit is connected to the cylinder cavity of the small nozzle hydraulic cylinder, and the high-speed electro-hydraulic servo valve controls high-pressure oil to be supplied to the small nozzle hydraulic cylinder through the small nozzle servo oil circuit.

[0014] In some embodiments, a sleeve is further included, which is coaxially fixed in the central cavity, and the small nozzle is axially movable through the sleeve; the space between the tail end of the sleeve and the tail end of the central cavity forms the cylinder cavity of the small nozzle hydraulic cylinder, and the micro piston is disposed on the outer periphery of the small nozzle and located in the cylinder cavity of the small nozzle hydraulic cylinder.

[0015] In some embodiments, the space between the micro piston and the tail end of the central cavity and the space between the micro piston and the sleeve are respectively connected to the two small needle servo oil circuits.

[0016] In some embodiments, the tail end of the small nozzle is fixed with a tail end support that slides with the central cavity, and the tail end support is provided with an axial through hole.

[0017] In some embodiments, the small needle servo oil circuit includes oil circuit sections radially opened on the wall of the central cavity and radially opened on the nozzle housing.

[0018] In some embodiments, the main nozzle is provided with a detector mounting position for mounting a detector. The detector mounting position is located on the rear side of the central cavity and communicates with the central cavity. The detector is used to detect the axial displacement of the small nozzle.

[0019] In some embodiments, the system further includes a control system that receives a total power adjustment command and decomposes the total power adjustment command into a large opening adjustment signal for controlling the main nozzle and a fine adjustment signal for controlling the small nozzle. When the amplitude of the total power adjustment command is large or the duration is long, the small nozzle is in the closed state, and the control system controls the main nozzle and the small nozzle to move axially synchronously through the large opening adjustment signal, thereby realizing slow coarse adjustment. When the overall power adjustment command is a small, rapid fluctuation, the control system keeps the position of the main nozzle unchanged and controls the rapid extension and retraction of the small nozzle through the fine-tuning signal, thereby achieving rapid fine-tuning.

[0020] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0021] Figure 1 This is a cross-sectional schematic diagram of the impact turbine nozzle with dual-needle low-power fluctuation adjustment according to an embodiment of the present invention. Figure 2 This is a schematic diagram of the main nozzle and the small nozzle according to an embodiment of the present invention; Figure 3 This is a schematic diagram showing the state of the small nozzle and the main nozzle being fully closed according to an embodiment of the present invention; Figure 4 This is a schematic diagram showing the state of the small nozzle being fully closed and the main nozzle being partially open in an embodiment of the present invention; Figure 5 This is a schematic diagram showing the state of the small nozzle fully closed and the main nozzle fully open in an embodiment of the present invention; Figure 6 This is a schematic diagram showing the state of the small nozzle and the main nozzle separated according to an embodiment of the present invention; Figure 7 This is a schematic diagram showing the fully open small nozzle and fully open main nozzle states in an embodiment of the present invention; Figure 8 This is a schematic diagram of the operation of the main nozzle servo oil circuit and the small nozzle servo oil circuit in an embodiment of the present invention.

[0022] Figure Labels Dual-needle low-power fluctuation adjustable impact turbine nozzle 1000; nozzle housing 1; nozzle orifice 101; central chamber 102; main nozzle 2; central cavity 201; detector mounting position 202; large piston 203; main nozzle drive mechanism 3; main nozzle hydraulic cylinder 301; main nozzle servo oil circuit 302; small nozzle 4; micro piston 401; tail end support 402; small nozzle drive mechanism 5; small nozzle hydraulic cylinder 501; small nozzle servo oil circuit 502; sleeve 6; disc spring module 7. Detailed Implementation

[0023] Embodiments of the present invention are described in detail below. Examples of these embodiments are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0024] The following is combined with Figures 1 to 8 This invention describes an embodiment of an impact turbine nozzle 1000 with dual-needle low-power fluctuation adjustment.

[0025] like Figures 1 to 8 As shown in the figure, the dual-needle low-power fluctuation adjustable impact turbine nozzle 1000 of this invention is installed at the end of the water distribution ring pipe of the hydropower station to form a high-speed water jet to impact the turbine runner.

[0026] The dual-needle low-power fluctuation regulating impulsive turbine nozzle 1000 of this invention includes a nozzle housing 1, a main nozzle 2, a main nozzle drive mechanism 3, a small nozzle 4 and a small nozzle drive mechanism 5, and adjusts the output power of the impulsive turbine by adjusting the water jet flow rate.

[0027] The nozzle housing 1 has a nozzle port 101 at its axial front end. The water jet enters the nozzle housing 1 from the axial rear end and is ejected from the annular flow surface at the nozzle port 101. The water jet impacts the impulse turbine and provides output power to the impulse turbine.

[0028] The main nozzle 2 is axially movable within the nozzle housing 1. The main nozzle 2 is large in size, heavy in mass, and has high inertia. Through axial movement, it can significantly adjust the annular flow surface within the nozzle orifice 101 and undertake a wide range of load adjustments.

[0029] The main nozzle drive mechanism 3 is used to drive the main nozzle 2 to move slowly axially in order to slowly and coarsely adjust the annular flow area inside the nozzle orifice 101.

[0030] When the impulse turbine requires significant output power adjustment, such as during turbine start-up, shutdown, or large-scale load increases and decreases, the main nozzle drive mechanism 3 drives the main nozzle 2 to move slowly axially. When the main nozzle 2 retracts axially within the nozzle housing 1, the annular flow area increases, the water jet flow rate increases, and thus the output power of the impulse turbine increases. Conversely, when the main nozzle 2 extends outward from the nozzle housing 1, the annular flow area decreases, the water jet flow rate decreases, and the output power of the impulse turbine decreases.

[0031] The small nozzle 4 is coaxially mounted within the main nozzle 2, allowing axial movement relative to it. The small nozzle 4 is coaxially positioned at the head of the main nozzle 2 and can perform independent axial extension and retraction relative to the main nozzle 2. The small nozzle 4 is small in size, lightweight, and has low inertia, enabling precise fine-tuning under small loads.

[0032] The small nozzle drive mechanism 5 is used to drive the small nozzle 4 to move rapidly axially, so as to quickly fine-tune the annular flow area inside the nozzle orifice 101.

[0033] When the output power of the impulse turbine needs to be adjusted rapidly with a small amplitude, such as when it needs to participate in grid frequency regulation or suppress power fluctuations, the small nozzle drive mechanism 5 drives the small nozzle 4 to move axially rapidly.

[0034] When the impulse turbine needs to rapidly fine-tune its output power (e.g., to participate in grid frequency regulation or suppress power fluctuations), the small nozzle drive mechanism 5 drives the small nozzle 4 to perform rapid axial extension and retraction. Specifically, when it is necessary to reduce the impulse turbine power, the small nozzle 4 extends towards the nozzle orifice 101, reducing the inner annular flow area. When it is necessary to increase the impulse turbine power, the small nozzle 4 retracts into the main nozzle 2, increasing the inner annular flow area.

[0035] In the embodiment of the present invention, when the dual-needle low-power fluctuation adjustable impulse turbine nozzle 1000 is running, the main nozzle drive mechanism 3 drives the main nozzle 2 to move slowly axially to perform slow coarse adjustment of the annular flow area inside the nozzle orifice 101. For example, from... Figure 3 The main nozzle 2 is fully closed. Figure 4 The main nozzle 2 is in the open state, and the small nozzle 4 is not involved in the adjustment process.

[0036] With the main nozzle 2 in a partially open state (see...) Figure 4 For applications requiring large opening adjustments (such as large power dispatch commands or large low-frequency deviations), the main nozzle drive mechanism 3 can drive the main nozzle 2 to move slowly for coarse adjustments (such as from...). Figure 4 The main nozzle is in a split state between two parts. Figure 5(The main nozzle 2 is in the fully open state). When rapid fine-tuning is required (such as high-frequency micro-fluctuations in the power grid frequency), the main nozzle 2 can remain locked, and the small nozzle drive mechanism 5 is used to drive the small nozzle 4 to move rapidly axially. See [link / reference] Figure 5 The small nozzle 4 is fully off. Figure 6 The small nozzle 4 is in the start-up state, then... Figure 7 The small nozzle 4 is in the fully open state. When the small nozzle 4 extends, it reduces the annular flow area inside the nozzle orifice 101, causing a momentary decrease in the flow rate and kinetic energy of the water jet, thereby reducing the output power of the turbine. Conversely, quickly retracting the extended small nozzle 4 will instantly increase the flow rate and increase the output power of the turbine. Because the small nozzle 4 and the small nozzle drive mechanism 5 are lightweight and have a short stroke, their operating frequency and response speed are much higher than those of the main nozzle 2, thus achieving rapid and precise adjustment of power.

[0037] The dual-needle low-power fluctuation adjustment nozzle 1000 for impulse turbines of this invention has the following advantages: First, it has a fast adjustment speed: When making rapid fine adjustments to the annular flow area, because the mass and inertia of the small nozzle 4 are smaller than those of the main nozzle 2, the response time of the small nozzle 4 when the small nozzle drive mechanism 5 drives the small nozzle 4 to move axially can be shorter. When the impulse turbine requires a large-scale adjustment of output power, the main nozzle drive mechanism 3 is used to drive the axis of the main nozzle 2 to move, while the small nozzle 4 remains in a locked position or moves synchronously with the main nozzle 2 but does not participate in the adjustment. In this way, the main nozzle 2 is responsible for large-scale load adjustment, and the small nozzle 4 is responsible for small-scale power correction, resulting in a faster adjustment speed. Secondly, it offers high adjustment precision. On one hand, the smaller nozzle 4 has a smaller mass and volume than the main nozzle 2, making it easier to accurately position the smaller nozzle 4 during axial movement, thus precisely adjusting the annular flow area. On the other hand, the smaller nozzle 4 is lightweight and has low inertia, requiring less adjustment power from the smaller nozzle drive mechanism 5 compared to the main nozzle drive mechanism 3, which further enhances adjustment precision. Thirdly, it reduces component wear and impact. The dual-needle, low-power fluctuation adjustment of the impact turbine nozzle 1000 uses the smaller nozzle drive mechanism 5 to drive the smaller nozzle 4 axially quickly, enabling rapid fine-tuning of the annular flow area within the nozzle orifice 101. This avoids frequent driving of the large, heavy, and highly inertial main nozzle 2, reducing wear and impact on components.

[0038] In summary, the dual-needle low-power fluctuation regulation of the impulsive turbine nozzle 1000, through the main nozzle drive mechanism 3 driving the main nozzle 2 to slowly coarsely adjust the annular flow area inside the nozzle orifice 101, and through the small nozzle drive mechanism 5 driving the small nozzle 4 to quickly finely adjust the annular flow area inside the nozzle orifice 101, can effectively suppress grid frequency fluctuations and enhance grid stability.

[0039] In some embodiments, a central cavity 201 is provided in the front section of the main nozzle 2, and the main body of the small nozzle 4 is disposed in the central cavity 201; when the small nozzle 4 is completely retracted into the central cavity 201, the small nozzle 4 is in a closed state, and the outer contour of the head of the small nozzle 4 and the main nozzle 2 forms a smooth and continuous streamlined flow surface (see...). Figures 1 to 5 A smooth, continuous streamlined flow surface can reduce hydraulic losses, improve the smoothness of the water jet on the flow surface, and ensure the stable output power of the impulse turbine.

[0040] In some embodiments, the inertia and stroke of the small nozzle drive mechanism 5 are less than those of the main nozzle drive mechanism 3, and the action response frequency of the small nozzle drive mechanism 5 is higher than that of the main nozzle drive mechanism 3. The smaller inertia and shorter stroke allow the small nozzle drive mechanism 5 to adjust faster.

[0041] In some embodiments, the small nozzle drive mechanism 5 includes a small nozzle hydraulic cylinder 501, a small nozzle servo oil circuit 502, and a high-speed electro-hydraulic servo valve (not shown in the figure). A miniature piston 401 within the small nozzle hydraulic cylinder 501 is connected to the small nozzle 4. The small nozzle servo oil circuit 502 is connected to the cylinder cavity of the small nozzle hydraulic cylinder 501. The high-speed electro-hydraulic servo valve controls high-pressure oil to be supplied to the small nozzle hydraulic cylinder 501 via the small nozzle servo oil circuit 502. When rapid fine-tuning is required, the high-speed electro-hydraulic servo valve switches the oil circuit direction according to the fine-tuning signal, and high-pressure oil enters the cylinder cavity of the small nozzle hydraulic cylinder 501 via the small nozzle servo oil circuit 502. The high-pressure oil pushes the miniature piston 401 to move axially, and the miniature piston 401 drives the small nozzle 4 to move independently axially relative to the main nozzle 2. Figure 8 As shown, according to the adjustment of the oil circuit direction, the high-pressure oil enters the cylinder chamber of the small nozzle hydraulic cylinder 501 through the servo oil circuit 502 of the left small nozzle. The high-pressure oil pushes the micro piston 401 to move axially to the right. The micro piston 401 drives the small nozzle 4 to extend out of the main nozzle 2, reducing the annular flow area inside the nozzle orifice 101.

[0042] In some embodiments, a sleeve 6 is further included, which is coaxially fixed in the central cavity 201. The small nozzle 4 can move axially through the sleeve 6. The space between the tail end of the sleeve 6 and the tail end of the central cavity 201 forms the cylinder cavity of the small nozzle hydraulic cylinder 501. The miniature piston 401 is disposed on the outer periphery of the small nozzle 4 and located in the cylinder cavity of the small nozzle hydraulic cylinder 501. The sleeve 6 provides a guide track for the axial movement of the small nozzle 4, preventing the small nozzle 4 from deflecting and ensuring coaxiality with the main nozzle 2. It also prevents oil leakage from the cylinder cavity.

[0043] In some embodiments, the space between the micro piston 401 and the tail end of the central cavity 201, and the space between the micro piston 401 and the sleeve 6, are respectively connected to the two small needle servo oil circuits 502. Figure 8As shown, there are two small nozzle servo hydraulic circuits 502, one on the left and one on the right. The left small nozzle servo hydraulic circuit 502 connects to the left cylinder chamber, and the right small nozzle servo hydraulic circuit 502 connects to the right cylinder chamber. Figure 8 As shown, when high-pressure oil enters the left small nozzle servo oil circuit 502, the micro piston 401 drives the small nozzle 4 to extend to the right, reducing the annular flow area inside the nozzle orifice 101, and the right small nozzle servo oil circuit 502 is used for oil return; conversely, when high-pressure oil enters the right small nozzle servo oil circuit 502, the micro piston 401 drives the small nozzle 4 to retract to the left, increasing the annular flow area inside the nozzle orifice 101, and the left small nozzle servo oil circuit 502 is used for oil return.

[0044] In some embodiments, the tail end of the small nozzle 4 is fixed with a tail end support 402 that slides with the central cavity 201. The tail end support 402 is provided with an axial through hole (not shown in the figure). The tail end support 402 supports the tail of the small nozzle 4, preventing the small nozzle 4 from deflecting. High-pressure oil can pass through the axial through hole, preventing the high-pressure oil from being blocked in the small nozzle hydraulic cylinder 501. The design is reasonable.

[0045] In some embodiments, the small nozzle servo oil circuit 502 includes oil circuit sections radially opened on the wall of the central cavity 201 and radially opened on the nozzle housing 1. High-pressure oil is supplied through the small nozzle servo oil circuit 502 pre-embedded inside the nozzle housing 1 and controlled by a high-speed electro-hydraulic servo valve to drive the displacement of the miniature piston 401 inside the small nozzle hydraulic cylinder 501, thereby realizing the rapid reciprocating motion of the small nozzle 4.

[0046] In some embodiments, the main nozzle 2 is provided with a detector mounting position 202 for mounting a detector (not shown in the figure). The detector mounting position 202 is located on the rear side of the central cavity 201 and communicates with the central cavity 201. The detector is used to detect the axial displacement of the small nozzle 4. In this way, the small nozzle 4 can adjust the annular flow area inside the nozzle orifice 101 with higher accuracy.

[0047] In some embodiments, the main nozzle drive mechanism 3 includes a main nozzle hydraulic cylinder 301, a main nozzle servo oil circuit 302, and a large electro-hydraulic servo valve; the large piston 203 in the main nozzle hydraulic cylinder 301 is fixed to the tail end of the main nozzle 2, the main nozzle servo oil circuit 302 is connected to the cylinder cavity of the main nozzle hydraulic cylinder 301, and the large electro-hydraulic servo valve controls high-pressure oil to be supplied to the main nozzle hydraulic cylinder 301 through the main nozzle servo oil circuit 302. Specifically, the main nozzle hydraulic cylinder 301 includes a cylinder body; a central chamber 102 is provided in the nozzle housing 1, the cylinder body is located in the rear section of the central chamber 102, the large piston 203 can slide axially through the front end of the cylinder body and is nested in the tail end of the main nozzle 2; the front section of the central chamber 102 and the chamber in the cylinder body form the chamber of the main nozzle hydraulic cylinder 301.

[0048] The working principle of the dual-needle low-power fluctuation adjustable impact turbine nozzle 1000 in this embodiment is as follows: When an increased opening is required, the large electro-hydraulic servo valve opens, and high-pressure oil enters the cylinder chamber of the main nozzle hydraulic cylinder 301 through the main nozzle servo oil circuit 302, pushing the large piston 203 to extend the main nozzle 2. The annular flow area inside the nozzle orifice 101 decreases, and the water jet flow rate decreases. When a decreased opening is required, the large electro-hydraulic servo valve switches direction, and high-pressure oil enters the central chamber 102 through another main nozzle servo oil circuit 302, pushing the large piston 203 to retract the main nozzle 2 into the nozzle housing 1. The annular flow area inside the nozzle orifice 101 increases, and the water jet flow rate increases.

[0049] In some embodiments, a disc spring module 7 is also included. The disc spring module 7 is located in the front section of the central chamber 102 and sleeved on the main nozzle 2. The front end of the disc spring module 7 is fixed, and the rear end of the disc spring module 7 is used to abut against the front end face of the large piston 203. On the one hand, when the large piston 203 moves rapidly (such as when the main nozzle 2 moves axially from left to right), the disc spring module 7 can absorb the impact force and store the energy, and then smoothly transfer it to the large piston 203. On the other hand, the disc spring module 7 can reduce mechanical impact and provide support and protection for the main body of the main nozzle 2.

[0050] In some embodiments, a control system (not shown) is also included. The control system receives a general power regulation command and decomposes the general power regulation command into a large-aperture adjustment signal for controlling the main nozzle 2 and a fine-tuning signal for controlling the small nozzle 4. The general power regulation command here may come from a speed governor or the power grid frequency.

[0051] When the amplitude of the total power adjustment command is large or the duration is long, the small nozzle 4 is in the closed state. The control system controls the main nozzle 2 and the small nozzle 4 to move axially synchronously through the large opening adjustment signal, thereby realizing slow coarse adjustment.

[0052] When the overall power adjustment command is a small, rapid fluctuation, the control system keeps the position of the main nozzle 2 unchanged and controls the rapid extension and retraction of the small nozzle 4 through the fine-tuning signal, thereby achieving rapid fine-tuning.

[0053] When the impulse turbine needs to make significant power adjustments, such as unit start-up and shutdown, or large-scale increases or decreases in load, the control system drives the main nozzle 2 to slowly move to the target position, while the small nozzle 4 remains in the closed state, moving synchronously with the main nozzle 2 and not participating in the adjustment.

[0054] For example, when the impulse turbine is running stably under heavy load, the control system keeps the main nozzle 2 at a fixed large opening. At this time, the control system collects the grid frequency in real time and compares it with the rated frequency, generating a fine-tuning signal for the small nozzle 4 based on the frequency deviation. Taking a rated frequency of 50Hz as an example, when the grid frequency is higher than 50Hz, it indicates that the grid's power generation is relatively high compared to the load, requiring the impulse turbine to reduce its output. The control system drives the small nozzle 4 to extend towards the nozzle orifice 101, reducing the annular flow area of ​​the nozzle orifice 101 and decreasing the water jet flow rate, thereby reducing the output power of the impulse turbine. When the grid frequency is lower than 50Hz, it indicates that the grid load is relatively high compared to the power generation, requiring the impulse turbine to increase its output. The control system drives the small nozzle 4 to retract into the central cavity 201 of the main nozzle 2, increasing the annular flow area of ​​the nozzle orifice 101 and increasing the water jet flow rate, thereby increasing the output power of the impulse turbine.

[0055] Furthermore, before the small nozzle 4 performs rapid fine-tuning, the control system can extend the small nozzle 4 partially out of the central cavity 201 and maintain it at a preset frequency modulation midpoint position. The small nozzle 4 then performs rapid extension and retraction with a short stroke based on this frequency modulation midpoint position: extending the small nozzle 4 further reduces power, while retracting it increases power. Because the small nozzle 4 is lightweight, has low inertia, a short stroke, and a fast response speed, it can rapidly and accurately modulate the nozzle jet flow rate even when the main nozzle 2 is essentially stationary, enabling the impulse turbine's output power to respond promptly to changes in the power grid frequency.

[0056] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be regarded as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A dual-needle, low-power fluctuation adjustable impact turbine nozzle, characterized in that, include: Nozzle housing; The nozzle housing has a nozzle orifice at its axial front end; The main nozzle is axially movable and disposed within the nozzle housing; A main nozzle drive mechanism is used to drive the main nozzle to move slowly axially to slowly coarsely adjust the annular flow area inside the nozzle orifice. The small nozzle is coaxially disposed within the main nozzle and is axially movable relative to the main nozzle. The small nozzle drive mechanism is used to drive the small nozzle to move rapidly axially, so as to quickly fine-tune the annular flow area inside the nozzle orifice.

2. The impact turbine nozzle with low-power fluctuation adjustment via dual-needle spraying as described in claim 1, characterized in that, The main nozzle has a central cavity in its front section, and the main body of the small nozzle is located in the central cavity. When the small nozzle is completely retracted into the central cavity, the small nozzle is in a closed state, and the outer contour of the head of the small nozzle and the main nozzle form a smooth and continuous streamlined flow surface.

3. The impact turbine nozzle with low-power fluctuation adjustment via dual nozzles as described in claim 2, characterized in that, The inertia and stroke of the small nozzle drive mechanism are less than those of the main nozzle drive mechanism, and the action response frequency of the small nozzle drive mechanism is higher than that of the main nozzle drive mechanism.

4. The impact turbine nozzle with low-power fluctuation adjustment via dual nozzles as described in claim 3, characterized in that, The small nozzle drive mechanism includes a small nozzle hydraulic cylinder, a small nozzle servo oil circuit, and a high-speed electro-hydraulic servo valve; the miniature piston in the small nozzle hydraulic cylinder is connected to the small nozzle, the small nozzle servo oil circuit is connected to the cylinder cavity of the small nozzle hydraulic cylinder, and the high-speed electro-hydraulic servo valve controls high-pressure oil to be supplied to the small nozzle hydraulic cylinder through the small nozzle servo oil circuit.

5. The impact turbine nozzle with low-power fluctuation adjustment via dual nozzles as described in claim 4, characterized in that, It also includes a sleeve, which is coaxially fixed in the central cavity, and the small nozzle can move axially through the sleeve; the space between the tail end of the sleeve and the tail end of the central cavity forms the cylinder cavity of the small nozzle hydraulic cylinder, and the micro piston is disposed on the outer periphery of the small nozzle and located in the cylinder cavity of the small nozzle hydraulic cylinder.

6. The impact turbine nozzle with low-power fluctuation adjustment via dual nozzles as described in claim 5, characterized in that, The space between the micro piston and the tail end of the central cavity, and the space between the micro piston and the sleeve, are respectively connected to the two small needle servo oil circuits.

7. The impact turbine nozzle with low-power fluctuation adjustment via dual nozzles as described in claim 5, characterized in that, The tail end of the small nozzle is fixed with a tail end support that slides with the central cavity, and the tail end support is provided with an axial through hole.

8. The impact turbine nozzle with low-power fluctuation adjustment via dual nozzles as described in claim 3, characterized in that, The small needle servo oil circuit includes oil circuit sections that are radially opened on the wall of the central cavity and radially opened on the nozzle housing.

9. The impact turbine nozzle with low-power fluctuation adjustment via dual nozzles as described in claim 2, characterized in that, The main nozzle has a detector mounting position for mounting a detector. The detector mounting position is located on the rear side of the central cavity and communicates with the central cavity. The detector is used to detect the axial displacement of the small nozzle.

10. The impact turbine nozzle with dual-needle low-power fluctuation adjustment according to any one of claims 1-9, characterized in that, It also includes a control system, which receives a total power adjustment command and decomposes the total power adjustment command into a large opening adjustment signal for controlling the main nozzle and a fine adjustment signal for controlling the small nozzle. When the amplitude of the total power adjustment command is large or the duration is long, the small nozzle is in the closed state, and the control system controls the main nozzle and the small nozzle to move axially synchronously through the large opening adjustment signal, thereby realizing slow coarse adjustment. When the overall power adjustment command is a small, rapid fluctuation, the control system keeps the position of the main nozzle unchanged and controls the rapid extension and retraction of the small nozzle through the fine-tuning signal, thereby achieving rapid fine-tuning.

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