A control method for forced air supply of axial flow fixed-blade turbine

Abstract

The present invention belongs to the technical field of fluid machinery and engineering equipment, and specifically discloses a control method for forced air supply of an axial flow fixed blade turbine. By collecting the water head and real-time power data of the turbine and comparing them with the turbine operating characteristic curve, it is determined whether the turbine is in the vortex zone or the non-vortex zone. When it is in the vortex zone, forced air supply is performed. When it is in the non-vortex zone, the forced air supply device is automatically closed, saving energy for driving the air compressor air source. The present invention is adaptable to a variety of different turbine operating conditions. Through this control method, the purpose of automatically starting and stopping the air supply device under different turbine operating conditions and controlling the air supply flow rate can be achieved. On the basis of ensuring the energy conversion efficiency of the axial flow fixed blade turbine, the problem of insufficient air supply causing the vortex to be eliminated, which in turn causes hydraulic vibration of the tailwater pipe components, is fully prevented, and the problem of wasting energy for driving the air compressor air source due to excessive air supply is eliminated.

Description

Technical Field

[0001] The present invention belongs to the technical field of fluid machinery and engineering equipment, and in particular relates to a control method for forced air supply of an axial flow fixed-blade turbine. Background Art

[0002] Because the runner blades of axial-flow fixed-pitch turbines are rigidly attached to the hub, output can often only be adjusted by adjusting the opening of the guide vanes when the water head changes. This type of turbine often operates under biased operating conditions but cannot adapt effectively to these conditions, reducing energy conversion efficiency and causing hazards such as hydraulic vibration, which affects the normal and stable operation of the unit. The main cause of hydraulic vibration is the formation of vortices in the draft tube, which causes pressure pulsations. These pressure pulsations propagate upstream, causing vibrations in the turbine unit.

[0003] To reduce or eliminate the hydraulic vibration caused by vortexes, air is often injected into the draft tube to eliminate the pressure difference in the vortex. This air injection can be done naturally or by force. This involves using an air injection device to naturally connect the inside and outside of the draft tube, or by using an air injection device and an air compressor to forcibly pump air in.

[0004] Existing methods for controlling forced air supply in axial-flow fixed-blade turbines typically rely on natural air supply or an air compressor with a fixed air supply flow rate. This air supply control method is not well adapted to various turbine operating conditions. Under low-flow conditions, the high intensity of the vortex bands can easily lead to insufficient air supply and an inability to eliminate the vortex bands. Under high-flow conditions, the low intensity of the vortex bands can easily lead to excessive air supply, wasting energy that drives the air compressor, affecting the energy conversion efficiency of the axial-flow fixed-blade turbine, and causing economic losses. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the purpose of the present invention is to provide a control method for forced air supply of an axial flow fixed-blade turbine, so as to solve the problem that the existing forced air supply method cannot adapt to a variety of different turbine operating conditions.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] The present invention provides a control method for forced air supply of an axial flow fixed-blade turbine, comprising:

[0008] S1: Collect turbine water level sensor data and calculate turbine head;

[0009] S2: collects real-time power data of turbine;

[0010] S3: Combine the turbine head and real-time power data and compare them with the turbine operating characteristic curve to determine whether the turbine is in the vortex zone or the non-vortex zone, and determine whether to perform forced air replenishment through the programmable controller;

[0011] S4: If forced air supply is required, the programmable controller automatically calculates the real-time air supply volume flow rate based on the air supply volume flow rate-power control curve of forced air supply under different working conditions and performs forced air supply.

[0012] Furthermore, if forced air supply is not required, the programmable controller automatically drives the air compressor to remain in a stopped state.

[0013] Furthermore, the step of collecting turbine water level sensor data and calculating turbine head includes:

[0014] The upstream water level sensor and downstream water level sensor data of the turbine are collected through the upstream water level sensor and the downstream water level sensor data of the turbine, the upstream and downstream water level difference of the turbine is obtained by real-time monitoring, and the turbine head under the working condition is calculated.

[0015] Furthermore, the step of collecting real-time power data of the turbine includes:

[0016] The real-time power data of the turbine is collected through the turbine output power detection sensor.

[0017] Furthermore, the turbine operating characteristic curve diagram is based on the vortex belt test data of the fixed-blade turbine, and the vortex belt boundary line is drawn based on whether obvious vortex belts are generated in the tailwater pipe and whether there is obvious pressure pulsation phenomenon in various parts of the tailwater pipe; with the vortex belt boundary line as the boundary, the area on the left side of the boundary line is the tailwater pipe vortex belt area, and the area on the right side of the boundary line is the non-vortex belt area.

[0018] Furthermore, when the turbine is in the vortex zone, air is forcibly supplied to the turbine.

[0019] Furthermore, the programmable controller automatically calculates the real-time air supply volume flow rate, including: calling the air supply volume flow rate data stored in the programmable controller to automatically calculate the real-time air supply volume flow rate; the air supply volume flow rate is related to the head and power under the real-time working conditions of the turbine, and the air supply volume flow rate is obtained according to the air supply volume flow rate-power control curve of forced air supply under different working conditions.

[0020] Furthermore, the programmable controller controls the air compressor to output the air supply volume flow to the forced air supply device to force air supply to the turbine.

[0021] Furthermore, the air supply volume flow rate is related to the head parameter under the real-time working condition of the turbine, and the function of power is a piecewise function with a negative logarithmic property, and its function expression is:

[0022]

[0023] Where: V is the volume flow rate of the air supply, in m 3 / s; P is the real-time operating power of the turbine, in MW; H is the real-time operating head of the turbine, in m; k and b are fitting parameters, where the value of k is between 0.5-0.8, and the value of b is between 4-8; P0 is the operating power on the vortex boundary line in the schematic diagram of the turbine operating characteristic curve; the control function shows a negative logarithmic relationship in the vortex zone and a zero air supply volume flow rate in the non-vortex zone.

[0024] Furthermore, in the vortex zone of the tailwater pipe, when it is in a small flow condition, the programmable controller drives the air compressor to automatically increase the air supply flow; when it is in a large flow condition, the programmable controller drives the air compressor to automatically adjust the air supply volume flow to a smaller value.

[0025] The present invention has at least the following beneficial effects:

[0026] 1. The present invention collects the water head and real-time power data of the turbine, compares them with the turbine operating characteristic curve, and determines whether the turbine is in the vortex zone or the non-vortex zone. When it is in the vortex zone, forced air supply is performed. When it is in the non-vortex zone, the forced air supply device is automatically closed, saving energy for driving the air compressor air source. The present invention is adaptable to a variety of different turbine operating levels. Through this control method, it can achieve the purpose of automatically starting and stopping the air supply device under different turbine operating conditions and controlling the air supply flow rate. On the basis of ensuring the energy conversion efficiency of the axial flow fixed blade turbine, it fully prevents the problem of insufficient air supply causing the vortex to be eliminated, which in turn causes hydraulic vibration of the tailwater pipe components, and eliminates the problem of wasting energy for driving the air compressor air source due to excessive air supply.

[0027] 2. When the present invention is in the vortex zone of the tailwater pipe and is under low flow conditions, the air supply flow rate is appropriately increased to fully eliminate the vortex and reduce the hydraulic vibration caused by the vortex; when it is under high flow conditions, the air supply volume flow rate is automatically adjusted to a smaller level due to the small vortex intensity, thereby minimizing the impact on the energy conversion efficiency of the axial flow fixed-blade turbine. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0029] Figure 1 It is a schematic diagram of the process of the present invention;

[0030] Figure 2Schematic diagram of the operating characteristic curve of the hydraulic turbine of the present invention;

[0031] Figure 3 This is the air supply volume flow-power control curve of the forced air supply under different working conditions of the present invention. DETAILED DESCRIPTION

[0032] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other.

[0033] The following detailed description is an exemplary description and is intended to provide further detailed description of the present invention. Unless otherwise indicated, all technical terms used in the present invention have the same meaning as those generally understood by those skilled in the art to which the present invention belongs. The terms used in the present invention are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention.

[0034] like Figure 1 As shown, a control method for forced air supply of an axial flow fixed-blade turbine includes:

[0035] S1: The upstream water level sensor and downstream water level sensor data of the turbine are collected through the upstream water level sensor and the downstream water level sensor. The upstream and downstream water level difference of the turbine can be monitored in real time, and the turbine head under the working condition can be calculated.

[0036] S2: Collect real-time power data of the turbine through the turbine output power detection sensor.

[0037] S3: Combine the turbine head and real-time power data and compare them with the turbine operation characteristic curve to determine the position of the operating point of the turbine during operation on the turbine characteristic curve, and obtain the distance between the real-time operating condition and the vortex zone boundary line; judge whether the turbine is in the vortex zone or the non-vortex zone; determine whether to perform forced air replenishment through the programmable controller; if the turbine is in the vortex zone, force air replenishment is performed on the turbine.

[0038] like Figure 2 The figure shows the operating characteristic curve of the turbine, showing the relationship between the turbine head H (m) and the power P (kW). The operating characteristic curve of the turbine is based on the vortex belt test data of a certain type of fixed-blade turbine. The vortex belt boundary line is determined based on whether obvious vortex belts are generated in the tailwater tube and whether there is obvious pressure pulsation in various parts of the tailwater tube. With the vortex belt boundary line as the boundary, the area to the left of the boundary line is the tailwater tube vortex belt area, and the area to the right of the boundary line is the non-vortex belt area. When the turbine is in the tailwater tube vortex belt area, the farther the distance from the vortex belt boundary line is, the larger the vortex belt generated is and the greater the amount of air supply required.

[0039] S4: If forced air supply is required, the air supply volume flow data stored in the programmable controller is called up to automatically calculate the real-time air supply volume flow rate. The air supply volume flow rate is related to the head and power under the real-time operating conditions of the turbine. The air supply volume flow rate is calculated based on the air supply volume flow-power control curve for forced air supply under different operating conditions. The air supply volume flow rate is converted into an electrical signal representing the air compressor air source pressure and output to the air compressor, controlling the air compressor to output the air supply volume flow rate to the forced air supply device. If forced air supply is not required, the programmable controller automatically drives the air compressor to remain in a stopped state.

[0040] like Figure 3 The figure shows the air supply volume flow-power control curve under different working conditions of the turbine; the air supply volume flow (m 3 The relationship between the air supply volume flow rate (m / s) and power (MW) is a piecewise function, showing a negative logarithmic relationship in the vortex zone and zero in the non-vortex zone. The air supply volume flow rate is related to the head parameters under the real-time operating conditions of the turbine, and the function of power is a piecewise function with a negative logarithmic property. Its function expression is:

[0041]

[0042] In the above formula, V is the volume flow rate of the air supply, in m 3 / s; P is the turbine's real-time operating power, in MW; H is the turbine's real-time operating head, in m; k and b are fitting parameters, with k ranging from 0.5 to 0.8 and b ranging from 4 to 8. P0 is the operating power at the vortex boundary line in the turbine's operating characteristic curve. The air supply volume flow rate is obtained based on the air supply volume flow rate-power control curve for different turbine operating heads. In the draft tube vortex zone, under low flow conditions, that is, operating to the left of the vortex boundary line as shown in the turbine's operating characteristic curve, the programmable controller drives the air compressor to appropriately increase the air supply flow rate to fully eliminate the vortex and reduce the hydraulic vibration caused by the vortex. Under high flow conditions, that is, operating to the right of the vortex boundary line as shown in the turbine's operating characteristic curve, due to the low vortex intensity, the programmable controller drives the air compressor to automatically adjust the air supply volume flow rate to a lower level, minimizing the impact on the energy conversion efficiency of the axial-flow fixed-pitch turbine.

[0043] It is understood from common technical knowledge that the present invention may be implemented by other embodiments that do not depart from its spirit or essential features. Therefore, the embodiments disclosed above are, in all respects, merely illustrative and not exclusive. All modifications within the scope of the present invention or equivalent to the scope of the present invention are intended to be encompassed by the present invention.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A control method for forced air supply of an axial flow fixed-blade turbine, characterized in that: include: S1: Collect turbine water level sensor data and calculate turbine head; S2: collects real-time power data of turbine; S3: Combine the turbine head and real-time power data and compare them with the turbine operating characteristic curve to determine whether the turbine is in the vortex zone or the non-vortex zone, and determine whether to perform forced air replenishment through the programmable controller; S4: If forced air supply is required, the programmable controller automatically calculates the real-time air supply volume flow rate based on the forced air supply volume flow rate-power control curve under different working conditions and controls the air compressor to force air supply; The turbine operating characteristic curve is based on the vortex belt test data of the fixed-blade turbine. The vortex belt boundary line is delineated based on whether obvious vortex belts are generated in the draft tube and whether there is obvious pressure pulsation phenomenon in various parts of the draft tube. The area to the left of the boundary line is the draft tube vortex belt area, and the area to the right of the boundary line is the vortex belt-free area. When the turbine is in the vortex zone, the turbine is forcibly supplied with air; The programmable controller automatically calculates the real-time gas supplement volume flow rate, including: calling the gas supplement volume flow rate data stored in the programmable controller to automatically calculate the real-time gas supplement volume flow rate; The air supply volume flow rate is related to the head and power under the real-time working conditions of the turbine. The air supply volume flow rate is obtained according to the air supply volume flow rate-power control curve of forced air supply under different working conditions.

2. The control method for forced air supply of an axial flow fixed-blade turbine according to claim 1, characterized in that: If forced air supply is not required, the programmable controller automatically drives the air compressor to remain in a stopped state.

3. The control method for forced air supply of an axial flow fixed-pitch turbine according to claim 1, characterized in that: The step of collecting turbine water level sensor data and calculating turbine head includes: The upstream water level sensor and downstream water level sensor data of the turbine are collected through the upstream water level sensor and the downstream water level sensor data of the turbine, the upstream and downstream water level difference of the turbine is obtained by real-time monitoring, and the turbine head under the working condition is calculated.

4. The control method for forced air supply of an axial flow fixed-pitch turbine according to claim 1, characterized in that: The step of collecting real-time power data of the turbine includes: The real-time power data of the turbine is collected through the turbine output power detection sensor.

5. The control method for forced air supply of an axial flow fixed-blade turbine according to claim 1, characterized in that: The programmable controller controls the air compressor to output the air supply volume flow to the forced air supply device to force air supply to the turbine.

6. A control method for forced air supply of an axial flow fixed-pitch turbine according to claim 5, characterized in that: The air supply volume flow rate is related to the head parameter under the real-time working condition of the turbine, and the function of power is a piecewise function with negative logarithmic properties. Its function expression is: Where: is the volume flow rate of the air supply, in m 3 / s; P is the real-time operating power of the turbine, in MW; H is the real-time operating water head of the turbine, in m; and are fitting parameters, among which The value of is between 0.5-0.8, The value of is between 4-8; is the operating power on the vortex boundary line in the turbine operating characteristic curve diagram; the control function shows a negative logarithmic relationship in the vortex zone and a zero air supply volume flow rate in the non-vortex zone.

7. A control method for forced air supply of an axial flow fixed-pitch turbine according to claim 6, characterized in that: In the vortex zone of the tailwater pipe, when it is under low flow conditions, the programmable controller drives the air compressor to automatically increase the air supply flow; when it is under high flow conditions, the programmable controller drives the air compressor to automatically adjust the air supply volume flow to a smaller value.

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