Method and device for eliminating low-frequency oscillation of forced mechanism of hydroelectric generating set

Abstract

The invention discloses a hydroelectric generating set forced mechanism low-frequency oscillation elimination method and device, and the method comprises the steps: monitoring the power oscillation inherent frequency of a hydroelectric generating set at different load sections, and determining the resonant frequency early warning range of the pressure pulsation of a draft tube of the hydroelectric generating set according to the power oscillation inherent frequency of the hydroelectric generating set; a hydroelectric generating set combination strategy considering the vibration area is calculated to obtain the resonance adjustable load capacity, and the guide vane opening degree corresponding to each hydroelectric generating set is reversely calculated according to the resonance adjustable load capacity; when it is monitored that the hydroelectric generating set draft tube pressure pulsation frequency is within the resonance frequency early warning range and the amplitude exceeds the set value, the multiple hydroelectric generating sets are controlled to act in a coordinated mode to adjust the guide vane opening degree. Under the condition that a prime motor and a water diversion system are not changed, forced power oscillation accidentally occurring in the vibration crossing area of the large hydropower station can be rapidly eliminated.

Description

Technical Field

[0001] The invention relates to the technical field of automatic control of hydroelectric generator sets, and in particular to a method and a device for eliminating low-frequency oscillation of a forced mechanism of a hydroelectric generator set. Background Art

[0002] In areas with a high proportion of new energy and hydropower in new power systems, the risks of low-frequency oscillation, ultra-low-frequency oscillation in power grids and forced oscillation caused by the characteristics of hydropower units have caused the risks of safe operation of power grids and hydropower units to become more prominent. The Xiangjiaba Power Plant, the Three Gorges Power Plant, and the Baihetan Power Plant have all experienced forced mechanism power oscillations during active power regulation under specific working conditions, causing the synchronous phasor measurement device to send a low-frequency oscillation alarm to the National Dispatching Center, affecting the operation of nearby power grids and units.

[0003] The existing technologies related to the oscillation of hydropower units mainly focus on oscillation monitoring, mechanism analysis, disturbance source location and control methods. For the forced oscillation caused by the hydraulic characteristics of hydropower units, the Chinese patent "A control method for preventing the oscillation of power regulation of hydropower units" proposes the method of adaptive PID parameters of unit power regulation and adding filtering links in the power measurement link. Many units do not adopt PID regulation, so the method lacks wide applicability. The document "Analysis of the Cause of Low-Frequency Oscillation of Unit 3 of Ertan Hydropower Station" introduces that the Ertan Hydropower Station suppresses the pressure pulsation and output swing of the tailwater pipe by optimizing the main shaft air supply method, lengthening the discharge cone, and installing guide plates on the tailwater pipe. However, the technical implementation has high requirements on site conditions, is difficult and takes a long time to construct. The document "A method for suppressing active oscillation of large hydropower units using damping sills" installs damping sills at specific parts of the branch channel of the tailwater channel of the power station to form a weir flow in the branch channel. The purpose of energy dissipation and vibration reduction is achieved through the local head loss generated on the weir. This technology also requires on-site construction, and its effect remains to be verified. Summary of the invention

[0004] In view of the current problems of insufficient control capability, single suppression measures and weak elimination methods of low-frequency oscillations of forced mechanism of hydropower units, the present invention proposes a method and device for eliminating low-frequency oscillations of forced mechanism of hydropower units, which can quickly eliminate the forced power oscillations that occasionally occur when a large hydropower station crosses the vibration zone without changing the prime mover and the water diversion system.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A method for eliminating low-frequency oscillation of a forced mechanism of a hydropower unit, comprising:

[0007] Monitor the natural frequency of power oscillation of hydropower units at different load sections, and determine the early warning range of the resonance frequency of tailwater pipe pressure pulsation of hydropower units based on the natural frequency of power oscillation of hydropower units;

[0008] The combination strategy of hydropower units considering the vibration zone is calculated to obtain the resonant adjustable load, and the guide vane opening corresponding to each hydropower unit is reversely calculated based on the resonant adjustable load;

[0009] When it is detected that the pressure pulsation frequency of the tailwater pipe of the hydropower unit falls within the resonance frequency warning range and the amplitude exceeds the set value, multiple hydropower units are controlled to coordinate their actions to adjust the guide vane opening.

[0010] Furthermore, the monitoring of the power oscillation natural frequency of the hydropower units in different load sections includes: the generator is connected to the grid, the power system stabilizer is exited, a 2% generator stator voltage step test is performed, and the changes in the power oscillation natural frequency and damping ratio of the hydropower units in different water heads and different load sections are tested, and the swing amplitude and number of active power are recorded by a recording instrument to obtain the measured natural oscillation frequency.

[0011] Furthermore, the calculation of the combination strategy of hydropower units considering the vibration zone obtains the resonant adjustable load, including: calculating the load distribution of the hydropower units considering the vibration zone according to the start-up status of the hydropower units in the hydropower station, and finding the optimal number of generators and the load distribution strategy for each unit under the given water volume according to the principle of equal incremental rate, so that the output power of the hydropower station remains unchanged while satisfying the constraints.

[0012] Furthermore, the constraint conditions include hydropower station flow constraint, spinning reserve constraint and operation range constraint.

[0013] Furthermore, when it is monitored that the pressure pulsation frequency of the tailwater pipe of the hydropower unit falls within the resonance frequency warning range and the amplitude exceeds the set value, multiple hydropower units are controlled to coordinate actions to adjust the guide vane opening, including: monitoring the tailwater pressure pulsation of the hydropower unit, if the frequency of the tailwater pressure pulsation falls within the resonance frequency warning range and the amplitude of the pulsation is greater than the set value, initiating active preventive action; the active preventive action includes: in combination with the power oscillation of the hydropower unit, the machine increases the guide vane opening, and adjusts the load increase to the resonance adjustable load; at the same time, another machine cooperates to reduce the load, and adjusts the load reduction to the resonance adjustable load.

[0014] A device for eliminating low-frequency oscillation of a forced mechanism of a hydropower unit, comprising:

[0015] The frequency monitoring module is configured to monitor the natural frequency of power oscillation of the hydropower unit in different load sections, and determine the resonant frequency warning range of the tailwater pipe pressure pulsation of the hydropower unit according to the natural frequency of power oscillation of the hydropower unit;

[0016] The load calculation module is configured to calculate the combination strategy of the hydropower units taking into account the vibration zone to obtain the resonant adjustable load, and reversely calculate the guide vane opening corresponding to each hydropower unit according to the resonant adjustable load;

[0017] The frequency control module is configured to control multiple hydropower units to coordinate actions and adjust the guide vane opening when the pressure pulsation frequency of the tailwater pipe of the hydropower unit falls within the resonance frequency warning range and the amplitude exceeds the set value.

[0018] Furthermore, in the frequency monitoring module, the natural frequency of power oscillation of hydropower units in different load sections is monitored, including: the generator is connected to the grid, the power system stabilizer is exited, a 2% generator stator voltage step test is performed, and the changes in the natural frequency of power oscillation and damping ratio of hydropower units with different water heads and different load sections are tested, and the swing amplitude and number of active power are recorded by a recording instrument to obtain the measured natural oscillation frequency.

[0019] Furthermore, in the load calculation module, a combination strategy of hydropower units taking into account the vibration zone is calculated to obtain a resonant adjustable load, including: calculating the load distribution of hydropower units taking into account the vibration zone according to the start-up status of the hydropower units in the hydropower station, and finding the optimal number of generators and the load distribution strategy for each unit under the given water volume according to the principle of equal incremental rate, so that the output power of the hydropower station remains unchanged while satisfying the constraints.

[0020] Furthermore, the constraint conditions include hydropower station flow constraint, spinning reserve constraint and operation range constraint.

[0021] Furthermore, in the frequency control module, when it is monitored that the pressure pulsation frequency of the tailwater pipe of the hydropower unit falls within the resonance frequency warning range and the amplitude exceeds the set value, multiple hydropower units are controlled to coordinate actions to adjust the guide vane opening, including: monitoring the tailwater pressure pulsation of the hydropower unit, if the frequency of the tailwater pressure pulsation falls within the resonance frequency warning range and the amplitude of the pulsation is greater than the set value, initiating active prevention actions; the active prevention actions include: in combination with the power oscillation of the hydropower unit, the machine increases the guide vane opening, and adjusts the load increase to the resonance adjustable load; at the same time, another machine cooperates to reduce the load, and adjusts the load reduction to the resonance adjustable load.

[0022] The beneficial effects of the present invention are:

[0023] 1. The present invention can quickly eliminate the forced power oscillation that occasionally occurs when a large hydropower station crosses the vibration zone without changing the prime mover and the water diversion system. The present invention adopts a combined optimization dispatching method for hydropower units. On the one hand, the resonance frequency band is determined according to the measured natural frequency of the oscillation of the unit power in different load sections. On the other hand, according to the startup situation in the plant, the combination scheme of the hydropower units considering the vibration zone is calculated to obtain the resonant adjustable load, and finally the hydropower unit responds to the forced mechanism low-frequency oscillation in seconds, thereby reducing the number of low-frequency oscillation alarms sent by the synchronous phasor measurement device to the dispatching center, and reducing the impact on the nearby power grid and unit operation.

[0024] 2. The present invention aims at the problems of insufficient control capability of low-frequency oscillation of forced mechanism of hydropower units, single suppression measures, weak elimination methods, etc., and takes into account the inability to avoid operation in the resonance zone and the inability to eliminate the resonance phenomenon. Adhering to the principle of prevention first, the present invention starts active prevention when the hydropower unit enters the vortex zone, and utilizes the second-level response of the hydropower unit guide vane to control the effective frequency of the unit power fluctuation within the 15s disturbance interval, thereby eliminating the low-frequency oscillation alarm issued by the synchronous phasor measurement device, and promoting the hydropower unit to quickly pass through the resonance zone and reach the stable zone for operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a flow chart of a method for eliminating low-frequency oscillation of a hydropower unit forced mechanism according to Example 1 of the present invention.

[0026] Figure 2 This is a flow chart of a method for eliminating low-frequency oscillation of a hydropower unit forced mechanism according to Example 2 of the present invention.

[0027] Figure 3 This is a recording diagram of the measured natural frequency of power oscillation of the unit according to Example 2 of the present invention.

[0028] Figure 4 This is a field test waveform diagram of the application effect of Example 2 of the present invention. DETAILED DESCRIPTION

[0029] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific implementation methods of the present invention are now described. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the embodiments described are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0030] Example 1

[0031] The low-frequency oscillation phenomenon of the forced oscillation mechanism triggered when a large hydropower station crosses the vibration zone is accidental, but the essential inducement, namely the hydraulic factors of the hydropower unit, always exists objectively. This is a problem that requires long-term attention and needs to be solved.

[0032] Based on this, this embodiment provides a method for eliminating low-frequency oscillation of a hydropower unit forced mechanism, such as Figure 1 As shown, including:

[0033] Monitor the natural frequency of power oscillation of hydropower units at different load sections, and determine the early warning range of the resonance frequency of tailwater pipe pressure pulsation of hydropower units based on the natural frequency of power oscillation of hydropower units;

[0034] The combination strategy of hydropower units considering the vibration zone is calculated to obtain the resonant adjustable load, and the guide vane opening corresponding to each hydropower unit is reversely calculated based on the resonant adjustable load;

[0035] When it is detected that the pressure pulsation frequency of the tailwater pipe of the hydropower unit falls within the resonance frequency warning range and the amplitude exceeds the set value, multiple hydropower units are controlled to coordinate their actions to adjust the guide vane opening.

[0036] Preferably, the power oscillation natural frequency of the hydropower units in different load sections is monitored, including: the generator is connected to the grid, the power system stabilizer is exited, a 2% generator stator voltage step test is performed, the changes in the power oscillation natural frequency and damping ratio of the hydropower units in different water heads and different load sections are tested, and the swing amplitude and frequency of the active power are recorded by a recording instrument to obtain the measured natural oscillation frequency.

[0037] It should be noted that by testing the changes in the unit power oscillation natural frequency and damping ratio at different heads and loads through a 2% generator stator voltage step test, it is possible to avoid using the unit power oscillation natural frequency under the "stable zone" operating condition to represent the unit power oscillation natural frequency in the "resonance zone". In addition, based on the unit power oscillation natural frequency and damping ratio in the "resonance zone", the early warning range of the tailwater pressure pulsation resonance frequency is determined, preferably 0.95 to 1.05 times the power oscillation natural frequency.

[0038] Preferably, the combination strategy of the hydropower units considering the vibration zone is calculated to obtain the resonant adjustable load, including: according to the startup status of the hydropower units in the hydropower station, the load distribution of the hydropower units considering the vibration zone is calculated, and according to the principle of equal incremental rate, the optimal number of generators and the load distribution strategy of each unit are found under the given water volume, so that the output power of the hydropower station remains unchanged under the condition of satisfying the constraint conditions. More preferably, the constraint conditions include the flow constraint of the hydropower station, the spinning reserve constraint and the operation range constraint.

[0039] Preferably, when it is detected that the pressure pulsation frequency of the tailwater pipe of the hydropower unit falls within the resonance frequency warning range and the amplitude exceeds the set value, multiple hydropower units are controlled to coordinate actions to adjust the guide vane opening, including: monitoring the tailwater pressure pulsation of the hydropower unit, if the frequency of the tailwater pressure pulsation falls within the resonance frequency warning range, and the amplitude of the pulsation is greater than the set value, the active prevention action is initiated; the active prevention action includes: in combination with the power oscillation of the hydropower unit, the machine increases the guide vane opening, and adjusts the load increase to the resonance adjustable load; at the same time, another machine cooperates to reduce the load, and adjusts the load reduction to the resonance adjustable load. It should be noted that the coordinated action of multiple hydropower units to adjust the guide vane opening helps to shorten the time it takes for the hydropower unit to cross the unstable operation zone.

[0040] Example 2

[0041] This embodiment is based on embodiment 1:

[0042] This embodiment provides a method for eliminating low-frequency oscillation of a hydropower unit forced mechanism, such as Figure 2 As shown, the following steps are included:

[0043] Step 1: When the generator is connected to the grid, first exit the power system stabilizer PSS and conduct a 2% generator stator voltage step test. At the same time, start the wave recorder to record the swing amplitude and frequency of the active power to obtain the measured natural oscillation frequency of the machine, such as Figure 3 and Figure 4 shown.

[0044] Step 2: Select 95%-105% of the measured natural oscillation frequency of the machine as the resonance frequency band;

[0045] Step 3: According to the startup status of the hydropower station, calculate the combination of hydropower units taking into account the vibration zone, and obtain the resonant adjustable load. According to the principle of equal incremental rate, find the optimal number of generators and load distribution of each unit under the given water volume, so that the output power of the hydropower station remains unchanged while meeting the constraints.

[0046] Step 4: Based on the resonant adjustable load, each hydropower unit in the station needs to reversely calculate the corresponding guide vane opening adjustment value.

[0047] Step 5: Monitor and predict the tailwater pressure pulsation of the unit to ensure the advance amount of active preventive action. If the frequency of the tailwater pressure pulsation is in the resonant frequency band and the amplitude of the pulsation is greater than 5% of the rated pressure value, initiate active preventive action.

[0048] Step 6: In combination with the power oscillation of the unit, this machine quickly increases the guide vane opening and adjusts the load increase to the resonant adjustable load. At the same time, the other machine cooperates to reduce the load and adjusts the load reduction to the resonant adjustable load.

[0049] Step 7: After the active preventive action of the unit is completed, the unit enters the next monitoring cycle.

[0050] Example 3

[0051] This embodiment provides a device for eliminating low-frequency oscillation of a hydropower unit forced mechanism, comprising:

[0052] The frequency monitoring module is configured to monitor the natural frequency of power oscillation of the hydropower unit in different load sections, and determine the resonant frequency warning range of the tailwater pipe pressure pulsation of the hydropower unit according to the natural frequency of power oscillation of the hydropower unit;

[0053] The load calculation module is configured to calculate the combination strategy of the hydropower units taking into account the vibration zone to obtain the resonant adjustable load, and reversely calculate the guide vane opening corresponding to each hydropower unit according to the resonant adjustable load;

[0054] The frequency control module is configured to control multiple hydropower units to coordinate actions and adjust the guide vane opening when the pressure pulsation frequency of the tailwater pipe of the hydropower unit falls within the resonance frequency warning range and the amplitude exceeds the set value.

[0055] Preferably, in the frequency monitoring module, the natural frequency of power oscillation of hydropower units in different load sections is monitored, including: the generator is connected to the grid, the power system stabilizer is exited, a 2% generator stator voltage step test is performed, and the changes in the natural frequency of power oscillation and damping ratio of hydropower units with different water heads and different load sections are tested, and the swing amplitude and number of active power are recorded by a recording instrument to obtain the measured natural oscillation frequency.

[0056] Preferably, in the load calculation module, the combination strategy of the hydropower units considering the vibration zone is calculated to obtain the resonant adjustable load, including: according to the start-up status of the hydropower units in the hydropower station, the load distribution of the hydropower units considering the vibration zone is calculated, and according to the principle of equal incremental rate, the optimal number of generators and the load distribution strategy for each unit are found under the given water volume, so that the output power of the hydropower station remains unchanged while satisfying the constraints.

[0057] Preferably, the constraint conditions include hydropower station flow constraint, spinning reserve constraint and operation range constraint.

[0058] Preferably, in the frequency control module, when it is monitored that the pressure pulsation frequency of the tailwater pipe of the hydropower unit falls within the resonance frequency warning range and the amplitude exceeds the set value, multiple hydropower units are controlled to coordinate actions to adjust the guide vane opening, including: monitoring the tailwater pressure pulsation of the hydropower unit, if the frequency of the tailwater pressure pulsation falls within the resonance frequency warning range, and the amplitude of the pulsation is greater than the set value, initiating active preventive action; the active preventive action includes: in combination with the power oscillation of the hydropower unit, the machine increases the guide vane opening, and adjusts the load increase to the resonance adjustable load; at the same time, another machine cooperates to reduce the load, and adjusts the load reduction to the resonance adjustable load.

[0059] Example 4

[0060] This embodiment is based on embodiment 1:

[0061] This embodiment provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, a method for eliminating low-frequency oscillation of a hydropower unit forced mechanism in embodiment 1 is implemented. The computer program may be in source code form, object code form, executable file, or some intermediate form.

[0062] Example 5

[0063] This embodiment is based on embodiment 1:

[0064] This embodiment provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements a method for eliminating low-frequency oscillations of a hydropower unit forced mechanism in Embodiment 1. The computer program may be in source code form, object code form, executable file, or some intermediate form, etc. The storage medium includes: any entity or device capable of carrying computer program code, recording medium, computer memory, read-only memory (ROM), random access memory (RAM), electric carrier signal, telecommunication signal, and software distribution medium, etc. It should be noted that the content contained in the storage medium may be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the storage medium does not include electric carrier signals and telecommunication signals.

[0065] It should be noted that, for the aforementioned method embodiments, for the sake of simplicity of description, they are expressed as a series of action combinations, but those skilled in the art should be aware that the present application is not limited by the order of the actions described, because according to the present application, certain steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily required by the present application.

Claims

1. A method for eliminating low-frequency oscillation of a hydropower unit forced mechanism, characterized in that: include: Monitor the natural frequency of power oscillation of hydropower units at different load sections, and determine the early warning range of the resonance frequency of tailwater pipe pressure pulsation of hydropower units based on the natural frequency of power oscillation of hydropower units; The combination strategy of hydropower units considering the vibration zone is calculated to obtain the resonant adjustable load, and the guide vane opening corresponding to each hydropower unit is reversely calculated based on the resonant adjustable load; When it is detected that the pressure pulsation frequency of the tailwater pipe of the hydropower unit falls within the resonance frequency warning range and the amplitude exceeds the set value, multiple hydropower units are controlled to coordinate their actions to adjust the guide vane opening.

2. A method for eliminating low-frequency oscillation of a hydropower unit forced mechanism according to claim 1, characterized in that: The monitoring of the power oscillation natural frequency of the hydropower unit in different load sections includes: connecting the generator to the grid, exiting the power system stabilizer, performing a 2% generator stator voltage step test, testing the changes in the power oscillation natural frequency and damping ratio of the hydropower unit in different water heads and different load sections, and recording the swing amplitude and number of active power through a recording instrument to obtain the measured natural oscillation frequency.

3. A method for eliminating low-frequency oscillation of a hydropower unit forced mechanism according to claim 1, characterized in that: The calculation of the combination strategy of the hydropower units considering the vibration zone to obtain the resonant adjustable load includes: calculating the load distribution of the hydropower units considering the vibration zone according to the start-up status of the hydropower units in the hydropower station, and finding the optimal number of generators and the load distribution strategy of each unit under the given water volume according to the principle of equal incremental rate, so that the output power of the hydropower station remains unchanged under the condition of satisfying the constraint conditions.

4. A method for eliminating low-frequency oscillation of a hydropower unit forced mechanism according to claim 3, characterized in that: The constraints include hydropower station flow constraints, spinning reserve constraints and operation range constraints.

5. A method for eliminating low-frequency oscillation of a hydropower unit forced mechanism according to claim 1, characterized in that: When it is detected that the pressure pulsation frequency of the tailwater pipe of the hydropower unit falls within the resonance frequency warning range and the amplitude exceeds the set value, multiple hydropower units are controlled to coordinate actions to adjust the guide vane opening, including: monitoring the tailwater pressure pulsation of the hydropower unit, if the frequency of the tailwater pressure pulsation falls within the resonance frequency warning range, and the amplitude of the pulsation is greater than the set value, initiating active prevention action; the active prevention action includes: in combination with the power oscillation of the hydropower unit, the machine increases the guide vane opening, and adjusts the load increase to the resonance adjustable load; at the same time, another machine cooperates to reduce the load, and adjusts the load reduction to the resonance adjustable load.

6. A device for eliminating low-frequency oscillation of a hydropower unit forced mechanism, characterized in that: include: The frequency monitoring module is configured to monitor the natural frequency of power oscillation of the hydropower unit in different load sections, and determine the resonant frequency warning range of the tailwater pipe pressure pulsation of the hydropower unit according to the natural frequency of power oscillation of the hydropower unit; The load calculation module is configured to calculate the combination strategy of the hydropower units taking into account the vibration zone to obtain the resonant adjustable load, and reversely calculate the guide vane opening corresponding to each hydropower unit according to the resonant adjustable load; The frequency control module is configured to control multiple hydropower units to coordinate actions and adjust the guide vane opening when the pressure pulsation frequency of the tailwater pipe of the hydropower unit falls within the resonance frequency warning range and the amplitude exceeds the set value.

7. A device for eliminating low-frequency oscillation of a hydropower unit forced mechanism according to claim 6, characterized in that: In the frequency monitoring module, the power oscillation natural frequency of the hydropower unit in different load sections is monitored, including: the generator is connected to the grid, the power system stabilizer is exited, a 2% generator stator voltage step test is performed, and the changes in the power oscillation natural frequency and damping ratio of the hydropower unit in different water heads and different load sections are tested, and the swing amplitude and number of active power are recorded by a recording instrument to obtain the measured natural oscillation frequency.

8. A device for eliminating low-frequency oscillation of a hydropower unit forced mechanism according to claim 6, characterized in that: In the load calculation module, a combination strategy of hydropower units considering the vibration zone is calculated to obtain a resonant adjustable load, including: calculating the load distribution of hydropower units considering the vibration zone according to the startup status of the hydropower units in the hydropower station, and finding the optimal number of generators and the load distribution strategy of each unit under the given water volume according to the principle of equal incremental rate, so that the output power of the hydropower station remains unchanged while satisfying the constraint conditions.

9. A device for eliminating low-frequency oscillation of a hydropower unit forced mechanism according to claim 8, characterized in that: The constraints include hydropower station flow constraints, spinning reserve constraints and operation range constraints.

10. A device for eliminating low-frequency oscillation of a hydropower unit forced mechanism according to claim 6, characterized in that: In the frequency control module, when it is detected that the pressure pulsation frequency of the tailwater pipe of the hydropower unit falls within the resonance frequency warning range and the amplitude exceeds the set value, multiple hydropower units are controlled to coordinate actions to adjust the guide vane opening, including: monitoring the tailwater pressure pulsation of the hydropower unit, if the frequency of the tailwater pressure pulsation falls within the resonance frequency warning range, and the amplitude of the pulsation is greater than the set value, starting an active preventive action; the active preventive action includes: in combination with the power oscillation of the hydropower unit, the machine increases the guide vane opening, and adjusts the load increase to the resonance adjustable load; at the same time, another machine cooperates to reduce the load, and adjusts the load reduction to the resonance adjustable load.

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