Protection and control method of unit speed signal device based on gradient speed delay strategy

Abstract

The present invention relates to a protection and control method for a unit speed signal device based on a gradient speed delay strategy. Utilizing the inherent laws of the start-up and shutdown processes of a hydro-turbine generator set, and according to the unit status, the method controls the output speed signal by reasonably delaying the adjacent speed signals for the 0% speed output by the speed signal device, the mechanical brake damper speed, the electrical brake speed, the idling state exit high-pressure oil jacking device speed, the no-load state excitation device speed, the first-level overspeed speed, and the second-level overspeed speed signals, thereby avoiding the risk of the speed signal device outputting an erroneous speed or 0% speed when a speed measurement signal source jumps or is disconnected. The present invention also proposes a method for real-time monitoring of the creep of the hydro-turbine generator set, which can promptly issue a creep alarm signal so that operation and maintenance personnel can take timely measures to prevent the accident from expanding.

Description

Technical Field

[0001] The present invention belongs to the field of hydropower generation control, and in particular relates to a protection and control method for a unit speed signal device based on a gradient speed delay strategy. Background Art

[0002] The speed signaling device is a critical signal detection device in hydro-turbine generator sets. The speed signal it provides is transmitted to the monitoring system and directly controls the generator set's startup, shutdown, emergency shutdown, and overspeed protection processes. The PLC-based speed signaling device operates by using a high-speed counter module to count residual pressure and gear frequency measurement signals and convert them into a speed signal. Existing speed signaling devices mostly operate independently, outputting speed signals based solely on the residual pressure and gear frequency measurement signals collected by the device itself. These fault protection logic is poorly modifiable, has a single function, and offers low reliability, posing the risk of erroneous speed signal output. Both the residual pressure and gear frequency measurement signals are susceptible to disconnection and transient faults, leading to deviations in speed measurement, a failure to accurately reflect the actual speed, and the output of erroneous speed signals, impacting the normal process control of the monitoring system. They can even cause the turbine generator set to inadvertently engage the mechanical brake damper at high speeds, resulting in significant equipment damage. Summary of the Invention

[0003] The purpose of the present invention is to address the above-mentioned problems and provide a protection and control method for a unit speed signal device based on a gradient speed delay strategy. By utilizing the inherent laws of the start-up and shutdown process of a hydro-turbine generator set, according to the state of the unit, the speed signal device outputs 0% speed, mechanical brake damper speed, electrical brake speed, idling state exit high-pressure oil jacking device speed, no-load state excitation device speed, first-level overspeed speed, and second-level overspeed speed signals, and controls the output speed signal by reasonably delaying the adjacent speed signals, thereby avoiding the risk of the speed signal device outputting an incorrect speed or 0% speed when the speed measurement signal source jumps or breaks.

[0004] The technical solution of the present invention is a unit speed signal device protection control method based on a gradient speed delay strategy. When the unit is in a stationary state or in the startup process or shutdown process, the protection control method obtains the unit speed signal N by measuring the frequency of the gear disc. GR When the unit is in the no-load state or the power generation state, the protection control method obtains the speed signal N of the unit by measuring the residual voltage frequency PT The protection control method sets the rated speed N n As 100% speed.

[0005] N PT A line break fault is defined as: the PLC pulse counter stops refreshing for T1 seconds.

[0006] N PT The jump fault is defined as: within T2 seconds, the frequency feedback deviation within n1 consecutive PLC scan cycles is greater than F d1 Hz, count once, the cumulative number of times is greater than N2 times.

[0007] N GR A line break fault is defined as: the PLC pulse counter stops refreshing for T3 seconds;

[0008] N GR The jump fault is defined as: within T4 seconds, the deviation between the maximum and minimum frequency feedback values ​​in N3 consecutive PLC scan cycles is greater than F d2 Hz, count 1 time, the cumulative number of times is greater than N4 times.

[0009] The unit status data S is retrieved from the PLC of the speed governor electrical control system via Ethernet communication. S is an integer value defined by the speed governor control system PLC. S = 1, 2, 3, and 4 respectively indicate that the unit is in the static state, startup process, no-load state, generating state, or shutdown process.

[0010] Define the start time of the hydropower unit at standstill, i.e. 0% speed, as t1. Start the hydropower generator unit at the maximum acceleration speed until it is overspeed. The speed signal device of the hydropower unit outputs the mechanical brake speed, i.e. 15%N n The time is t 2m The speed signal device of the hydropower unit outputs the electric braking speed, which is 60%N n The time is t 3m The speed signal device of the hydropower unit outputs the idling state and exits the high-pressure oil lifting device, that is, the speed of 90%N n The time is t 4m , the speed signal device of the hydropower unit outputs 95%N n The time is t 5m , the speed signal device of the hydropower unit outputs the rated speed N n The time is t Nm , the speed signal device of the hydropower unit outputs 115%N n The time is t 6m , the speed signal device of the hydropower unit outputs 154%N n The time is t 7m .

[0011] Time interval T m12 = t 2m ― t1;

[0012] Time interval T m23 = t 3m ― t 2m ;

[0013] Time interval T m34 = t 4m ― t 3m ;

[0014] Time interval T m45 = t 5m ― t 4m ;

[0015] Time interval T m5N = t Nm ― t 5m ;

[0016] Time interval T mN6 = t 6m ― t Nm ;

[0017] Time interval T m67 = t 7m ― t 6m ;

[0018] The time interval T m12 、T m23 、T m34 、T m45 、T m56 Set to the minimum time interval during the gradient speed rise process of the unit. If the gradient speed rise time interval during the unit startup process is greater than or equal to the minimum time interval, the corresponding speed signal output by the speed signal device of the hydropower unit will be used as the trigger source signal for the unit's mechanical brake, electrical brake, withdrawal of high-pressure oil jacking device, excitation device, first-level overspeed, and second-level overspeed emergency shutdown control. Otherwise, the corresponding unit shutdown, excitation or shutdown control will not be performed to avoid the speed measurement signal source from jumping or breaking, which may cause the speed signal device to output an incorrect speed or 0% speed.

[0019] Preferably, during the startup of the unit, the speed signal N obtained by the gear frequency measurement method is GR , N GR >15.1%Nn, and the unit speed increases from 0% speed to 15%N n The time interval t 12 ≥T m12 , the unit status is in the startup process, that is, the unit status S=1, then the hydropower unit speed signal device outputs a "greater than 15% rated speed" signal to the monitoring system, which is used as the source signal for the unit's mechanical brake action.

[0020] Preferably, during the startup of the unit, the speed signal N obtained by the gear frequency measurement method is GR , N GR >60.1%Nn, and the unit speed increases from 15% speed to 60%Nn The time interval t 23 ≥T m23 , the unit status is in the startup process, that is, the unit status S=1, then the hydropower unit speed signal device outputs a "greater than 60% rated speed" signal to the monitoring system, which is used as the source signal for the unit's electric brake action.

[0021] Preferably, during the startup of the unit, the speed signal N obtained by the gear frequency measurement method is GR , N GR >90%Nn, and the unit speed increases from 60% speed to 90%N n The time interval t 34 ≥T m34 , the unit status is the startup process, that is, the unit status S=1, then the hydropower unit speed signal device outputs a "greater than 90% rated speed" signal to the monitoring system, which is used as the source signal of the unit's high-pressure oil lifting device.

[0022] Preferably, during the startup of the unit, the speed signal N obtained by the gear frequency measurement method is GR , N GR >95%Nn, and the unit speed increases from 90% speed to 95%N n The time interval t 45 ≥T m45 , the unit state is no-load, that is, the unit state S=1, then the hydropower unit speed signal device outputs a "greater than 95% rated speed" signal to the monitoring system, which is used as the source signal for the unit to start the excitation device.

[0023] Preferably, during the startup of the unit, the speed signal N is obtained by the residual pressure frequency measurement method. PT , N PT >95%Nn, and the unit speed increases from 95% speed to 100%N n The time interval t 5N ≥T m5N , the unit state is no-load, that is, the unit state S=2, then the hydropower unit speed signal device outputs a "greater than or equal to 100% rated speed" signal to the monitoring system.

[0024] Preferably, the speed signal N obtained by the residual voltage frequency measurement method PT , N PT >115%Nn, and the unit speed increases from the rated speed to 115%N n The time interval t N6 ≥T mN6 , the unit status is no-load, that is, the unit status S=2, then the hydropower unit speed signal device outputs a "greater than 115% rated speed" signal to the monitoring system. This signal is used as the source signal for the unit's first-level overspeed protection to start the emergency shutdown process and drop the water inlet gate.

[0025] Preferably, the speed signal N obtained by the gear frequency measurement method is GR , N GR >154%Nn, and the unit speed is from 115%N n The speed increases to 154%N n The time interval t 67 ≥T m67 , the unit state is no-load, that is, the unit state S=2, then the hydropower unit speed signal device outputs a "greater than 154% rated speed" signal to the monitoring system. This signal is used as the source signal for the unit's secondary overspeed protection to start the emergency shutdown process and drop the water inlet gate.

[0026] Preferably, the unit speed reaches the second overspeed speed, that is, 154%N n After that, start the emergency shutdown process and drop the water inlet gate to shut down the turbine generator set as quickly as possible. Obtain the minimum time interval of each speed signal during the process of the unit dropping from the secondary overspeed to 0% speed. The unit speed signal device outputs 154%N n The signal time is During the shutdown process, the unit speed signal device outputs 115%N n The signal time is , the unit speed signal device outputs the rated speed N n The signal time is , the unit speed signal device outputs 95%N n The signal time is , the unit speed signal device outputs 90%N n The signal time is , the unit speed signal device outputs 60%N n The signal time is , the unit speed signal device outputs 15%N n The signal time is , the unit speed signal device outputs 0%N n The signal time is .

[0027] Time interval ;

[0028] Time interval ;

[0029] Time interval ;

[0030] Time interval ;

[0031] Time interval ;

[0032] Time interval ;

[0033] Time interval ;

[0034] After the unit starts the shutdown process, when the unit is in the no-load state, the residual voltage frequency measurement method detects N PT <153.9%N n , then the speed signal device of the hydropower unit outputs "less than 154%N n Speed ​​signal reset" to the monitoring system.

[0035] When the unit is in no-load state, N is detected by residual voltage frequency measurement. PT <114.9%N n And by 154%N n Speed ​​drops to 115%N n The time interval t of the speed 76 >T m76 When the speed signal device of the hydropower unit outputs "less than 115% speed signal reset" to the monitoring system.

[0036] When the unit is in no-load state, N is detected by residual voltage frequency measurement. PT <“99.9%N n "And by 115%N n Speed ​​drops to 100%N n The time interval t of the speed 6n >T m6N When the speed signal device of the hydropower unit outputs "less than 100% speed signal reset" to the monitoring system.

[0037] During the unit shutdown process, the N GR <“94.9%N n " and 100% N n Speed ​​drops to 95%N n The time interval t of the speed n5 >T mN5 When the speed is less than 95%, the signal reset is output to the monitoring system.

[0038] During the unit shutdown process, the N GR <89.9%N n , and the unit consists of 95%N n Speed ​​drops to 90%N n The time interval t of the speed 54 >T m54 When the speed is less than 90%, the signal reset is output to the monitoring system.

[0039] During the unit shutdown process, when the speed signal N obtained by the gear frequency measurement method isGR ≤60%N n , and the unit speed is from 90%N n Speed ​​drops to 60%N n Time interval , the unit status is in the shutdown process, that is, the unit status S=4, then the hydropower unit speed signal device outputs a "less than or equal to 60% rated speed" signal to the monitoring system, which is used as the source signal for the unit's electric brake action.

[0040] Preferably, when the speed signal N obtained by the gear frequency measurement method is GR ≤15%N n , and the unit speed is from 60%N n Speed ​​drops to 15%N n Time interval , the unit status is in the shutdown process, that is, the unit status S=4, then the hydropower unit speed signal device outputs a "less than or equal to 15% rated speed" signal to the monitoring system, which is used as the source signal for the unit's mechanical brake action.

[0041] During the unit shutdown process, the speed signal N obtained by the gear disc frequency measurement method is recorded GR And the speed signal N obtained by residual pressure frequency measurement PT The moment when both are 0 is t 0, and the moment when the speed signal device of the unit outputs the signal of "less than or equal to 15% rated speed" to t The time interval at time 0 is not less than , the unit speed signal device outputs a "0% rated speed" signal.

[0042] Preferably, the guide vanes of the unit are in a fully closed state, and the creep pulse count of the unit is detected to be greater than N0 and has an increasing trend through the gear disc frequency measurement method, and the current moment is t If the time interval at time 0 is not less than T0, the unit speed signal device will send out a "unit creep alarm" signal, and T0 represents the delay threshold of creep detection.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] 1) This invention proposes a speed delay protection control strategy for the PLC-based speed signal device of a hydro-turbine generator set. By adding reasonable adjacent speed delay protection to the speed signal of the unit and simultaneously retrieving the unit status data for comprehensive diagnosis of the unit operating condition, the safety hazards and risks caused by malfunction of the speed signal of the unit are effectively prevented.

[0045] 2) The present invention ensures that the unit is in a shutdown state by adding a delay strategy after the 0% speed action and reading the relevant data of the unit status. It can monitor the unit creep signal in real time and avoid false alarm signals.

[0046] 3) The present invention provides a method for real-time monitoring of the creep of a hydro-generator set, which can promptly issue a creep alarm signal and effectively prevent false alarms, so that operation and maintenance personnel can take timely measures to prevent the accident from escalating. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The present invention will be further described below with reference to the accompanying drawings and examples.

[0048] Figure 1 This is a schematic diagram of the principle of outputting speed signals from a speed signal device of a unit adopting a gradient speed delay strategy.

[0049] Figure 2 This is a detection flow chart of the unit creep alarm according to an embodiment of the present invention.

[0050] Figure 3 Schematic diagram of the logic operation for outputting a “greater than 15% rated speed” signal in an embodiment of the present invention.

[0051] Figure 4 Schematic diagram of the logic operation for outputting a “greater than 60% rated speed” signal in an embodiment of the present invention.

[0052] Figure 5 Schematic diagram of the logic operation for outputting a "greater than or equal to 90% rated speed" signal in an embodiment of the present invention.

[0053] Figure 6 Schematic diagram of the logic operation for outputting a "greater than or equal to 95% rated speed" signal in an embodiment of the present invention.

[0054] Figure 7 Schematic diagram of the logic operation for outputting a "greater than or equal to 100% rated speed" signal in an embodiment of the present invention.

[0055] Figure 8 Schematic diagram of the logic operation for outputting a "greater than or equal to 115% rated speed" signal in an embodiment of the present invention.

[0056] Figure 9 Schematic diagram of the logic operation for outputting a "greater than or equal to 154% rated speed" signal in an embodiment of the present invention.

[0057] Figure 10 Schematic diagram of the logic operation for outputting a "less than 154% rated speed" signal in an embodiment of the present invention.

[0058] Figure 11 Schematic diagram of the logic operation for outputting a "less than 115% rated speed" signal in an embodiment of the present invention.

[0059] Figure 12Schematic diagram of the logic operation for outputting a “less than 100% rated speed” signal in an embodiment of the present invention.

[0060] Figure 13 Schematic diagram of the logic operation for outputting a "less than 95% rated speed" signal in an embodiment of the present invention.

[0061] Figure 14 Schematic diagram of the logic operation for outputting a "less than 90% rated speed" signal in an embodiment of the present invention.

[0062] Figure 15 Schematic diagram of the logic operation for outputting a "less than or equal to 60% rated speed" signal in an embodiment of the present invention.

[0063] Figure 16 Schematic diagram of the logic operation for outputting a "less than or equal to 15% rated speed" signal in an embodiment of the present invention.

[0064] Figure 17 Schematic diagram of the logic operation of outputting a “0% rated speed” signal in an embodiment of the present invention.

[0065] Figure 18 This is a logical operation diagram for outputting a "greater than 0% rated speed" signal during the unit startup process from a static state. DETAILED DESCRIPTION

[0066] like Figure 1 As shown in the figure, the protection and control method of the speed signal device of the unit based on the gradient speed delay strategy utilizes the inherent laws of the start-up and shutdown process of the hydro-generator unit. According to the unit status, the speed signal device outputs 0% speed, mechanical brake damper speed, electrical brake speed, idling state exit high-pressure oil jacking device speed, no-load state excitation device speed, first-level overspeed speed, and second-level overspeed speed signals according to the adjacent speed signal actions. Reasonable delay is used to control the output speed signal, thereby avoiding the risk of the speed signal device outputting an incorrect speed or 0% speed when the speed measurement signal source jumps or breaks.

[0067] The specific implementation of the present invention is described by taking a 460MW Francis turbine generator set as an example.

[0068] According to Figure 1 The schematic diagram shown in FIG. 1 shows a specific implementation method.

[0069] The rated speed of the turbine generator set is taken as 100% speed; N1 is the 0% speed of the turbine generator set in the static state; N2 is the speed at which the mechanical brake is applied during the shutdown process of the unit, specifically 15% speed; N3 is the speed at which the electrical brake is applied during the shutdown process of the unit, specifically 60% speed; N4 is the speed at which the monitoring system determines that the unit has entered the idling state and the high-pressure oil lifting device is exited at the same time, specifically 90% speed; N5 is the speed at which the monitoring system determines that the unit has entered the no-load state during the startup process of the unit and the excitation device is applied at the same time, specifically 95% speed; N6 is the first-level overspeed speed of the unit. When the unit speed reaches the first-level overspeed and the main distribution device refuses to move, the emergency shutdown process is initiated and the water inlet gate is lowered, specifically 115% speed; N7 is the second-level overspeed speed of the unit. When the unit speed reaches the second-level overspeed, the emergency shutdown process is initiated and the water inlet gate is lowered, specifically 154% speed; N e Reset dead zone for speed signal action, specifically 0.1% speed.

[0070] According to the data of the overspeed test of the hydro-generator set under the highest water head of 203m, the unit is kept at manual uniform speed start-up, and the time required for the unit speed to increase from 0 speed to 15% speed is 15s, that is, T m12 = 15s; the time required for the unit speed to increase from 15% to 60% is 20s, that is, T m23 = 20s; the time required for the unit speed to increase from 60% to 90% is 25s, that is, T m34 = 25s; The time required for the unit speed to increase from 90% to 95% is 8s, that is, T m45 = 8s; the time required for the unit speed to increase from 95% to the rated speed is 10s, that is, T m5N = 10s; the time required for the unit speed to increase from the rated speed to 115% speed is 10s, that is, T mN6 = 10s; the time required for the unit speed to increase from 115% to 154% is 60s, that is, T m67 = 60s.

[0071] Since most hydro-generator sets currently use a flexible start-up method to reduce hydraulic pipeline vibration and reduce the stress on the turbine, the start-up time of the set is longer, which is slower than manual uniform speed start-up. Therefore, the above speed time interval is shorter than the normal start-up speed interval.

[0072] According to the data of the load rejection test of the hydro-turbine generator set under full load, the time required for the unit to increase from the rated speed to 115% of the first-level overspeed speed is 5s, and the time required for the speed to decrease from 115% to the rated speed is 15s.

[0073] During the overspeed test of the unit, when the second level overspeed is reached, the monitoring system starts the emergency shutdown process and drops the water inlet gate. The governor emergency shutdown solenoid valve is activated, closing the guide vanes at the maximum speed. At the same time, the mechanical overspeed valve is activated, cutting off the oil circuit. In this way, the unit shutdown is faster than the normal shutdown of the unit, the unit speed drops faster, and the speed interval is shorter than the normal shutdown speed interval. According to the test data, the time required for the unit speed to drop from 154% to 115% is 35s, that is, T m76 = 35s; the time required for the unit speed to drop from 115% to the rated speed is 10s, that is, T m6N = 10s; the time required for the unit speed to drop from the rated speed to 95% speed is 4s, that is, T mN5 = 4s; the time required for the unit speed to drop from 95% to 90% is 3s, that is, T m54 = 3s; the time required for the unit speed to drop from 90% to 60% is 50s, that is, T m43 =50s; the time required for the unit speed to drop from 60% speed to 15% speed is 60s, that is, T m32 = 60s; the time required for the unit speed to drop from 15% speed to 0% speed is 16s, that is, T m21 = 16s.

[0074] The speed signal device measures itself and processes the speed signal N of the unit in real time by the residual pressure frequency measurement. PT , gear disc frequency measurement speed signal N GR When the unit is in a stationary state or in the process of starting or stopping, the speed signal device frequency measurement selects the gear disc frequency measurement speed signal N GR When the unit is in no-load state or generating state, the frequency measurement selection is the residual pressure frequency measurement speed signal N PT For the main.

[0075] N PT The disconnection fault is defined as: the PLC pulse counter stops refreshing for 2 seconds; N PT A jump fault is defined as: within 5 seconds, the frequency measurement feedback deviation is greater than 10Hz in two consecutive PLC scan cycles, counted once, and the cumulative number of times is greater than 3 times.

[0076] N GR The disconnection fault is defined as: the PLC pulse counter stops refreshing for 10 seconds; N GR A jump fault is defined as: within 5 seconds, the deviation between the maximum and minimum values ​​of the frequency measurement feedback in 10 consecutive PLC scan cycles is greater than 10Hz, counted once, and the cumulative number of times is greater than 3 times.

[0077] The unit status data S is read from the PLC of the speed governor electrical control system via Ethernet communication. S is an integer value defined by the speed governor control system PLC. Different values ​​of S indicate whether the unit is in the static state, startup process, no-load state, generating state, or shutdown process. When S=0, the turbine generator set is in the static state; when S=1, the turbine generator set is in the startup process; when S=2, the turbine generator set is in the no-load state; when S=3, the turbine generator set is in the generating state; and when S=4, the turbine generator set is in the shutdown process.

[0078] like Figure 18 As shown in the figure, when the unit changes from static state to startup process, N GR When the speed is >0.1% rated speed, the output is "greater than 0% speed signal". This signal is a normally closed contact and sent to the monitoring system, so the output is "0% speed signal reset" to the monitoring system.

[0079] like Figure 3 As shown, “AND” means logical operation, “TON” means delayed output, and “GT” means greater than. When the unit is in the startup process, N GR >15.1% rated speed and the timing starts from the rising edge of the speed greater than 0% and reaches T m12 Time, T m12 =15s, output "greater than 15% speed signal", this signal is sent to the monitoring system through the normally closed contact, so output "less than or equal to 15% speed signal reset" to the monitoring system.

[0080] like Figure 4 As shown, when the unit is in the startup process, N GR >60.1% rated speed and the timing starts from the rising edge of the speed greater than 15% and reaches T m23 Time, T m23 =20s, output "greater than 60% speed signal", this signal is sent to the monitoring system through the normally closed contact, so output "less than or equal to 60% speed signal reset" to the monitoring system.

[0081] like Figure 5 As shown, "GE" means greater than or equal to. When the unit is in the startup process, N GR ≥"90% rated speed" and the timing starts from the rising edge of the speed greater than 60% and reaches T m34 Time, T m34=25s, output "greater than or equal to 90% speed signal", this signal is a normally open contact sent to the monitoring system, so the output "greater than or equal to 90% speed signal action" is sent to the monitoring system; this signal is the criterion for withdrawing the high-pressure oil jacking device during the startup of the hydro-generator set, and it is also the sign that the monitoring system has successfully opened the speed governor. Adding adjacent speed delay protection can effectively prevent the signal from being mistakenly output in advance when the signal measurement source jumps, causing the monitoring to misjudge the unit status and withdraw the high-pressure oil jacking device in advance, causing the unit to run at low speed and damage the thrust bearing oil film.

[0082] like Figure 6 As shown, when the unit is in the startup process, N GR ≥"95% rated speed" and the timing starts from the rising edge of the speed greater than 90% and reaches T m45 Time, T m45 =8s, output "greater than or equal to 95% speed signal", this signal is a normally open contact sent to the monitoring system, so the output "greater than or equal to 95% speed signal action" is sent to the monitoring system; this signal is when the monitoring system determines that the unit has entered the no-load speed during the unit startup process, and at the same time, the excitation device is put into operation. Adding adjacent speed delay protection can effectively prevent the signal from being mistakenly output in advance when the signal measurement source jumps, causing the monitoring to misjudge the unit status and put the excitation device into operation in advance. Putting the excitation device into operation at low speed or 0 speed may cause the rotor winding to burn out.

[0083] like Figure 7 As shown in the figure, when the unit is in no-load state, the frequency measurement signal source is mainly residual pressure frequency measurement, N PT ≥ “100% rated speed” and the timing starts from the rising edge of the speed greater than 95% and reaches T m5N Time, T m5N =10s, output “greater than or equal to rated speed signal”.

[0084] like Figure 8 As shown in the figure, when the unit is in no-load state, the frequency measurement signal source is mainly residual pressure frequency measurement. Considering the load rejection test of the hydro-generator unit, N PT ≥ “115% rated speed” and the timing starts from the rising edge greater than the rated speed and reaches T mN6 Time, T mN6 =5s, output "greater than or equal to 115% speed signal", this signal is a normally open contact sent to the monitoring system, so the output "greater than or equal to 115% speed signal action" is sent to the monitoring system; this signal is the first-level overspeed of the turbine generator set. When the unit speed reaches the first-level overspeed and the main distribution device refuses to move, the emergency shutdown process is started and the water inlet gate is lowered. Adding adjacent speed delay protection can effectively prevent the signal from being mistakenly output in advance when the signal measurement source jumps, causing the monitoring system to misjudge the unit's first-level overspeed. If the main distribution device refusal signal is activated at this time, the unit will mistakenly start the emergency shutdown process.

[0085] like Figure 9 As shown in the figure, when the unit is in no-load state, the frequency measurement signal source is mainly residual pressure frequency measurement, N PT ≥ “154% rated speed” and the timing starts from the rising edge of the speed greater than 115% and reaches T m67 Time, T m67 =60s, output "greater than or equal to 154% speed signal". This signal is a normally open contact and sent to the monitoring system, so the output "greater than or equal to 154% speed signal action" is sent to the monitoring system; this signal is the second-level overspeed of the turbine generator set. When the unit speed reaches the second-level overspeed, the emergency shutdown process is initiated and the water inlet gate is lowered. Adding adjacent speed delay protection can effectively prevent the signal from being mistakenly output in advance when the signal measurement source jumps, causing the monitoring system to misjudge the unit's second-level overspeed and mistakenly initiate the emergency shutdown process.

[0086] like Figure 10 As shown, "LT" means less than. When the unit is in no-load state, the frequency measurement signal source is mainly based on residual pressure frequency measurement. When N PT < "153.9% rated speed", then output "greater than or equal to 154% speed signal reset", output "greater than or equal to 154% speed signal reset", and "less than 154% rated speed signal" to the monitoring system;

[0087] like Figure 11 As shown in the figure, when the unit is in no-load state, the frequency measurement signal source is mainly residual pressure frequency measurement, N PT <114.9% rated speed and the timing starts from the rising edge of the speed less than 154% and reaches T m76 Time, T m76 =35s, output "greater than or equal to 115% speed signal reset" and "less than 115% rated speed signal" to the monitoring system.

[0088] like Figure 12 As shown in the figure, when the unit is in no-load state, the frequency measurement signal source is mainly residual pressure frequency measurement, N PT <"99.9% rated speed" and the timing starts from the rising edge of the speed less than 115% and reaches T m6N Time, T m6N =10s, output "greater than or equal to rated speed signal reset" and "less than 100% rated speed signal" to the monitoring system.

[0089] like Figure 13 As shown in the figure, when the unit is in the shutdown process, the frequency measurement signal source is mainly the gear frequency measurement, N GR <"94.9% rated speed" and the timing starts from the rising edge of the speed less than the rated speed and reaches T mN5 Time, T mN5=4s, output "greater than or equal to 95% rated speed signal reset" and "less than 95% rated speed signal" to the monitoring system.

[0090] like Figure 14 As shown in the figure, when the unit is in the shutdown process, the frequency measurement signal source is mainly the gear frequency measurement, N GR < “89.9% rated speed” and the timing starts from the rising edge of the speed less than 95% and reaches T m54 Time, T m54 =3s, output "greater than or equal to 90% rated speed signal reset" and "less than 90% rated speed signal" to the monitoring system.

[0091] like Figure 15 As shown, "LE" means less than or equal to. When the unit is in the shutdown process, the frequency measurement signal source is mainly based on the gear frequency measurement, N GR ≤60% rated speed and the timing starts from the rising edge of the speed less than 90% and reaches T m43 Time, T m43 =50s, output "less than or equal to 60% speed signal action" to the monitoring system; this signal is the speed for electrical braking during unit shutdown. Adding adjacent speed delay protection can effectively prevent the signal from being mistakenly output in advance when the signal measurement source jumps, causing the unit to be electrically braked at high speed. Since the electrical braking torque is inversely proportional to the unit speed, the braking torque is small and the braking effect is not ideal.

[0092] like Figure 16 As shown in the figure, when the unit is in the shutdown process, the frequency measurement signal source is mainly the gear frequency measurement, N GR ≤15% rated speed and the timing starts from the rising edge of the speed less than 60% and reaches T m32 Time, T m32 =60s, output "less than or equal to 15% speed signal action" to the monitoring system; this signal is the speed of mechanical braking during normal shutdown of the unit. Adding adjacent speed delay protection can effectively prevent the signal from being mistakenly output in advance when the signal measurement source jumps, causing the unit to be mechanically braked at a high speed, resulting in deformation and wear of the mechanical brake damper, or even causing the brake block to fly out and damage the generator stator winding.

[0093] like Figure 17 As shown, “EQ” means equal to. When the unit is in a stationary state, N PT 、N GR The measured values ​​are all 0 and the timing starts from the moment the unit speed signal device issues the "less than 15% speed" signal and reaches T m21 Time, T m21=16s, output "0% speed signal action" to the monitoring system; this signal is the criterion for the monitoring system to judge that the unit has entered the shutdown state and exited the electrical brake and mechanical brake. Adding adjacent speed delay protection can effectively prevent the signal from being mistakenly output in advance when the signal measurement source jumps or is disconnected, resulting in the exit of the electrical brake and mechanical brake before the unit is completely shut down, thereby causing the risk of unit creep or inertial shutdown.

[0094] Record the speed signal N obtained by the gear wheel frequency measurement method GR And the speed signal N obtained by residual pressure frequency measurement PT The moment when both are 0 is t 0, calculate the number of pulses of the gear disc frequency measurement, read the unit status data, if the unit is in shutdown state and the unit guide vane is in full close state, and the current time t is t The time interval at time 0 is greater than or equal to T0, and the creep pulse count of the unit is detected to be greater than N0, and the gear speed signal N GR If the pulse count of is greater than the pulse count of the previous PLC scan cycle, the "unit creep alarm" signal is output. Figure 2 shown.

[0095] The present invention proposes a speed delay protection control strategy for a PLC-based unit speed signal device of a hydro-turbine generator set. By adding a reasonable adjacent speed minimum interval delay protection to the unit speed signal and simultaneously retrieving the unit status data for comprehensive diagnosis of the unit operating condition, the safety hazards and risks caused by malfunction of the unit speed signal can be effectively prevented.

[0096] The above description is only a specific implementation case of the invention. The technical features of the invention are not limited thereto. Any changes or modifications made by any technician in the relevant field within the field of the invention are included in the protection scope of the invention.

Claims

1. A unit speed signal device protection and control method based on a gradient speed delay strategy is characterized in that: When the unit is in a stationary state, in the process of starting up, or in the process of stopping, the protection control method obtains the speed signal of the unit by measuring the frequency of the gear disc; when the unit is in an unloaded state or in a generating state, the protection control method obtains the speed signal of the unit by measuring the frequency of the residual voltage; The protection control method sets the rated speed N n As 100% speed, Define the start time of the hydropower unit at standstill, i.e. 0% speed, as t1. Start the hydropower generator unit at the maximum acceleration speed until it is overspeed. The speed signal device of the hydropower unit outputs the mechanical brake speed, i.e. 15%N n The time is t 2m The speed signal device of the hydropower unit outputs the electric braking speed, which is 60%N n The time is t 3m The speed signal device of the hydropower unit outputs the idling state and exits the high-pressure oil lifting device, that is, the speed of 90%N n The time is t 4m , the speed signal device of the hydropower unit outputs 95%N n The time is t 5m , the speed signal device of the hydropower unit outputs the rated speed N n The time is t Nm , the speed signal device of the hydropower unit outputs 115%N n The time is t 6m , the speed signal device of the hydropower unit outputs 154%N n The time is t 7m , Time interval T m12 = t 2m ― t1; Time interval T m23 = t 3m ― t 2m ; Time interval T m34 = t 4m ― t 3m ; Time interval T m45 = t 5m ― t 4m ; Time interval T mN6 = t 6m ― t Nm ; Time interval T m67 = t 7m ― t 6m ; The time interval T m12 、T m23 、T m34 、T m45 、T m56 Set to the minimum time interval during the gradient speed rise process of the unit. If the gradient speed rise time interval during the unit startup process is greater than or equal to the minimum time interval, the corresponding speed signal output by the speed signal device of the hydropower unit will be used as the trigger source signal for the unit's mechanical brake, electrical brake, withdrawal of high-pressure oil jacking device, excitation device, first-level overspeed, and second-level overspeed emergency shutdown control. Otherwise, the corresponding unit shutdown, excitation or shutdown control will not be performed to avoid the speed measurement signal source from jumping or breaking, which may cause the speed signal device to output an incorrect speed or 0% speed.

2. The protection and control method for the unit speed signal device according to claim 1, characterized in that: Speed ​​signal N obtained by gear frequency measurement GR , N GR >15.1%Nn, and the unit speed increases from 0% speed to 15%N n The time interval t 12 ≥T m12 , the unit status is in the startup process, that is, the unit status S=1, then the hydropower unit speed signal device outputs a "greater than 15% rated speed" signal to the monitoring system, which is used as the source signal for the unit's mechanical brake action.

3. The protection and control method for the unit speed signal device according to claim 1, characterized in that: Speed ​​signal N obtained by gear frequency measurement GR , N GR >60.1%Nn, and the unit speed increases from 15% speed to 60%N n The time interval t 23 ≥T m23 , the unit status is in the startup process, that is, the unit status S=1, then the hydropower unit speed signal device outputs a "greater than 60% rated speed" signal to the monitoring system, which is used as the source signal for the unit's electric brake action.

4. The protection and control method for the unit speed signal device according to claim 1, characterized in that: Speed ​​signal N obtained by gear frequency measurement GR , N GR >90%Nn, and the unit speed increases from 60% speed to 90%N n The time interval t 34 ≥T m34 , the unit status is in the startup process, that is, the unit status S=1, then the hydropower unit speed signal device outputs a "greater than 90% rated speed" signal to the monitoring system, which is used as the source signal of the unit's high-pressure oil lifting device.

5. The protection and control method for the unit speed signal device according to claim 1, characterized in that: Speed ​​signal N obtained by gear frequency measurement GR , N GR >95%Nn, and the unit speed increases from 90% speed to 95%N n The time interval t 45 ≥T m45 , the unit status is in the startup process, that is, the unit status S=1, then the hydropower unit speed signal device outputs a "greater than 95% rated speed" signal to the monitoring system, which is used as the source signal for the unit's excitation device.

6. The protection and control method for the unit speed signal device according to claim 1, characterized in that: The speed signal N obtained by the residual pressure frequency measurement method PT , N PT >115%Nn, and the unit speed increases from the rated speed to 115%N n The time interval t N6 ≥T mN6 , the unit status is no-load, that is, the unit status S=2, then the hydropower unit speed signal device outputs a "greater than 115% rated speed" signal to the monitoring system. This signal is used as the source signal for the unit's first-level overspeed protection to start the emergency shutdown process and drop the water inlet gate.

7. The protection and control method for the unit speed signal device according to claim 1, characterized in that: Speed ​​signal N obtained by gear frequency measurement GR , N GR >154%Nn, and the unit speed is from 115%N n The speed increases to 154%N n The time interval t 67 ≥T m67 , the unit state is no-load, that is, the unit state S=2, then the hydropower unit speed signal device outputs a "greater than 154% rated speed" signal to the monitoring system. This signal is used as the source signal for the unit's secondary overspeed protection to initiate the emergency shutdown process and drop the water inlet gate.

8. The protection and control method for the unit speed signal device according to claim 1, characterized in that: The unit speed reaches the second level overspeed, i.e. 154%N n After that, the emergency shutdown process is started and the water inlet gate is lowered to shut down the turbine generator set as quickly as possible. The minimum time interval of each speed signal during the process of the unit dropping from the second-level overspeed to 0% speed is obtained. The unit speed signal device outputs 154%N n The signal time is During the shutdown process, the unit speed signal device outputs 115%N n The signal time is , the unit speed signal device outputs the rated speed N n The signal time is , the unit speed signal device outputs 95%N n The signal time is , the unit speed signal device outputs 90%N n The signal time is , the unit speed signal device outputs 60%N n The signal time is , the unit speed signal device outputs 15%N n The signal time is , the unit speed signal device outputs 0%N n The signal time is , Time interval ; Time interval ; Time interval ; Time interval ; Time interval ; Time interval ; Time interval ; During the shutdown process of the unit, when the unit is in the no-load state, the frequency measurement signal source is mainly based on the residual pressure frequency measurement, N PT The speed signal is obtained by the residual pressure frequency measurement method, and N PT <"153.9%N n "The output of the hydropower unit speed signal device is less than 154%N n Speed ​​signal reset" to the monitoring system; when the unit is in no-load state, N PT <"114.9%N n "And by 154%N n Speed ​​drops to 115%N n The time interval t of the speed 76 >T m76 When the speed signal device of the hydropower unit outputs "less than 115% speed signal reset" to the monitoring system; when the unit is in the no-load state, N PT <"99.9%N n " and 115% N n Speed ​​drops to 100%N n The time interval t of the speed 6n >T m6N When the speed signal device of the hydropower unit outputs "less than 100% speed signal reset" to the monitoring system; When the unit is in the process of shutdown, after the speed signal device of the hydropower unit outputs "less than 100% speed signal reset" to the monitoring system, the frequency measurement signal source is mainly based on the gear frequency measurement, N GR is the speed signal obtained by the gear frequency measurement method, N GR <"94.9%N n " and 100% N n Speed ​​drops to 95%N n The time interval t of the speed n5 >T mN5 When the unit is in the shutdown process, the frequency measurement signal source is mainly based on the gear frequency measurement, N GR <"89.9%N n "And 95%N n Speed ​​drops to 90%N n The time interval t of the speed 54 >T m54 When the speed signal N is less than 90%, it outputs "less than 90% speed signal reset" to the monitoring system; when the speed signal N GR ≤60%N n , and the unit speed is from 90%N n Speed ​​drops to 60%N n Time interval , the unit status is in the shutdown process, that is, the unit status S=4, then the hydropower unit speed signal device outputs a "less than or equal to 60% rated speed" signal to the monitoring system, which is used as the source signal for the unit's electric brake action.

9. The protection and control method for the unit speed signal device according to claim 8, characterized in that: When the speed signal N obtained by the gear frequency measurement method GR ≤15%N n , and the unit speed is from 60%N n Speed ​​drops to 15%N n Time interval , the unit status is in the shutdown process, that is, the unit status S=4, then the hydropower unit speed signal device outputs a "less than or equal to 15% rated speed" signal to the monitoring system, which is used as the source signal for the unit's mechanical brake action.

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