Methods, devices and systems for analyzing the starting frequency of hydro-generator units

Abstract

This invention discloses a method, apparatus, and system for analyzing the starting frequency of a hydro-generator unit. The method includes: acquiring the measured guide vane opening of the turbine in real time; proportionally adjusting the measured guide vane opening according to the unit's head parameters to obtain a predicted guide vane opening; inputting the predicted guide vane opening into the first-order inertial element of the hydro-generator unit to obtain a predicted frequency; comparing the predicted frequency with the measured frequency of the hydro-generator unit, and deciding whether to retain the measured frequency or use the predicted frequency instead based on the comparison result. This invention can determine the rationality of the measured frequency of the hydro-generator unit, automatically filter interference signals, and improve the unit's start-up success rate.

Description

Technical Field

[0001] This invention belongs to the field of hydro-generator set change trend analysis, specifically relating to a method, device and system for analyzing the starting frequency of hydro-generator sets. Background Technology

[0002] During the startup process of a hydro-generator unit, the unit's frequency needs to be measured throughout the entire process from 0 to 100Hz to determine the unit's speed in segments and to pre-implement appropriate startup control measures. Current technologies typically use turbine-terminal voltage transformers and geared disc speed probes for frequency signal measurement. The turbine-terminal voltage transformer primarily detects a signal of the same frequency induced in the stator by the magnetic field generated by the rotating residual magnetism of the generator rotor. This signal is mainly affected by low speeds; at initial startup speeds, the induced voltage amplitude of the turbine-terminal voltage transformer is very small, below 0.1V, making it difficult to detect and susceptible to interference. Generally, the signal amplitude only reaches above 1V when the generator speed reaches over 90%, or when the generator excitation system is activated and the transformer voltage reaches its rated value, resulting in a more stable and easily measurable signal. The geared speed sensor probe is mounted on the generator shaft to detect the unit's speed and convert it into frequency. It is easily affected by vibrations and shocks during generator startup, causing unstable and fluctuating readings. Furthermore, due to factors such as shaft oscillation, gear spacing, and probe sensing distance, the probe's signal is less stable than that of the voltage transformer at the generator terminal, resulting in larger readings. It is generally used for measuring speeds within 0% to 95% of the rated speed. In near-rated steady-state conditions, the voltage transformer signal is typically used. Therefore, the influence of gear machining, probe installation, and generator startup vibrations on the probe signal can still lead to signal abnormalities and malfunctions during generator startup. Additionally, it cannot accurately measure low-speed generator values, and even after a delay, interference between the voltage transformer and geared probe signals can occur, resulting in inconsistent readings and making accurate generator frequency measurement difficult.

[0003] In addition, some anomalies often occur in the frequency measurement of hydro-generator units during actual operation. For example, a sudden surge of water during startup may cause vibration of the turbine top cover, causing the gear disc speed measuring probe to vibrate and generate abnormal high-frequency signals, which may lead to false overspeed shutdown signals and startup failure. Secondly, at the initial stage of unit startup, due to the low speed, the amplitude of the residual voltage frequency measurement signal of the generator terminal voltage transformer is small and easily undetectable, or easily interfered with, or the signal amplitude may hover around the critical point of the measuring device, resulting in unstable measurement values. All of these factors can affect the frequency measurement of the unit, causing the unit speed relay to malfunction and the unit startup to fail. Summary of the Invention

[0004] To address the aforementioned problems, this invention proposes a method, device, and system for analyzing the starting frequency of a hydro-generator unit. This method can determine the rationality of the measured frequency of the hydro-generator unit, automatically filter interference signals, and improve the success rate of unit startup.

[0005] To achieve the above-mentioned technical objectives and effects, the present invention is implemented through the following technical solution:

[0006] In a first aspect, the present invention provides a method for analyzing the starting frequency of a hydro-generator set, comprising:

[0007] Real-time acquisition of the measured guide vane opening of the water turbine;

[0008] The measured guide vane opening is proportionally adjusted based on the unit head parameters to obtain the predicted guide vane opening.

[0009] The predicted guide vane opening is input into the first-order inertial element of the hydro-generator unit to obtain the predicted frequency of the hydro-generator unit.

[0010] The predicted frequency of the hydro-generator unit is compared with the measured frequency of the hydro-generator unit, and based on the comparison result, it is decided whether to retain the measured frequency of the hydro-generator unit or to use the predicted frequency of the hydro-generator unit instead of the measured frequency.

[0011] Optionally, the expression for the proportional coefficient used in the proportional adjustment is:

[0012]

[0013] The formula for calculating the predicted guide vane opening is as follows:

[0014]

[0015] In the formula, K is the proportionality coefficient, H0 is the design head of the turbine, and H MAX For the maximum head, H MIN y′ represents the minimum head, H represents the currently measured head, y′ represents the predicted guide vane opening, and y represents the actual measured guide vane opening.

[0016] Optionally, the first-order inertial element of the hydro-generator unit is expressed as follows:

[0017]

[0018]

[0019] In the formula, Δt is the calculation step size, and y i Let y be the measured guide vane opening at time i. i ' is the predicted guide vane opening at time i, f ei Let f be the predicted frequency of the hydro-generator unit at time i.e(i-1) Let K be the predicted frequency of the hydro-generator unit at time i-1, K be the proportional coefficient, Ta be the time constant of the unit's rotational inertia, and GD be the frequency of the generator unit. 2 This refers to the flywheel torque of the rotating part of the hydro-generator unit, measured in kg*m². This torque can usually be found in the manufacturer's documentation. N Rated speed of the hydro-generator unit, unit: r / min, P N Rated power of the hydro-generator unit, unit: kW.

[0020] Optionally, the step of comparing the predicted frequency of the hydro-generator unit with the measured frequency of the hydro-generator unit, and deciding whether to retain the measured frequency of the hydro-generator unit or use the predicted frequency of the hydro-generator unit instead of the measured frequency based on the comparison result, includes the following steps:

[0021] By comparing the predicted frequency of the hydro-generator unit at time i with the measured frequency of the hydro-generator unit, the absolute value of the frequency deviation, |Δf|, is obtained.

[0022] If |Δf| is less than or equal to the first preset frequency threshold, it indicates that the measured frequency of the hydro-generator unit is normal. Then, the measured frequency of the hydro-generator unit at time i is retained and output as the current frequency of the hydro-generator unit.

[0023] If |Δf| is greater than or equal to the first preset frequency threshold, it indicates that the measured frequency of the hydro-generator unit is abnormal. At the same time, if the predicted frequency of the hydro-generator unit is less than the second preset frequency threshold, it indicates that the hydro-generator unit is in the initial startup stage. In this case, the predicted frequency of the hydro-generator unit at time i is retained and output as the current frequency of the hydro-generator unit. If the predicted frequency of the hydro-generator unit is greater than or equal to the second preset frequency threshold, it indicates that the hydro-generator unit is in the intermediate rising stage. The predicted frequency of the hydro-generator unit is discarded, and the measured frequency of the hydro-generator unit at time i-1 is retained and output as the current frequency of the hydro-generator unit. The second preset frequency threshold is greater than the first preset frequency threshold.

[0024] Optionally, the first preset frequency threshold is 2.5Hz; the second preset frequency threshold is 5Hz.

[0025] Secondly, the present invention provides a hydro-generator set start-up frequency analysis device, comprising:

[0026] The acquisition module is used to acquire the measured guide vane opening of the water turbine in real time;

[0027] A proportional adjustment module is used to proportionally adjust the measured guide vane opening to obtain the predicted guide vane opening.

[0028] The frequency prediction module is used to input the predicted guide vane opening into the first-order inertial element of the hydro-generator set to obtain the predicted frequency of the hydro-generator set.

[0029] The frequency analysis module is used to compare the predicted frequency of the hydro-generator set with the measured frequency of the hydro-generator set, and decide whether to use the measured frequency or the predicted frequency of the hydro-generator set as the current frequency of the hydro-generator set based on the comparison result.

[0030] Optionally, the expression for the proportional coefficient used in the proportional adjustment is:

[0031]

[0032] The formula for calculating the predicted guide vane opening is as follows:

[0033]

[0034] In the formula, K is the proportionality coefficient, H0 is the design head of the turbine, and H MAX For the maximum head, H MIN y′ represents the minimum head, H represents the currently measured head, y′ represents the predicted guide vane opening, and y represents the actual measured guide vane opening.

[0035] Optionally, the first-order inertial element of the hydro-generator unit is expressed as follows:

[0036]

[0037]

[0038] In the formula, Δt is the calculation step size, and y i Let y be the measured guide vane opening at time i. i ' is the predicted guide vane opening at time i, f ei Let f be the predicted frequency of the hydro-generator unit at time i. e(i-1) Let K be the predicted frequency of the hydro-generator unit at time i-1, K be the proportional coefficient, Ta be the time constant of the unit's rotational inertia, and GD be the frequency of the generator unit. 2 This refers to the flywheel torque of the rotating part of the hydro-generator unit, measured in kg*m². This torque can usually be found in the manufacturer's documentation. N Rated speed of the hydro-generator unit, unit: r / min, P N Rated power of the hydro-generator unit, unit: kW.

[0039] Optionally, the step of comparing the predicted frequency of the hydro-generator unit with the measured frequency of the hydro-generator unit, and deciding whether to retain the measured frequency of the hydro-generator unit or use the predicted frequency of the hydro-generator unit instead of the measured frequency based on the comparison result, includes the following steps:

[0040] By comparing the predicted frequency of the hydro-generator unit at time i with the measured frequency of the hydro-generator unit, the absolute value of the frequency deviation, |Δf|, is obtained.

[0041] If |Δf| is less than or equal to the first preset frequency threshold, it indicates that the measured frequency of the hydro-generator unit is normal. Then, the measured frequency of the hydro-generator unit at time i is retained and output as the current frequency of the hydro-generator unit.

[0042] If |Δf| is greater than or equal to the first preset frequency threshold, it indicates that the measured frequency of the hydro-generator unit is abnormal. At the same time, if the predicted frequency of the hydro-generator unit is less than the second preset frequency threshold, it indicates that the hydro-generator unit is in the initial startup stage. In this case, the predicted frequency of the hydro-generator unit at time i is retained and output as the current frequency of the hydro-generator unit. If the predicted frequency of the hydro-generator unit is greater than or equal to the second preset frequency threshold, it indicates that the hydro-generator unit is in the intermediate rising stage. The predicted frequency of the hydro-generator unit is discarded, and the measured frequency of the hydro-generator unit at time i-1 is retained and output as the current frequency of the hydro-generator unit.

[0043] Thirdly, the present invention provides a hydro-generator set start-up frequency analysis system, including a storage medium and a processor;

[0044] The storage medium is used to store instructions;

[0045] The processor is configured to operate according to the instructions to perform the method according to any one of the first aspects.

[0046] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0047] This invention uses the guide vane opening motion law during turbine startup as a reference to calculate the predicted frequency of the turbine generator set and predict the turbine speed change trend. It is independent of the speed measurement signal, and the guide vane opening measurement signal is generally not affected during the unit startup process. Therefore, the predicted speed signal is very stable.

[0048] Traditional filtering methods typically employ data averaging, median filtering, and first-order filtering, all based on sampled data. Interference data participates in these calculations, affecting the filtering effect. While longer filtering periods smooth the data, they introduce sampling delays, causing real-time control errors. The frequency sampling period for a hydro turbine governor is typically 20ms, and the filtering lag time constant generally does not exceed 150ms. This invention uses the frequency predicted by the first-order inertial element of the hydro generator and the real-time data of the guide vane opening as a filtering reference for the unit's measured frequency, resulting in good real-time performance, low delay, and high reliability. Attached Figure Description

[0049] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein:

[0050] Figure 1 This is a graph showing the trend of measured starting frequency variation of hydro-generator units in existing technologies;

[0051] Figure 2 This is a schematic diagram illustrating the calculation of the predicted frequency of a hydro-generator unit according to an embodiment of the present invention;

[0052] Figure 3 This diagram illustrates the trend of guide vane opening variation in existing hydro-generator units.

[0053] Figure 4 This is a schematic diagram illustrating the trend of unit speed increase in predicting the start-up law of guide vane opening according to an embodiment of the present invention.

[0054] Figure 5 This is a flowchart illustrating the verification of the measured frequency of a hydro-generator unit according to an embodiment of the present invention.

[0055] Figure 6 This is a schematic diagram illustrating the verification of the measured frequency of a hydro-generator unit according to an embodiment of the present invention. Detailed Implementation

[0056] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the scope of protection of the invention.

[0057] The application principle of the present invention will be described in detail below with reference to the accompanying drawings.

[0058] Example 1

[0059] Through actual startup and measurement tests of the hydro-generator unit, it was found that during startup, the speed increase trend of the hydro-generator unit, with the change of guide vane opening, resembles a first-order inertial element. Figure 1 As shown, when starting a hydro-generator unit, the guide vanes are typically started in stages. First, the guide vanes are opened to the starting position, generally 1.2-1.5 times the no-load opening. Once the speed reaches approximately 70%, they are closed back to 1.1-1.2 times the no-load opening. Finally, when the speed reaches over 97%, PID control is engaged, and the governor automatically adjusts the unit frequency to 50Hz, awaiting grid connection. See [link to relevant documentation] for details. Figure 3 Therefore, in this embodiment of the invention, the hydro-generator model is simplified into a first-order inertial element. The current turbine guide vane opening measurement value Y is input, and the predicted guide vane opening value Y' is calculated based on the turbine head measurement value H. Then, through the first-order inertial model of the hydro-generator, the predicted frequency or speed of the hydro-generator is output. The inertial time constant Ta of the rotating part of the hydro-generator can be calculated according to the actual unit parameters or obtained through experimental methods.

[0060] This invention provides a method for analyzing the starting frequency of a hydro-generator set, comprising the following steps:

[0061] (1) Real-time acquisition of the measured guide vane opening of the water turbine;

[0062] (2) The measured guide vane opening is proportionally adjusted to obtain the predicted guide vane opening;

[0063] (3) Input the predicted guide vane opening into the first-order inertial element of the hydro-generator set to obtain the predicted frequency of the hydro-generator set;

[0064] (4) Compare the predicted frequency of the hydro-generator set with the measured frequency of the hydro-generator set, and decide whether to retain the measured frequency of the hydro-generator set or use the predicted frequency of the hydro-generator set instead of the measured frequency of the hydro-generator set based on the comparison result.

[0065] In one specific embodiment of the present invention, the expression for the proportional coefficient used in the proportional adjustment is:

[0066]

[0067] The formula for calculating the predicted guide vane opening is as follows:

[0068]

[0069] In the formula, K is the proportionality coefficient, H0 is the design head of the turbine, and H MAX For maximum head, H MIN y′ represents the minimum head, H represents the currently measured head, y′ represents the predicted guide vane opening, and y represents the actual measured guide vane opening.

[0070] In one specific embodiment of the present invention, the moment of inertia Ta can be calculated based on the actual moment of inertia of the unit, and the calculation formula is as follows:

[0071]

[0072] In the formula, Ta is the unit's rotational inertia time constant, and GD 2 This refers to the flywheel torque of the rotating part of the hydro-generator unit, measured in kg*m². This torque can usually be found in the manufacturer's documentation. N Rated speed of the hydro-generator unit, unit: r / min, P N Rated power of the hydro-generator unit, unit: kW.

[0073] The Laplace transfer function expression for the hydro-generator model is:

[0074]

[0075] Written in difference form:

[0076]

[0077] The expression for the first-order inertial element of the hydro-generator unit is obtained by refining the expression:

[0078]

[0079] In the formula, Δt is the calculation step size (the interval between two sampling periods), which is generally taken as 10ms, and y i Let y be the measured guide vane opening at time i. i ' is the predicted guide vane opening at time i, f ei Let f be the predicted frequency of the hydro-generator unit at time i. e(i-1) Let be the predicted frequency of the hydro-generator unit at time i-1 (the previous cycle), K be the proportional coefficient, and Ta be the time constant of the unit's rotational inertia.

[0080] In one specific embodiment of the present invention, the step of comparing the predicted frequency of the hydro-generator unit with the measured frequency of the hydro-generator unit, and deciding whether to retain the measured frequency of the hydro-generator unit or to use the predicted frequency of the hydro-generator unit instead of the measured frequency based on the comparison result, includes the following steps:

[0081] Compare the predicted frequency f of the hydro-generator unit at time i. ei The measured frequency f of the hydro-generator unit 0i The absolute value of the frequency deviation, |Δf|, is obtained.

[0082] If |Δf| is less than or equal to the first preset frequency threshold, it indicates that the measured frequency f of the hydro-generator unit is... 0i If normal, then retain and output the measured frequency f of the hydro-generator unit at time i. 0i As the current frequency of the hydro-generator unit;

[0083] If |Δf| is greater than or equal to the first preset frequency threshold, it indicates that the measured frequency f of the hydro-generator unit is... 0i An anomaly, and at the same time, if the predicted frequency f of the hydro-generator unit... ei If the frequency is less than the second preset frequency threshold, it indicates that the hydro-generator unit is in the initial startup stage. Therefore, the predicted frequency f of the hydro-generator unit at time i is retained and output. ei As the current frequency of the hydro-generator unit; if the predicted frequency of the hydro-generator unit is f ei If the frequency is greater than or equal to the second preset frequency threshold, it indicates that the hydro-generator unit is in the intermediate rising phase, and the predicted frequency f of the hydro-generator unit is discarded. ei Retain and output the measured frequency f of the hydro-generator unit at time i-1 (the previous cycle). 0(i-1)The current frequency of the hydro-generator unit; the second preset frequency threshold is greater than the first preset frequency threshold. In specific implementation, the first preset frequency threshold is 2.5Hz; the second preset frequency threshold is 5Hz, see details below. Figure 5 .

[0084] The following is combined with Figure 5 The present invention will be described in detail with reference to a specific embodiment.

[0085] (A) According to Figure 3 The guide vane opening was controlled by the guide vane variation law, and the measured values ​​of the guide vane were collected;

[0086] (B) Reference Figure 2 Calculate the predicted frequency f of the hydro-generator unit at time i. ei ;

[0087] The predicted frequency will increase according to the law determined by the first-order inertial element and the time constant Ta. The guide vane opening at the final stable frequency of the hydro-generator at 50Hz is the no-load opening Ynl. The entire predicted frequency change process is shown in [reference needed]. Figure 4 The no-load opening degree Ynl is generally related to the turbine head, such as... Figure 4 In this context, the no-load opening is 0.2. Different water heads correspond to different no-load openings; the higher the water head, the smaller the no-load opening, and vice versa. Generally, turbine manufacturers provide a table showing the correspondence between no-load opening and water head, as shown in Table 1. This data table is stored in the program, and the current no-load opening can be obtained by linear conversion based on different water heads.

[0088] Table 1: Correspondence between no-load opening degree and water head provided by the turbine manufacturer

[0089]

[0090] (C) Compare the predicted frequency of the hydro-generator unit at time i with the measured frequency of the hydro-generator unit at time i obtained by using the voltage transformer or toothed disc probe signal to obtain the frequency deviation Δf, and take the absolute value to obtain |Δf|.

[0091] If |Δf| is less than or equal to 2.5Hz (2.5Hz is a set threshold that can be modified), it indicates that the measured frequency f of the hydro-generator unit at time i is... 0i If normal, then output the measured frequency f of the hydro-generator unit at time i. 0i This represents the current frequency of the hydro-generator unit at time i.

[0092] If |Δf| is greater than 2.5Hz, it indicates that the measured frequency f of the hydro-generator unit at time i is... 0i An anomaly occurs when the predicted frequency f of the hydro-generator unit at time i is abnormal. eiIf the frequency is less than 5Hz, it indicates that the hydro-generator unit is in the initial startup stage. Therefore, the predicted frequency f of the hydro-generator unit at time i is output. ei As the current frequency of the hydro-generator unit at time i, if the predicted frequency f of the hydro-generator unit at time i... ei If the frequency is greater than or equal to 5Hz, it indicates that the speed of the hydro-generator unit is in the middle rising stage. Therefore, the sampled data is considered to have interference and is discarded. The measured frequency f of the hydro-generator unit at time i-1 is then output. 0(i-1) For the current frequency of the hydro-generator unit at time i, please refer to [link / reference]. Figure 5 .

[0093] See Figure 6 Based on the comparison diagram of the predicted frequency and the measured frequency of the turbine generator set at time i, this invention can calculate the frequency increase from 0 at the initial startup of the unit according to the guide vane change pattern. Using this data as a reference, it corrects the frequency (speed) measurement jumps caused by weak residual voltage signals from the current transformer or inaccurate measurements by the gear plate probe during turbine generator set startup. Once the turbine generator set speed signal is measurable (generally, the speed is greater than 95%, generator excitation is engaged, and the current transformer voltage is high), it can be processed according to steps (A)-(C) above. If there are spikes in the signal change process exceeding the set threshold, they can be automatically compared and discarded, while the previous measurement value is retained as a reference. A refresh can be performed once a normal signal arrives.

[0094] Example 2

[0095] This invention provides a device for analyzing the starting frequency of a hydro-generator set, comprising:

[0096] The acquisition module is used to acquire the measured guide vane opening of the water turbine in real time;

[0097] A proportional adjustment module is used to proportionally adjust the measured guide vane opening to obtain the predicted guide vane opening.

[0098] The frequency prediction module is used to input the predicted guide vane opening into the first-order inertial element of the hydro-generator set to obtain the predicted frequency of the hydro-generator set.

[0099] The frequency analysis module is used to compare the predicted frequency of the hydro-generator set with the measured frequency of the hydro-generator set, and decide whether to use the measured frequency or the predicted frequency of the hydro-generator set as the current frequency of the hydro-generator set based on the comparison result.

[0100] In one specific embodiment of the present invention, the expression for the proportional coefficient used in the proportional adjustment is:

[0101]

[0102] The formula for calculating the predicted guide vane opening is as follows:

[0103]

[0104] In the formula, K is the proportionality coefficient, H0 is the design head of the turbine, and H MAX For maximum head, H MIN y′ represents the minimum head, H represents the currently measured head, y′ represents the predicted guide vane opening, and y represents the actual measured guide vane opening.

[0105] In one specific embodiment of the present invention, the moment of inertia Ta can be calculated based on the actual moment of inertia of the unit, and the calculation formula is as follows:

[0106]

[0107] In the formula, Ta is the unit's rotational inertia time constant, and GD 2 This refers to the flywheel torque of the rotating part of the hydro-generator unit, measured in kg*m². This torque can usually be found in the manufacturer's documentation. N Rated speed of the hydro-generator unit, unit: r / min, P N Rated power of the hydro-generator unit, unit: kW;

[0108] The Laplace transfer function expression for the hydro-generator model is:

[0109]

[0110] Written in difference form:

[0111]

[0112] The expression for the first-order inertial element of the hydro-generator unit is obtained by refining the expression:

[0113]

[0114] In the formula, Δt is the calculation step size, which is generally taken as 10 ms, and y i Let y be the measured guide vane opening at time i. i ' is the predicted guide vane opening at time i, f ei Let f be the predicted frequency of the hydro-generator unit at time i. e(i-1) Let be the predicted frequency of the hydro-generator unit at time i-1, K be the proportional coefficient, and Ta be the time constant of the unit's rotational inertia.

[0115] In one specific embodiment of the present invention, the step of comparing the predicted frequency of the hydro-generator unit with the measured frequency of the hydro-generator unit, and deciding whether to retain the measured frequency of the hydro-generator unit or to use the predicted frequency of the hydro-generator unit instead of the measured frequency based on the comparison result, includes the following steps:

[0116] Compare the predicted frequency f of the hydro-generator unit at time i. ei The measured frequency f of the hydro-generator unit 0i The absolute value of the frequency deviation, |Δf|, is obtained.

[0117] If |Δf| is less than or equal to the first preset frequency threshold, it indicates that the measured frequency f of the hydro-generator unit is... 0i If normal, then retain and output the measured frequency f of the hydro-generator unit at time i. 0i As the current frequency of the hydro-generator unit;

[0118] If |Δf| is greater than or equal to the first preset frequency threshold, it indicates that the measured frequency f of the hydro-generator unit is... 0i An anomaly, and at the same time, if the predicted frequency f of the hydro-generator unit... ei If the frequency is less than the second preset frequency threshold, it indicates that the hydro-generator unit is in the initial startup stage. Therefore, the predicted frequency f of the hydro-generator unit at time i is retained and output. ei As the current frequency of the hydro-generator unit; if the predicted frequency of the hydro-generator unit is f ei If the frequency is greater than or equal to the second preset frequency threshold, it indicates that the hydro-generator unit is in the intermediate rising phase, and the predicted frequency f of the hydro-generator unit is discarded. ei Retain and output the measured frequency f of the hydro-generator unit at time i-1 (the previous cycle). 0(i-1) The current frequency of the hydro-generator unit is used; the second preset frequency threshold is greater than the first preset frequency threshold. In specific implementation, the first preset frequency threshold is 2.5Hz; the second preset frequency threshold is 5Hz.

[0119] The following is combined Figure 5 The present invention will be described in detail with reference to a specific embodiment.

[0120] (A) According to Figure 3 The guide vane opening was controlled by the guide vane variation law, and the measured values ​​of the guide vane were collected;

[0121] (B) Reference Figure 2 Calculate the predicted frequency f of the hydro-generator unit at time i. ei ;

[0122] The predicted frequency will increase according to the law determined by the first-order inertial element and the time constant Ta. The guide vane opening at the final stable frequency of the hydro-generator at 50Hz is the no-load opening Ynl. The entire predicted frequency change process is shown in [reference needed]. Figure 4 The no-load opening degree Ynl is generally related to the turbine head, such as... Figure 4 In this context, the no-load opening is 0.2. Different water heads correspond to different no-load openings; the higher the water head, the smaller the no-load opening, and vice versa. Generally, turbine manufacturers provide a table showing the correspondence between no-load opening and water head, as shown in Table 1. This data table is stored in the program, and the current no-load opening can be obtained by linear conversion based on different water heads.

[0123] Table 1: Correspondence between no-load opening degree and water head provided by the turbine manufacturer

[0124]

[0125] (C) Compare the predicted frequency of the hydro-generator unit at time i with the measured frequency of the hydro-generator unit at time i obtained by using the voltage transformer or toothed disc probe signal to obtain the frequency deviation Δf, and take the absolute value to obtain |Δf|.

[0126] If |Δf| is less than or equal to 2.5Hz (2.5Hz is a set threshold that can be modified), it indicates that the measured frequency f of the hydro-generator unit at time i is... 0i If normal, then output the measured frequency f of the hydro-generator unit at time i. 0i This represents the current frequency of the hydro-generator unit at time i.

[0127] If |Δf| is greater than 2.5Hz, it indicates that the measured frequency f of the hydro-generator unit at time i is... 0i An anomaly occurs when the predicted frequency f of the hydro-generator unit at time i is abnormal. ei If the frequency is less than 5Hz, it indicates that the hydro-generator unit is in the initial startup stage. Therefore, the predicted frequency f of the hydro-generator unit at time i is output. ei As the current frequency of the hydro-generator unit at time i, if the predicted frequency f of the hydro-generator unit at time i... ei If the frequency is greater than or equal to 5Hz, it indicates that the speed of the hydro-generator unit is in the middle rising stage. Therefore, the sampled data is considered to have interference and is discarded. The measured frequency f of the hydro-generator unit at time i-1 is then output. 0(i-1) For the current frequency of the hydro-generator unit at time i, please refer to [link / reference]. Figure 5 .

[0128] See Figure 6Based on the comparison diagram of the predicted frequency and the measured frequency of the turbine generator set at time i, this invention can calculate the frequency increase from 0 at the initial startup of the unit according to the guide vane change pattern. Using this data as a reference, it corrects the frequency (speed) measurement jumps caused by weak residual voltage signals from the current transformer or inaccurate measurements by the gear plate probe during turbine generator set startup. Once the turbine generator set speed signal is measurable (generally, the speed is greater than 95%, generator excitation is engaged, and the current transformer voltage is high), it can be processed according to steps (A)-(C) above. If there are spikes in the signal change process exceeding the set threshold, they can be automatically compared and discarded, while the previous measurement value is retained as a reference. A refresh can be performed once a normal signal arrives.

[0129] Example 3

[0130] This invention provides a hydro-generator start-up frequency analysis system, including a storage medium and a processor;

[0131] The storage medium is used to store instructions;

[0132] The processor is configured to operate according to the instructions to execute the method according to any one of Embodiment 1.

[0133] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for analyzing the starting frequency of a hydro-generator unit, characterized in that, include: Real-time acquisition of the measured guide vane opening of the water turbine; The measured guide vane opening is proportionally adjusted based on the unit head parameters to obtain the predicted guide vane opening. The predicted guide vane opening is input into the first-order inertial element of the hydro-generator unit to obtain the predicted frequency of the hydro-generator unit; the predicted frequency of the hydro-generator unit is compared with the measured frequency of the hydro-generator unit, and based on the comparison result, it is decided whether to retain the measured frequency of the hydro-generator unit or use the predicted frequency of the hydro-generator unit instead of the measured frequency; including the following steps: By comparing the predicted frequency of the hydro-generator unit at time i with the measured frequency of the hydro-generator unit, the absolute value of the frequency deviation, |Δf|, is obtained. If |Δf| is less than or equal to the first preset frequency threshold, it indicates that the measured frequency of the hydro-generator unit is normal. Then, the measured frequency of the hydro-generator unit at time i is retained and output as the current frequency of the hydro-generator unit. If |Δf| is greater than or equal to the first preset frequency threshold, it indicates that the measured frequency of the hydro-generator unit is abnormal. At the same time, if the predicted frequency of the hydro-generator unit is less than the second preset frequency threshold, it indicates that the hydro-generator unit is in the initial startup stage. In this case, the predicted frequency of the hydro-generator unit at time i is retained and output as the current frequency of the hydro-generator unit. If the predicted frequency of the hydro-generator unit is greater than or equal to the second preset frequency threshold, it indicates that the hydro-generator unit is in the intermediate rising stage. The predicted frequency of the hydro-generator unit is discarded, and the measured frequency of the hydro-generator unit at time i-1 is retained and output as the current frequency of the hydro-generator unit. The second preset frequency threshold is greater than the first preset frequency threshold.

2. The method for analyzing the starting frequency of a hydro-generator unit according to claim 1, characterized in that: The expression for the proportional coefficient used in the proportional adjustment is: The formula for calculating the predicted guide vane opening is as follows: In the formula, K is the proportionality coefficient, H0 is the design head of the turbine, and H MAX For maximum head, H MIN y′ represents the minimum head, H represents the currently measured head, y′ represents the predicted guide vane opening, and y represents the actual measured guide vane opening.

3. The method for analyzing the starting frequency of a hydro-generator unit according to claim 1, characterized in that: The first-order inertial element of the hydro-generator unit is expressed as follows: In the formula, Δt is the calculation step size, and y i Let y be the measured guide vane opening at time i. i ' is the predicted guide vane opening at time i, f ei Let f be the predicted frequency of the hydro-generator unit at time i. e(i-1) Let K be the predicted frequency of the hydro-generator unit at time i-1, K be the proportional coefficient, Ta be the time constant of the unit's rotational inertia, and GD be the frequency of the generator unit. 2 This refers to the flywheel torque of the rotating part of the hydro-generator unit, measured in kg*m². This torque can usually be found in the manufacturer's documentation. N Rated speed of the hydro-generator unit, unit: r / min, P N Rated power of the hydro-generator unit, unit: kW.

4. The method for analyzing the starting frequency of a hydro-generator unit according to claim 1, characterized in that: The first preset frequency threshold is 2.5Hz; the second preset frequency threshold is 5Hz.

5. A device for analyzing the starting frequency of a hydro-generator set, characterized in that, include: The acquisition module is used to acquire the measured guide vane opening of the water turbine in real time; A proportional adjustment module is used to proportionally adjust the measured guide vane opening to obtain the predicted guide vane opening. The frequency prediction module is used to input the predicted guide vane opening into the first-order inertial element of the hydro-generator set to obtain the predicted frequency of the hydro-generator set. The frequency analysis module is used to compare the predicted frequency of the hydro-generator unit with the measured frequency of the hydro-generator unit, and determine whether the measured frequency or the predicted frequency of the hydro-generator unit is used as the current frequency of the hydro-generator unit based on the comparison result. This includes the following steps: By comparing the predicted frequency of the hydro-generator unit at time i with the measured frequency of the hydro-generator unit, the absolute value of the frequency deviation, |Δf|, is obtained. If |Δf| is less than or equal to the first preset frequency threshold, it indicates that the measured frequency of the hydro-generator unit is normal. Then, the measured frequency of the hydro-generator unit at time i is retained and output as the current frequency of the hydro-generator unit. If |Δf| is greater than or equal to the first preset frequency threshold, it indicates that the measured frequency of the hydro-generator unit is abnormal. At the same time, if the predicted frequency of the hydro-generator unit is less than the second preset frequency threshold, it indicates that the hydro-generator unit is in the initial startup stage. In this case, the predicted frequency of the hydro-generator unit at time i is retained and output as the current frequency of the hydro-generator unit. If the predicted frequency of the hydro-generator unit is greater than or equal to the second preset frequency threshold, it indicates that the hydro-generator unit is in the intermediate rising stage. The predicted frequency of the hydro-generator unit is discarded, and the measured frequency of the hydro-generator unit at time i-1 is retained and output as the current frequency of the hydro-generator unit. The second preset frequency threshold is greater than the first preset frequency threshold.

6. The starting frequency analysis device for a hydro-generator set according to claim 5, characterized in that, The expression for the proportional coefficient used in the proportional adjustment is: The formula for calculating the predicted guide vane opening is as follows: In the formula, K is the proportionality coefficient, H0 is the design head of the turbine, and H MAX For maximum head, H MIN y′ represents the minimum head, H represents the currently measured head, y′ represents the predicted guide vane opening, and y represents the actual measured guide vane opening.

7. The starting frequency analysis device for a hydro-generator set according to claim 5, characterized in that, The first-order inertial element of the hydro-generator unit is expressed as follows: In the formula, Δt is the calculation step size, and y i Let y be the measured guide vane opening at time i. i ' is the predicted guide vane opening at time i, f ei Let f be the predicted frequency of the hydro-generator unit at time i. e(i-1) Let K be the predicted frequency of the hydro-generator unit at time i-1, K be the proportional coefficient, Ta be the time constant of the unit's rotational inertia, and GD be the frequency of the generator unit. 2 This refers to the flywheel torque of the rotating part of the hydro-generator unit, measured in kg*m². This torque can usually be found in the manufacturer's documentation. N Rated speed of the hydro-generator unit, unit: r / min, P N Rated power of the hydro-generator unit, unit: kW.

8. A hydro-generator set start-up frequency analysis system, characterized in that: Including storage media and processor; The storage medium is used to store instructions; The processor is configured to operate according to the instructions to perform the method according to any one of claims 1-4.

Images