A diagnostic control method for low-frequency oscillation of power units based on FDB language

Abstract

The invention provides a multi-period unit power low-frequency oscillation diagnosis and control method based on FDB language. The method is developed through a periodic sampling alarm function block. The periodic sampling alarm module has the following functions: sampling an input analog quantity X according to a set sampling period T and a sampling number N, and making a difference S between adjacent samples (new sample and old sample) in absolute value; when the absolute values ​​of these differences meet the set alarm logic, the output Alm is 1, otherwise it is 0; and the periodic interval sampling value is output through a global variable storage; when a reset signal R is 1 or the sampling period T changes, the module is restored to be initialized and sampling is restarted; within a corresponding detection period, a power peak value and a valley value are detected, and a timer detection period, a counter count number, a sampling period and a sampling number are modified online by having a flexible parameter online modification function, and the optimal parameters are adjusted in time according to the actual system conditions, so as to improve the accuracy and availability of low-frequency oscillation detection.

Description

Technical Field

[0001] The invention relates to the field of computer monitoring systems for hydropower plants, and in particular to a multi-period unit power low-frequency oscillation diagnosis and control method based on FDB language. Background Art

[0002] After the asynchronous interconnection of Yunnan power grid, the operating scale of the synchronous power grid is only 10% of the original. The proportion of hydropower startup is large, and the system damping is weakened. During the asynchronous interconnection of Yunnan power grid, low-frequency and ultra-low-frequency oscillations occurred due to water hammer effect and primary frequency regulation parameter matching problems. The oscillation frequency is low and the oscillation amplitude is not large. It is difficult to detect in time under the current unmanned mode, which may cause the oscillation to intensify and affect the stability of the power grid. In the new power system with rapid growth of wind power and photovoltaic installed capacity, system disturbances and low-frequency oscillations are particularly prominent.

[0003] At present, the computer monitoring system of hydropower plants is basically not equipped with active and reactive low-frequency oscillation alarm control logic and strategy. It only relies on manual monitoring by on-site duty personnel and historical curve trend analysis. There is a large lag problem, which cannot detect low-frequency oscillations in time and trigger corresponding strategies to quell the oscillations in time, avoiding further damage to the system stability. Therefore, we make improvements on this and propose a multi-period unit power low-frequency oscillation diagnosis and control method based on FDB language. Summary of the invention

[0004] The purpose of the present invention is to solve the problems raised by the existing background technology, to achieve the above-mentioned generator set active power, reactive power low-frequency oscillation, so that the computer monitoring system can detect the alarm in time and automatically deal with the low-frequency oscillation in time according to the preset strategy, and remind the operation staff to intervene and deal with the invention purpose accordingly, the present invention provides the following technical solutions:

[0005] A multi-period unit power low-frequency oscillation diagnosis and control method based on FDB language, S1 periodic sampling alarm function block development: Periodic sampling alarm module function: according to the set sampling period T and sampling number N, the input analog quantity X is sampled, and the adjacent samples are differenced S new sample - old sample absolute value; when the absolute value of these differences meets the set alarm logic, the output Alm is 1, otherwise it is 0; and the periodic interval sampling value is stored and output through the global variable; when the reset signal R is 1 or the sampling period T changes, the module resumes initialization and restarts sampling;

[0006] S2 Active power and reactive power oscillation detection algorithm is implemented: In the local control unit controller of the computer monitoring system, the low-frequency vibration detection logic is built through the FBD function block. The detection cycle timer sets the corresponding oscillation detection cycle according to the power oscillation frequency. The power peak and valley values ​​are detected within the corresponding detection cycle. When the preset peak and valley value counts are reached, the corresponding logic is triggered;

[0007] S3 low-frequency oscillation output alarm control logic, when the low-frequency vibration of the preset logic is detected, the low-frequency oscillation alarm signal is sent to the upper computer of the monitoring system to remind the operator; the output control signal communicates with the AGC / AVC device and automatically exits the AGC / AC control of the power oscillation unit after the first delay time limit, and exits the LCU single-unit active or reactive automatic regulation of the unit after the second delay time limit;

[0008] S4 has a flexible online parameter modification function, which can modify the timer detection period, counter count times, sampling period, and sampling number online, and adjust the optimal parameters in time according to the actual system conditions to improve the accuracy and usability of low-frequency oscillation detection.

[0009] As a preferred technical solution of the present invention, the low-frequency oscillation diagnosis control strategy includes timing logic, oscillation detection judgment logic, oscillation detection counter, and output logic.

[0010] As a preferred technical solution of the present invention, the timing logic: provides a reference time for the power oscillation detection cycle, resets the counter and oscillation detection judgment logic logic at the moment the set time is reached and starts the next detection cycle; the timing loop time sets different timing sampling times according to different sampling intervals.

[0011] As a preferred technical solution of the present invention, the oscillation detection judgment logic is:

[0012] This sampling value: P n

[0013] Last sampling value: P n-1

[0014] The last sampling value: P n-2

[0015] P n -P n-1 >Pset and P n-2 -P n-1 >Pset, the output oscillation detection counter counts +1.

[0016] As a preferred technical solution of the present invention, the oscillation detection judgment logic, P n With P n-1Sampling is performed at time intervals of 0.2s, 1s, 2s, 4s, 6s, and 8s respectively, and corresponding oscillation detection and judgment logic program segments are enabled according to different sampling intervals.

[0017] As a preferred technical solution of the present invention, the oscillation detection counter outputs to the next link when the oscillation detection counter counts to a set number of times and power oscillation occurs.

[0018] As a preferred technical solution of the present invention, the oscillation detection counter is connected to the oscillation detection judgment logic data circuit.

[0019] As a preferred technical solution of the present invention, the output logic outputs the judgment result according to a predetermined logic to give an alarm and perform related control outputs.

[0020] As a preferred technical solution of the present invention, when the detection setting time is reached in S2, the periodic sampling alarm module, the rising oscillation counter, and the falling oscillation counter are cleared to start the next period of power oscillation monitoring.

[0021] As a preferred technical solution of the present invention, the third time limit output in S3 acts on the excitation AVR and the speed regulator to achieve control mode switching; and outputs the peak and valley values ​​and the oscillation frequency range during the low-frequency oscillation to the monitoring screen of the monitoring host computer.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] In the scheme of the present invention:

[0024] 1. Developed through the periodic sampling alarm function block, the periodic sampling alarm module functions: according to the set sampling period T and the number of samples N, the input analog quantity X is sampled, and the adjacent samples are subtracted by the absolute value of the new sample minus the old sample; when the absolute value of these differences meets the set alarm logic, the output Alm is 1, otherwise it is 0; and the periodic interval sampling value is stored and output through the global variable; when the reset signal R is 1 or the sampling period T changes, the module resumes initialization and restarts sampling;

[0025] 2. Realized by active power and reactive power oscillation detection algorithm: In the local control unit controller of the computer monitoring system, the low-frequency vibration detection logic is built through the FBD function block. The detection cycle timer sets the corresponding oscillation detection cycle according to the power oscillation frequency. The power peak and valley values ​​are detected within the corresponding detection cycle. When the preset peak and valley value counts are reached, the corresponding logic is triggered;

[0026] 3. Through the low-frequency oscillation output alarm control logic, when the low-frequency vibration of the predetermined logic is detected, the low-frequency oscillation alarm signal is sent to the monitoring system host computer to remind the operating personnel; the output control signal communicates with the AGC / AVC device to automatically exit the power oscillation unit single-machine AGC / or AC control after the first delay time limit, and exit the unit LCU single-machine active or reactive automatic adjustment after the second delay time limit. The third delay time limit output acts on the excitation AVR and speed regulator to realize the control mode switching; and the peak and valley values ​​and oscillation frequency range during the low-frequency oscillation period are output to the monitoring screen of the monitoring host computer;

[0027] 4. Through the flexible online parameter modification function, the timer detection cycle, counter counting times, sampling cycle, and sampling number can be modified online, and the optimal parameters can be adjusted in time according to the actual situation of the system to ensure the accuracy and availability of low-frequency oscillation detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A brief logic block diagram of the low-frequency oscillation diagnostic control strategy provided by the present invention. DETAILED DESCRIPTION

[0029] To make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution in the embodiment of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiment is a specific implementation of the present invention and is not limited to all embodiments.

[0030] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents some embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features and technical solutions in the embodiments can be combined with each other. It should be noted that similar numbers and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0032] Example 1: Please refer to Figure 1, A diagnostic control method for low-frequency oscillation of power of multi-period unit based on FDB language, A diagnostic control method for low-frequency oscillation of power of multi-period unit based on FDB language, S1 periodic sampling alarm function block development: Periodic sampling alarm module function: According to the set sampling period T and sampling number N, the input analog quantity X is sampled, and the adjacent samples are subjected to the difference S new sample - the absolute value of the old sample; when the absolute value of these differences meets the set alarm logic, the output Alm is 1, otherwise it is 0; and the periodic interval sampling value is output through the global variable storage; when the reset signal R is 1 or the sampling period T changes, the module resumes initialization and restarts sampling;

[0033] S2 Active power and reactive power oscillation detection algorithm is implemented: In the local control unit controller of the computer monitoring system, the low-frequency vibration detection logic is built through the FBD function block. The detection cycle timer sets the corresponding oscillation detection cycle according to the power oscillation frequency. The power peak and valley values ​​are detected within the corresponding detection cycle. When the preset peak and valley value counts are reached, the corresponding logic is triggered;

[0034] S3 low-frequency oscillation output alarm control logic, when the low-frequency vibration of the preset logic is detected, the low-frequency oscillation alarm signal is sent to the upper computer of the monitoring system to remind the operator; the output control signal communicates with the AGC / AVC device and automatically exits the AGC / AC control of the power oscillation unit after the first delay time limit, and exits the LCU single-unit active or reactive automatic regulation of the unit after the second delay time limit;

[0035] S4 has a flexible online parameter modification function, which can modify the timer detection period, counter count times, sampling period, and sampling number online, and adjust the optimal parameters in time according to the actual system conditions to improve the accuracy and usability of low-frequency oscillation detection.

[0036] The low-frequency oscillation diagnosis control strategy includes timing logic, oscillation detection judgment logic, oscillation detection counter, and output logic.

[0037] Timing logic: Provides the reference time for the power oscillation detection cycle. When the set time is reached, the counter and oscillation detection judgment logic are reset and the next detection cycle begins. The timing loop time sets different timing sampling times according to different sampling intervals.

[0038] Oscillation detection judgment logic:

[0039] This sampling value: P n； Last sampling value: P n-1 The last sampling value: P n-2

[0040] P n -P n-1 >Pset and P n-2-P n-1 >Pset, the output oscillation detection counter counts +1.

[0041] Oscillation detection judgment logic, P n With P n-1 Sampling is performed at time intervals of 0.2s, 1s, 2s, 4s, 6s, and 8s respectively, and corresponding oscillation detection and judgment logic program segments are enabled according to different sampling intervals.

[0042] Oscillation detection counter: When the oscillation detection counter counts to the set number of times and power oscillation occurs, it is output to the next link.

[0043] The oscillation detection counter is connected to the oscillation detection judgment logic data circuit, and the output logic outputs the judgment result according to the predetermined logic to give an alarm and related control output.

[0044] The third time limit output in S3 acts on the excitation AVR and the speed regulator to realize the control mode switching; and outputs the peak and valley values ​​and the oscillation frequency range during the low-frequency oscillation to the monitoring screen of the monitoring host computer.

[0045] Working principle: During the use of the present invention, a multi-cycle unit power low-frequency oscillation diagnosis and control method based on FDB language, a multi-cycle unit power low-frequency oscillation diagnosis and control method based on FDB language, S1 periodic sampling alarm function block development: Periodic sampling alarm module function: According to the set sampling period T and sampling number N, the input analog quantity X is sampled, and the adjacent samples are subjected to the difference S new sampling - the absolute value of the old sampling; when the absolute value of these differences meets the set alarm logic, the output Alm is 1, otherwise it is 0; and the period interval sampling value is output through the global variable storage; when the reset signal R is 1 or the sampling period T changes, the module restores initialization and restarts sampling; S2 active power and reactive power oscillation detection algorithm is realized: in the computer monitoring system on-site control unit controller, the low-frequency oscillation is built through the FBD function block Dynamic detection logic, the detection cycle timer sets the corresponding oscillation detection cycle according to the power oscillation frequency, detects the power peak and valley value in the corresponding detection cycle, and triggers the corresponding logic when the preset peak and valley value count is reached; S3 low-frequency oscillation output alarm control logic, when the low-frequency vibration of the predetermined logic is detected, the low-frequency oscillation alarm signal is sent to the upper computer of the monitoring system to remind the operator; the output control signal communicates with the AGC / AVC device to automatically exit the power oscillation unit stand-alone AGC / or AC control after the first delay time limit, and exit the unit LCU stand-alone active or reactive automatic adjustment after the second delay time limit; S4 has a flexible parameter online modification function, online modification of the timer detection cycle, counter count times, sampling cycle, sampling number, timely adjustment of the optimal parameters according to the actual system situation, so that the low-frequency oscillation detection accuracy and usability. The low-frequency oscillation diagnosis control strategy includes timing logic, oscillation detection judgment logic, oscillation detection counter, and output logic. Timing logic: Give the reference time of the power oscillation detection cycle. When the set time is reached, the counter and oscillation detection judgment logic are reset and the next detection cycle begins. The timing loop time sets different timing sampling times according to different sampling intervals. Oscillation detection judgment logic: This sampling value: P n Last sampling value: P n-1 The last sampling value: P n-2 P n -P n-1 >Pset and P n-2 -P n-1 >Pset, then the output oscillation detection counter count +1. Oscillation detection judgment logic, P n With P n-1Sampling is performed at time intervals of 0.2s, 1s, 2s, 4s, 6s, and 8s respectively, and the corresponding oscillation detection judgment logic program segment is enabled according to different sampling intervals. Oscillation detection counter, when the oscillation detection counter counts to the set number of times and power oscillation occurs, it is output to the next link. The oscillation detection counter is connected to the oscillation detection judgment logic data circuit. The output logic will issue an alarm and related control output according to the predetermined logic for the judgment result. When the detection setting time is reached in S2, the periodic sampling alarm module, the rising oscillation counter, and the falling oscillation counter are cleared to start the next cycle of power oscillation monitoring. The third time limit output in S3 acts on the excitation AVR and the speed regulator to realize the control mode switching; and the peak and valley values ​​and the oscillation frequency range during the low-frequency oscillation are output to the monitoring screen of the monitoring host computer.

[0046] The above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described in the present invention. Although the present invention has been described in detail with reference to the above embodiments, the present invention is not limited to the above specific implementation methods. Therefore, any modification or replacement of the present invention; and all technical solutions and improvements thereof that do not depart from the spirit and scope of the invention are included in the scope of the claims of the present invention.

Claims

1. A method for diagnosing and controlling low-frequency oscillation of power of a multi-period unit based on FDB language, characterized in that: The following steps are involved: Development of S1 periodic sampling alarm function block: Function of periodic sampling alarm module: Sample the input analog quantity X according to the set sampling period T and sampling number N, and make the difference S of the adjacent samples (new sample - old sample absolute value); when the absolute value of these differences meets the set alarm logic, the output Alm is 1, otherwise it is 0; and the periodic interval sampling value is stored and output through the global variable; when the reset signal R is 1 or the sampling period T changes, the module resumes initialization and restarts sampling; S2 Active power and reactive power oscillation detection algorithm is implemented: In the local control unit controller of the computer monitoring system, the low-frequency vibration detection logic is built through the FBD function block. The detection cycle timer sets the corresponding oscillation detection cycle according to the power oscillation frequency. The power peak and valley values ​​are detected within the corresponding detection cycle. When the preset peak and valley value counts are reached, the corresponding logic is triggered; S3 low-frequency oscillation output alarm control logic, when the low-frequency vibration of the preset logic is detected, the low-frequency oscillation alarm signal is sent to the upper computer of the monitoring system to remind the operator; the output control signal communicates with the AGC / AVC device and automatically exits the AGC / AC control of the power oscillation unit after the first delay time limit, and exits the LCU single-unit active or reactive automatic regulation of the unit after the second delay time limit; S4 has a flexible online parameter modification function, which can modify the timer detection period, counter count times, sampling period, and sampling number online, and adjust the optimal parameters in time according to the actual system conditions to improve the accuracy and usability of low-frequency oscillation detection.

2. According to claim 1, a method for diagnosing and controlling low-frequency oscillation of power of a multi-period unit based on FDB language is characterized in that: The low-frequency oscillation diagnosis control strategy includes timing logic, oscillation detection judgment logic, oscillation detection counter, and output logic.

3. The method for diagnosing and controlling low-frequency oscillation of power of a multi-period unit based on FDB language according to claim 2 is characterized in that: The timing logic: provides a reference time for the power oscillation detection cycle, resets the counter and oscillation detection judgment logic logic at the moment the set time is reached and starts the next detection cycle; the timing loop time sets different timing sampling times according to different sampling intervals.

4. The method for diagnosing and controlling low-frequency oscillation of power of a multi-period unit based on FDB language according to claim 3 is characterized in that: The oscillation detection judgment logic: This sampling value: P n Last sampling value: P n-1 The last sampling value: P n-2 P n -P n-1 >Pset and P n-2 -P n-1 >Pset, the output oscillation detection counter counts +1.

5. The method for diagnosing and controlling low-frequency oscillation of power of a multi-period unit based on FDB language according to claim 4 is characterized in that: The oscillation detection judgment logic, P n With P n-1 Sampling is performed at time intervals of 0.2s, 1s, 2s, 4s, 6s, and 8s respectively, and corresponding oscillation detection and judgment logic program segments are enabled according to different sampling intervals.

6. The method for diagnosing and controlling low-frequency oscillation of power of a multi-period unit based on FDB language according to claim 5 is characterized in that: The oscillation detection counter outputs to the next link if the power oscillation occurs when the oscillation detection counter counts to a set number of times.

7. The method for diagnosing and controlling low-frequency oscillation of power of a multi-period unit based on FDB language according to claim 6 is characterized in that: The oscillation detection counter is connected to the oscillation detection judgment logic data circuit.

8. The method for diagnosing and controlling low-frequency oscillation of power of a multi-period unit based on FDB language according to claim 7 is characterized in that: The output logic outputs the judgment result according to a predetermined logic to give an alarm and related control output.

9. The method for diagnosing and controlling low-frequency oscillation of power of a multi-period unit based on FDB language according to claim 8 is characterized in that: When the detection setting time is reached in S2, the periodic sampling alarm module, the rising oscillation counter, and the falling oscillation counter are cleared to start the next period of power oscillation monitoring.

10. The FDB language-based multi-period unit power low-frequency oscillation diagnosis and control method according to claim 9, characterized in that: The third time limit output in S3 acts on the excitation AVR and the speed regulator to realize the control mode switching; and the peak and valley values ​​and the oscillation frequency range during the low-frequency oscillation are output to the monitoring screen of the monitoring host computer.

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