Whole power station AVC and unit PID logic optimization method and system under weak power grid

Abstract

The invention discloses a power station whole plant AVC and unit PID logic optimization method and system under a weak power grid, and the method comprises the steps: optimizing whole plant AVC control parameters to deal with system oscillation, reactive power, voltage jump and other external conditions under the weak power grid, and effectively reducing the whole plant AVC abnormal exit frequency caused by the power grid. The whole-plant AVC operation rate and reliability are improved, and the human intervention frequency of a whole-plant AVC control mode is reduced so as to improve the operation on-duty efficiency; the reactive PID control parameters of the unit are optimized to limit the outlet voltage of the unit, so that the purpose of limiting the voltage of a high-voltage bus within an overvoltage tripping constant value range is achieved; by adding a reactive power sudden change over-fast backward reactive PID function of a unit, unit reactive PID error adjustment and whole plant voltage error adjustment under extreme working conditions of large sudden change or oscillation of a power grid and abnormal backward of whole plant AVC are prevented.

Description

Technical Field

[0001] The present invention relates to the technical field of hydropower generation, and in particular to a method and system for optimizing AVC and unit PID logic of a power station under a weak power grid. Background Art

[0002] At present, all hydropower stations in the power industry use automatic voltage control AVC and unit reactive PID power regulation mode to achieve the purpose of reactive power balance of the power grid and voltage regulation of the high-voltage busbar of the power station. This method has been widely used in domestic power stations and has a good regulation effect. Sanghe Secondary Hydropower Station continues to use this traditional control method and the domestic power station's full-plant AVC and unit PID experience parameters, but after it was put into operation, the full-plant AVC and unit reactive PID abnormal exit and voltage misregulation frequently occurred. There were even accidents of overvoltage tripping of the outgoing line circuit breaker and load shedding of the whole plant caused by the misregulation of the unit reactive PID under extreme working conditions, which brought great hidden dangers to the operation and duty, safe and stable operation of the power station.

[0003] The main reason is that Cambodia's power grid has weak power grid foundation, frequent accidents, insufficient reactive power regulation means, poor power grid stability and other external conditions, which in turn cause frequent and large fluctuations in voltage and reactive power. In extreme cases, it even causes sudden changes in unit reactive power and misadjustment of unit reactive PID, resulting in frequent exit of AVC of the entire plant due to power grid reasons, out-of-control of high-voltage bus voltage, interference with operation monitoring panel, frequent intervention of operation duty personnel, and other consequences that are not conducive to the safe and stable operation of the power plant. Summary of the invention

[0004] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0005] To this end, the present invention proposes a power plant-wide AVC and unit PID logic optimization method under a weak power grid, which reduces the frequency of abnormal AVC exit of the whole plant and improves the AVC operation rate and reliability of the whole plant.

[0006] Another object of the present invention is to provide a power plant-wide AVC and unit PID logic optimization device under a weak power grid.

[0007] To achieve the above-mentioned purpose, the present invention proposes, on one hand, a method for optimizing the AVC and PID logic of a power plant under a weak power grid, comprising:

[0008] Modify the plant-wide AVC high-voltage bus voltage operating limit setting;

[0009] Modify the limit value of the difference between the AVC voltage setting value and the actual value of the whole plant;

[0010] Modify the upper limit value of the reactive PID stator voltage of the unit;

[0011] Added a new reactive power sudden change too fast retreat reactive PID function module, and arranged the function module on the PLC program of the local control unit of the unit;

[0012] Based on the modified and newly added results, the AVC and unit PID control parameters and logic of the entire plant are optimized.

[0013] The power plant-wide AVC and unit PID logic optimization method under a weak power grid according to an embodiment of the present invention may also have the following additional technical features:

[0014] In one embodiment of the present invention, the plant-wide AVC high-voltage bus voltage operation limit constant is arranged in the AVC module of the power station core database, which is the voltage limit range for the high-voltage bus operation of the plant-wide AVC. If this range is exceeded, the plant-wide AVC will exit.

[0015] In one embodiment of the present invention, the limit value of the difference between the plant-wide AVC voltage setting value and the actual value is arranged in the AVC module of the power station core database, which is the maximum limit of the difference between the voltage setting value and the actual voltage value under the plant-wide AVC voltage control mode. Under normal operating conditions, the plant-wide AVC control module of the power station adjusts the high-voltage bus voltage according to the voltage setting value, that is, under ideal conditions, the measured values ​​of the two are equal. When the high-voltage bus voltage suddenly changes due to system reasons and the mutation range exceeds the set value, the plant-wide AVC exits.

[0016] In one embodiment of the present invention, the upper limit value of the reactive PID stator voltage of the unit is arranged in the PLC program of the unit's local control unit, which is a limit value set to limit the excessive output bus voltage of the unit. When the output bus voltage of the unit reaches this set value, the reactive power increase function will be locked.

[0017] In one embodiment of the present invention, the method for implementing the reactive power mutation over-fast retreat reactive PID function module of the unit is:

[0018] With a period of 0.5 seconds, the actual measured reactive power value of the current unit is compared with the historical value 0.5 seconds ago. If the absolute value of the difference between the two exceeds 5MVar, it is judged that the reactive power of the unit has changed too quickly, and the reactive PID control function of the unit is automatically exited. At the same time, the host computer alarm is issued to remind the operating staff on duty to quickly intervene in the control to stabilize the high-voltage bus voltage.

[0019] In one embodiment of the present invention, modifying the plant-wide AVC high-voltage bus voltage operation limit setting value includes:

[0020] Modify the monitoring system host computer database / whole plant / object / AVC and use the bus voltage to calculate the AVC voltage high limit value within the measuring point.

[0021] In one embodiment of the present invention, modifying the difference limit between the plant-wide AVC voltage setting value and the actual value includes:

[0022] Modify the difference between the local voltage setting value and the actual value in the monitoring system host computer database / advanced functions / factory parameters.

[0023] In one embodiment of the present invention, modifying the upper limit value of the reactive PID stator voltage of the unit includes:

[0024] Modify the stator voltage upper limit value of the INIT segment parameter of the unit PLC program.

[0025] In one embodiment of the present invention, a reactive power mutation over-fast retreat reactive PID function module is added, and the function module is arranged on the PLC program of the local control unit of the unit, including:

[0026] Add Q_CACHE.VAL variable in Tasks / Main Task / MainProgram / Program Tags to store reactive power history data before 0.5 seconds;

[0027] Add T_500MS second base in TIMER_FLAG in Data Types-Userdefined;

[0028] Add the function of obtaining the second base in Tasks / Main Task / MainProgram / Main program segment;

[0029] Add program judgment in Tasks / Main Task / MainProgram / PID_Q to return reactive power PID and send fault signal;

[0030] Modify the host computer database / Unit 1 / Switch quantity / DI

[617] measurement point definition: The reactive power measurement value of Unit 1 changes too quickly, and the reactive PID exits.

[0031] To achieve the above-mentioned purpose, the present invention proposes, on the other hand, a power plant-wide AVC and unit PID logic optimization system under a weak power grid, comprising:

[0032] The first modification module is used to modify the AVC high-voltage bus voltage operation limit setting value of the whole plant;

[0033] The second modification module is used to modify the difference limit between the set value and the actual value of the AVC voltage of the whole plant;

[0034] The third modification module is used to modify the upper limit value of the reactive PID stator voltage of the unit;

[0035] Reactive power reduction module is used to add a reactive power reduction PID function module when the reactive power of the unit suddenly changes too fast, and the function module is arranged on the PLC program of the local control unit of the unit;

[0036] The optimization module is used to optimize the AVC and unit PID control parameters and logic of the entire plant based on the modified results and new results.

[0037] The method and system for optimizing the AVC and unit PID logic of the power plant under a weak power grid according to the embodiment of the present invention can improve the coordination efficiency of the AVC and unit PID of the whole plant under a weak power grid, reduce the frequency of abnormal exit of the AVC of the whole plant due to power grid reasons, reduce the voltage misregulation of the whole plant under extreme working conditions, improve the operation rate and reliability of the AVC of the whole plant, and reduce the work pressure of the operation duty personnel.

[0038] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0040] Figure 1 is a flow chart of a method for optimizing AVC and unit PID logic of a power station under a weak power grid according to an embodiment of the present invention;

[0041] Figure 2 is a schematic diagram of a plant-wide AVC high-voltage bus voltage operation limit setting value according to an embodiment of the present invention;

[0042] Figure 3 1 is a schematic diagram of modifying the limit value of the difference between the set value and the actual value of the AVC voltage of the whole plant according to an embodiment of the present invention;

[0043] Figure 4 is a schematic diagram of modifying the upper limit value of the stator voltage of a generator set according to an embodiment of the present invention;

[0044] Figure 5 is a schematic diagram of the first step of a reactive power sudden change too fast retreat reactive PID function of a newly added unit according to an embodiment of the present invention;

[0045] Figure 6 is a schematic diagram of the second step of the reactive power sudden change too fast retreat reactive PID function of the newly added unit according to an embodiment of the present invention;

[0046] Figure 7 is a schematic diagram of the third step of the reactive power sudden change too fast retreat reactive PID function of the newly added unit according to an embodiment of the present invention;

[0047] Figure 8 is a schematic diagram of the fourth step of the reactive power sudden change too fast retreat reactive PID function of the newly added unit according to an embodiment of the present invention;

[0048] Fig. 9 is a schematic diagram of the fifth step of the reactive power sudden change too fast retreat reactive PID function of the newly added unit according to an embodiment of the present invention;

[0049] Fig.10 It is a structural diagram of a power plant-wide AVC and unit PID logic optimization system under a weak power grid according to an embodiment of the present invention. DETAILED DESCRIPTION

[0050] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0051] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0052] The following describes a method and system for optimizing the AVC and unit PID logic of a power station under a weak power grid according to an embodiment of the present invention with reference to the accompanying drawings.

[0053] Figure 1 is a flow chart of a method for optimizing the AVC and unit PID logic of a power plant under a weak power grid according to an embodiment of the present invention. Figure 1 As shown, the method includes:

[0054] S1, modify the AVC high-voltage bus voltage operating limit setting for the entire plant.

[0055] Specifically, the present invention relaxes the plant-wide AVC high-voltage bus voltage operation limit constant, which is arranged in the AVC module of the power station core database, and is the voltage limit interval for the high-voltage bus operation of the plant-wide AVC. Exceeding this interval will cause the plant-wide AVC to exit. The voltage limit interval is modified from 225kV-246kV to 225kV-250kV. After this step is implemented, the plant-wide AVC over-limit exit event caused by a short-term sudden change of the high-voltage bus voltage to the range of 246kV-250kV will be avoided.

[0056] The operation method of relaxing the plant-wide AVC high-voltage bus voltage operation limit setting according to the embodiment of the present invention is as follows: Figure 2As shown, modify the AVC voltage high limit in the monitoring system host computer database / whole plant / object / "AVC bus voltage calculation" measurement point from 246kV to 250kV.

[0057] S2, modify the limit value of the difference between the AVC voltage setting value and the actual value of the whole plant.

[0058] Specifically, the present invention relaxes the limit value of the difference between the AVC voltage setting value and the actual value of the whole plant. The set value is arranged in the AVC module of the core database of the power station. It is the maximum limit of the difference between the voltage setting value and the voltage actual value under the AVC voltage control mode of the whole plant. Under normal operation, the AVC control module of the whole plant of the power station adjusts the high-voltage bus voltage according to the voltage setting value, that is, under ideal conditions, the measured values ​​of the two are equal. When the high-voltage bus voltage suddenly changes due to system reasons and the mutation range exceeds the set value, it will cause the whole plant AVC to exit. The set value is changed from 5kV to 10kV. After the implementation of this step, the AVC limit exit event of the whole plant caused by the large mutation of the high-voltage bus voltage to the range of 5-10kV will be avoided.

[0059] The operation method of relaxing the limit value of the difference between the set value and the actual value of the AVC voltage of the whole plant in the embodiment of the present invention is as follows: Figure 3 As shown: Modify the difference between the local voltage setting value and the actual value in the monitoring system host computer database / advanced functions / factory parameters from 5kV to 10kV.

[0060] S3, modify the upper limit value of the unit reactive PID stator voltage.

[0061] Specifically, the present invention optimizes the upper limit of the stator voltage of the unit, which is arranged in the PLC program of the local control unit of the unit. It is a limit value set to limit the excessive bus voltage of the unit outlet. When the bus voltage of the unit outlet reaches the set value, the reactive power increase function will be locked to prevent the local control unit from continuously "increasing excitation" to increase the system voltage. The set value is modified from 6.669kV (110% rated phase voltage) to 6.401kV (105% Un rated phase voltage) to match the 230kV line overvoltage protection tripping set value (105% Un and 30s delay tripping), to prevent the line circuit breaker overvoltage tripping and the whole plant load shedding accident caused by the unit reactive PID misadjustment.

[0062] The operating method for optimizing the upper limit value of the stator voltage of the unit according to the embodiment of the present invention is as follows: Figure 4 As shown: Modify the stator voltage upper limit value PID.VD_MAX of the unit PLC program INIT segment parameter from 6.669kV to 6.401kV.

[0063] S4, add a reactive power sudden change too fast retreat reactive PID function module for the unit, and arrange the function module on the PLC program of the unit's local control unit.

[0064] Specifically, a new function of exiting the reactive PID when the reactive power of the unit changes too fast is added. This function is arranged in the PLC program of the unit's local control unit. The function is implemented by comparing the current measured reactive power value of the unit with the historical value 0.5 seconds ago with a period of 0.5 seconds. If the absolute value of the difference between the two exceeds 5MVar, it is judged that the reactive power of the unit changes too fast, and the reactive PID control function of the unit is automatically exited. At the same time, the upper computer alarm is issued to remind the operating staff on duty to quickly intervene in the control to stabilize the high-voltage bus voltage. The selection of the fixed value of 5MVar / 0.5 seconds is a comprehensive consideration with the goal of avoiding the normal reactive power regulation process of the unit and the small fluctuations and oscillations of the voltage and reactive power of the power grid.

[0065] The operation method of the newly added unit reactive power sudden change too fast to retreat reactive PID function in the embodiment of the present invention comprises the following steps:

[0066] 1) Add the Q_CACHE.VAL variable in Tasks / Main Task / MainProgram / Program Tags to store the reactive power history data before 0.5 seconds. The specific changes are as follows: Figure 5 shown.

[0067] 2) Add T_500MS second base to TIMER_FLAG in Data Types-Userdefined. The specific changes are as follows Figure 6 shown.

[0068] 3) Add the function of obtaining the second base in Tasks / Main Task / MainProgram / Main program segment. The specific changes are as follows: Figure 7 shown.

[0069] 4) Add program judgment in Tasks / Main Task / MainProgram / PID_Q to return reactive power PID and send fault signal. The specific modification is as follows: Figure 8 shown.

[0070] 5) Modify the host computer database / unit 1 / switch quantity / DI

[617] (corresponding to DUMMY.DI[9] in the PLC program) measurement point definition to "unit 1 reactive power measurement value changes too fast, reactive PID exits" for the duty operator station briefing alarm. The specific modification is as follows: Fig. 9 shown.

[0071] S5, based on the modified results and the newly added results, optimize the AVC and unit PID control parameters and logic of the whole plant.

[0072] The present invention utilizes existing hardware equipment and automatic control programs of the monitoring system to optimize the AVC and unit PID control parameters and logic of the whole plant to adapt to external conditions such as system oscillation, reactive power, voltage mutation, etc. under the weak power grid of the Kingdom of Cambodia, so that the high-voltage bus voltage of the power station can be controlled. In extreme cases, the reactive PID adjustment function of the unit is exited to prevent the reactive PID misadjustment of the unit from causing the high-voltage bus voltage of the power station to exceed the rated range, thereby improving the AVC commissioning rate and reliability of the whole plant.

[0073] Therefore, the present invention optimizes the AVC constant of the whole plant, relaxes the operating range of the AVC high-voltage bus voltage of the whole plant and the AVC constant of the whole plant when the voltage fluctuation is too large, so as to avoid the exit of the AVC of the whole plant caused by frequent and large-scale oscillation or fluctuation of the grid voltage or reactive power, so that the AVC is still controllable and the bus voltage can be adjusted quickly; the reactive PID function of the unit reactive power sudden change too fast is added to ensure that the reactive PID function of the unit is automatically exited under extreme circumstances, and the bus voltage is stabilized by manual intervention; the upper limit value of the reactive PID stator voltage of the unit is optimized to limit the unit outlet voltage, thereby achieving the purpose of limiting the high-voltage bus voltage within the overvoltage tripping constant range.

[0074] The beneficial effects of the present invention are:

[0075] After the implementation of this invention, according to the annual statistical data of the power station, the number of abnormal AVC exits in the whole plant was reduced from 57 times to 6 times, avoiding most of the power station voltage and reactive power oscillations caused by weak power grids, oscillations and other reasons, effectively improving the AVC commissioning rate and reliability of the whole plant, and improving the work efficiency of the operating staff on duty. At the same time, the setting of the reactive power sudden change of the unit too quickly to exit the reactive PID function avoids the misadjustment of the reactive PID of the unit under extreme working conditions, and prevents further overvoltage tripping of the outgoing line circuit breaker and load shedding accidents of the whole plant.

[0076] According to the method for optimizing the AVC and unit PID logic of a power station under a weak power grid according to an embodiment of the present invention, the frequency of abnormal exit of the AVC of the whole plant due to power grid reasons is effectively reduced, the commissioning rate and reliability of the AVC of the whole plant are improved, and the frequency of human intervention in the AVC control mode of the whole plant is reduced to improve the operation and duty efficiency; the unit reactive PID control parameters are optimized to limit the unit export voltage, thereby achieving the purpose of limiting the high-voltage bus voltage within the overvoltage tripping set value range; and a reactive PID function is added to prevent the unit reactive PID mis-adjustment and the whole plant voltage mis-adjustment under extreme conditions such as large-scale sudden changes or oscillations in the power grid and abnormal exit of the AVC of the whole plant.

[0077] In order to implement the above embodiment, Fig.10 As shown, this embodiment also provides a power plant-wide AVC and unit PID logic optimization system 10 under a weak power grid, including:

[0078] The first modification module 100 is used to modify the plant-wide AVC high-voltage bus voltage operation limit set value;

[0079] The second modification module 200 is used to modify the difference limit between the set value and the actual value of the AVC voltage of the whole plant;

[0080] The third modification module 300 is used to modify the upper limit value of the reactive PID stator voltage of the unit;

[0081] Reactive power reduction module 400 is used to add a reactive power reduction PID function module for the unit reactive power mutation too fast, and arrange the function module on the PLC program of the unit local control unit;

[0082] The optimization module 500 is used to optimize the AVC and unit PID control parameters and logic of the whole plant based on the modification results and the new addition results.

[0083] According to the power plant-wide AVC and unit PID logic optimization system under a weak power grid according to the embodiment of the present invention, the frequency of abnormal exit of the whole plant AVC caused by power grid reasons is effectively reduced, the commissioning rate and reliability of the whole plant AVC are improved, and the frequency of human intervention in the whole plant AVC control mode is reduced to improve the operation and duty efficiency; the unit reactive PID control parameters are optimized to limit the unit outlet voltage, thereby achieving the purpose of limiting the high-voltage bus voltage within the overvoltage tripping set value range; and the reactive PID function of the unit reactive power mutation is added too quickly to prevent the unit reactive PID mis-adjustment and the whole plant voltage mis-adjustment under extreme conditions such as large-scale mutation or oscillation of the power grid and abnormal exit of the whole plant AVC.

[0084] In order to implement the above embodiments, the present application also proposes a non-temporary computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the method described in the above embodiments is implemented.

[0085] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0086] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

Claims

1. A method for optimizing AVC and PID logic of a power plant under weak power grid, characterized in that: include: Modify the plant-wide AVC high-voltage bus voltage operating limit setting; Modify the limit value of the difference between the AVC voltage setting value and the actual value of the whole plant; Modify the upper limit value of the reactive PID stator voltage of the unit; Added a new reactive power sudden change too fast retreat reactive PID function module, and arranged the function module on the PLC program of the local control unit of the unit; Based on the modified and newly added results, the AVC and unit PID control parameters and logic of the entire plant are optimized.

2. The method according to claim 1, characterized in that The plant-wide AVC high-voltage bus voltage operation limit constant is arranged in the AVC module of the power station core database, which is the voltage limit range for the high-voltage bus operation of the plant-wide AVC. If the range is exceeded, the plant-wide AVC will exit.

3. The method according to claim 1, characterized in that The limit value of the difference between the plant-wide AVC voltage setting value and the actual value is arranged in the AVC module of the power station core database. It is the maximum limit of the difference between the voltage setting value and the voltage actual value under the plant-wide AVC voltage control mode. Under normal operation, the plant-wide AVC control module of the power station adjusts the high-voltage bus voltage according to the voltage setting value, that is, under ideal conditions, the two measured values ​​are equal. When the high-voltage bus voltage suddenly changes due to system reasons and the sudden change range exceeds the set value, the plant-wide AVC exits.

4. The method according to claim 1, characterized in that: The upper limit value of the reactive PID stator voltage of the unit is arranged in the PLC program of the local control unit of the unit. It is a limit value set to limit the excessive voltage of the unit's export bus. When the unit's export bus voltage reaches this set value, the reactive power increase function will be locked.

5. The method according to claim 1, characterized in that The method for implementing the reactive power mutation too fast retreat reactive PID function module of the unit is as follows: With a period of 0.5 seconds, the actual measured reactive power value of the current unit is compared with the historical value 0.5 seconds ago. If the absolute value of the difference between the two exceeds 5MVar, it is judged that the reactive power of the unit has changed too quickly, and the reactive PID control function of the unit is automatically exited. At the same time, the host computer alarm is issued to remind the operating staff on duty to quickly intervene in the control to stabilize the high-voltage bus voltage.

6. The method according to claim 1, characterized in that Modify the plant-wide AVC high-voltage bus voltage operating limit setting, including: Modify the monitoring system host computer database / whole plant / object / AVC and use the bus voltage to calculate the AVC voltage high limit value within the measuring point.

7. The method according to claim 1, characterized in that Modify the difference limit between the AVC voltage setting value and the actual value of the whole plant, including: Modify the difference between the local voltage setting value and the actual value in the monitoring system host computer database / advanced functions / factory parameters.

8. The method according to claim 1, characterized in that Modify the upper limit value of the reactive PID stator voltage of the unit, including: Modify the stator voltage upper limit value of the INIT segment parameter of the unit PLC program.

9. The method according to claim 1, characterized in that: A new reactive power sudden change too fast retreat reactive PID function module is added, and the function module is arranged on the PLC program of the local control unit of the unit, including: Add Q_CACHE.VAL variable in Tasks / Main Task / MainProgram / Program Tags to store reactive power history data before 0.5 seconds; Add T_500MS second base in TIMER_FLAG in Data Types-Userdefined; Add the function of obtaining the second base in Tasks / Main Task / MainProgram / Main program segment; Add program judgment in Tasks / Main Task / MainProgram / PID_Q to return reactive power PID and send fault signal; Modify the host computer database / Unit 1 / Switch quantity / DI[617] measurement point definition: The reactive power measurement value of Unit 1 changes too quickly, and the reactive PID exits.

10. A power plant AVC and unit PID logic optimization system under weak power grid, characterized in that: include: The first modification module is used to modify the AVC high-voltage bus voltage operation limit setting value of the whole plant; The second modification module is used to modify the difference limit between the set value and the actual value of the AVC voltage of the whole plant; The third modification module is used to modify the upper limit value of the reactive PID stator voltage of the unit; Reactive power reduction module is used to add a reactive power reduction PID function module when the reactive power of the unit suddenly changes too fast, and the function module is arranged on the PLC program of the local control unit of the unit; The optimization module is used to optimize the AVC and unit PID control parameters and logic of the entire plant based on the modified results and new results.

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