High-stability hydropower station grid-connected reactive power closed-loop control method

Abstract

The invention provides a high-stability hydropower station grid-connected reactive power closed-loop control method, and the method comprises the steps: generating an increase and decrease magnetic locking signal according to a PSS additional voltage amplitude, and on this basis, outputting an increase and decrease magnetic pulse to an excitation system through a unit monitoring system based on a reactive set value, a reactive feedback value and the increase and decrease magnetic locking signal, and the excitation system calculates an excitation voltage given value based on the voltage given value, the voltage feedback value, the PSS voltage added value and the increased and decreased magnetic pulse, and outputs the excitation voltage given value to an excitation power unit to generate a target excitation voltage. On the basis of accurately controlling the reactive power, the problem of reactive over-regulation caused by PSS regulation and monitoring increase and decrease magnetic superposition is avoided, the reactive disturbance of a unit is reduced, and the safety and stability of a power system are improved.

Description

Technical Field

[0001] The invention relates to the technical field of power station grid-connected regulation, in particular to a high-stability hydropower station grid-connected reactive power closed-loop control method. Background Art

[0002] The reactive power regulation system of the hydropower station computer monitoring system is the basis for the power plant AVC to realize the GIS bus voltage control of the power station. The reactive power regulation of the unit usually adopts the pulse regulation method, which can be divided into automatic closed-loop control and manual open-loop control mode. The manual open-loop control mode adopts the operator's manual increase and decrease of magnetism, and the pulse width is fixed; the automatic closed-loop control uses the reactive target value as the control object, the reactive actual value as feedback, and the automatic closed-loop regulation of the excitation increase and decrease of magnetism pulse width. Generally, the reactive power regulation of the unit operates in the closed-loop control mode.

[0003] When the active power of the unit fluctuates and the PSS adjustment is activated, the reactive power of the unit will change, causing the automatic closed-loop control of the monitoring system to send magnetic pulses to the excitation system. At this time, the PSS adjustment of the excitation system and the increase and decrease of magnetic pulses are superimposed on each other, which may cause the reactive power of the unit to be over-regulated, causing the unit to exit AVC and other problems, affecting the stable operation of the unit.

[0004] At present, the reactive power regulation of the unit usually adopts the pulse regulation method, which can be divided into automatic closed-loop control and manual open-loop control mode. The manual open-loop control mode adopts the operator to manually increase or decrease the magnetism, and the pulse width is fixed; the automatic closed-loop control uses the reactive power target value as the control object, the reactive power actual value as feedback, and the automatic closed-loop regulation of the excitation increase or decrease of the magnetism pulse width. Generally, the reactive power regulation of the unit operates in the closed-loop control mode.

[0005] Existing reactive power regulation has the following defects: (1) At present, there is a lack of consideration of the synergistic relationship between the monitoring increase and decrease of magnetic control and the PSS regulation control when the generator is connected to the grid in the reactive power regulation of the unit. When the two controls are superimposed, it may cause the unit to be over-regulated, affecting the stable operation of the unit; (2) Since PSS regulation has no dead zone, there is currently a lack of methods to directly determine the PSS regulation action. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a highly stable closed-loop control method for the grid-connected reactive power of a hydropower station. On the basis of accurately controlling the reactive power, the problem of reactive over-regulation caused by the superposition of PSS regulation and monitoring increase and decrease of magnetic field is avoided, the reactive disturbance of the unit is reduced, and the safety and stability of the power system are improved.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is: a high-stability hydropower station grid-connected reactive power closed-loop control method, comprising the following steps: Step 1: PSS calculates the additional control voltage according to the active power and speed signal of the unit through the isolation link, inertia link, low-pass filter link, and phase compensation link; Step 2: The excitation system generates an increase or decrease magnetic locking signal according to the additional control voltage and sends it to the monitoring system; Step 3: The monitoring system calculates the increase and decrease magnetic pulses through the PID module according to the reactive set value and the reactive feedback value. At this time, if the increase and decrease magnetic locking signal is activated, the monitoring system will not output the increase and decrease magnetic pulses to the excitation system; if the increase and decrease magnetic locking signal is restored, the monitoring system will output the increase and decrease magnetic pulses to the excitation system; Step 4: The excitation system calculates the comprehensive voltage deviation value according to the voltage setting value, voltage feedback value, additional control voltage, and increase or decrease magnetic pulses, and calculates the excitation voltage setting value through the PID module; Step 5: The excitation voltage setting value is output to the excitation power unit to generate the corresponding excitation voltage and adjust the reactive power of the unit.

[0008] Preferably, in step 2, the technical method of increasing or decreasing the magnetic locking signal is as follows: Step 1: Real-time acquisition of the additional control voltage U output by the unit PSS PSS And store it in array U PSS [n]; Step 2: Find the additional control voltage U closest to the current moment by comparison and discrimination method PSS The maximum value U PSS [max] and minimum value U PSS [min], the specific judgment conditions are: U PSS [max]>U PSS [max+1]&U PSS [max]>U PSS [max-1]; U PSS [min] PSS [min+1]&U PSS [min] PSS [min-1]; Step 3: According to the additional control voltage U PSS Real-time value and 5% rated voltage U N The size determines whether PSS is in action, that is, it satisfies U PSS [n]>5%U N or UPSS[n]<-5%U N When , it is judged that PSS is in action, and the magnetic locking signal LOCK=1 is increased or decreased; Step 4: Determine the additional control voltage U closest to the current moment PSS ​​The difference between the maximum and minimum values ​​and 5% of the rated voltage U N The size determines whether the PSS action is restored, that is, it satisfies (U PSS [max]-U PSS [min])<5%U N When , it is judged that the PSS action is reset, and the increase or decrease magnetic locking signal LOCK = 0.

[0009] Preferably, in step three, the excitation system converts the pulse width of the received increase or decrease magnetic pulse signal into an increase or decrease voltage value.

[0010] Preferably, in step five, the conduction angle of the power semiconductor is controlled so that the excitation power unit generates the required excitation voltage, thereby adjusting the reactive power of the unit.

[0011] The present invention provides a highly stable hydropower station grid-connected reactive power closed-loop control method, which generates an increase-decrease magnetic locking signal according to the PSS additional voltage amplitude. On this basis, the unit monitoring system outputs an increase-decrease magnetic pulse to the excitation system based on the reactive setting value, reactive feedback value, and increase-decrease magnetic locking signal. The excitation system calculates the excitation voltage given value based on the voltage given value, voltage feedback value, PSS voltage additional value, and increase-decrease magnetic pulse, and outputs it to the excitation power unit to generate the target excitation voltage. On the basis of precise control of reactive power, the problem of reactive over-regulation caused by the superposition of PSS regulation and monitoring increase-decrease magnetic is avoided, the reactive disturbance of the unit is reduced, and the safety and stability of the power system are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The present invention will be further described below in conjunction with the accompanying drawings and embodiments: Figure 1 This is the logic diagram of the PSS regulation action locking monitoring increase and decrease magnetic determination of the present invention; Figure 2 The structure diagram of the grid-connected reactive power closed-loop control of the present invention is shown in FIG. DETAILED DESCRIPTION

[0013] A high-stability hydropower station grid-connected reactive power closed-loop control method comprises the following steps: Step 1: PSS calculates the additional control voltage according to the active power and speed signal of the unit through the isolation link, inertia link, low-pass filter link, and phase compensation link; Step 2: The excitation system generates an increase or decrease magnetic locking signal according to the additional control voltage and sends it to the monitoring system; Step 3: The monitoring system calculates the increase and decrease magnetic pulses through the PID module according to the reactive set value and the reactive feedback value. At this time, if the increase and decrease magnetic locking signal is activated, the monitoring system will not output the increase and decrease magnetic pulses to the excitation system; if the increase and decrease magnetic locking signal is restored, the monitoring system will output the increase and decrease magnetic pulses to the excitation system; Step 4: The excitation system calculates the comprehensive voltage deviation value according to the voltage setting value, voltage feedback value, additional control voltage, and increase or decrease magnetic pulses, and calculates the excitation voltage setting value through the PID module; Step 5: The excitation voltage setting value is output to the excitation power unit to generate the corresponding excitation voltage and adjust the reactive power of the unit.

[0014] Preferably, Figure 1 As shown, in step 2, the technical method of increasing or decreasing the magnetic locking signal is as follows: Step 1: Real-time acquisition of the additional control voltage U output by the unit PSS PSS And store it in array U PSS [n]; Step 2: Find the additional control voltage U closest to the current moment by comparison and discrimination method PSS The maximum value U PSS [max] and minimum value U PSS [min], the specific judgment conditions are: U PSS [max]>U PSS [max+1]&U PSS [max]>U PSS [max-1]; U PSS [min] PSS [min+1]&U PSS [min] PSS [min-1]; Step 3: According to the additional control voltage U PSS Real-time value and 5% rated voltage U N The size determines whether PSS is in action, that is, it satisfies U PSS [n]>5%U N or UPSS[n]<-5%U N When , it is judged that PSS is in action, and the magnetic locking signal LOCK=1 is increased or decreased; Step 4: Determine the additional control voltage U closest to the current moment PSS The difference between the maximum and minimum values ​​and 5% of the rated voltage U N The size determines whether the PSS action is restored, that is, it satisfies (U PSS [max]-U PSS [min])<5%U N When , it is judged that the PSS action is reset, and the increase or decrease magnetic locking signal LOCK = 0.

[0015] Preferably, in step three, the excitation system converts the pulse width of the received increase or decrease magnetic pulse signal into an increase or decrease voltage value.

[0016] ​​Preferably, in step five, the conduction angle of the power semiconductor is controlled so that the excitation power unit generates the required excitation voltage, thereby adjusting the reactive power of the unit.

[0017] like Figure 2 As shown, the bus PT and machine-end PT collect the bus and machine-end voltages and send them to the I / O module of the excitation system. The machine-end PT and CT collect the voltage and current of the generator and send them to the automatic meter reading system, calculate the active power and reactive power of the generator, convert them into 4-20mA signals and send them to the I / O module of the excitation system and the I / O module of the monitoring system. The speed device collects the speed of the unit and converts the speed signal into a 4-20mA signal and sends it to the I / O module of the excitation system. The PSS module in the excitation system PLC calculates the additional control voltage in real time based on the collected speed signal and active power signal, and sends the increase and decrease magnetic locking signal to the monitoring system through the I / O module based on the judgment conditions. In the case of not receiving the increase and decrease magnetic locking signal, the I / O module of the monitoring system calculates the increase and decrease magnetic pulses based on the reactive setting and reactive feedback and sends them to the excitation system through the I / O module. The excitation system PLC calculates the increase or decrease voltage value according to the pulse width, and superimposes the basic voltage setting value and the additional control voltage value to form a comprehensive given value of the machine-end voltage. The voltage deviation value is calculated with the machine-end voltage feedback value and output to the PID calculation module. After calculation, a comprehensive control signal is formed and output to the excitation power unit through the I / O module to control the conduction angle of the power semiconductor, thereby adjusting the excitation voltage and the reactive power of the unit.

[0018] The above embodiments are only preferred technical solutions of the present invention and should not be regarded as limiting the present invention. The protection scope of the present invention shall be the technical solutions recorded in the claims, including equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A highly stable closed-loop control method for reactive power of a hydropower station grid-connected, characterized in that: The following steps are involved: Step 1: PSS calculates the additional control voltage according to the active power and speed signal of the unit through the isolation link, inertia link, low-pass filter link, and phase compensation link; Step 2: The excitation system generates an increase or decrease magnetic locking signal according to the additional control voltage and sends it to the monitoring system; Step 3: The monitoring system calculates the increase and decrease magnetic pulses through the PID module according to the reactive set value and the reactive feedback value. At this time, if the increase and decrease magnetic locking signal is activated, the monitoring system will not output the increase and decrease magnetic pulses to the excitation system; if the increase and decrease magnetic locking signal is restored, the monitoring system will output the increase and decrease magnetic pulses to the excitation system; Step 4: The excitation system calculates the comprehensive voltage deviation value according to the voltage setting value, voltage feedback value, additional control voltage, and increase or decrease magnetic pulses, and calculates the excitation voltage setting value through the PID module; Step 5: The excitation voltage setting value is output to the excitation power unit to generate the corresponding excitation voltage and adjust the reactive power of the unit.

2. According to the high-stability hydropower station grid-connected reactive power closed-loop control method of claim 1, it is characterized in that: In step 2, the technical method of increasing or decreasing the magnetic locking signal is as follows: Step 1: Real-time acquisition of the additional control voltage U output by the unit PSS PSS And store it in array U PSS [n]; Step 2: Find the additional control voltage U closest to the current moment by comparison and discrimination method PSS The maximum value U PSS [max] and minimum value U PSS [min], the specific judgment conditions are: U PSS [max]>U PSS [max+1]&U PSS [max]>U PSS [max-1]; U PSS [my] PSS [min+1]&U PSS [my] PSS [min-1];​​ Step 3: According to the additional control voltage U PSS Real-time value and 5% rated voltage U N The size determines whether PSS is in action, that is, it satisfies U PSS [n]>5%U N or UPSS[n]<-5%U N When , it is judged that PSS is in action, and the magnetic locking signal LOCK=1 is increased or decreased; Step 4: Determine the additional control voltage U closest to the current moment PSS The difference between the maximum and minimum values ​​and 5% of the rated voltage U N The size determines whether the PSS action is restored, that is, it satisfies (U PSS [max]-U PSS [min])<5%U N When , it is judged that the PSS action is reset, and the increase or decrease magnetic locking signal LOCK = 0.

3. According to the high stability closed-loop control method for reactive power of hydropower station grid connection of claim 1, it is characterized in that: In the step three, the excitation system converts the pulse width of the received increase and decrease magnetic pulse signal into an increase and decrease voltage value.

4. According to the high stability closed-loop control method for reactive power of a hydropower station connected to the grid of claim 1, it is characterized in that: In the step five, the conduction angle of the power semiconductor is controlled so that the excitation power unit generates the required excitation voltage, thereby adjusting the reactive power of the unit.

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