PTQ intelligent quasi-synchronous controller
In the power system, the parallel operation of synchronous generators and line transformers is often carried out. In order to ensure safe and rapid integration of synchronous generators into the grid, a quasi-synchronous controller must be used. The PTQ2000A1 microcomputer intelligent quasi-synchronization controller measures the voltage, frequency, phase, acceleration, and slip rate of the synchronized object by a combination of software and hardware, and has high measurement accuracy and accuracy. In the generator working mode, the voltage and frequency can be adjusted with variable parameters using fuzzy control. There are two ways to adjust voltage, one is pulse width adjustment suitable for analog potentiometer adjustment of servo motor control, and the other is count (time) adjustment suitable for digital control. Frequency modulation (speed) control adopts fuzzy control theory and has a wide range of parameter selection. It can be applied to hydraulic speed governors controlled by servo valves and speed governors controlled by DC servo motors, as well as speed governors controlled by ordinary AC motors. machine. It takes the PIC microcontroller as the core and has the characteristics of high integration, high reliability, simple hardware, and perfect performance.
PTQ2000A1 microcomputer intelligent quasi-synchronization controller has high synchronization accuracy and fast grid connection speed, and provides closing and locking functions. It can be used for the parallel connection of synchronous generators and line transformers. Mainly used in the control equipment of small and medium power plants.
2. Main functions
2.1. The parallel generator will automatically adjust the frequency and voltage in the selected way, calculate the slip and predict the closing phase angle after reaching the set value, and issue the closing command with the selected lead time (when the user selects "automatic closing") to complete the parallel operating. When the user selects "Manual Approval", the user must continue to press the external "Approval" button to issue a closing command. The "Manual Approval" function also provides a remote control method for the host computer. During the parallel process, the phase difference indicator light directly indicates the phase relationship between the generator and the power grid. If the synchronization is successful, the indicator light will stay at the same point and will soon be blocked. If the unsuccessful indicator will not stay on the synchronization point, it will automatically start the next synchronization control after about 10 seconds. But it will automatically add the "Manual Approval" function, which can be cleared with the "Parameter" key or the external "Approval" key. In addition, this device retains the function of "no voltage closing". When it is confirmed that the external power grid is indeed without power, the external "Approval" button can be used to issue a closing command. If the power grid has power, the operation is invalid and must be sent through the synchronization control. Close command.
2.2. Before closing in the same period, the frequency modulation (speed) circuit can work under any circumstances (except the generator itself is disconnected), tracking the grid frequency, and locking 50Hz when the grid is disconnected. Frequency (speed) adjustment adopts fuzzy control for variable parameter adjustment. For speed governors controlled by hydraulic speed governors and DC servo motors, the parameter 11 FM pulse width can be set smaller, and for general AC motor governors, the parameter 11 pulse width should be set larger. For systems with a smaller moment of inertia, you can set the parameter 12 FM interval smaller, and vice versa.
2.3. Before the synchronous closing, the voltage regulating circuit will not operate when the generator frequency GF<42Hz, and will normally adjust at 45Hz~55Hz, and the rated voltage will be locked when the grid is disconnected. There are two options for voltage regulation: pulse width regulation and counting regulation, which are respectively suitable for analog potentiometer regulation and digital regulation controlled by servo motor. See the next section.
2.4. For the parallel connection of line transformers, if the line transformer has a loop, the device will detect whether the power grids on both sides of the transformer are "same frequency" before closing simultaneously. If the same frequency, it will output a "same frequency" signal (deceleration signal generation), and wait for parallel If the voltage is "high" (buck signal), "low" (boost signal), "power angle" is within the set range, if yes, output the "power angle conforming" signal (generation of speed signal). Only when "same frequency", "power angle conforms", and "pressure difference" are met at the same time can the closing command be issued. When "no voltage closing" is selected, an external connection can be used when it is confirmed that there is no power on either side. "Approve" button to issue a closing command.
2.5. All control outputs are passive switch signals. When the control relays act, the corresponding indicator lights are on. When the external load power supply is AC, it is recommended to connect a 0.1uf capacitor in parallel with the load. When the load power supply is DC, connect a diode in anti-parallel to the load; when the load capacity is large, it is recommended to use an intermediate relay for transition.
2.6. During normal operation, the digital tube can display generator voltage (high 2 digits display UF, low 4 digits display voltage value), generator frequency (FF), grid voltage (UE), grid frequency (FE), generator and grid voltage Difference (Ud), frequency difference between generator and grid (Fd), phase difference between generator and grid (Pd). Use the plus and minus keys to cycle through the selection, and the corresponding auxiliary indicator lights at the same time to make the meaning more clear.
2.77. Press the parameter key to enter the parameter setting state, usually starting from the last parameter, the upper 2 digits display the parameter number, and the lower 4 digits display the parameter content. Press again to enter the next parameter setting. Press the parameter key continuously for more than 0.8 seconds or exit the parameter setting state without any operation within 6 seconds. For specific operations, see VI-4, and for the meaning of parameters, see Section III.
2.8. This device has multiple fault detection functions:
(A) The grid is disconnected (the grid voltage and frequency are displayed as 0, and the fault indication is maintained for 76 seconds)
(B) Generator offline (generator voltage and frequency display as 0, fault indication continues)
(C) Grid frequency deviation>3Hz (refer to grid frequency display, fault indication continues)
(D) Generator frequency deviation>5Hz (except when starting, see display, fault indication continues)
(E) The grid voltage is abnormal (over and undervoltage, refer to the grid voltage display, the fault indication continues, and the fault relay operates)
(F) Generator overvoltage (see generator voltage display, fault indication continues, fault relay operates)
These faults are not allowed to send synchronous closing commands.
3. Parameter description
3.1. Parameter 00, input voltage 400V/100V selection, the parameter content is displayed as U400/U100, use the plus (minus) key to select it to match the input voltage value, the factory setting is 100V.
3.2. Parameter 01, line/generator working mode selection, the parameter content is displayed as nnnn/FFFF, the factory setting is the generator working mode, and the display is FFFF. If the user does not specifically request the working mode, it will be locked to the generator mode.
3.3. Parameter 02, closing mode selection, automatic closing/manual approval, displayed as HEAU/HE--, factory setting is automatic closing, displayed as HEAU.
3.4. Parameter 03, lead time setting, the setting range is 0.1S~2.5S, and the setting accuracy is 0.01S. The lead time is used to compensate for a series of delays from the closing command of the quasi-synchronization device to the actual closing. The factory setting is 0.3S.
3.5. Parameter 04, allowable voltage difference setting, the setting range is 2%~10% of rated voltage (line mode is 2%~18%). The setting accuracy is 0.1%. In generator mode, the system will make positive bias adjustment according to this set value (positive difference is 1.5 times of set value, negative difference is 0.5 times of set value), the factory setting is 4%.
3.6. Parameter 05, allowable frequency difference setting, the setting range is ±0.05Hz~±0.6Hz. The setting accuracy is 0.01Hz, and the factory setting is 0.2Hz.
3.7. Parameter 06, allowable power angle (phase angle) setting in line working mode, the setting range is 10°~60°, the setting accuracy is 1°, and the factory setting is 30°. This parameter has no meaning in generator working mode.
3.8. Parameter 07, pressure adjustment pulse width setting, this parameter is meaningful when parameter 4 selects pulse width adjustment. The setting range is 0.1S~0.8S, the total adjustment width (adjustment width + adjustment interval) is about 1S, and the setting accuracy is 0.01S. In fact, this setting is only a basic setting. When the system is actually adjusted, it will automatically change coefficient adjustment (variable adjustment) Interval or variable width). The factory setting is 0.3S.
3.9. Parameter 08, count and adjust the number of times setting, when parameter 4 selects count adjustment, this parameter is meaningful. The setting range is 2~10, and the factory setting is 4. The actual adjustment is also variable coefficient (change the adjustment interval and times).
3.10. Parameter 09, speed pulse width setting, the setting range is 0.2S~2.5S, and the setting accuracy is 0.1S. It is used in conjunction with parameter 12 for variable coefficient adjustment. The factory setting is 0.4S.
3.11. Parameter 10, closing width setting, the setting range is 0.3S~1S, the setting accuracy is 0.01S, and the factory setting is 0.5S.
3.12. Parameter 11, overvoltage value setting, its meaning is the ratio of overvoltage value to rated voltage, the setting range is 110~130%. The factory setting is 120%. The overvoltage setting of the generator and the grid voltage is the same. In addition, there is also an undervoltage setting for the grid voltage, which is set at 70%.
3.13. Parameter 12, generator CT rated current value setting, its value is a percentage of CT nominal value. For example: a current transformer with a nominal value of 5A, if 4A is selected as the rated value, the percentage is 80%, 80 is the parameter value, and the factory is 80 (if there is no special requirement, there is no three-phase current overcurrent) .
4. System block diagram and operation panel diagram
Device panel diagram
5. Device technical conditions
5.1. Power supply AC: 110V~280V/50Hz, DC: 110V~250V
5.2. input signal:
Generator standard voltage: 0V~100V+30V (or 0V~400V+120V)
Grid standard voltage: 0V~100V+30V (or 0V~400V+120V)
Note that the standard voltages are respectively taken from the same-named phases of the voltage transformers on both sides of the object being synchronized. Choose 100V when using standard voltage transformers, and choose 400V when using 380V line voltage directly. In addition, parameter 0 must be modified accordingly.
5.3. output signal:
The six switching signals of increasing speed (power angle conforming), decelerating (same frequency), boosting (lower), stepping down (higher), simultaneous closing and failure, are output by relay.
The contact capacity is AC resistive 220V/5A; AC resistive 380V/2A; DC 110V/0.8A, DC 220V/0.2A. When the external load power supply is AC, it is recommended to connect a 0.1uf capacitor in parallel to the load coil. When the load power supply is DC, connect a diode in anti-parallel to the load coil; when the load capacity is large, it is recommended to use an intermediate relay for transition.
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