Microcomputer quasi-synchronization device capable of automatically setting constant value

Abstract

The invention discloses a microcomputer automatic quasi-synchronization device capable of automatically setting a fixed value, main hardware comprises a working power supply module, a waveform shaping module, an A / D conversion module, a CPU module, a main control module, a control panel and an output module, and main software flows comprise a quasi-synchronization closing flow, a non-pressure closing flow, an angle difference and ratio difference measurement flow and a leading time measurement flow. Compared with a common microcomputer automatic quasi-synchronizing device, the automatic quasi-synchronizing device has the advantages that the CPU module has the functions of calculating angular difference, differential pressure and leading time, and the control panel is additionally provided with an angular difference and differential pressure measurement function handle and a leading time measurement function handle, so that constant values of compensation angles, voltage compensation coefficients and leading time can be automatically generated.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of microcomputer quasi-synchronization device of power system, and particularly to a microcomputer quasi-synchronization device with automatic setting of setting value. BACKGROUND

[0002] The microcomputer quasi-synchronization device of power system is an important automatic device in power system, which ensures that the breaker is automatically closed when the parameters such as voltage, frequency and phase angle of the generator to be connected to the grid reach the synchronization condition, thereby avoiding the impact caused by non-synchronization closing.

[0003] The existing microcomputer quasi-synchronization device needs to manually calculate and implant the angle difference, voltage difference and lead time parameters, which are extremely important for the quasi-synchronization device. If the setting is wrong, it will cause non-synchronization connection to the grid, which will cause a huge impact on the grid and the generator, and even cause an accident.

[0004] In view of the above, the present application provides a microcomputer quasi-synchronization device with automatic setting of setting value, which can quickly and conveniently solve the above problems. SUMMARY

[0005] The purpose of the present application is to provide a microcomputer quasi-synchronization device with automatic setting of setting value.

[0006] To achieve the above purpose, the present application provides the following technical solutions: The hardware of the microcomputer quasi-synchronization device mainly includes a working power supply module, an isolation transformer, a waveform shaping module, an A / D conversion module, a CPU module, a main control module, a control panel and an output module, as shown in FIG. Figure 1 The control panel mainly includes an electronic step table, an angle difference and voltage difference measurement on-off switch, a lead time measurement on-off switch, a key and a liquid crystal display, as shown in FIG. Figure 2 The TV secondary side voltage of the standby side and the system side is converted into digital quantity by the waveform shaping module and the A / D conversion module, and the angle difference, voltage difference and lead time parameters are automatically generated by the CPU flow.

[0007] The setting value of the microcomputer quasi-synchronization device is set in advance, and the lead time, compensation angle and voltage compensation coefficient must be automatically set by the microcomputer quasi-synchronization device or manually implanted after being measured and calculated by the setting personnel.

[0008] Parameter 1: lead time, which is the time from the closing command to the closing of the main contact of the breaker. It can be automatically implanted by the "lead time measurement" function of the device, or it can be obtained by actual measurement. The value range of this parameter is 40ms-1000ms, and the scale is 10ms. The preset value is 100ms.

[0009] Parameter 2: Closing allowable voltage difference, which represents the maximum voltage difference applied to the two synchronization voltages of the synchronization device during closing. It can be positive or negative, and the positive and negative values can be different. Generally, the positive and negative values are equal. The smaller the parameter, the less the reactive impact during closing, but the closing time is correspondingly extended. The parameter value range is -10V~+10V, with a scale of 0.1V. The preset value is -3V~+3V.

[0010] Parameter 3: Closing allowable frequency difference, which represents the maximum frequency difference allowed on both sides of the circuit breaker during closing. It can be positive or negative, and the positive and negative values can be different. The smaller the parameter, the longer the speed adjustment time. The parameter value range is -0.30Hz~+0.30Hz, with a scale of 0.01Hz. The preset value is -0.2Hz~0.2Hz.

[0011] Parameter 4: Voltage compensation coefficient, which refers to the coefficient for converting the system side voltage secondary side value to the generator side voltage secondary side value. The value is between 0.5 and 2, with a scale of 0.001. The preset value is 1.

[0012] Parameters 5 and 6: System side voltage lower limit value and upper limit value. They can be set, and the device will alarm if the system side voltage exceeds the set value during synchronization. The lower limit value range is 70~105V, and the upper limit value range is 90~130V, with a scale of 1V. The preset value is 90V for the lower limit and 115V for the upper limit. Parameters 7 and 8: System side frequency lower limit value and upper limit value. They can be set, and the device will alarm if the system frequency exceeds the set value during synchronization. The lower limit value is 44~58Hz, and the upper limit value is 50~64Hz, with a scale of 0.5Hz. The preset value is 45Hz for the lower limit and 55Hz for the upper limit.

[0013] Parameter 9: Synchronization side voltage setting coefficient, which is between 0.5 and 2, with a scale of 0.001.

[0014] Parameters 10 and 11: Synchronization side voltage lower limit value and upper limit value. They can be set, and the device will alarm if the synchronization side voltage exceeds the set value during synchronization. The lower limit value range is 70~100V, and the upper limit value range is 90~130V, with a scale of 1V.

[0015] Parameter 12: Compensation angle, which refers to the phase shift angle of the system voltage. The parameter value range is -60 0 ~60 0 (Attention: take "-" if leading voltage is needed, and take "+" if lagging voltage is needed), and the typical value is 0°. Do not modify this value when there is no △ / Y or Y / △ transformation. The preset value is 0°.

[0016] Parameter 13: voltage regulation period, value range 1000-15000 ms, can be set as required. Default value: 3000 ms.

[0017] Parameter 14: voltage regulation timeout time, value range 1-20 min, can be set as required. Default value: 3 min.

[0018] Parameter 15: frequency regulation period, value range 1000-15000 ms, can be set as required. Default value: 3000 ms.

[0019] Parameter 16: frequency regulation timeout time, value range 1-20 min, can be set as required. Default value: 3 min.

[0020] Parameter 17: synchronization timeout time, value range 3-200 min, can be set as required. Default value: 5 min.

[0021] 1. Synchronization voltage compensation angle Since the step-up transformer of the power plant often adopts Y / ∆-11 (or Y / ∆-1) connection, the corresponding phase voltages of the star side and the delta side have a phase shift of 30 0 degrees. If the synchronization device uses the same phase voltage of the high and low voltage side TV of the transformer, the synchronization device will have a voltage phase difference of 30 0 degrees on both sides of the circuit breaker when the grid is connected. Therefore, the phase shift of the transformer must be compensated. The traditional method is to use a corner transformer, or to select the output of the TV secondary that can compensate for the phase shift to compensate for the phase shift. The synchronization device simplifies the design and uses software to realize the corner.

[0022] In order to simplify the calculation and implantation of the compensation angle, the synchronization device can use the "angle difference and voltage difference measurement" function to automatically realize the calculation and implantation of the compensation angle. Figure 3

[0023] When the generator and the YN, d11 connection transformer unit are connected, the synchronization angle difference of No. 1 generator GS1 can be measured automatically. The positions can be QS1, QF1, QS3 closed, QF2, QF3 open, the generator with the transformer and the bus zero step-up; or QS1, QS3 closed, QF1, QF2, QF3 open, and after the generator with the transformer in no-load state, QF1 is closed to charge the bus without voltage. TV1, TV3 are in the same system, start the angle difference and voltage difference measurement process, and the device can automatically calculate and implant the compensation angle.

[0024] Automatic calculation of compensation angle: After starting the angle difference and voltage difference measurement process, the phase angle θ1AB of the secondary side voltage of TV1 and the phase angle θ3AB of the secondary side voltage of TV3 are sampled. ​

[0025] CPU calculates compensation angle Δθ = θ1AB - θ3AB The generator is connected to the grid through the YN, d11 connection transformer The artificial implantation compensation angle, phase compensation should be determined according to the specific connection group of the transformer, the phase shift angle setting. System side synchronous voltage to lead, phase shift angle take "- ", lag, phase shift angle take "+", no transformer between the two synchronous voltage, phase shift angle take 0 0 .

[0026] It should be noted that only in the case of synchronization check signal and closing signal output, closing output is valid.

[0027] 2, about voltage compensation coefficient setting This synchronization device to simplify the calculation and implantation of voltage compensation coefficient, can use "angle difference pressure difference measurement" function to hand start angle difference pressure difference measurement process ( Figure 3 ) Automatic implementation of compensation angle calculation and implantation. The operation method and angle difference automatic compensation are the same.

[0028] Automatic calculation of voltage compensation coefficient: After starting the angle difference pressure difference measurement process, the effective value U1AB of TV1 secondary side voltage and the phase angle U3AB of TV3 secondary side voltage are sampled.

[0029] CPU calculates voltage compensation coefficient k = θU3AB ÷ θU1AB Manual implantation of voltage compensation coefficient: (1) When there is a transformer between the two synchronization voltages.

[0030] System side voltage setting coefficient = 1.000 In this way, the system side voltage entering the synchronization device changes with the high voltage bus voltage, that is: the system voltage entering the synchronization device = high voltage bus voltage / high voltage TV change The voltage compensation coefficient setting formula is: Voltage compensation coefficient = main transformer ratio • machine end TV ratio / high voltage side TV change If the main transformer rated ratio is 236KV / 20KV, the tap is +2.5%, the machine end TV ratio is 20KV / 100V, and the high voltage side TV ratio is 20KV / 100V, then the voltage compensation coefficient (2) When there is no transformer between the two synchronization voltages, which is equivalent to the main transformer ratio being 1, at this time: Voltage compensation coefficient k = 1 3, lead time setting To simplify the calculation and implantation of the lead time, this synchronization device allows users to initiate the lead time measurement process using the "lead time measurement" function. Figure 4 It automatically calculates and implants the pre-guide time.

[0031] The automatic lead time measurement method is as follows: When automatically measuring the lead time of generator GS1 (No. 1), QS1 and QS3 are closed, and QF1, QF2, and QF3 are open, with the generator connected to the transformer in an unloaded state. The lead time measurement process is initiated, and the synchronizing device issues a no-voltage closing command to QF1. The time t1 when the automatic quasi-synchronizing device closes the QF1 circuit breaker is measured, and the time t2 when the voltage delivered from the system-side voltage transformer TV2 to the automatic quasi-synchronizing device rises to the threshold value are measured. The difference between these two time values ​​is calculated to obtain the lead time.

[0032] To avoid electromagnetic interference, the voltage threshold for lead-ahead time measurement should be >5V or <-5V.

[0033] The maximum error in automatic lead time measurement occurs when the secondary voltage crosses zero from -5V to 5V, or when the secondary voltage crosses zero from 5V to -5V. T=arcsin[5÷(100×√2)]×(1÷50÷360)×2=0.000225s=0.225ms The maximum error of the automatic lead time measurement meets the specifications.

[0034] CPU calculates the lead time t = t2 - t1 The artificial lead time is calculated by measuring the circuit breaker closing time.

[0035] In the above technical solution, the microcomputer-based automatic quasi-synchronization device for automatically setting fixed values ​​provided by the present invention has the following beneficial effects: 1. This invention enables the automatic calculation and generation of angle difference, pressure difference, and lead time parameters. These parameters are extremely important for quasi-synchronous devices; incorrect settings can lead to asynchronous grid connection, causing significant impact on the power grid and generators, and even triggering accidents. Automatic generation avoids human errors that may occur during manual calculation, thus improving the efficiency of parameter calculation.

[0036] 2. This invention enables the automatic implantation of setpoints for angle difference, pressure difference, and lead time. It avoids errors that may occur when manually implanting setpoints and improves the efficiency of setpoint implantation. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the present application; Figure 2 This is the control chart for this application; Figure 3 This is one of the flowcharts in this application; Figure 4 Flowchart No. 2 for the present application.

Claims

1. A microcomputer-based quasi-synchronous device for automatically setting set values, characterized in that: With the function of collecting and calculating angle difference, ratio difference and lead time.

2. The microcomputer-based automatic setting value setting device for phase synchronization according to claim 1, characterized by: The measurement process of angle difference and ratio difference.

3. The microcomputer-based automatic setting value setting device for phase synchronization according to claim 1, characterized by: The measurement process of lead time.

4. The microcomputer-based automatic setting value setting device for phase synchronization according to claim 1, characterized by: The "angle difference and ratio difference measurement" function knob (2) and the "lead time measurement" function knob (3) on the control panel.

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