A protection method for a high-power DC power supply in thermal engineering applications without feedback protection

Abstract

The present invention relates to a protection method for a high-power DC power supply in thermal engineering applications without feedback protection, comprising the following steps: (1) establishing a real-time matching relationship between DC voltage and DC current; (2) commissioning the DC power supply system; (3) operating the DC power supply system and judging whether the main DC feedback is normal; (4) judging whether the standby DC feedback is normal; (5) judging whether the AC current feedback is normal; (6) judging whether the DC voltage feedback is normal; (7) repeating steps (3) to (6). If the main DC feedback is restored under the locked control angle and the protection state is started, the high-power DC power supply resumes normal operation. In the technical solution of the present invention, two DC sensors are used as the main feedback, the AC current feedback is used as the secondary feedback, and the DC voltage feedback is used as the third feedback to ensure that in the case of the absence of a certain feedback signal, the current will not get out of control instantaneously, resulting in a sharp increase in power and damage to the load accident.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-power DC power supplies for thermal engineering applications, and particularly relates to a protection method for a high-power DC power supply for thermal engineering applications with missing feedback protection. Background Art

[0002] Thermal engineering application is one of the important experiments in nuclear energy research. A high-power DC power supply is required to heat a nuclear energy material load to simulate the operation of the load under nuclear energy heating conditions in order to obtain important data for nuclear energy research. Usually, the load is made of precious metal materials. When heated to the critical state by the DC power supply, timely protection is required. If the current rises sharply and exceeds a certain critical value in a certain experimental stage, the experimental load will be damaged due to instantaneous over-power. And missing feedback is the main reason for current out-of-control in high-power DC power supplies. Therefore, preventing missing feedback in high-power DC power supplies and the operation conditions and handling measures of the power supply after missing feedback are very important in thermal engineering applications.

[0003] Currently, a stable current operation mode is adopted in high-power DC power supply devices for thermal engineering applications. The high-power DC power supply is a negative feedback control with the feedback signal as one of the input signals for current stabilization control. When the feedback signal is missing, the control system will get out of control and the current will rise sharply instantaneously, resulting in accidents. The following methods are adopted in high-power DC power supply devices to handle abnormal feedback situations: when the feedback current exceeds the rated value, an alarm signal will be sent. When the feedback current value exceeds a certain set value (generally 125% of the rated value), the high-power DC power supply will take the fault handling measure of blocking pulses and shutting down. The high-power DC power supply will use the DC current as the main feedback and the high-voltage AC side current as the secondary feedback. When the main feedback is missing, the secondary feedback will be used as the protection signal to ensure that the power supply device will not get out of control. When both the main feedback of the DC current and the secondary feedback of the AC current are missing or abnormal, the high-power DC power supply device can only protect the equipment by means of relay protection tripping through the distribution system monitoring. Often in this case, the accident has already occurred, and the load or the high-power DC power supply itself has been damaged. And in nuclear energy thermal engineering applications, during operation, if the feedback suddenly disappears, on the one hand, the current cannot rise out of control, otherwise a major accident of load damage will occur, and on the other hand, the current needs to be stabilized at the original normal operation state, otherwise the load operation will not be interrupted, resulting in the loss of interruption of application data acquisition.

[0004] In summary, for the prevention of missing feedback and the protection and measures of high-power DC current after the problem of missing feedback occurs, the requirements for the stable operation of the power supply in thermal engineering applications similar to nuclear energy research cannot be solved. Summary of the Invention

[0005] The object of the present invention is to provide a protection method for a high-power DC power supply in thermal engineering applications with missing feedback protection, which can improve the reliability of feedback signals and effectively prevent out-of-control accidents of power supply current.

[0006] The above object is achieved by the following technical solution: A protection method for a high-power DC power supply in thermal engineering applications with missing feedback protection, which uses a main DC sensor and a standby DC sensor as the main DC feedback and the standby DC feedback respectively, the AC current feedback as the secondary feedback, and the DC voltage feedback as the third feedback. The specific steps are as follows:

[0007] (1) The DC power supply system establishes a load prediction model for thermal engineering loads through multiple operation experiments and big data analysis. Through the load prediction model, a real-time matching relationship between DC voltage and DC current is established.

[0008] (2) Run the DC power supply system in a trial operation. Through the load prediction model in step (1), preset the phase-shifting control angle, check the relationship between the control angle and the output current, and determine whether the main DC feedback is normal. If it is normal, go to step (3); if not, lock the control angle and the given value and stop running.

[0009] (3) Run the DC power supply system. Determine whether the main DC feedback is normal. If it is normal, continue to determine whether the feedback difference between the given value and the main DC feedback is normal. If it is normal, operate normally; if not, lock the control angle and start protection, and go to step (4); if the main DC feedback is not normal, go to step (4).

[0010] (4) Determine whether the standby DC feedback is normal. If it is normal, continue to determine whether the difference between the given value and the standby DC feedback is normal. If it is normal, operate normally; if not, lock the control angle and start protection, and go to step (5); if the standby DC feedback is not normal, directly go to step (5).

[0011] (5) Determine whether the AC current feedback is normal. If it is normal, determine whether the difference between the given value and the AC current feedback is normal. If it is normal, operate normally; if not, lock the control angle and start protection, and go to step (6); if the AC current feedback is not normal, directly go to step (5).

[0012] (6) Determine whether the DC voltage feedback is normal. If it is normal, determine whether the relationship between the given value and the DC voltage is within the predetermined range. If it is within the predetermined range, after converting the feedback DC voltage into a feedback DC current through the load prediction model, the system operates normally; if it is not within the predetermined range, lock the control angle and start protection; if the DC voltage feedback is not normal, and all the above feedback judgments are in an abnormal state, then through the preset actions, lock the control angle and start protection, or stop urgently.

[0013] (7) Steps (3) to (6) are carried out in a loop. If the main DC feedback is restored under the condition of locking the control angle and starting the protection state, the high-power DC power supply resumes normal operation.

[0014] The technical solution of the present invention uses one main and one standby DC sensor as the main feedback, AC current feedback as the secondary feedback, and DC voltage feedback as the third feedback to ensure that in the case of the absence of a certain feedback signal in the power supply device, the current will not get out of control instantaneously, resulting in a sharp increase in power and damaging the load accident. Specifically, the DC power supply system first conducts multiple running experiments. The system software program establishes a load prediction model of the thermal load through big data analysis, judges whether the main feedback signal of the device is normal by means of presetting the control angle, and establishes a real-time matching relationship between the DC voltage and the DC current through the load model, so as to ensure that when the feedback signal is missing, the current can be locked at a certain normal operating value. At the same time, by switching to the operating condition with voltage as the feedback, it is ensured that the power supply device can normally conduct thermal application experiments until the experiment ends and the machine is shut down for inspection when the main DC current feedback is missing, thus ensuring that the research on nuclear energy load will not be interrupted.

[0015] A further technical solution is to use a DC voltage sensor to collect the DC voltage signal of the high-power DC power supply. In step (6), the theoretical output DC current value is obtained in real time as the feedback signal through the load prediction model and the feedback DC voltage value, and the control angle is locked to ensure that the output current is stable and does not fluctuate.

[0016] A further technical solution is that in step (5), the AC current feedback uses the AC current signal on the primary side of the transformer as the feedback input to realize the conversion of the DC output current and the AC current on the primary side. When the signals of both the main DC feedback and the standby DC feedback fail, the effective value of the AC current on the primary side is verified to judge whether there is a lack of feedback.

[0017] A further technical solution is that in step (3) or step (4), the absolute value control method is adopted. When the signal of the main DC feedback or the standby DC feedback is sent to the controller, the maximum value is taken as the feedback signal. When the feedback difference between the given value and the main DC feedback or the standby DC feedback exceeds a certain value, an alarm signal is issued and the system continues to run.

[0018] A further technical solution is that when the DC current feedback including the main DC feedback and the standby DC feedback fails, it automatically switches to the AC current feedback in step (5). When the DC feedback returns to normal, the system continues to use the DC current feedback signal.

[0019] A further technical solution is that in steps (3) to (6), a given signal is compared with a DC current feedback signal, an AC current feedback signal obtained through conversion and calculation, or a feedback DC current signal converted by a load prediction model. When the given signal and the feedback signal exceed the set value, negative feedback judgment is performed. If there is a lack of feedback, the control angle is locked and negative feedback is carried out.

[0020] Compared with the prior art, the present invention adopts a multi-redundancy method with four signals as feedback signals, which improves the reliability of the feedback signals, prevents extreme situations, and simultaneously prevents the occurrence of a situation where the feedback signals are missing, thereby preventing the out-of-control accident of the power supply current in terms of hardware. The present invention establishes a load model based on the output DC voltage and current values collected during normal operation, establishes the relationship between the DC voltage and current in real time, detects the feedback signals before the large current operation by presetting the control angle, judges whether each real-time feedback value is normal by judging the deviation between the theoretical feedback value and the real-time feedback value in real time, and establishes the voltage-current relationship through the load model. When each current feedback fails, the DC power supply device can operate stably and prevent current fluctuations.

[0021] It has the following advantages: Four feedback signals are collected, namely the collection of one main and one standby output DC signals, the collection of AC current signals, and the collection of DC voltage signals, thereby improving the reliability of the feedback signals. During normal operation, the DC voltage and DC current values are collected to establish a load prediction model, thereby providing a judgment basis for confirming whether the DC power supply device is operating normally. By the method of presetting the control angle, the output DC voltage value, DC current value, and AC current value are collected to judge whether there are abnormal conditions in each feedback signal, so as to avoid the situation that a fault exists in the feedback signal at the beginning but is not known, and blindly starting the operation. The fault diagnosis can be placed in the initial state. The deviation between the theoretical feedback value and the feedback value is used to judge whether the feedback value is normal. When the feedback is abnormal, through a hierarchical exclusion method, until the DC voltage feedback signal. When the main feedback fails, the theoretical output DC current value is obtained in real time as the feedback signal through the load model and the feedback DC voltage value, thereby ensuring that the power supply device can operate normally and the output current is stable without fluctuations. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0023] Figure 1 It is a schematic flow chart of a protection method for a high-power DC power supply with missing feedback protection involved in an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] The present invention will be described in detail below with reference to the accompanying drawings. The description in this part is only exemplary and explanatory, and should not have any restrictive effect on the protection scope of the present invention. In addition, those skilled in the art can make corresponding combinations of the features in the embodiments and different embodiments according to the description of this document.

[0025] The embodiments of the present invention are as follows. Refer to Figure 1 , a protection method for a high-power DC power supply in a thermal engineering application without feedback protection, which uses a main DC sensor and a standby DC sensor as the main DC feedback and the standby DC feedback respectively, the AC current feedback as the secondary feedback, and the DC voltage feedback as the third feedback. The specific steps are as follows:

[0026] (1) The DC power supply system establishes a load prediction model of the thermal engineering load through multiple operation experiments and big data analysis, and through the load prediction model, establishes a real-time matching relationship between the DC voltage and the DC current;

[0027] (2) Run the DC power supply system in a trial operation. Through the load prediction model in step (1), preset the phase-shifting control angle, check the relationship between the control angle and the output current, and judge whether the main DC feedback is normal. If it is, go to step (3); if not, lock the control angle and the given value and stop running;

[0028] (3) Run the DC power supply system, judge whether the main DC feedback is normal. If it is normal, continue to judge whether the feedback difference between the given value and the main DC feedback is normal. If it is normal, operate normally; if not, lock the control angle and start protection, and enter step (4); if the main DC feedback is not normal, enter step (4);

[0029] (4) Judge whether the standby DC feedback is normal. If it is normal, continue to judge whether the difference between the given value and the standby DC feedback is normal. If it is normal, operate normally; if not, lock the control angle and start protection, and enter step (5); if the standby DC feedback is not normal, directly enter step (5).

[0030] (5) Judge whether the AC current feedback is normal. If it is normal, judge whether the difference between the given value and the AC current feedback is normal. If it is normal, operate normally; if not, lock the control angle and start protection, and enter step (6); if the AC current feedback is not normal, directly enter step (5);

[0031] (6) Determine whether the DC voltage feedback is normal. If it is normal, then determine whether the relationship between the given value and the DC voltage is within the predetermined range. If it is within the predetermined range, then through the load prediction model, convert the feedback DC voltage into a feedback DC current, and the system operates normally. If it is not within the predetermined range, then lock the control angle and start the protection. If the DC voltage feedback is abnormal, and the above feedback judgments are all in abnormal states, then through the preset actions, enter the locked control angle and start the protection, or stop urgently.

[0032] (7) Steps (3) to (6) are performed in a loop. If the main DC feedback is restored in the state of locking the control angle and starting the protection, the high-power DC power supply resumes normal operation.

[0033] It should be noted that for the locking of the control angle and starting the protection described in steps (3) to (6), starting the protection means entering the protection mode, protecting the running application data to prevent data loss, and the subsequent operation can start from the data obtained from the protection.

[0034] The technical solution of the present invention uses one main and one standby DC sensor as the main feedback, uses the AC current feedback as the secondary feedback, and uses the DC voltage feedback as the third feedback to ensure that in the case of the absence of a certain feedback signal in the power supply device, the current will not get out of control instantaneously, resulting in a sharp increase in power and damaging the load accident. Specifically, the DC power supply system first conducts multiple running experiments, and the system software program establishes a load prediction model of the thermal load through big data analysis. By presetting the control angle method, it judges whether the main feedback signal of the device is normal, and through the load model, establishes the real-time matching relationship between the DC voltage and the DC current, so as to ensure that when the feedback signal is missing, the current can be locked at a certain normal operating value. At the same time, by switching to the operating condition with the voltage as the feedback, it ensures that the power supply device can normally conduct the thermal application experiment until the experiment ends and the machine is shut down for inspection in the case of the absence of the main DC current feedback, thus ensuring that the research on the nuclear energy load will not be interrupted.

[0035] On the basis of the above embodiment, in another embodiment of the present invention, a DC voltage sensor is used to collect the DC voltage signal of the high-power DC power supply. In step (6), through the load prediction model and the feedback DC voltage value, the theoretical output DC current value is obtained in real time as the feedback signal, and the control angle is locked to ensure that the output current is stable and does not fluctuate.

[0036] On the basis of the above embodiment, in another embodiment of the present invention, in step (5), the AC current feedback uses the AC current signal on the primary side of the transformer as the feedback input to realize the conversion of the DC output current and the AC current on the primary side. When the signals of the main DC feedback and the standby DC feedback both fail, the effective value of the AC current on the primary side is verified to judge whether there is a lack of feedback.

[0037] Based on the above embodiment, in another embodiment of the present invention, in step (3) or step (4), an absolute value control method is adopted, and when the signal of the main DC feedback or the backup DC feedback is sent to the controller, the maximum value is taken as the feedback signal, and when the feedback difference between the given and the main DC feedback or the backup DC feedback exceeds a certain value, an alarm signal is issued, and the system continues to operate.

[0038] Based on the above embodiment, in another embodiment of the present invention, when a DC current feedback including the main DC feedback and the backup DC feedback fails, it automatically switches to the AC current feedback in step (5). When the DC feedback returns to normal, the system continues to use the DC current feedback signal.

[0039] On the basis of the above embodiment, in steps (3) to (6) described in another embodiment of the present invention, a given signal is compared with a DC current feedback signal, an AC current feedback signal after conversion operation, or a feedback DC current signal converted by a load prediction model. When the given signal and the feedback signal exceed the set value, a negative feedback judgment is performed. If there is a lack of feedback, the control angle is locked and negative feedback is performed.

[0040] The negative feedback protection measures adopted by the present invention are as follows;

[0041] Dual DC control: The current feedback signal adopts dual DC feedback and absolute value control method; when two DC feedbacks are sent to the controller, the maximum value is taken as the feedback signal, and an alarm signal is issued when the difference between the two feedbacks exceeds a certain value. However, it does not affect the operation of the equipment.

[0042] AC-DC control: The current feedback signal is mainly DC, supplemented by AC; if the DC feedback fails, the system automatically switches to AC feedback. After the DC feedback returns to normal, the system uses the DC feedback signal and the AC feedback is in hot standby.

[0043] DC voltage control: The system uses DC voltage as the final protection acquisition signal of the feedback system. In thermal applications, when the main circuit of the high-power DC power supply operates normally and the current feedback signal has problems due to load or sensor equipment, the voltage signal exists. The output DC voltage is collected as the feedback signal. The current feedback is not used as the main feedback until the current feedback signal is restored.

[0044] Given-feedback parameter comparison: The control system compares the given signal with the DC feedback signal or the converted AC feedback signal. When the given and feedback signals exceed the set value, a negative feedback judgment is performed. If there is a lack of feedback, the control angle is locked and negative feedback protection is performed.

[0045] Load model simulator: The controller determines whether the initial state of the system is normal through the load model simulation program, locks the control angle, and prevents large changes in the current, thereby protecting the load and the rectifier system from impact. During operation, when both the AC-DC feedback (or DC-DC feedback) disappear, the load model preset voltage feedback is used to ensure that the current can maintain stable operation.

[0046] The biggest difference between the present invention and the prior art lies in the advancement of the grinding path planning, and the basis of this advancement lies in the use of a computer vision system to preliminarily locate the defective areas of the casting to be ground in advance. At the same time, the present invention can also preliminarily evaluate the detected grinding points, and on this basis, optimize the subsequent grinding path to a certain extent, and achieve a breakthrough in grinding efficiency relying on this innovation point.

[0047] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A protection method for a high-power DC power supply in thermal engineering applications without feedback protection, characterized in that, A main DC sensor and a standby DC sensor are respectively used as the main DC feedback and the standby DC feedback, the AC current feedback is used as the secondary feedback, and the DC voltage feedback is used as the third feedback. The specific steps are as follows: (1) The DC power supply system establishes a load prediction model for the thermal load through multiple operation experiments and big data analysis. Through the load prediction model, a real-time matching relationship between the DC voltage and the DC current is established; (2) The DC power supply system is put into trial operation. Through the load prediction model in step (1), the phase-shifting control angle is preset, the relationship between the control angle and the output current is tested, and it is judged whether the main DC feedback is normal. If it is, go to step (3); if not, lock the control angle and the given value and stop the operation; (3) The DC power supply system is operated. It is judged whether the main DC feedback is normal. If it is normal, continue to judge whether the feedback difference between the given value and the main DC feedback is normal. If it is normal, the system operates normally; if it is not normal, lock the control angle and start the protection, and go to step (4); if the main DC feedback is not normal, go to step (4); (4) It is judged whether the standby DC feedback is normal. If it is normal, continue to judge whether the difference between the given value and the standby DC feedback is normal. If it is normal, the system operates normally; if it is not normal, lock the control angle and start the protection, and go to step (5); if the standby DC feedback is not normal, directly go to step (5); (5) It is judged whether the AC current feedback is normal. If it is normal, judge whether the difference between the given value and the AC current feedback is normal. If it is normal, the system operates normally; if it is not normal, lock the control angle and start the protection, and go to step (6); if the AC current feedback is not normal, directly go to step (5); (6) It is judged whether the DC voltage feedback is normal. If it is normal, judge whether the relationship between the given value and the DC voltage is within the predetermined range. If it is within the predetermined range, after converting the feedback DC voltage into a feedback DC current through the load prediction model, the system operates normally; if it is not within the predetermined range, lock the control angle and start the protection; if the DC voltage feedback is not normal, and all the above feedback judgments are in an abnormal state, then through the preset actions, enter the state of locking the control angle and starting the protection, or emergency stop; (7) Steps (3) to (6) are carried out in a loop. If the main DC feedback is restored in the state of locking the control angle and starting the protection, the high-power DC power supply returns to the normal operation state.

2. The protection method of the high-power DC power supply for thermal applications without feedback protection according to claim 1, characterized in that, A DC voltage sensor is used to collect the DC voltage signal of the high-power DC power supply. In step (6), through the load prediction model and the feedback DC voltage value, the theoretical output DC current value is obtained in real time as the feedback signal, and the control angle is locked to ensure that the output current is stable and does not fluctuate.

3. The protection method of the high-power DC power supply for thermal applications without feedback protection according to claim 2, characterized in that, In step (5), the AC current feedback uses the AC current signal on the primary side of the transformer as the feedback input to realize the conversion of the DC output current and the AC current on the primary side. When the signals of both the main DC feedback and the standby DC feedback fail, by verifying the effective value of the AC current on the primary side, it is judged whether there is a lack of feedback.

4. The protection method for a high-power DC power supply in thermal applications without feedback protection according to claim 2 or 3, characterized in that, In the step (3) or step (4), the absolute value control method is adopted. When the signals of the main DC feedback or the standby DC feedback are sent to the controller, the maximum value is taken as the feedback signal. When the feedback difference between the given value and the main DC feedback or the standby DC feedback exceeds a certain value, an alarm signal is sent and the system continues to operate.

5. The protection method of a high-power DC power supply for thermal applications without feedback protection according to claim 2, characterized in that, When a fault occurs in the DC current feedback including the main DC feedback and the standby DC feedback, it automatically switches to the AC current feedback in step (5). When the DC feedback returns to normal, the system continues to use the DC current feedback signal.

6. The protection method of a high-power DC power supply for thermal applications without feedback protection according to claim 1, characterized in that, In the steps (3) to (6), the given signal is compared with the DC current feedback signal, the AC current feedback signal obtained through conversion operation, or the feedback DC current signal converted by the load prediction model. When the given value and the feedback signal exceed the set value, negative feedback judgment is performed. If there is a lack of feedback, the control angle is locked and negative feedback is carried out.

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