阅读说明：本技术 变换器的控制方法及系统、风电系统 (Control method and system of converter and wind power system ) 是由 韩振铎 刘嘉明 方杭杭 吴立建 王海洋 于 2020-08-03 设计创作，主要内容包括：本发明公开了一种变换器的控制方法及系统、风电系统,所述控制方法应用于并联型变换器,并联型变换器中每个变换器的每相分别设置一个电流传感器,控制方法包括以下步骤：S1、通过电流传感器获取相电流数据；S2、根据相电流数据判断对应的电流传感器是否故障,若是,则执行步骤S3和步骤S4；S3、获取故障电流传感器的所属相,并根据与所属相同相的至少一个无故障电流传感器的相电流数据计算得到一电流修正值；S4、使用电流修正值替换所属相中故障电流传感器的相电流数据。本发明采样电流传感器检测到的所有电流信号,判断出是否该电流传感器出现故障,然后对检测到的故障电流信号,使用修正电流信号代替,最后保证系统的正常运行。(The invention discloses a control method and a control system of converters and a wind power system, wherein the control method is applied to parallel converters, each phase of each converter in the parallel converters is respectively provided with a current sensor, and the control method comprises the following steps: s1, acquiring phase current data through a current sensor; s2, judging whether the corresponding current sensor has a fault according to the phase current data, if so, executing a step S3 and a step S4; s3, obtaining the phase of the fault current sensor, and calculating to obtain a current correction value according to the phase current data of at least one fault-free current sensor with the same phase as the phase of the fault current sensor; and S4, replacing the phase current data of the fault current sensor in the phase with the current correction value. The invention samples all current signals detected by the current sensor, judges whether the current sensor has faults or not, and then replaces the detected fault current signals with correction current signals, thereby finally ensuring the normal operation of the system.)

1. A control method of converters, applied to a parallel type converter in which one current sensor is provided for each phase of each converter, comprising the steps of:

s1, acquiring phase current data through the current sensor;

s2, judging whether the corresponding current sensor has a fault according to the phase current data, if so, executing a step S3 and a step S4;

s3, obtaining the phase of the fault current sensor, and calculating to obtain a current correction value according to the phase current data of at least one fault-free current sensor with the same phase as the phase of the fault current sensor;

and S4, replacing the phase current data of the fault current sensor in the phase with the current correction value.

2. The method of controlling a converter according to claim 1, wherein the step of determining whether the corresponding current sensor is faulty or not based on the phase current data specifically comprises:

obtaining a characteristic value according to the phase current data;

and judging whether the characteristic value exceeds a current threshold value.

3. The method of controlling an inverter of claim 1, wherein the inverter includes a plurality of operating conditions, and the step of determining whether the corresponding current sensor is faulty based on the phase current data includes:

determining the current operation condition of the converter and a characteristic value according to the phase current data;

obtaining a current threshold value according to the current operation condition;

and judging whether the characteristic value exceeds the current threshold value.

4. The method for controlling a converter according to claim 2 or 3, wherein if the characteristic value exceeds the current threshold, the step S2 further comprises:

and judging whether the duration of the characteristic value exceeding the current threshold exceeds a detection time threshold, if so, executing the step S3 and the step S4.

5. The control method of the inverter according to claim 1, wherein the step S2 further includes:

setting a flag bit for the fault current sensor;

step S4 specifically includes:

and detecting whether any current sensor in the phase of the current transformer has a zone bit, and if so, replacing the phase current data detected by the current sensor with the zone bit with the current correction value.

6. The method for controlling a converter according to claim 1, wherein step S3 specifically includes:

and carrying out mean value processing on the phase current data of the fault-free current sensor in the phase to which the current correction value belongs to obtain the current correction value.

7. The method of controlling a converter according to claim 1, wherein the converter includes any one of a converter, an inverter, and a rectifier.

8. The control system of the converter is characterized by being applied to a parallel converter, wherein each phase of each converter in the parallel converter is provided with a current sensor, and the control system comprises a first judgment module, a calculation module and a replacement module;

the current sensor is used for acquiring phase current data;

the first judging module is used for judging whether the corresponding current sensor has a fault according to the phase current data, and if so, the calculating module is called;

the calculation module is used for acquiring the phase of the fault current sensor and calculating a current correction value according to phase current data of at least one fault-free current sensor which is in the same phase as the phase of the fault current sensor;

the replacement module is used for replacing the phase current data of the fault current sensor in the phase with the current correction value.

9. The control system of a converter according to claim 8, wherein said first judging module includes a calculating unit;

the computing unit is used for obtaining a characteristic value according to the phase current data;

the first judging module is used for judging whether the characteristic value exceeds a current threshold value.

10. The control system of the converter according to claim 8, wherein the converter comprises a plurality of operating conditions, and the first judging module comprises a condition determining unit, a calculating unit and a current threshold determining unit;

the working condition determining unit is used for determining the current operating working condition of the converter according to the phase current data;

the computing unit is used for obtaining a characteristic value according to the phase current data;

the current threshold value determining unit is used for obtaining a current threshold value according to the current operation working condition;

the first judging module is used for judging whether the characteristic value exceeds the current threshold value.

11. The control system of a converter according to claim 9 or 10, characterized in that the control system further comprises a second judgment module;

and when the judgment result of the first judgment module is yes, the second judgment module is used for judging whether the duration time that the characteristic value exceeds the current threshold exceeds a detection time threshold, and if so, the calculation module is called.

12. The control system of a converter of claim 8, further comprising a flag setting module and a detection module;

the flag bit setting module is used for setting a flag bit for the fault current sensor;

the detection module is used for detecting whether any current sensor in the phase of the current sensor has a flag bit, and if so, the replacement module is called;

the replacement module is used for replacing the phase current data detected by the current sensor with the zone bit by using the current correction value.

13. The converter control system of claim 8 wherein said calculation module is configured to average phase current data from said fault-free current sensor in said phase to obtain said current correction.

14. The control system of a converter according to claim 8, wherein the converter includes any one of a converter, an inverter, and a rectifier.

15. A wind power system realized by the control method of the converter according to any one of claims 1 to 7.

Technical Field

The invention belongs to the field of fault detection, and particularly relates to a control method and system of a converter and a wind power system.

Background

With the increasing demand of people for power resources, the development of wind power generation becomes more important. Due to abundant offshore wind power resources and large potential development amount, the method has attracted extensive attention of researchers and enterprises. At present, the capacity of an offshore direct-drive wind turbine generator set is developed in a large-capacity and large-scale trend, the capacity of an existing offshore wind power direct-drive converter is more than 5MW or even more than 10MW, and the output current range of a corresponding matched converter is more than 5200A or more than 12000A. The traditional converter power grade formed by a single power module cannot meet the existing requirement, and a plurality of power modules are connected in parallel for control in a common requirement. However, the operation environment of the offshore wind turbine is severe, and the current sensor is easy to have corresponding fault phenomena during detection. Compared with the traditional converter with a single power module, the converter with the multiple parallel power modules has more current sensors and higher failure rate.

Aiming at the problem that the reliability of the whole system is influenced by the fault of the current sensor, the conventional solution is to directly stop the whole system, but for the offshore high-power converter, the operation and maintenance cost is high, and the stop of the whole control system brings about great cost loss. In the existing literature, a stator and rotor current sensor fault judgment method for a single power module in a doubly-fed wind generator is provided, but the method needs a complex control model for judging the current sensor fault, has high requirements on the performance of a microprocessor, is only limited to the judgment of the fault, and still has no good processing means for subsequent fault processing.

Disclosure of Invention

The invention aims to overcome the defects that the reliability of the whole system is affected by the fault of a current sensor and the fault is difficult to process in the prior art, and provides a control method and a system of a converter and a wind power system.

The invention solves the technical problems through the following technical scheme:

a control method of converters applied to a parallel type converter in which one current sensor is provided for each phase of each converter, respectively, the control method comprising the steps of:

s1, acquiring phase current data through the current sensor;

s2, judging whether the corresponding current sensor has a fault according to the phase current data, if so, executing a step S3 and a step S4;

s3, obtaining the phase of the fault current sensor, and calculating to obtain a current correction value according to the phase current data of at least one fault-free current sensor with the same phase as the phase of the fault current sensor;

and S4, replacing the phase current data of the fault current sensor in the phase with the current correction value.

Preferably, the step of determining whether the corresponding current sensor fails according to the phase current data specifically includes:

obtaining a characteristic value according to the phase current data;

and judging whether the characteristic value exceeds a current threshold value.

Preferably, the converter includes a plurality of operating conditions, and the step of determining whether the corresponding current sensor is faulty according to the phase current data specifically includes:

determining the current operation condition of the converter and a characteristic value according to the phase current data;

obtaining a current threshold value according to the current operation condition;

and judging whether the characteristic value exceeds the current threshold value.

Preferably, if the characteristic value exceeds the current threshold, the step S2 further includes:

and judging whether the duration of the characteristic value exceeding the current threshold exceeds a detection time threshold, if so, executing the step S3 and the step S4.

Preferably, step S2 further includes:

setting a flag bit for the fault current sensor;

step S4 specifically includes:

and detecting whether any current sensor in the phase of the current transformer has a zone bit, and if so, replacing the phase current data detected by the current sensor with the zone bit with the current correction value.

Preferably, step S3 specifically includes:

and carrying out mean value processing on the phase current data of the fault-free current sensor in the phase to which the current correction value belongs to obtain the current correction value.

Preferably, the converter includes any one of a converter, an inverter and a rectifier.

A control system of converters is applied to a parallel converter, each phase of each converter in the parallel converter is provided with a current sensor, and the control system comprises a first judgment module, a calculation module and a replacement module;

the current sensor is used for acquiring phase current data;

the first judging module is used for judging whether the corresponding current sensor has a fault according to the phase current data, and if so, the calculating module is called;

the calculation module is used for acquiring the phase of the fault current sensor and calculating a current correction value according to phase current data of at least one fault-free current sensor which is in the same phase as the phase of the fault current sensor;

the replacement module is used for replacing the phase current data of the fault current sensor in the phase with the current correction value.

Preferably, the first determining module includes a calculating unit;

the computing unit is used for obtaining a characteristic value according to the phase current data;

the first judging module is used for judging whether the characteristic value exceeds a current threshold value.

Preferably, the converter comprises a plurality of operating conditions, and the first judging module comprises a condition determining unit, a calculating unit and a current threshold determining unit;

the working condition determining unit is used for determining the current operating working condition of the converter according to the phase current data;

the computing unit is used for obtaining a characteristic value according to the phase current data;

the current threshold value determining unit is used for obtaining a current threshold value according to the current operation working condition;

the first judging module is used for judging whether the characteristic value exceeds the current threshold value.

Preferably, the control system further comprises a second judgment module;

and when the judgment result of the first judgment module is yes, the second judgment module is used for judging whether the duration time that the characteristic value exceeds the current threshold exceeds a detection time threshold, and if so, the calculation module is called.

Preferably, the control system further comprises a flag bit setting module and a detection module;

the flag bit setting module is used for setting a flag bit for the fault current sensor;

the detection module is used for detecting whether any current sensor in the phase of the current sensor has a flag bit, and if so, the replacement module is called;

the replacement module is used for replacing the phase current data detected by the current sensor with the zone bit by using the current correction value.

Preferably, the calculation module is configured to perform an average processing on the phase current data of the non-faulty current sensor in the phase to obtain the current correction value.

Preferably, the converter includes any one of a converter, an inverter and a rectifier.

A wind power system is realized by adopting the control method of the converter.

The positive progress effects of the invention are as follows: the invention relates to a control method for a current sensor in a converter after a fault occurs, which comprises the steps of firstly sampling all current signals detected by the current sensor, judging whether the current sensor has the fault or not, then replacing the detected fault current signals with correction current signals, and finally ensuring the normal operation of a system. When the control method of the converter is used in the wind power system, the operation stability and reliability of the wind power system can be effectively improved, namely, when a current sensor in the system has a fault, the system can continue to operate normally without emergency shutdown immediately, so that unnecessary offshore operation and maintenance times are reduced, the offshore operation and maintenance cost is reduced, and the operation efficiency of the wind power system is improved.

Drawings

Fig. 1 is a flowchart of a control method of an inverter according to embodiment 1 of the present invention.

Fig. 2 is a flowchart of step 30 in the control method of the inverter according to embodiment 1 of the present invention.

Fig. 3 is a flowchart of a control method of an inverter according to embodiment 2 of the present invention.

Fig. 4 is a flowchart of a control method of an inverter according to embodiment 3 of the present invention.

Fig. 5 is a schematic block diagram of a wind power generation system according to embodiment 3 of the present invention.

Fig. 6 is a block diagram schematically showing a control system of an inverter according to embodiment 4 of the present invention.

Fig. 7 is a block diagram schematically showing a control system of an inverter according to embodiment 5 of the present invention.

Fig. 8 is a block diagram schematically showing a control system of an inverter according to embodiment 6 of the present invention.

Detailed Description

The invention is further illustrated by the following examples, which are not intended to limit the scope of the invention.