阅读说明：本技术 高压直流输电系统的触发角控制方法、系统、装置及介质 (Trigger angle control method, system, device and medium for high-voltage direct-current transmission system ) 是由 刘磊 滕予非 李小鹏 张纯 于 2021-10-15 设计创作，主要内容包括：本发明公开了高压直流输电系统的触发角控制方法、系统、装置及介质,控制方法包括以下步骤：实时采集逆变侧的交流母线电压和直流电流,并对交流母线电压进行Clark变换,得到旋转矢量幅值；根据旋转矢量幅值构造换相电压预测波形,以及根据直流电流获取换相面积预测值；根据换相电压预测波形和换相面积预测值计算触发角指令预测值；获取逆变侧控制系统生成的触发角指令值,并从触发角指令预测值和触发角指令值中选择小的指令值对高压直流输电系统的触发角进行控制。本发明的目的在于提供一种高压直流输电系统的触发角控制方法、系统、装置及介质,可有效的减少换相失败,保障高压直流输电系统和大电网的安全稳定运行。(The invention discloses a trigger angle control method, a trigger angle control system, a trigger angle control device and a trigger angle control medium of a high-voltage direct-current power transmission system, wherein the trigger angle control method comprises the following steps: collecting alternating current bus voltage and direct current at an inversion side in real time, and performing Clark conversion on the alternating current bus voltage to obtain a rotation vector amplitude; constructing a commutation voltage prediction waveform according to the rotation vector amplitude, and acquiring a commutation area prediction value according to the direct current; calculating a trigger angle instruction predicted value according to the phase change voltage predicted waveform and the phase change area predicted value; and acquiring a trigger angle instruction value generated by the inverter side control system, and selecting a small instruction value from the trigger angle instruction predicted value and the trigger angle instruction value to control the trigger angle of the high-voltage direct-current power transmission system. The invention aims to provide a trigger angle control method, a trigger angle control system, a trigger angle control device and a trigger angle control medium for a high-voltage direct-current power transmission system, which can effectively reduce commutation failure and ensure safe and stable operation of the high-voltage direct-current power transmission system and a large power grid.)

1. The trigger angle control method of the high-voltage direct current transmission system is characterized by comprising the following steps of:

collecting alternating current bus voltage and direct current at an inversion side in real time, and performing Clark conversion on the alternating current bus voltage to obtain a rotation vector amplitude;

constructing a commutation voltage prediction waveform according to the rotation vector amplitude, and acquiring a commutation area prediction value according to the direct current;

calculating a trigger angle instruction predicted value according to the commutation voltage predicted waveform and the commutation area predicted value;

and acquiring a trigger angle instruction value generated by the inverter side control system, and selecting a small instruction value from the trigger angle instruction predicted value and the trigger angle instruction value to control the trigger angle of the high-voltage direct-current power transmission system.

2. The firing angle control method for an hvdc transmission system in accordance with claim 1, wherein said commutation voltage prediction waveform is:

wherein, U_p(ωt_p) Predicting the waveform for the commutation voltage, t being the sampling time, t_pPredicting a time variation corresponding to the waveform at [0, π ] for the constructed commutation voltage]Within range, | u_αβ(ω t) | is the rotation obtained by clark transformation of the inverse side AC bus voltage at time tVector magnitude, k_uIs | u_αβ(ω t) | maximum drop rate in one period, θ is the flip angle of the inversion side under normal operating conditions, u_αβ(ωt+ωt_p- θ) is t + t_pAnd (4) carrying out clark transformation on the alternating-current bus voltage on the inversion side at the time of theta/omega to obtain a rotation vector amplitude.

3. The firing angle control method for an hvdc transmission system in accordance with claim 1, wherein said commutation area prediction value is obtained by:

wherein A is a commutation area prediction value, A₀Is the commutation margin area which can ensure the successful commutation, A₁Is a predicted value of commutation overlap area, U_LnIs the effective value of the voltage of the rated inversion side AC line, gamma_nIs the nominal off-angle, ω is the nominal angular frequency of the system, L_rIs a commutation inductor; i is_dIs a direct current, k_IIs the maximum rising slope, μ, of the DC current in a cycle_nIs the commutation overlap angle under normal operating conditions.

4. The method of firing angle control of an hvdc power transmission system in accordance with claim 1, wherein said firing angle command prediction value is obtained by:

wherein alpha is_pAnd pi is a circumferential rate for the firing angle command predicted value.

5. A firing angle control system for a high voltage direct current transmission system, comprising:

the acquisition module is used for acquiring alternating current bus voltage and direct current at an inversion side in real time and performing Clark conversion on the alternating current bus voltage to obtain a rotation vector amplitude;

the processing module is used for constructing a commutation voltage prediction waveform according to the rotation vector amplitude and acquiring a commutation area prediction value according to the direct current;

the calculation module is used for calculating a trigger angle instruction predicted value according to the commutation voltage predicted waveform and the commutation area predicted value;

the acquisition module is used for acquiring a trigger angle instruction value generated by the inverter side control system;

and the control module is used for selecting a small instruction value from the trigger angle instruction predicted value and the trigger angle instruction value to control the trigger angle of the high-voltage direct-current power transmission system.

6. The firing angle control system for an hvdc transmission system in accordance with claim 5, wherein said commutation voltage prediction waveform is:

wherein, U_p(ωt_p) Predicting the waveform for the commutation voltage, t being the sampling time, t_pPredicting a time variation corresponding to the waveform at [0, π ] for the constructed commutation voltage]Within range, | u_αβ(ω t) | is a rotation vector amplitude, k, obtained by clark transformation of the inverse side alternating current bus voltage at the time t_uIs | u_αβ(ω t) | maximum drop rate in one period, θ is the flip angle of the inversion side under normal operating conditions, u_αβ(ωt+ωt_p- θ) is t + t_pAnd (4) carrying out clark transformation on the alternating-current bus voltage on the inversion side at the time of theta/omega to obtain a rotation vector amplitude.

7. The firing angle control system for an hvdc transmission system in accordance with claim 5, wherein said commutation area prediction value is:

wherein A is a commutation area prediction value, A₀Is the commutation margin area which can ensure the successful commutation, A₁Is a predicted value of commutation overlap area, U_LnIs the effective value of the voltage of the rated inversion side AC line, gamma_nIs the nominal off-angle, ω is the nominal angular frequency of the system, L_rIs a commutation inductor; i is_dIs a direct current, k_IIs the maximum rising slope, μ, of the DC current in a cycle_nIs the commutation overlap angle under normal operating conditions.

8. The firing angle control system for an hvdc power transmission system in accordance with claim 5, wherein said firing angle command prediction value is:

wherein alpha is_pAnd pi is a circumferential rate for the firing angle command predicted value.

9. An electronic device comprising a processor and a memory;

the memory to store the processor-executable instructions;

the processor configured to perform the firing angle control method of the HVDC transmission system of any of claims 1-4.

10. Computer readable storage medium, characterized in that it comprises a stored computer program which when run performs a method of firing angle control of a high voltage direct current power transmission system according to any of claims 1-4.

Technical Field

The invention relates to the technical field of control of direct-current transmission systems, in particular to a trigger angle control method, a trigger angle control system, a trigger angle control device and a trigger angle control medium of a high-voltage direct-current transmission system.

Background

China is vast in territory, more than 80% of energy is distributed in the west and the north, and about 75% of electric energy consumption is concentrated in coastal economically developed areas in the middle and the east, and the supply and demand distances are 800-3000 kilometers. The high-voltage direct-current transmission plays a significant role in the energy optimization configuration in China due to the advantages of the high-voltage direct-current transmission in long-distance and large-capacity power transmission. At present, hundreds of millions of kilowatts of power of large energy bases in the three northeast and southwest regions are transmitted to the middle part of thousands of kilometers away and the southeast coastal load center through dozens of loops of HVDC transmission lines. The basic principle of high-voltage direct-current transmission is as follows: the method comprises the steps of rectifying the alternating current at the power transmitting end of a high-voltage direct-current transmission system by using a current converter, converting three-phase alternating current into direct current, transmitting the electric energy through a high-voltage direct-current transmission line, inverting the electric energy at the power receiving end of the high-voltage direct-current transmission system by using the current converter, converting the direct current into three-phase alternating current, and transmitting the electric energy to an alternating current system at the power receiving end.

The high-voltage direct-current transmission converter adopts a thyristor without self-turn-off capability as a basic converter element, and if the valve which is expected to be turned off is not completely turned off within the action time of reverse voltage, the valve voltage is turned on again after being changed from negative to positive, and the phenomenon is called commutation loss failure. Commutation failure is one of the most common failure modes in hvdc transmission systems and usually occurs on the inverting side. Statistics show that 7-circuit DC transmission projects in east China from 2010 to 2015 have commutation failures occurring as many as 330 times. The failure of phase conversion leads to sudden increase of direct current, impact is generated on a converter valve, even direct current locking is caused, and the safe and stable operation of a power grid is seriously threatened. With the increasingly compact coupling of the alternating current and direct current systems in China, the commutation failure is more frequent, the performance is more complex, and the influence range is further expanded.

The small turn-off angle of the converter is the root cause of phase commutation failure, but the turn-off angle cannot be directly controlled, and the turn-off angle needs to be indirectly adjusted by controlling the trigger angle. At present, a commutation failure prediction control link is generally adopted in engineering to realize the rapid control of a trigger angle after a fault, and the core of the method lies in the discrimination of three-phase faults and single-phase faults. However, the control means depending on the failure determination does not have the commutation failure preventive capability until the failure is recognized, and the control hysteresis is serious.

Disclosure of Invention

The invention aims to provide a trigger angle control method, a trigger angle control system, a trigger angle control device and a trigger angle control medium for a high-voltage direct-current power transmission system, which can effectively reduce commutation failure and ensure safe and stable operation of the high-voltage direct-current power transmission system and a large power grid.

The invention is realized by the following technical scheme:

the trigger angle control method of the high-voltage direct-current transmission system comprises the following steps:

collecting alternating current bus voltage and direct current at an inversion side in real time, and performing Clark conversion on the alternating current bus voltage to obtain a rotation vector amplitude;

constructing a commutation voltage prediction waveform according to the rotation vector amplitude, and acquiring a commutation area prediction value according to the direct current;

calculating a trigger angle instruction predicted value according to the commutation voltage predicted waveform and the commutation area predicted value;

and acquiring a trigger angle instruction value generated by the inverter side control system, and selecting a small instruction value from the trigger angle instruction predicted value and the trigger angle instruction value to control the trigger angle of the high-voltage direct-current power transmission system.

The small turn-off angle of the converter is the root cause of phase commutation failure, but the turn-off angle cannot be directly controlled, and the turn-off angle needs to be indirectly adjusted by controlling the trigger angle. At present, a commutation failure prediction control link is generally adopted in engineering to realize the rapid control of a trigger angle after a fault, and the core of the method lies in the discrimination of three-phase faults and single-phase faults. However, the control means depending on the failure determination does not have the commutation failure preventive capability until the failure is recognized, and the control hysteresis is serious. Based on the above, the application provides a trigger angle control method for a high-voltage direct-current power transmission system, which realizes real-time prediction of a trigger angle instruction value capable of avoiding commutation failure by constructing a commutation voltage prediction waveform at each sampling point and combining a commutation mechanism. Compared with the existing commutation failure prediction control technology, the trigger angle prediction instruction provided by the application can immediately respond after a fault, dynamic adjustment of the trigger angle can be realized without fault judgment, and commutation failure prevention can be realized by effectively utilizing the time period in which the fault occurs but is not recognized.

Preferably, the commutation voltage prediction waveform is:

wherein, U_p(ωt_p) Predicting the waveform for the commutation voltage, t being the sampling time, t_pPredicting a time variation corresponding to the waveform at [0, π ] for the constructed commutation voltage]Within range, | u_αβ(ω t) | is a rotation vector amplitude, k, obtained by clark transformation of the inverse side alternating current bus voltage at the time t_uIs | u_αβ(ω t) | maximum drop rate in one period, θ is the flip angle of the inversion side under normal operating conditions, u_αβ(ωt+ωt_p- θ) is t + t_pAnd (4) carrying out clark transformation on the alternating-current bus voltage on the inversion side at the time of theta/omega to obtain a rotation vector amplitude.

Preferably, the commutation area prediction value is obtained by the following formula:

wherein A is a commutation area prediction value, A₀Is the commutation margin area which can ensure the successful commutation, A₁Is a predicted value of commutation overlap area, U_LnIs the effective value of the voltage of the rated inversion side AC line, gamma_nIs the nominal off-angle, ω is the nominal angular frequency of the system, L_rIs a commutation inductor; i is_dIs a direct current, k_IIs the maximum rising slope, μ, of the DC current in a cycle_nIs the commutation overlap angle under normal operating conditions.

Preferably, the firing angle command prediction value is obtained by the following formula:

wherein alpha is_pThe predicted value is the trigger angle command, and pi is the circumferential rate.

A firing angle control system for a high voltage direct current transmission system comprising:

the acquisition module is used for acquiring alternating current bus voltage and direct current at an inversion side in real time and performing Clark conversion on the alternating current bus voltage to obtain a rotation vector amplitude;

the processing module is used for constructing a commutation voltage prediction waveform according to the rotation vector amplitude and acquiring a commutation area prediction value according to the direct current;

the calculation module is used for calculating a trigger angle instruction predicted value according to the commutation voltage predicted waveform and the commutation area predicted value;

the acquisition module is used for acquiring a trigger angle instruction value generated by the inverter side control system;

and the control module is used for selecting a small instruction value from the trigger angle instruction predicted value and the trigger angle instruction value to control the trigger angle of the high-voltage direct-current power transmission system.

The small turn-off angle of the converter is the root cause of phase commutation failure, but the turn-off angle cannot be directly controlled, and the turn-off angle needs to be indirectly adjusted by controlling the trigger angle. At present, a commutation failure prediction control link is generally adopted in engineering to realize the rapid control of a trigger angle after a fault, and the core of the method lies in the discrimination of three-phase faults and single-phase faults. However, the control means depending on the failure determination does not have the commutation failure preventive capability until the failure is recognized, and the control hysteresis is serious. Based on the above, the application provides a trigger angle control method for a high-voltage direct-current power transmission system, which realizes real-time prediction of a trigger angle instruction value capable of avoiding commutation failure by constructing a commutation voltage prediction waveform at each sampling point and combining a commutation mechanism. Compared with the existing commutation failure prediction control technology, the trigger angle prediction instruction provided by the application can immediately respond after a fault, dynamic adjustment of the trigger angle can be realized without fault judgment, and commutation failure prevention can be realized by effectively utilizing the time period in which the fault occurs but is not recognized.

Preferably, the commutation voltage prediction waveform is:

wherein, U_p(ωt_p) Predicting the waveform for the commutation voltage, t being the sampling time, t_pPredicting a time variation corresponding to the waveform at [0, π ] for the constructed commutation voltage]Within range, | u_αβ(ω t) | is a rotation vector amplitude, k, obtained by clark transformation of the inverse side alternating current bus voltage at the time t_uIs | u_αβ(ω t) | maximum drop rate in one period, θ is the flip angle of the inversion side under normal operating conditions, u_αβ(ωt+ωt_p- θ) is t + t_pAnd (4) carrying out clark transformation on the alternating-current bus voltage on the inversion side at the time of theta/omega to obtain a rotation vector amplitude.

Preferably, the predicted commutation area value is:

wherein A is a commutation area prediction value, A₀Is the commutation margin area which can ensure the successful commutation, A₁Is a predicted value of commutation overlap area, U_LnIs the effective value of the voltage of the rated inversion side AC line, gamma_nIs the nominal off-angle, ω is the nominal angular frequency of the system, L_rIs a commutation inductor; i is_dIs a direct current, k_IIs the maximum rising slope, μ, of the DC current in a cycle_nIs the commutation overlap angle under normal operating conditions.

Preferably, the firing angle command prediction value is:

wherein alpha is_pThe predicted value is the trigger angle command, and pi is the circumferential rate.

An electronic device comprising a processor and a memory;

the memory to store the processor-executable instructions;

the processor is configured to perform the firing angle control method of the high voltage direct current power transmission system as described above.

Computer readable storage medium comprising a stored computer program which when run performs a firing angle control method for a high voltage direct current power transmission system as described above.

Compared with the prior art, the invention has the following advantages and beneficial effects:

1. the trigger angle prediction instruction can respond immediately after a fault, dynamic adjustment of the trigger angle can be realized without fault judgment, and commutation failure prevention can be realized by effectively utilizing the time period when the fault occurs but is not recognized;

2. the structure and hardware of the high-voltage direct-current transmission system do not need to be changed, the control function can be realized only by acquiring the electric quantity signals in real time based on the existing measuring points of the system and performing simple operations such as addition, subtraction, comparison and the like, the requirements on hardware and software are low, the speed is high, the real-time performance is good, and the method is suitable for engineering application.

Drawings

The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention. In the drawings:

FIG. 1 is a schematic flow chart of a control method according to the present invention;

FIG. 2 is a comparison of the turn-off angle response for a three-phase fault using the control method of the present invention and a conventional strategy;

fig. 3 is a comparison of the turn-off angle response under a single-phase fault using the control method of the present invention and a conventional strategy.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to examples and accompanying drawings, and the exemplary embodiments and descriptions thereof are only used for explaining the present invention and are not meant to limit the present invention.

Example 1

The embodiment provides a trigger angle control method of a high-voltage direct-current power transmission system, as shown in fig. 1, including the following steps:

step 1: data acquisition and processing

Collecting alternating current bus voltage and direct current at an inversion side in real time, and performing Clark conversion on the collected alternating current bus voltage to obtain a rotation vector amplitude; meanwhile, in order to acquire and utilize the data acquired before in the later period, the control protection device of the high-voltage direct-current power transmission system stores the acquired data for at least one period.

Step 2: commutation voltage prediction waveform structure

Constructing a section of commutation voltage prediction waveform U according to the rotation vector amplitude obtained at each sampling time t_p；

Wherein, U_p(ωt_p) Predicting the waveform for the commutation voltage, t being the sampling time, t_pPredicting a time variation corresponding to the waveform at [0, π ] for the constructed commutation voltage]Within range, | u_αβ(ω t) | is a rotation vector amplitude, k, obtained by clark transformation of the inverse side alternating current bus voltage at the time t_uIs | u_αβ(ω t) | maximum drop rate in one period, θ is the flip angle of the inversion side under normal operating conditions, u_αβ(ωt+ωt_p- θ) is t + t_pAnd (4) carrying out clark transformation on the alternating-current bus voltage on the inversion side at the time of theta/omega to obtain a rotation vector amplitude.

And step 3: commutation area prediction value calculation

Calculating a predicted value A of the commutation area according to the direct current collected at each sampling time t;

wherein A is₀Is the commutation margin area which can ensure the successful commutation, A₁Is a predicted value of commutation overlap area, U_LnIs the effective value of the voltage of the rated inversion side AC line, gamma_nIs the nominal off-angle, ω is the nominal angular frequency of the system, L_rIs a commutation inductor; i is_dIs a direct current, k_IIs the maximum rising slope, μ, of the DC current in a cycle_nIs the commutation overlap angle under normal operating conditions.

And 4, step 4: firing angle command prediction value calculation

At each sampling time t, a firing angle prediction instruction value alpha is calculated from the construction result of step 2 and the calculation result of step 3_p，α_pSatisfies the following conditions:

wherein pi is the circumference ratio.

And 5: firing angle control

And acquiring a trigger angle instruction value generated by the inverter side control system, comparing the trigger angle instruction predicted value with the trigger angle instruction value, and selecting a small instruction value (the small instruction value is selected from the trigger angle instruction value and the trigger angle instruction predicted value in the embodiment) to control the trigger angle of the high-voltage direct-current power transmission system.

The principle of this solution is explained as follows:

the high-voltage direct-current power transmission system constructs a section of commutation voltage prediction waveform U at each sampling moment t_p：

It can be seen that the commutation voltage prediction waveform is essentially a section of sine half-wave, the phase [0, theta ] part is obtained by directly calculating historical voltage data, and the phase [ theta, pi ] part is obtained by predicting the voltage data at the current sampling moment and the voltage drop condition in a period, and the possible worst working condition is considered.

During the actual commutation, the relationship between commutation voltage, dc current and commutation duration can be expressed as:

wherein α is a trigger angle, μ is a commutation overlap angle, and a is an area enclosed by the commutation voltage in the commutation period, which is referred to as commutation overlap area for short.

In analogy to the above, the predicted waveform for the commutation voltage includes:

wherein alpha is_pArtificially set firing angle, mu_pIs alpha_pOverlap angle of commutation under influence, A_pIs alpha_pArea of commutation overlap under influence. From the above equation, similar to the actual commutation process, the duration of the predicted commutation process is uniquely determined by the firing angle under specific operating conditions (dc current, predicted commutation voltage, commutation reactance). Therefore, the firing angle command satisfying the condition can be obtained by reverse-deriving from the desired off-angle.

Under the conditions of inverter side alternating current system fault and the like, both direct current and commutation voltage can change, but the correlation relationship can still be satisfied if the above formula is derived from a commutation mechanism. Therefore, the trigger angle prediction instruction alpha capable of ensuring sufficient commutation margin can be calculated in real time based on the predicted waveform of the measured current and the commutation voltage_pTo reduce the probability of commutation failure of the system:

wherein the content of the first and second substances,A₀the area of the commutation margin which can ensure the successful commutation is obtained by referring to the area of the commutation margin under the normal working condition:

A₁the method is a predicted value of commutation overlapping area, and the commutation overlapping area is the product of equivalent commutation reactance and direct current. Because the calculation of the predicted trigger angle is carried out in real time, the updating time of the predicted trigger angle is infinitely close to the phase change starting time, and the current at the phase change starting time is approximate to the current at the current time. In addition, the dc current at the commutation end time is estimated in consideration of the most severe current rise possible based on the current sampling data of the last cycle. Based on this, A₁Can be expressed as:

wherein, I_{d_ave}Is the predicted average value of the current at the start and stop of commutation, k_IIs the maximum rising slope, μ, of the DC current in a cycle_nIs the commutation overlap angle under normal operating conditions.

Example 2

The present embodiment provides a firing angle control system for a high-voltage direct-current power transmission system based on embodiment 1, including:

the acquisition module is used for acquiring alternating current bus voltage and direct current at an inversion side in real time and performing Clark conversion on the alternating current bus voltage to obtain a rotation vector amplitude;

the processing module is used for constructing a commutation voltage prediction waveform according to the rotation vector amplitude and acquiring a commutation area prediction value according to the direct current;

wherein, the predicted waveform of the commutation voltage is as follows:

wherein, U_p(ωt_p) Predicting the waveform for the commutation voltage, t being the sampling time, t_pPredicting a time variation corresponding to the waveform at [0, π ] for the constructed commutation voltage]Within range, | u_αβ(ω t) | is a rotation vector amplitude, k, obtained by clark transformation of the inverse side alternating current bus voltage at the time t_uIs | u_αβ(ω t) | maximum drop rate in one period, θ is the flip angle of the inversion side under normal operating conditions, u_αβ(ωt+ωt_p- θ) is t + t_pAnd (4) carrying out clark transformation on the alternating-current bus voltage on the inversion side at the time of theta/omega to obtain a rotation vector amplitude.

The predicted value of the commutation area is as follows:

wherein A is a commutation area prediction value, A₀Is the commutation margin area which can ensure the successful commutation, A₁Is a predicted value of commutation overlap area, U_LnIs the effective value of the voltage of the rated inversion side AC line, gamma_nIs the nominal off-angle, ω is the nominal angular frequency of the system, L_rIs a commutation inductor; i is_dIs a direct current, k_IIs the maximum rising slope, μ, of the DC current in a cycle_nIs the commutation overlap angle under normal operating conditions.

The calculation module is used for calculating a trigger angle instruction predicted value according to the phase commutation voltage predicted waveform and the phase commutation area predicted value;

the predicted value of the trigger angle instruction is as follows:

wherein alpha is_pAnd pi is a circumferential rate for the firing angle command predicted value.

The acquisition module is used for acquiring a trigger angle instruction value generated by the inverter side control system;

and the control module is used for selecting a small instruction value from the trigger angle instruction predicted value and the trigger angle instruction value to control the trigger angle of the high-voltage direct-current power transmission system.

Example 3

The present embodiment provides an electronic device based on embodiment 1, including a processor and a memory;

a memory for storing processor-executable instructions;

a processor configured to perform the firing angle control method of the high voltage direct current power transmission system as provided in embodiment 1.

Example 4

The present embodiment provides a computer-readable storage medium on the basis of embodiment 1, comprising a stored computer program which, when running, executes the firing angle control method of the high-voltage direct current transmission system as provided in embodiment 1.

Example 5

In order to verify that the control method provided by the application can reduce the effect of commutation failure, in the embodiment, a CIGRE direct-current transmission standard test system in the PSCAD/EMTDC is adopted as a simulation model. Three-phase earth faults and single-phase earth faults are respectively arranged at an alternating current bus on the inversion side of the high-voltage direct current transmission system, the faults last for 0.01s, and fault inductances are respectively 1.1H and 0.7H, compared with the influence of whether the method is put into or not on the turn-off angle response condition, the simulation result is shown in fig. 2 and fig. 3.

As can be seen from fig. 2, under the conventional commutation failure prediction control strategy, the turn-off angle falls to 0 degree due to voltage disturbance, and the high-voltage direct-current power transmission system has commutation failure. After the strategy of the invention is adopted, the falling of the turn-off angle is obviously reduced, and the commutation failure is effectively prevented. As can be seen from the waveform comparison of the turn-off angle in fig. 3, the present invention can still prevent the occurrence of commutation failure under single-phase fault. Therefore, the control method or the control system provided by the invention can effectively avoid the phase commutation failure phenomenon under the three-phase fault and the single-phase fault.

The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are merely exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.