Direct current transmission system operation risk optimization method based on multi-dimensional analysis

Abstract

The application relates to the technical field of direct current transmission systems, in particular to a direct current transmission system operation risk optimization method based on multi-dimensional analysis, wherein the direct current transmission system comprises a rectifier and an inverter, and the specific method comprises the following steps: performing harmonic interference risk assessment on the rectifier; performing power quality risk assessment on the inverter based on the result of harmonic risk control optimization; calculating inverter risk quality indexes based on the result of the power quality risk assessment; and performing inverter risk compensation optimization based on the inverter risk quality indexes. The application realizes the risk assessment of harmonic interference in the rectification process and the power quality risk assessment of the inversion process after interference control optimization, and further realizes more accurate assessment of the operation risk of the direct current transmission system, effectively solving the problem that the harmonic interference risk in the rectification process and the power quality risk in the inversion process are insufficiently related in the prior art.

Description

Technical Field

[0001] This application relates to the field of DC transmission system technology, and in particular to a method for optimizing the operation risk of DC transmission systems based on multidimensional analysis. Background Technology

[0002] Against the backdrop of global energy transition, High Voltage Direct Current (HVDC) transmission systems, as a highly efficient and long-distance power transmission technology, have been widely applied, especially in areas such as inter-regional power dispatch and large-scale renewable energy integration, where they possess unique advantages. However, as the importance of HVDC systems in power grids gradually increases, scientifically assessing their operational risks and ensuring their safe and stable operation has become a crucial task in power system operation and management. In risk assessment of HVDC systems, single-dimensional assessment methods are no longer sufficient to fully reveal their potential risks. Traditional HVDC operational risk assessment methods typically focus on a single dimension, failing to comprehensively consider the multi-factor influences during system operation and neglecting the interactions between various risks.

[0003] Existing risk assessments for DC transmission systems typically rely on a combination of methods and tools, involving data acquisition, modeling and analysis, simulation, risk identification, assessment, and decision support. By collecting real-time operational data from various devices in the DC transmission system, such as current, voltage, temperature, and equipment load, and utilizing intelligent sensors and remote monitoring systems, the health status of the equipment can be obtained.

[0004] In DC transmission systems, rectifiers inevitably generate harmonics when converting AC to DC. However, inverters, when converting DC to AC, have high requirements for the quality of the input power. For example, if there are many harmonics in the input current or voltage, the output waveform of the inverter may be affected, leading to problems such as reduced power factor and distortion of output voltage waveform, which further poses risks to the operation of the DC transmission system.

[0005] In related technologies, the control strategies of rectifiers and inverters are mostly independent, lacking a real-time monitoring and feedback mechanism for their mutual influence. For example, harmonics or waveform irregularities generated during rectification may cause power quality problems at the inverter input. However, due to insufficient feedback adjustment mechanisms, the inverter may not adjust its control strategy in time to cope with these changes, leading to operational risks in the DC transmission system and a decrease in system reliability. There is a problem of insufficient correlation between the harmonic interference risk of the rectification process and the power quality risk of the inverter process in the DC transmission system. Summary of the Invention

[0006] The main objective of this application is to propose a method for optimizing the operational risks of DC transmission systems based on multidimensional analysis, in order to solve the aforementioned problems.

[0007] To achieve the above objectives, this application proposes a method for optimizing the operational risk of a DC transmission system based on multidimensional analysis. The DC transmission system includes a rectifier and an inverter. The method includes the following steps: A harmonic interference risk assessment is conducted on the rectifier, the harmonic interference risk value is calculated based on the results of the assessment, and the harmonic risk management and control are optimized based on the harmonic interference risk value. Based on the results of harmonic risk management optimization, power quality risk assessment is performed on the inverter. Based on the results of the power quality risk assessment, inverter risk quality index is calculated, and inverter risk compensation optimization is performed based on the inverter risk quality index.

[0008] In some embodiments, calculating the harmonic interference risk value based on the results of the harmonic interference risk assessment specifically includes: Obtain the results of the harmonic interference risk assessment of the rectifier, including harmonic interference current monitoring data and harmonic interference voltage monitoring data; Based on the harmonic interference current monitoring data and harmonic interference voltage monitoring data, the harmonic interference current index and harmonic interference voltage index are calculated. The harmonic interference risk value is obtained by weighting and coupling the harmonic interference current index and harmonic interference voltage index with the corresponding current risk interference compensation amount and voltage risk interference compensation amount.

[0009] In some embodiments, the optimization of harmonic risk management based on harmonic interference risk values ​​specifically includes: The obtained harmonic interference risk value is compared with a reference harmonic interference risk threshold, which is obtained from a preset database. If the harmonic interference risk value is less than the reference harmonic interference risk threshold, the rectification risk assessment result is recorded as the rectification harmonic interference risk is controllable, the first-level harmonic interference control optimization is performed, and a monitoring instruction is sent to conduct a power quality risk assessment. If the harmonic interference risk value is greater than the reference harmonic interference risk threshold, the rectification risk assessment result will be recorded as a rectification harmonic interference risk warning, the secondary harmonic interference control optimization will be executed, and a pause monitoring command will be sent.

[0010] In some embodiments, the execution of harmonic interference level-one control optimization specifically includes: The deviation between the harmonic interference risk value and the minimum reference interference risk threshold is input into a preset database for mapping to obtain the first-level filtering optimization strength. The first-level filtering optimization strength is then input into the harmonic filter to perform first-level harmonic filtering processing on the output current signal and the output voltage signal respectively. The current interference regulation force is generated based on the mapping relationship between the harmonic interference risk value and the output current interference regulation force. The output current interference regulation force is then input to the PID controller to control and optimize the output current. The output voltage interference regulation level is generated based on the mapping relationship between the harmonic interference risk value and the output voltage interference regulation level. The output voltage interference regulation level is then input to the voltage regulator to control and optimize the output voltage.

[0011] In some embodiments, the execution of harmonic interference secondary control optimization specifically includes: The deviation between the harmonic interference risk value and the minimum reference interference risk threshold is input into a preset database for mapping to obtain the secondary filtering optimization strength. The secondary filtering optimization strength is then input into the harmonic filter to perform secondary harmonic filtering on the output current signal and the output voltage signal respectively. The current interference regulation force is generated based on the mapping relationship between the harmonic interference risk value and the output current interference regulation force. The output current interference regulation force is then input to the PID controller to control and optimize the output current. The output voltage interference regulation level is generated based on the mapping relationship between the harmonic interference risk value and the output voltage interference regulation level. The output voltage interference regulation level is then input to the voltage regulator to control and optimize the output voltage.

[0012] In some embodiments, after performing the secondary harmonic interference control optimization, the method further includes: Obtain the harmonic interference risk value after optimizing the secondary harmonic interference control; The harmonic interference risk value is compared with a reference harmonic interference risk threshold. If the harmonic interference risk intervention value is less than the reference harmonic interference risk threshold, a harmonic interference level 2 control optimization end prompt is sent, and the system sends an instruction to perform a power quality risk assessment on the inverter. If the harmonic interference risk intervention value is greater than the reference harmonic interference risk threshold, the secondary harmonic interference control optimization will continue to be executed until the system sends an instruction to perform a power quality risk assessment on the inverter.

[0013] In some embodiments, the calculation of inverter risk quality indicators during the inverter process specifically includes: Acquire current risk quantification data and voltage risk quantification data of the inverter during the inverter process, and calculate current quality detection value and voltage quality detection value based on the current risk quantification data and voltage risk quantification data; The current quality and voltage quality detection values ​​are weighted and coupled with the corresponding inverter current quality risk compensation and inverter voltage quality risk compensation values, and then interactively processed with the inverter power factor for risk quality assessment to obtain the inverter risk quality index.

[0014] In some embodiments, before performing inverter risk compensation optimization based on the inverter risk quality index, the method further includes: The reference inverter risk quality threshold is obtained from the preset database, and the reference inverter risk quality threshold is compared with the inverter risk quality index. If the inverter risk quality index is less than the reference inverter risk quality threshold, the result of power quality risk assessment and monitoring will be recorded as qualified inverter power quality, inverter risk compensation optimization will not be performed, and the inverter risk quality index will be continuously monitored and judged. If the inverter risk quality index is greater than the reference inverter risk quality threshold, the result of power quality risk assessment and monitoring will be recorded as an inverter power quality risk warning, and inverter risk compensation optimization will be performed.

[0015] In some embodiments, the execution of inverter risk compensation optimization includes: The current quality detection value is mapped to a preset current filter adjustment intensity, and the transient current filter performs inverter risk compensation optimization on the current signal based on the mapping result. The inverter risk quality index is mapped to the preset inverter current compensation level, and the current balancer performs inverter risk compensation optimization on the input current based on the mapping result.

[0016] In some embodiments, the execution of inverter risk compensation optimization further includes: The voltage quality detection value is mapped to a preset voltage filter adjustment intensity, and the transient voltage filter performs inverter risk compensation optimization on the voltage signal based on the mapping result. The inverter risk quality index is mapped to the preset inverter voltage compensation level, and the voltage balancer performs inverter risk compensation optimization on the input voltage based on the mapping result.

[0017] The embodiments of this application include at least the following beneficial effects: This application provides a method for optimizing the operational risks of DC transmission systems based on multidimensional analysis. It assesses the harmonic interference risk of the rectifier process, optimizes harmonic risk control based on the harmonic interference risk value, then assesses the power quality risk of the inverter process in the DC transmission system, and finally optimizes inverter risk compensation based on the obtained power quality risk assessment. This achieves both the risk assessment of harmonic interference in the rectification process and the power quality risk assessment of the inverter process after interference control optimization, thus enabling a more accurate assessment of the operational risks of the DC transmission system. This effectively solves the problem in existing technologies where the correlation between harmonic interference risk in the rectification process and power quality risk in the inverter process of a DC transmission system is insufficient. Attached Figure Description

[0018] Figure 1 A logical structure diagram of the DC transmission system operation risk optimization method based on multidimensional analysis provided in the embodiments of this application; Figure 2 A logic diagram of the rectifier harmonic risk assessment method in the DC transmission system operation risk optimization method based on multidimensional analysis provided in the embodiments of this application.

[0019] Figure 3 A structural diagram of the harmonic interference primary control optimization steps of the DC transmission system operation risk optimization method based on multidimensional analysis provided in the embodiments of this application; Figure 4 The flowchart illustrates the process of determining whether to execute inverter risk compensation optimization in the DC transmission system operation risk optimization method based on multidimensional analysis provided in this application embodiment. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit it. In the following description, when referring to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with those of this application; they are merely examples of apparatuses and methods consistent with some aspects of the embodiments of this application as detailed in the appended claims.

[0021] It is understood that the terms “first,” “second,” etc., used in this application may be used herein to describe various concepts, but unless otherwise stated, these concepts are not limited by these terms. These terms are only used to distinguish one concept from another. For example, without departing from the scope of the embodiments of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the words “if,” “when,” or “in response to a determination” as used herein may be interpreted as “when…” or “when…” or “in response to a determination.”

[0022] As used in this application, the terms "at least one", "multiple", "each", "any", etc., "at least one" includes one, two or more, "multiple" includes two or more, "each" refers to each of the corresponding multiples, and "any" refers to any one of the multiples.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing embodiments of this application only and is not intended to limit this application.

[0024] In related technologies, during the process of rectifiers converting AC to DC in DC transmission systems, various harmonic components are generated due to the switching operation and nonlinear characteristics of the rectifiers. Especially during the rectifier startup and regulation process, harmonics may interfere with the inverter input. The main task of the inverter is to convert DC to AC, but in this process, its output voltage and current may not be in an ideal sinusoidal form, but are affected by power quality issues such as harmonics, frequency fluctuations, and short-term voltage dips. Factors such as the interaction between the rectifier and inverter, and changes in system load all affect power quality. However, current risk assessment methods for DC transmission systems often focus on the assessment of individual devices, lacking a holistic system-wide consideration, and are insufficient for global risk assessment of complex power networks.

[0025] In view of this, embodiments of this application propose a method for optimizing the operational risks of DC transmission systems based on multidimensional analysis.

[0026] refer to Figure 1 As shown, the DC transmission system of this application includes a rectifier and an inverter, and the specific method includes: A harmonic interference risk assessment is conducted on the rectifier, the harmonic interference risk value is calculated based on the assessment results, and the harmonic risk management and control are optimized based on the harmonic interference risk value. Based on the results of harmonic risk management optimization, power quality risk assessment is performed on the inverter. Based on the results of the power quality risk assessment, inverter risk quality index is calculated, and inverter risk compensation optimization is performed based on the inverter risk quality index.

[0027] refer to Figures 2-3 As shown, specifically, the harmonic interference risk value is calculated based on the results of the harmonic interference risk assessment, including: Obtain the results of the harmonic interference risk assessment of the rectifier, including current monitoring data and harmonic interference voltage monitoring data; The harmonic interference current monitoring data includes total harmonic current distortion, output current phase, and current reference fundamental phase. Specifically, the total harmonic current distortion is obtained through a harmonic analyzer, and the output current phase and current reference fundamental phase are obtained through a digital oscilloscope. The units of the output current phase, current reference fundamental phase, and reference minimum current phase error are consistent, all in degrees. The reference minimum current phase error is the minimum value of the averaged difference between the historical output current phase and current reference fundamental phase. The result of the ratio calculation of the difference between the averaged output current phase and the current reference fundamental phase is combined with the total harmonic current distortion for interference current interaction processing to obtain the harmonic interference current index. Interference current interaction processing is the process of obtaining a numerical expression for the harmonic interference current index, which is used to describe the interaction between the result of the proportional calculation of the difference between the averaged phase of the output current and the phase of the current reference fundamental wave, and the total harmonic current distortion. Specifically, as the difference between the averaged phase of the output current and the phase of the current reference fundamental frequency increases, the total harmonic current distortion also increases; the numerical expression for the harmonic interference current index is as follows: ; In the formula, This indicates the harmonic interference current index. This represents the total harmonic current distortion during the rectification process. This indicates the harmonic order number in the output current. , This indicates the highest order of harmonics in the output current. This indicates the phase of the output current containing the m-th harmonic. Indicates current reference Fundamental phase, This indicates the minimum reference current phase error.

[0028] Specifically, the harmonic interference voltage monitoring data includes total harmonic voltage distortion, output voltage phase, and voltage reference fundamental phase. Specifically, the total harmonic voltage distortion is obtained through a harmonic analyzer, and the output voltage phase and voltage reference fundamental phase are obtained through a digital oscilloscope. The units for the output voltage phase, voltage reference fundamental phase, and reference minimum voltage phase error are consistent, all being degrees. The reference minimum voltage phase error is the minimum value of the averaged difference between the collected historical output voltage phase and voltage reference fundamental phase. The result of calculating the proportion of the averaged difference between the output voltage phase and the voltage reference fundamental phase, and then performing interference voltage interaction processing with the total harmonic voltage distortion, yields the harmonic interference voltage index. Interference voltage interaction processing is the process of obtaining a numerical expression for the harmonic interference voltage index. This expression describes the interaction between the result of a proportional calculation of the difference in the averaged phase of the output voltage and the fundamental voltage reference phase, and the total harmonic voltage distortion. Specifically, as the difference in averaging between the output voltage phase and the voltage reference fundamental phase increases, the total harmonic voltage distortion also increases; the numerical expression for the harmonic interference voltage index is as follows: ; In the formula, Indicates the harmonic interference voltage index. This represents the total harmonic voltage distortion during the rectification process. This indicates the harmonic order number in the output voltage. , This indicates the highest order of harmonics in the output voltage. This indicates the phase of the output voltage of the qth harmonic. Indicates the phase of the voltage reference fundamental frequency. This indicates the minimum reference voltage phase error.

[0029] The harmonic interference risk value is obtained by weighting and coupling the harmonic interference current index and harmonic interference voltage index with the corresponding current risk interference compensation amount and voltage risk interference compensation amount.

[0030] The sum of the current risk interference compensation and the voltage risk interference compensation is 1, which are used to describe the influence of the harmonic interference current index and the harmonic interference voltage index on the harmonic interference risk value. The corresponding current risk interference compensation and voltage risk interference compensation are obtained by inputting the real-time harmonic interference current index and harmonic interference voltage index into a preset mapping set of harmonic interference current index, harmonic interference voltage index, and their corresponding compensation values ​​in the database. The numerical expression for the harmonic interference risk value is as follows: ; In the formula, Indicates the harmonic interference risk value. This indicates the amount of compensation for current risk interference. This indicates the amount of voltage risk interference compensation.

[0031] Furthermore, harmonic risk management optimization is carried out based on harmonic interference risk values, specifically including: The obtained harmonic interference risk value is compared with a reference harmonic interference risk threshold, which is obtained from a preset database. The harmonic interference risk threshold is set by professionals according to industry standards. For example, the reference harmonic interference risk threshold is set as the average of the collected historical harmonic interference risk values.

[0032] If the harmonic interference risk value is less than the reference harmonic interference risk threshold, the rectification risk assessment result is recorded as the rectification harmonic interference risk is controllable, the first-level harmonic interference control optimization is performed, and a monitoring instruction is sent to conduct a power quality risk assessment. If the harmonic interference risk value is greater than the reference harmonic interference risk threshold, the rectification risk assessment result will be recorded as a rectification harmonic interference risk warning, the secondary harmonic interference control optimization will be executed, and a pause monitoring command will be sent.

[0033] Specifically, the implementation of harmonic interference level 1 control optimization includes: The deviation between the harmonic interference risk value and the minimum reference interference risk threshold is input into a preset database for mapping to obtain the first-level filtering optimization strength. The first-level filtering optimization strength is then input into the harmonic filter to perform first-level harmonic filtering processing on the output current signal and the output voltage signal respectively. The current interference regulation force is generated based on the mapping relationship between the harmonic interference risk value and the output current interference regulation force. The output current interference regulation force is then input to the PID controller to control and optimize the output current. The output voltage interference regulation level is generated based on the mapping relationship between the wave interference risk value and the output voltage interference regulation level. The output voltage interference regulation level is then input to the voltage regulator to control and optimize the output voltage.

[0034] Specifically, the implementation of harmonic interference level 2 control optimization includes: The deviation between the harmonic interference risk value and the minimum reference interference risk threshold is input into a preset database for mapping to obtain the secondary filtering optimization strength. The secondary filtering optimization strength is then input into the harmonic filter to perform secondary harmonic filtering on the output current signal and the output voltage signal respectively. The current interference regulation force is generated based on the mapping relationship between the harmonic interference risk value and the output current interference regulation force. The output current interference regulation force is then input to the PID controller to control and optimize the output current. The output voltage interference regulation level is generated based on the mapping relationship between the wave interference risk value and the output voltage interference regulation level. The output voltage interference regulation level is then input to the voltage regulator to control and optimize the output voltage.

[0035] In this embodiment, the harmonic interference risk value represents the quantitative data of the harmonic interference current index and the harmonic interference voltage index used to assess the degree of harmonic interference risk during the rectification process of the rectifier in the DC transmission system. The harmonic interference risk value includes harmonic interference current and harmonic interference voltage indices, which work together to quantitatively assess the degree of harmonic interference risk in the rectifier process of a DC transmission system. Specifically, the harmonic interference risk value increases with the increase of the harmonic interference current and harmonic interference voltage indices. In addition, the harmonic interference risk value considers multiple parameters, taking into account the correlation and mutual influence between the parameters, and conducts a comprehensive analysis through quantitative methods. For example, as the difference between the averaged phase of the output current and the fundamental current reference phase increases, it usually means that the interference of harmonic current on the fundamental current increases. Since the intensity and phase difference of the harmonic current both affect the distortion of the current waveform, the total distortion of the harmonic current increases accordingly, which in turn increases the harmonic interference current index, i.e., the harmonic interference risk level of the rectifier process in the DC transmission system. As the difference between the averaged phase of the output voltage and the fundamental voltage reference phase increases, it means that the interference of the harmonic voltage on the fundamental voltage is more severe, which leads to an increase in the distortion of the voltage waveform, i.e., an increase in the total harmonic voltage distortion, an increase in the harmonic interference voltage index, and an increase in the harmonic interference risk level of the rectifier process in the DC transmission system. Meanwhile, the harmonic interference current index and the harmonic interference voltage index are also interrelated. Due to the nonlinear characteristics of the rectifier, harmonics not only affect the current waveform but also the voltage waveform. The harmonic components of the current in the rectifier affect the harmonic components in the voltage through the impedance of the DC transmission system, leading to an increase in voltage distortion. That is, as the harmonic interference current index increases, the harmonic interference voltage index also increases, and the harmonic interference risk level of the rectifier rectification process in the DC transmission system increases. This improves the reliability of the harmonic interference risk assessment of the rectifier rectification process in the DC transmission system.

[0036] In this embodiment, harmonic interference level one control optimization and harmonic interference level two control optimization are performed according to the harmonic risk assessment results, thereby achieving a more accurate judgment of the harmonic interference risk level of the rectifier rectification process in the DC transmission system, and thus improving the reliability of the impact analysis of the harmonic interference risk level of the rectifier rectification process on the power quality risk level of the inverter inverter process.

[0037] Furthermore, in a power transmission system, the rectifier is the power transmitter. It obtains electrical energy from the AC grid, converts it into DC, and actively sets and controls the most critical variable in the system, namely DC current. After acquiring DC current, it is input into the inverter. The inverter, as the power receiving end, converts the DC current back into AC current and sends it to the receiving end power grid to maintain the stability of the receiving end AC voltage.

[0038] Therefore, after optimizing harmonic risk management, an inverter power quality risk assessment and monitoring command is sent to conduct a power quality risk assessment of the inverter process in the DC transmission system. Based on the results of the power quality risk assessment, inverter risk quality indicators are calculated, and inverter risk compensation optimization is performed based on these indicators. Specifically: Acquire current risk quantification data and voltage risk quantification data of the inverter during the inverter process, and calculate current quality detection value and voltage quality detection value based on the current risk quantification data and voltage risk quantification data; The current quality and voltage quality detection values ​​are weighted and coupled with the corresponding inverter current quality risk compensation and inverter voltage quality risk compensation values, and then interactively processed with the inverter power factor for risk quality assessment to obtain the inverter risk quality index.

[0039] Specifically, the inverter power factor is obtained through a power quality analyzer. The sum of the inverter current quality risk compensation and the inverter voltage quality risk compensation is 1, which are used to describe the influence of the input current quality detection value and the input voltage quality detection value on the inverter risk quality index. The corresponding inverter current quality risk compensation and inverter voltage quality risk compensation are obtained by inputting the real-time input current quality detection value and the input voltage quality detection value into a preset mapping set of input current quality detection value and its corresponding compensation value in the database. The interactive processing of risk quality assessment yields the numerical expression of the inverter risk quality index, which describes the interaction between the weighted coupling result of the input current quality detection value and the input voltage quality detection value and the inverter power factor. Specifically, as the input current quality detection value and the input voltage quality detection value increase, the inverter power factor decreases. The numerical expression of the inverter risk quality index is as follows: ; In the formula, This represents the inverter risk quality index within the preset input evaluation time interval. This indicates the amount of inverter current quality risk compensation. This indicates the amount of inverter voltage quality risk compensation. This indicates the input current quality detection value. This indicates the input voltage quality detection value. This represents the inverter power factor.

[0040] Specifically, the input current risk quantification data includes the maximum input current, the minimum input current, and the current imbalance. The input current is obtained by a current sensor deployed at the inverter input terminal. The maximum and minimum input current values ​​are obtained by statistical analysis of the input current using the MAX and MIN functions in Excel. The units for the maximum, minimum, and amplitude fluctuation deviation of the input current are consistent, all being amperes. The amplitude fluctuation deviation of the input current is the result of calculating the difference between the historical maximum and minimum input current values. The current imbalance is obtained by a power quality analyzer.

[0041] The input current quality detection value is obtained by interleaving the calculated ratio of the difference between the maximum and minimum input current values ​​with the current imbalance. This current quality interleaving process yields the numerical expression for the input current quality detection value, which describes the interaction between the calculated ratio of the difference between the maximum and minimum input current values ​​and the current imbalance. Specifically, as the difference between the maximum and minimum input current values ​​increases, the current imbalance increases accordingly. The numerical expression for the input current quality detection value is as follows: ; In the formula, This represents the input current quality detection value within the preset input evaluation time interval. This indicates the maximum input current within the preset input evaluation time interval. This represents the minimum input current within the preset input evaluation time interval. This indicates the deviation in the amplitude of the input current. This indicates the current imbalance within the preset input evaluation time interval.

[0042] Specifically, the input voltage risk quantification data includes the maximum and minimum input voltage values, as well as the voltage imbalance. The input current is obtained by a voltage sensor deployed at the inverter input terminal. The maximum and minimum input voltage values ​​are obtained by statistical analysis of the input voltage using the MAX and MIN functions in Excel. The units for the maximum, minimum, and amplitude fluctuation deviation of the input voltage are consistent, all in volts. The amplitude fluctuation deviation of the input voltage is the result of calculating the difference between the historical maximum and minimum input voltage values. The voltage imbalance is obtained by a power quality analyzer. The input voltage quality detection value is obtained by interleaving the calculated ratio of the difference between the maximum and minimum input voltage values ​​with the voltage unbalance. This voltage quality interleaving process describes the interaction between the calculated ratio of the difference between the maximum and minimum input voltage values ​​and the voltage unbalance. Specifically, the voltage unbalance increases as the difference between the maximum and minimum input voltage values ​​increases. The numerical expression for the input voltage quality detection value is as follows: ; In the formula, This represents the input voltage quality detection value within the preset input evaluation time interval. This indicates the maximum input voltage within the preset input evaluation time interval. This represents the minimum input voltage within the preset input evaluation time interval. This indicates the deviation in the amplitude of the input voltage. This indicates the voltage imbalance within the preset input evaluation time interval.

[0043] In this embodiment, the inverter risk quality index is used to quantitatively assess the risk level of power quality during the inverter process in a DC transmission system. It represents the quantitative data of the input current quality detection value, input voltage quality detection value, and inverter power factor in assessing the risk level of power quality during the inverter process in a DC transmission system. The inverter risk quality index considers multiple parameters and the correlation and mutual influence between them to jointly analyze and quantitatively assess the risk level of power quality during the inverter process. For example, the difference between the maximum and minimum input current values ​​directly reflects the amplitude of current fluctuations. An increase in the difference indicates that the current waveform changes drastically within a preset input assessment time interval, potentially indicating large harmonic content or irregular fluctuations, leading to increased current imbalance. This increases the current imbalance degree, resulting in an increase in the input current quality detection value. Similarly, an increase in voltage imbalance means an increase in voltage fluctuation amplitude, i.e., an increase in the difference between the maximum and minimum input voltage values, resulting in an increase in the input voltage quality detection value. Furthermore, the input current quality detection value, input voltage quality detection value, and inverter power factor are also related. Poor current quality means that the inverter needs to operate in an unstable current environment, resulting in a lower inverter power factor. Poor voltage quality (e.g., large voltage fluctuations, high imbalance) will affect the stability of the inverter's input voltage, thereby reducing the inverter power factor. That is, as the input current quality detection value and input voltage quality detection value increase, the inverter power factor decreases accordingly. This improves the accuracy of the risk assessment of power quality during the inverter's inverter process.

[0044] Further reference Figure 4 As shown, before performing inverter risk compensation optimization based on inverter risk quality indicators, the following steps are also included: S101: Obtain a reference inverter risk quality threshold from a preset database, and compare the reference inverter risk quality threshold with the inverter risk quality indicators. The reference inverter risk quality threshold is set by professionals according to industry standards. For example, the reference inverter risk quality threshold may be set as the average of collected historical inverter risk quality indicators.

[0045] S102: If the inverter risk quality index is less than the reference inverter risk quality threshold, the result of power quality risk assessment and monitoring will be recorded as qualified inverter power quality, inverter risk compensation optimization will not be performed, and the inverter risk quality index will be continuously monitored and judged. S103: If the inverter risk quality index is greater than the reference inverter risk quality threshold, the result of power quality risk assessment and monitoring will be recorded as inverter power quality risk warning, and inverter risk compensation optimization will be performed.

[0046] Specifically, implementing inverter risk compensation optimization includes: The current quality detection value is mapped to a preset current filter adjustment intensity, and the transient current filter performs inverter risk compensation optimization on the current signal based on the mapping result. The inverter risk quality index is mapped to the preset inverter current compensation level, and the current balancer performs inverter risk compensation optimization on the input current based on the mapping result.

[0047] In some embodiments, the execution of inverter risk compensation optimization further includes: The voltage quality detection value is mapped to a preset voltage filter adjustment intensity, and the transient voltage filter performs inverter risk compensation optimization on the voltage signal based on the mapping result. The inverter risk quality index is mapped to the preset inverter voltage compensation level, and the voltage balancer performs inverter risk compensation optimization on the input voltage based on the mapping result.

[0048] Specifically, inverter risk compensation optimization includes inverter input current risk compensation optimization and inverter input voltage risk compensation optimization. Inverter input current risk compensation optimization includes current smoothing fluctuation processing and input current risk compensation optimization, while inverter input voltage risk compensation optimization includes voltage smoothing fluctuation processing and input voltage risk compensation optimization.

[0049] It should be added that current smoothing fluctuation processing means processing the input current signal with a transient current filter and adjusting the current filtering intensity. The current filtering intensity represents the result of mapping the input current quality detection value to the current fluctuation mapping set in the preset database. The current fluctuation mapping set represents the mapping relationship between the input current quality detection value and the current filtering intensity. Specifically, as the input current quality detection value increases, the current filtering intensity increases accordingly.

[0050] Input current risk compensation optimization means optimizing the input current by using a current balancer to compensate for the inverter current. The inverter current compensation level represents the result of mapping the inverter risk quality index to the inverter current compensation mapping set in the preset database. The inverter current compensation mapping set represents the mapping relationship between the inverter risk quality index and the inverter current compensation level. Specifically, as the inverter risk quality index increases, the inverter current compensation level also increases.

[0051] Voltage smoothing fluctuation processing refers to processing the input voltage signal with a transient voltage filter and adjusting the voltage filtering intensity. The voltage filtering intensity represents the result of mapping the input voltage quality detection value to a voltage fluctuation mapping set in a preset database. The voltage fluctuation mapping set represents the mapping relationship between the input voltage quality detection value and the voltage filtering intensity. Specifically, as the input voltage quality detection value increases, the voltage filtering intensity increases accordingly.

[0052] Input voltage risk compensation optimization means optimizing the input voltage by adjusting the inverter voltage compensation level through the voltage regulating transformer. The inverter voltage compensation level represents the result of mapping the inverter risk quality index into the inverter voltage compensation mapping set in the preset database. The inverter voltage compensation mapping set represents the mapping relationship between the inverter risk quality index and the inverter voltage compensation level. Specifically, as the inverter risk quality index increases, the inverter voltage compensation level also increases.

[0053] In this embodiment, the risk level of power quality during the inverter process in the DC transmission system is judged by combining a reference inverter risk quality threshold, and the input current and input voltage of the inverter are adjusted by inverter risk compensation optimization based on the inverter power quality risk assessment results. This effectively improves the power quality during the inverter process and thus improves the reliability of the inverter process risk assessment in the DC transmission system.

[0054] The embodiments described in this application are for the purpose of more clearly illustrating the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions provided by the embodiments of this application. As those skilled in the art will know, with the evolution of technology and the emergence of new application scenarios, the technical solutions provided by the embodiments of this application are also applicable to similar technical problems.

[0055] Those skilled in the art will understand that the technical solutions shown in the figures do not constitute a limitation on the embodiments of this application, and may include more or fewer steps than shown, or combine certain steps, or different steps.

[0056] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0057] Those skilled in the art will understand that all or some of the steps in the methods disclosed above, as well as the functional modules / units in the systems and devices, can be implemented as software, firmware, hardware, or suitable combinations thereof.

[0058] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0059] It should be understood that in this application, "at least one (item)" means one or more, and "more than" means two or more. "And / or" is used to describe the relationship between related objects, indicating that three relationships can exist. For example, "A and / or B" can represent three cases: only A exists, only B exists, and both A and B exist simultaneously, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one (item) of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one (item) of a, b, or c can represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple.

[0060] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of the units described above is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0061] The units described above as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0062] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0063] The preferred embodiments of the present application have been described above with reference to the accompanying drawings, but this does not limit the scope of the claims of the present application. Any modifications, equivalent substitutions, and improvements made by those skilled in the art without departing from the scope and substance of the embodiments of the present application shall be within the scope of the claims of the present application.

Claims

1. A method for optimizing the operational risk of a DC transmission system based on multidimensional analysis, wherein the DC transmission system includes a rectifier and an inverter, characterized in that, The method includes the following steps: A harmonic interference risk assessment is conducted on the rectifier, the harmonic interference risk value is calculated based on the assessment results, and the harmonic risk management and control are optimized based on the harmonic interference risk value. Based on the results of harmonic risk management optimization, power quality risk assessment is performed on the inverter. Based on the results of the power quality risk assessment, inverter risk quality index is calculated, and inverter risk compensation optimization is performed based on the inverter risk quality index.

2. The method for optimizing the operation risk of a DC transmission system based on multidimensional analysis according to claim 1, characterized in that, The calculation of the harmonic interference risk value based on the results of the harmonic interference risk assessment specifically includes: Obtain the results of the harmonic interference risk assessment of the rectifier, including harmonic interference current monitoring data and harmonic interference voltage monitoring data; Based on the harmonic interference current monitoring data and harmonic interference voltage monitoring data, the harmonic interference current index and harmonic interference voltage index are calculated. The harmonic interference risk value is obtained by weighting and coupling the harmonic interference current index and harmonic interference voltage index with the corresponding current risk interference compensation amount and voltage risk interference compensation amount.

3. The method for optimizing the operation risk of a DC transmission system based on multidimensional analysis according to claim 1, characterized in that, The optimization of harmonic risk management based on harmonic interference risk values ​​specifically includes: The obtained harmonic interference risk value is compared with a reference harmonic interference risk threshold, which is obtained from a preset database. If the harmonic interference risk value is less than the reference harmonic interference risk threshold, the rectification risk assessment result is recorded as the rectification harmonic interference risk is controllable, the first-level harmonic interference control optimization is performed, and a monitoring instruction is sent to conduct a power quality risk assessment. If the harmonic interference risk value is greater than the reference harmonic interference risk threshold, the rectification risk assessment result will be recorded as a rectification harmonic interference risk warning, the secondary harmonic interference control optimization will be executed, and a pause monitoring command will be sent.

4. The method for optimizing the operation risk of a DC transmission system based on multidimensional analysis according to claim 3, characterized in that, The aforementioned optimization of harmonic interference level 1 control specifically includes: The deviation between the harmonic interference risk value and the minimum reference interference risk threshold is input into a preset database for mapping to obtain the first-level filtering optimization strength. The first-level filtering optimization strength is then input into the harmonic filter to perform first-level harmonic filtering processing on the output current signal and the output voltage signal respectively. The current interference regulation force is generated based on the mapping relationship between the harmonic interference risk value and the output current interference regulation force. The output current interference regulation force is then input to the PID controller to control and optimize the output current. The output voltage interference regulation level is generated based on the mapping relationship between the harmonic interference risk value and the output voltage interference regulation level. The output voltage interference regulation level is then input to the voltage regulator to control and optimize the output voltage.

5. The method for optimizing the operation risk of a DC transmission system based on multidimensional analysis according to claim 3, characterized in that, The optimization of harmonic interference level 2 control specifically includes: The deviation between the harmonic interference risk value and the minimum reference interference risk threshold is input into a preset database for mapping to obtain the secondary filtering optimization strength. The secondary filtering optimization strength is then input into the harmonic filter to perform secondary harmonic filtering on the output current signal and the output voltage signal respectively. The current interference regulation force is generated based on the mapping relationship between the harmonic interference risk value and the output current interference regulation force. The output current interference regulation force is then input to the PID controller to control and optimize the output current. The output voltage interference regulation level is generated based on the mapping relationship between the harmonic interference risk value and the output voltage interference regulation level. The output voltage interference regulation level is then input to the voltage regulator to control and optimize the output voltage.

6. The method for optimizing the operation risk of a DC transmission system based on multidimensional analysis according to claim 5, characterized in that, After implementing the secondary harmonic interference control optimization, the following is also included: Obtain the harmonic interference risk value after optimizing the secondary harmonic interference control; The harmonic interference risk value is compared with a reference harmonic interference risk threshold. If the harmonic interference risk intervention value is less than the reference harmonic interference risk threshold, a harmonic interference level 2 control optimization end prompt is sent, and the system sends an instruction to perform a power quality risk assessment on the inverter. If the harmonic interference risk intervention value is greater than the reference harmonic interference risk threshold, the secondary harmonic interference control optimization will continue to be executed until the system sends an instruction to perform a power quality risk assessment on the inverter.

7. The method for optimizing the operation risk of a DC transmission system based on multidimensional analysis according to claim 1, characterized in that, The calculation of inverter risk quality indicators based on the results of power quality risk assessment specifically includes: Obtain the results of power quality risk assessment, including current risk quantification data and voltage risk quantification data of the inverter during the inverter process, and calculate current quality detection values ​​and voltage quality detection values ​​based on the current risk quantification data and voltage risk quantification data; The current quality and voltage quality detection values ​​are weighted and coupled with the corresponding inverter current quality risk compensation and inverter voltage quality risk compensation values, and then interactively processed with the inverter power factor for risk quality assessment to obtain the inverter risk quality index.

8. The method for optimizing the operation risk of a DC transmission system based on multidimensional analysis according to claim 7, characterized in that, Before performing inverter risk compensation optimization based on the inverter risk quality index, the process also includes: The reference inverter risk quality threshold is obtained from the preset database, and the reference inverter risk quality threshold is compared with the inverter risk quality index. If the inverter risk quality index is less than the reference inverter risk quality threshold, the result of power quality risk assessment and monitoring will be recorded as qualified inverter power quality, inverter risk compensation optimization will not be performed, and the inverter risk quality index will be continuously monitored and judged. If the inverter risk quality index is greater than the reference inverter risk quality threshold, the result of power quality risk assessment and monitoring will be recorded as an inverter power quality risk warning, and inverter risk compensation optimization will be performed.

9. The method for optimizing the operation risk of a DC transmission system based on multidimensional analysis according to claim 8, characterized in that, The optimization of performing inverter risk compensation includes: The current quality detection value is mapped to a preset current filter adjustment intensity, and the transient current filter performs inverter risk compensation optimization on the current signal based on the mapping result. The inverter risk quality index is mapped to the preset inverter current compensation level, and the current balancer performs inverter risk compensation optimization on the input current based on the mapping result.

10. The method for optimizing the operation risk of a DC transmission system based on multidimensional analysis according to claim 8, characterized in that, The optimization of inverter risk compensation also includes: The voltage quality detection value is mapped to a preset voltage filter adjustment intensity, and the transient voltage filter performs inverter risk compensation optimization on the voltage signal based on the mapping result. The inverter risk quality index is mapped to the preset inverter voltage compensation level, and the voltage balancer performs inverter risk compensation optimization on the input voltage based on the mapping result.

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