A method for optimizing power quality control in power plants

Abstract

The present invention relates to the field of electric power technology, and specifically to a method for optimizing and controlling power quality of a power plant, comprising the following steps: S1. power quality acquisition; S2. voltage and current analysis; S3. harmonic analysis; S4. power supply frequency stability trend analysis; S5. power quality problem identification; S6. strategy generation. The present invention obtains a voltage quality evaluation coefficient and a current quality evaluation coefficient of the power plant according to voltage data and current data of a power plant bus, obtains the severity of harmonics of the power plant according to the amplitude and frequency of each harmonic of the power plant, obtains the average rate of change of the power supply frequency stability according to the frequency value of each monitoring point at each time point of the power plant, thereby judging the overall trend of the power supply frequency stability of the power plant, and generates corresponding strategies by identifying power quality problems, thereby being able to timely discover various power quality problems, helping to maintain stable and reliable power supply of the power plant, and ensuring the normal operation and service life of electrical equipment.

Description

Technical Field

[0001] The present invention relates to the field of electric power technology, and in particular to a method for optimizing and controlling power quality of a power plant. Background Art

[0002] With the rapid development of modern industry and technology, the demand and dependence of power plants on electricity are increasing. In this context, power quality has become a crucial factor. Power quality covers voltage, current, frequency, harmonics and other aspects. Unstable or poor power quality will bring many problems to power plants, such as frequent equipment failures, reduced production efficiency, energy waste, etc.

[0003] In recent years, the widespread application of various nonlinear loads and power electronic equipment in power plants has made the power quality problem more prominent. For example, the frequent start and stop of large motors and the extensive use of frequency converters will lead to voltage fluctuations, harmonic generation and other adverse effects. In order to solve these problems, power quality optimization technology for power plants has emerged. This technology aims to improve power quality through a series of methods and means to ensure the stable, reliable and efficient operation of power systems in power plants.

[0004] For example, the existing Chinese patent with publication number CN105119295B discloses a power supply system with reactive power compensation function. This scheme sets up a system architecture consisting of a dispatching main station, a plant station, a variety of transmission lines and reactive power compensation devices, and adopts a main control server to uniformly control the reactive power compensation of power supply nodes at all levels, remote motors for data exchange, and reactive power compensation cabinets to set working parameters. It achieves comprehensive management and precise control of reactive power compensation in the power supply system, effectively improves voltage quality, reduces power loss, improves the efficiency and effect of reactive power compensation, and promotes the good operation and development of the power supply system.

[0005] However, the above patent has the following problems: First, the solution mainly focuses on the configuration and control of the reactive compensation device, and does not directly mention and implement the regulation of voltage and current based on voltage data and current data. This may lead to the inability to accurately achieve the reactive compensation effect, and the inability to flexibly adjust in real time according to the actual voltage and current conditions, which affects the stability and efficiency of the system operation to a certain extent.

[0006] Second, the solution does not involve harmonic control, which may affect the stability and reliability of power supply, interfere with the normal operation of sensitive electronic equipment, and cause unnecessary power loss. Summary of the invention

[0007] In order to overcome the shortcomings of the background technology, an embodiment of the present invention provides a power quality optimization control method for a power plant, which can effectively solve the problems involved in the above-mentioned background technology.

[0008] The purpose of the present invention can be achieved through the following technical solutions: a method for optimizing and controlling power quality of a power plant, the method comprising the following steps: S1. Power quality acquisition: real-time monitoring of power quality parameters of the power plant bus, the power quality parameters including voltage data and current data.

[0009] S2. Voltage and current analysis: The voltage quality evaluation coefficient of the power station is obtained based on the voltage and current data of the power station busbar. , Current quality evaluation coefficient .

[0010] S3. Harmonic analysis: Obtain the amplitude and frequency of each harmonic of the plant and analyze the severity of the harmonics of the plant .

[0011] S4. Analysis of power supply frequency stability trend: The frequency fluctuation degree of the power plant is analyzed based on the frequency value of each monitoring point at each time point in the power plant, and the average change rate of the power supply frequency stability is further obtained, so as to judge the overall trend of the power supply frequency stability of the power plant.

[0012] S5. Identification of power quality problems: Identify power quality problems based on the power plant’s voltage quality evaluation coefficient, current quality evaluation coefficient, harmonic severity, and overall trend of power supply frequency stability.

[0013] S6. Strategy generation: Generate corresponding strategies based on the analysis of the identified power quality problems.

[0014] Preferably, the voltage data includes voltage effective value, voltage fluctuation degree, and voltage deviation value, and the current data includes current effective value and current imbalance.

[0015] Preferably, the specific analysis method for obtaining the power quality is as follows: in the first step, a number of time points are randomly selected according to the set time interval, recorded as each time point, and the voltage value of the plant station bus at each time point is detected by a voltmeter, recorded as , Indicates The number of the time point, , substituting it into the formula Get the effective value of the voltage of the plant bus , represents the number of time points, and through the formula Get the voltage fluctuation degree of the plant bus , read the preset standard voltage value from the management database, recorded as , substituting it into the formula Get the voltage deviation value of the plant bus .

[0016] The second step is to number each phase of the multi-phase circuit at the plant busbar in sequence. , the current value of each phase of the plant bus at each time point is detected by the ammeter, and recorded as the current value of each phase at each time point of the plant station, recorded as , through the formula Get the effective value of the current of the plant bus , Indicates the number of time points, Indicates the number of phases, from which the maximum and minimum values ​​are selected and recorded as the maximum phase current at each time point in the plant , minimum phase current , the average phase current of the plant at each time point is obtained by taking the average value of each phase current at each time point, which is recorded as , substituting it into the formula Get the current unbalance of the plant bus .

[0017] Preferably, the specific analysis method of the voltage quality evaluation coefficient is: respectively reading the voltage effective value of the plant station bus , voltage fluctuation degree , voltage deviation value , substituting it into the formula Get the voltage quality evaluation coefficient of the plant ,in Indicates the set rated voltage, Indicates the set current deviation reference value, represents a natural constant, They respectively represent the weight factors of the set voltage effective value, voltage fluctuation degree, and voltage deviation value.

[0018] Preferably, the specific analysis method of the current quality evaluation coefficient is: reading the effective value of the current of the plant station bus , Current unbalance , substituting it into the formula Get the current quality evaluation coefficient of the plant ,in Indicates the set rated current, They respectively represent the weight factors of the set current effective value and current imbalance.

[0019] Preferably, the specific analysis method of the harmonic severity of the power plant is: connect the power quality analyzer to the bus circuit, detect the amplitude and frequency of each harmonic of the power plant, and record the amplitude of each harmonic as , Indicates The number of subharmonics, , the average amplitude of the harmonics is obtained by taking the average value of the amplitude of each harmonic, which is recorded as , the frequency of each harmonic is compared with the preset frequency threshold, and the harmonics with frequencies greater than or equal to the preset frequency threshold are recorded as high-order harmonics, and their number is recorded as , which is substituted into the formula Get the severity of the harmonics in the plant , They represent the weighting factors of the set harmonic amplitude and the number of high-order harmonics, respectively. Indicates the order of harmonics.

[0020] Preferably, the specific analysis method of the power supply frequency stability of the power plant is: select a number of monitoring points in the power plant bus circuit according to the set distance, record them as each monitoring point, connect a digital frequency meter to each monitoring point to detect the frequency value of each monitoring point at each time point of the power plant, record them as , Indicates The number of the monitoring point, , the average frequency value of each monitoring point in the plant station is obtained by taking the average frequency value of each monitoring point at each time point, which is recorded as , substituting it into the formula Get the frequency fluctuation degree of the plant , represents the number of monitoring points, Indicates the number of time points and reads the effective current value of the plant busbar at the same time , voltage effective value , substituting it into the formula Get reactive power , Indicates the phase difference between voltage and current, and reads the voltage fluctuation degree of the plant bus , through the formula Get the power supply frequency stability of the plant , Indicates the reasonable value of the set reactive power, They represent the weight factors of the set power supply frequency fluctuation degree, reactive power, and voltage fluctuation degree, respectively. Represents a natural constant.

[0021] Preferably, the specific analysis method of the power supply frequency stability trend analysis is as follows: the first step is to read the power supply frequency stability, divide the plant station into several working periods according to the set duration, analyze the power supply frequency stability of each working period of the plant station according to the method of analyzing the power supply frequency stability, divide two adjacent working periods into a group, record them as each group of adjacent working periods, record a group of adjacent working periods in chronological order as the previous working period and the next working period, and record their power supply frequency stability as , Indicates The numbers of adjacent working periods of the group, , the power supply frequency stability of each group of adjacent working periods of the plant station is compared respectively. If the power supply frequency stability of the working period after a group of adjacent working periods is greater than or equal to that of the previous working period, it means that the power supply frequency stability trend of this group of adjacent working periods is increasing, and it is recorded as an increasing trend working period group. If the power supply frequency stability of the working period after a group of adjacent working periods is less than that of the previous working period, it means that the power supply frequency stability trend of this group of adjacent working periods is decreasing, and it is recorded as a decreasing trend working period group.

[0022] In the second step, the power supply frequency stability difference between the previous working period and the next working period in each upward trend working period group and the previous working period and the next working period in each downward trend working period group is obtained, which is recorded as , Indicates The number of the group of uptrend working periods, , Indicates The number of the downtrend session group, ,and , through the formula Get the average rate of change of power supply frequency stability If the average change rate of the power supply frequency stability is a positive number, it means that the overall trend of the power supply frequency stability of the plant is increasing. If the average change rate of the power supply frequency stability is a negative number, it means that the overall trend of the power supply frequency stability of the plant is decreasing. If the average change rate of the power supply frequency stability is 0, it means that the overall trend of the power supply frequency stability of the plant remains unchanged.

[0023] Preferably, the specific analysis method for identifying power quality problems is as follows: in the first step, the voltage quality evaluation coefficient, current quality evaluation coefficient, harmonic severity, and overall trend of power supply frequency stability of the power plant are read respectively.

[0024] In the second step, the voltage quality evaluation coefficient is compared with the preset normal range of the voltage quality evaluation coefficient. If the voltage quality evaluation coefficient is not within the preset normal range of the voltage quality evaluation coefficient, it means that there is a voltage problem in the plant; otherwise, it means that there is no voltage problem in the plant.

[0025] The third step is to compare the current quality evaluation coefficient with the preset current quality evaluation coefficient threshold. If the current quality evaluation coefficient is lower than the preset current quality evaluation coefficient threshold, it means that there is a current problem in the plant; otherwise, it means that there is no current problem in the plant.

[0026] The fourth step is to compare the harmonic severity with the preset harmonic severity threshold. If the harmonic severity is greater than or equal to the preset harmonic severity threshold, it means that the plant has a harmonic pollution problem, otherwise it means that the plant does not have a harmonic problem.

[0027] The fifth step, if the overall trend of the power supply frequency stability of the plant station is downward, it means that the plant station has a power supply frequency problem. If the overall trend of the power supply frequency stability of the plant station is upward, it means that the plant station does not have a power supply frequency problem. If the overall trend of the power supply frequency stability of the plant station remains unchanged, execute the sixth step.

[0028] The sixth step is to read the power supply frequency stability difference of each upward trend working period group and each downward trend working period group, and compare it with the preset power supply frequency stability difference threshold. If the power supply frequency stability difference of each upward trend working period group and each downward trend working period group is less than or equal to the preset power supply frequency stability difference threshold, it means that there is no power supply frequency problem in the plant. If the power supply frequency stability difference of a certain upward trend working period group or a certain downward trend working period group is greater than the preset power supply frequency stability difference threshold, it means that the power supply frequency stability fluctuation degree of the plant is unqualified and there is a power supply frequency problem.

[0029] Preferably, the specific analysis method for generating the strategy is as follows: in the first step, if there is a voltage problem at the plant, a corresponding voltage adjustment strategy is generated according to the voltage deviation, and the voltage adjustment strategy includes adjusting the transformer tap and switching on and off of the reactive compensation device.

[0030] In the second step, if there is a current problem at the plant, the cause of the abnormal current is analyzed to generate a corresponding current adjustment strategy, which includes equipment load adjustment and line optimization.

[0031] The third step is to install filters according to the severity of the harmonics if there is a harmonic pollution problem at the plant.

[0032] The fourth step is to adjust the operating status of the power generation equipment in the plant to stabilize the power supply frequency if there is a problem with the power supply frequency in the plant.

[0033] Compared with the prior art, the embodiments of the present invention have at least the following advantages or beneficial effects: 1. The present invention obtains the voltage quality evaluation coefficient and current quality evaluation coefficient of the power station based on the voltage data and current data of the power station, which can intuitively and clearly understand the quality level of the power station in terms of voltage and current, and provide a clear direction for further improvement and optimization.

[0034] 2. The present invention analyzes the severity of the harmonics of the plant based on the amplitude and frequency of each harmonic of the plant, and can detect potential harmonic problems in advance, avoid failures and shutdowns caused by harmonic interference, and ensure the continuity and stability of production.

[0035] 3. The present invention obtains the frequency fluctuation degree of the plant station based on the frequency value analysis of each monitoring point at each time point in the plant station, and further obtains the average change rate of the power supply frequency stability, so as to judge the overall trend of the power supply frequency stability of the plant station, and can timely discover the unstable state of the power supply frequency of the plant station, so as to facilitate the adoption of targeted measures to maintain stability, ensure the normal operation of equipment, and reduce the risk of failure caused by frequency fluctuations.

[0036] 4. The present invention identifies power quality problems based on the overall trend of the power plant's voltage quality evaluation coefficient, current quality evaluation coefficient, harmonic severity, and power supply frequency stability, and generates corresponding strategies. It can promptly discover various power quality problems, help maintain stable and reliable power supply to the power plant, and ensure the normal operation and service life of electrical equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The present invention is further described using the accompanying drawings, but the embodiments in the accompanying drawings do not constitute any limitation to the present invention. A person skilled in the art can obtain other drawings based on the following drawings without creative work.

[0038] Figure 1 It is a schematic diagram of the method flow of the present invention.

[0039] Figure 2 for Figure 1 Schematic diagram of the method flow of step S5 in FIG.

[0040] Figure 3 for Figure 1 Schematic diagram of the method flow of step S6 in FIG. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] See also Figure 1 As shown, the present invention provides a method for optimizing and controlling power quality of a power plant, the method comprising the following steps: S1. Power quality acquisition: real-time monitoring of power quality parameters of the power plant bus, the power quality parameters including voltage data and current data.

[0043] The voltage data includes voltage effective value, voltage fluctuation degree, and voltage deviation value, and the current data includes current effective value and current imbalance degree.

[0044] The specific analysis method for obtaining the power quality is as follows: the first step is to randomly select a number of time points according to the set time interval, record them as each time point, and use a voltmeter to detect the voltage value of the plant station bus at each time point, record them as , Indicates The number of the time point, , substituting it into the formula Get the effective value of the voltage of the plant bus , represents the number of time points, and through the formula Get the voltage fluctuation degree of the plant bus , read the preset standard voltage value from the management database, recorded as , substituting it into the formula Get the voltage deviation value of the plant bus By regularly detecting the voltage value at each time point and performing relevant calculations, the specific situation of the plant voltage can be grasped in real time, and the effective value, fluctuation degree and deviation of the voltage can be discovered in time, so as to take targeted adjustment measures to maintain voltage stability, which is conducive to ensuring the normal operation of equipment in the plant, reducing the risk of equipment failure and damage caused by abnormal voltage, and extending the service life of equipment.

[0045] The second step is to number each phase of the multi-phase circuit at the plant busbar in sequence. , the current value of each phase of the plant bus at each time point is detected by the ammeter, and recorded as the current value of each phase at each time point of the plant station, recorded as , through the formula Get the effective value of the current of the plant bus , Indicates the number of time points, Indicates the number of phases, from which the maximum and minimum values ​​are selected and recorded as the maximum phase current at each time point in the plant , minimum phase current , the average phase current of the plant at each time point is obtained by taking the average value of each phase current at each time point, which is recorded as , substituting it into the formula Get the current unbalance of the plant bus ; By calculating the effective value of current, the actual size and energy level of current can be accurately evaluated, providing an important basis for equipment operation and power distribution. By screening out the maximum phase current and the minimum phase current, the fluctuation range of current can be clarified, and the load condition of the circuit can be better understood, which facilitates the reasonable adjustment of load distribution and ensures the safe and stable operation of the circuit.

[0046] S2. Voltage and current analysis: The voltage quality evaluation coefficient of the power station is obtained based on the voltage and current data of the power station busbar. , Current quality evaluation coefficient .

[0047] The specific analysis method of the voltage quality evaluation coefficient is as follows: read the voltage effective value of the plant station busbar respectively , voltage fluctuation degree , voltage deviation value , substituting it into the formula Get the voltage quality evaluation coefficient of the plant ,in Indicates the set rated voltage, Indicates the set current deviation reference value, represents a natural constant, They respectively represent the weight factors of the set voltage effective value, voltage fluctuation degree, and voltage deviation value; they are conducive to comprehensively and accurately evaluating the voltage quality status of the plant and station, and can intuitively understand the degree of voltage quality so as to take targeted improvement measures in a timely manner.

[0048] It should be noted that, in a specific embodiment, It can be set to 0.4. It can be set to 0.4. It can be set to 0.2. The effective value of voltage may be relatively important because it directly reflects the basic level of voltage. The voltage fluctuation degree is also critical and has a greater impact on some sensitive equipment. Therefore, the corresponding weights of the effective value of voltage and the voltage fluctuation degree are larger.

[0049] The specific analysis method of the current quality evaluation coefficient is as follows: read the effective value of the current of the plant station bus , Current unbalance , substituting it into the formula Get the current quality evaluation coefficient of the plant ,in Indicates the set rated current, They represent the weight factors of the set current effective value and current imbalance respectively; they help to take targeted measures to improve current quality, such as adjusting load distribution, optimizing equipment operating parameters, etc., to ensure the normal operation and performance of equipment, and reduce the risk of equipment failure and damage due to current quality problems. At the same time, it is also conducive to more reasonable planning and management of the power system of the plant and station, and improve the overall operating efficiency and reliability.

[0050] It should be noted that, in a specific embodiment, It can be set to 0.5. It can be set to 0.5. The effective value of current directly reflects the basic condition of current and has an important impact on equipment operation. The weight of current imbalance cannot be ignored, especially in some occasions with high requirements for three-phase balance, so the corresponding weights are equal.

[0051] S3. Harmonic analysis: Obtain the amplitude and frequency of each harmonic of the plant and analyze the severity of the harmonics of the plant .

[0052] The specific analysis method of the harmonic severity of the power plant is: connect the power quality analyzer to the bus circuit, detect the amplitude and frequency of each harmonic of the power plant, and record the amplitude of each harmonic as , Indicates The number of subharmonics, , the average amplitude of the harmonics is obtained by taking the average value of the amplitude of each harmonic, which is recorded as , the frequency of each harmonic is compared with the preset frequency threshold, and the harmonics with frequencies greater than or equal to the preset frequency threshold are recorded as high-order harmonics, and their number is recorded as , which is substituted into the formula Get the severity of the harmonics in the plant , They represent the weighting factors of the set harmonic amplitude and the number of high-order harmonics, respectively. Indicates the number of harmonics; it is helpful to discover the severity of harmonic problems in time so as to take targeted control measures, such as installing filters, etc., thereby reducing the damage of harmonics to power equipment and improving the service life and reliability of equipment. It also helps to maintain the stable operation of the power system, avoid problems such as power quality degradation and interference caused by harmonics, and ensure the normal operation and performance of various electrical equipment in the plant.

[0053] It should be noted that, in a specific embodiment, It can be set to 0.6. It can be set to 0.4. Larger harmonic amplitudes often have more direct and significant impacts on electrical equipment and systems, which may cause equipment overheating, damage, malfunction and other problems. The number of high-order harmonics is also important. A larger number of high-order harmonics may mean a more complex harmonic environment and potential adverse effects. Therefore, the weight corresponding to the harmonic amplitude is slightly higher.

[0054] S4. Analysis of power supply frequency stability trend: The frequency fluctuation degree of the power plant is analyzed based on the frequency value of each monitoring point at each time point in the power plant, and the average change rate of the power supply frequency stability is further obtained, so as to judge the overall trend of the power supply frequency stability of the power plant.

[0055] The specific analysis method of the power supply frequency stability of the power plant is as follows: a number of monitoring points are selected in the power plant bus circuit according to the set distance, which are recorded as each monitoring point, and the frequency value of each monitoring point at each time point of the power plant is detected by connecting a digital frequency meter to each monitoring point, which is recorded as , Indicates The number of the monitoring point, , the average frequency value of each monitoring point in the plant station is obtained by taking the average frequency value of each monitoring point at each time point, which is recorded as , substituting it into the formula Get the frequency fluctuation degree of the plant , represents the number of monitoring points, Indicates the number of time points and reads the effective current value of the plant busbar at the same time , voltage effective value , substituting it into the formula Get reactive power , Indicates the phase difference between voltage and current, and reads the voltage fluctuation degree of the plant bus , through the formula Get the power supply frequency stability of the plant , Indicates the reasonable value of the set reactive power, They represent the weight factors of the set power supply frequency fluctuation degree, reactive power, and voltage fluctuation degree, respectively. Represents a natural constant. It is helpful to fully understand the power quality status of the plant and station, make targeted optimization and adjustments, ensure the stability, reliability and efficiency of power supply, avoid adverse effects on equipment due to frequency, voltage and other issues, and improve the overall operation efficiency and safety of the plant and station.

[0056] It should be noted that, in a specific embodiment, It can be set to 0.4. It can be set to 0.2. It can be set to 0.4. The power supply frequency fluctuation degree directly reflects the core indicator of frequency stability, which is crucial to the normal operation of many electrical equipment. The voltage fluctuation degree has a significant impact on equipment operation and power quality. Although reactive power will also have a certain impact on power supply stability, its weight may be slightly smaller than the first two. Therefore, the power supply frequency fluctuation degree and voltage fluctuation degree have higher corresponding weights.

[0057] It should be noted that the voltage expression is , the current expression is In a specific embodiment, , the current is , then the phase difference is , Represent the maximum values ​​of voltage and current respectively, is the angular frequency, is the time variable, are the initial phases of voltage and current respectively.

[0058] The specific analysis method of the power supply frequency stability trend analysis is as follows: the first step is to read the power supply frequency stability, divide the plant station into several working periods according to the set duration, analyze the power supply frequency stability of each working period of the plant station according to the method of analyzing the power supply frequency stability, divide two adjacent working periods into a group, record them as each group of adjacent working periods, record a group of adjacent working periods in chronological order as the previous working period and the next working period, and record their power supply frequency stability as , Indicates The numbers of adjacent working periods of the group, , respectively compare the power supply frequency stability of each group of adjacent working periods of the plant station. If the power supply frequency stability of the next working period of a group of adjacent working periods is greater than or equal to that of the previous working period, it means that the power supply frequency stability trend of the adjacent working periods of this group is increasing, and it is recorded as an increasing trend working period group. If the power supply frequency stability of the next working period of a group of adjacent working periods is less than that of the previous working period, it means that the power supply frequency stability trend of the adjacent working periods of this group is decreasing, and it is recorded as a decreasing trend working period group. By reading and analyzing the power supply frequency stability and dividing the working periods for targeted analysis, we can understand in detail the power supply frequency stability of the plant station in different time periods. Stability, grouping adjacent working periods and comparing them can clarify the changing trend of the power supply frequency stability, which helps to promptly discover possible abnormal fluctuations in the power supply frequency. For the upward trend working period group, we can pay attention to its further development to ensure the continuation of this good state, while for the downward trend working period group, we can give early warning and take corresponding measures to prevent possible power supply instability problems. This will enable more accurate power quality management and regulation, ensuring that the plant station can have a relatively stable power supply frequency in all time periods, thereby maintaining the normal operation of the equipment, reducing the adverse effects caused by frequency fluctuations, and improving the reliability and power quality of the entire plant station power supply.

[0059] In the second step, the power supply frequency stability difference between the previous working period and the next working period in each upward trend working period group and the previous working period and the next working period in each downward trend working period group is obtained by subtracting the power supply frequency stability difference between each upward trend working period group and each downward trend working period group, which is recorded as , Indicates The number of the group of uptrend working periods, , Indicates The number of the downtrend session group, ,and , through the formula Get the average rate of change of power supply frequency stability If the average change rate of power supply frequency stability is a positive number, it means that the overall trend of power supply frequency stability of the plant is rising; if the average change rate of power supply frequency stability is a negative number, it means that the overall trend of power supply frequency stability of the plant is falling; if the average change rate of power supply frequency stability is 0, it means that the overall trend of power supply frequency stability of the plant remains unchanged; it helps to accurately grasp the dynamic changes of power supply conditions in plants and stations, provide a basis for scientific decision-making, so as to reasonably arrange equipment maintenance, adjust operation strategies, etc., to ensure safe, stable and efficient operation of plants and stations.

[0060] S5. Identification of power quality problems: Identify power quality problems based on the power plant’s voltage quality evaluation coefficient, current quality evaluation coefficient, harmonic severity, and overall trend of power supply frequency stability.

[0061] See also Figure 2 As shown, the specific analysis method for identifying power quality problems is as follows: the first step is to read the voltage quality evaluation coefficient, current quality evaluation coefficient, harmonic severity, and overall trend of power supply frequency stability of the power plant respectively; this helps to timely discover potential power quality problems so that targeted measures can be taken to improve and optimize them, such as adjusting the operating parameters of the power supply equipment, performing harmonic control, etc., thereby ensuring that the power supply of the power plant is more stable and reliable, reducing damage to various electrical equipment caused by poor power quality, extending the service life of equipment, and improving production efficiency and safety.

[0062] The second step is to compare the voltage quality evaluation coefficient with the preset normal range of the voltage quality evaluation coefficient. If the voltage quality evaluation coefficient is not within the preset normal range of the voltage quality evaluation coefficient, it means that there is a voltage problem in the plant; otherwise, it means that there is no voltage problem in the plant. In this way, potential voltage problems can be discovered in advance to avoid adverse consequences such as equipment damage and production interruptions due to voltage abnormalities, thereby improving the stability and safety of plant operations.

[0063] The third step is to compare the current quality evaluation coefficient with the preset current quality evaluation coefficient threshold. If the current quality evaluation coefficient is lower than the preset current quality evaluation coefficient threshold, it means that there is a current problem in the plant; otherwise, it means that there is no current problem in the plant. It can accurately determine whether there is a current problem in the plant, improve the accuracy of problem diagnosis, facilitate timely discovery of current abnormalities, buy time for taking countermeasures, and avoid further expansion of the problem.

[0064] The fourth step is to compare the harmonic severity with the preset harmonic severity threshold. If the harmonic severity is greater than or equal to the preset harmonic severity threshold, it means that the plant has a harmonic pollution problem, otherwise it means that the plant does not have a harmonic problem. This helps to detect harmonic pollution in a timely manner so that control measures can be taken as early as possible to reduce its adverse effects on equipment and systems, ensure the stable operation of the power system, and reduce faults and abnormalities that may be caused by harmonics.

[0065] The fifth step: if the overall trend of the power supply frequency stability of the plant station is downward, it means that the plant station has a power supply frequency problem; if the overall trend of the power supply frequency stability of the plant station is upward, it means that the plant station does not have a power supply frequency problem; if the overall trend of the power supply frequency stability of the plant station remains unchanged, execute the sixth step; when it is found that the trend is downward, you can prepare in advance to deal with the power supply frequency problem to prevent possible adverse effects.

[0066] The sixth step is to read the power supply frequency stability difference of each upward trend working period group and each downward trend working period group, and compare it with the preset power supply frequency stability difference threshold. If the power supply frequency stability difference of each upward trend working period group and each downward trend working period group is less than or equal to the preset power supply frequency stability difference threshold, it means that there is no power supply frequency problem in the plant. If the power supply frequency stability difference of a certain upward trend working period group or a certain downward trend working period group is greater than the preset power supply frequency stability difference threshold, it means that the fluctuation degree of power supply frequency stability of the plant is unqualified and there is a power supply frequency problem. This helps to take timely measures to solve problems such as power supply frequency fluctuations, ensure the stability and reliability of power supply to the plant, and avoid damage to electrical equipment due to unstable frequency.

[0067] S6. Strategy generation: Generate corresponding strategies based on the analysis of the identified power quality problems.

[0068] See also Figure 3 As shown, the specific analysis method for generating the strategy is as follows: In the first step, if there is a voltage problem at the plant, a corresponding voltage adjustment strategy is generated according to the voltage deviation. The voltage adjustment strategy includes adjusting the transformer tap and the switching on and off of the reactive compensation device. The voltage condition can be improved quickly and effectively, and the voltage can be restored to a normal range to ensure the normal operation of the equipment.

[0069] It should be noted that, in a specific embodiment, the voltage quality evaluation coefficient of a certain plant is 0.85, while the preset normal range of the voltage quality evaluation coefficient is 0.9-1.1. At this time, it is determined that there is a voltage problem. The strategy may be to start the reactive compensation device and increase the reactive power input to increase the voltage.

[0070] In the second step, if there is a current problem at the plant, the cause of the abnormal current is analyzed to generate a corresponding current adjustment strategy. The current adjustment strategy includes equipment load adjustment and line optimization. Equipment load adjustment can make each device operate within a reasonable load range, improve equipment life and operating efficiency, and line optimization can reduce line losses and improve current transmission quality and stability.

[0071] It should be noted that, in a specific embodiment, the current quality evaluation coefficient of a plant is 0.7, and the preset current quality evaluation coefficient threshold is 0.8, which indicates that there is a current problem. Strategies such as adjusting the operating power of some equipment or optimizing the operating time of some high-energy-consuming equipment can be adopted.

[0072] The third step is to install filters according to the severity of harmonic pollution if there is a harmonic pollution problem in the plant; this can reduce the impact of harmonics on the normal operation of other electrical equipment and improve the reliability of the entire system.

[0073] It should be noted that, in a specific embodiment, if the harmonic severity reaches 30%, and the preset harmonic severity threshold is 20%, a filter of a specific frequency band may be installed to reduce the harmonic content.

[0074] The fourth step is to adjust the operating status of the power generation equipment in the plant to stabilize the power supply frequency if there is a power supply frequency problem in the plant. This can maintain the stability and reliability of the power supply to the plant and reduce the adverse effects caused by frequency fluctuations.

[0075] It should be noted that, in a specific embodiment, when the power supply frequency stability is 49 Hz and the preset power supply frequency stability threshold is 50 Hz, the speed or operating parameters of the generator set can be adjusted to increase the power supply frequency to a normal range.

[0076] The present invention obtains the voltage quality evaluation coefficient and the current quality evaluation coefficient of the plant station according to the voltage data and the current data of the plant station busbar, obtains the harmonic severity of the plant station according to the amplitude and the frequency of each harmonic of the plant station, and obtains the average change rate of the power supply frequency stability according to the frequency value of each monitoring point at each time point of the plant station, thereby judging the overall trend of the power supply frequency stability of the plant station, and generating corresponding strategies by identifying power quality problems, which can timely discover various power quality problems, help maintain stable and reliable power supply of the plant station, and ensure the normal operation and service life of electrical equipment.

[0077] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention and they are still covered by the protection scope of the present invention.

Claims

1. A power quality optimization control method for a power plant, characterized in that: The steps include: S1. Power quality acquisition: Real-time monitoring of power quality parameters of the plant bus, including voltage data and current data; S2. Voltage and current analysis: The voltage quality evaluation coefficient of the power station is obtained based on the voltage and current data of the power station busbar. , Current quality evaluation coefficient ; S3. Harmonic analysis: Obtain the amplitude and frequency of each harmonic of the plant and analyze the severity of the harmonics of the plant ; S4. Power supply frequency stability trend analysis: According to the frequency value of each monitoring point at each time point of the power station, the frequency fluctuation degree of the power station is analyzed, and the average change rate of the power supply frequency stability is further obtained, so as to judge the overall trend of the power supply frequency stability of the power station; S5. Identification of power quality problems: Identify power quality problems based on the voltage quality evaluation coefficient, current quality evaluation coefficient, harmonic severity, and overall trend of power supply frequency stability of the power plant; S6. Strategy generation: Generate corresponding strategies based on the analysis of the identified power quality problems; The specific analysis method for obtaining the power quality is as follows: In the first step, a number of time points are randomly selected according to the set time interval, which are recorded as each time point. The voltage value of the plant bus at each time point is detected by a voltmeter, which is recorded as , Indicates The number of the time point, , substituting it into the formula Get the effective value of the voltage of the plant bus , represents the number of time points, and through the formula Get the voltage fluctuation degree of the plant bus , read the preset standard voltage value from the management database, recorded as , substituting it into the formula Get the voltage deviation value of the plant bus ; The second step is to number each phase of the multi-phase circuit at the plant busbar in sequence. , the current value of each phase of the plant bus at each time point is detected by the ammeter, and recorded as the current value of each phase at each time point of the plant station, recorded as , through the formula Get the effective value of the current of the plant bus , Indicates the number of time points, Indicates the number of phases, from which the maximum and minimum values ​​are selected and recorded as the maximum phase current at each time point in the plant , minimum phase current , the average phase current of the plant at each time point is obtained by taking the average value of each phase current at each time point, which is recorded as , substituting it into the formula Get the current unbalance of the plant bus ; The specific analysis method of the voltage quality evaluation coefficient is: Read the effective value of the voltage of the plant busbar respectively , voltage fluctuation degree , voltage deviation value , substituting it into the formula Get the voltage quality evaluation coefficient of the plant ,in Indicates the set rated voltage, Indicates the set voltage deviation reference value, represents a natural constant, Respectively represent the weight factors of the set voltage effective value, voltage fluctuation degree, and voltage deviation value; The specific analysis method of the current quality evaluation coefficient is: Read the effective current value of the plant bus , Current imbalance , substituting it into the formula Get the current quality evaluation coefficient of the plant ,in Indicates the set rated current, They represent the weight factors of the set current effective value and current unbalance respectively; The specific analysis method of the harmonic severity of the plant is: Connect the power quality analyzer to the bus circuit to detect the amplitude and frequency of each harmonic in the plant and station, and record the amplitude of each harmonic as , Indicates The number of subharmonics, , the average amplitude of the harmonics is obtained by taking the average value of the amplitude of each harmonic, which is recorded as , the frequency of each harmonic is compared with the preset frequency threshold, and the harmonics with frequencies greater than or equal to the preset frequency threshold are recorded as high-order harmonics, and their number is recorded as , which is substituted into the formula Get the severity of the harmonics in the plant , They represent the weighting factors of the set harmonic amplitude and the number of high-order harmonics, respectively. Indicates the order of harmonics; The specific analysis method of the power supply frequency stability of the plant is: According to the set distance, several monitoring points are selected in the plant bus circuit, which are recorded as each monitoring point. The frequency value of each monitoring point at each time point of the plant is detected by connecting a digital frequency meter to each monitoring point, which is recorded as , Indicates The number of the monitoring point, , the average frequency value of each monitoring point in the plant station is obtained by taking the average frequency value of each monitoring point at each time point, which is recorded as , substituting it into the formula Get the frequency fluctuation degree of the plant , represents the number of monitoring points, Indicates the number of time points and reads the effective current value of the plant busbar at the same time , voltage effective value , substituting it into the formula Get reactive power , Indicates the phase difference between voltage and current, and reads the voltage fluctuation degree of the plant bus , through the formula Get the power supply frequency stability of the plant , They represent the weight factors of the set power supply frequency fluctuation degree, reactive power, and voltage fluctuation degree, respectively. represents a natural constant, Indicates the reasonable value of the set reactive power.

2. The power quality optimization control method for power plants according to claim 1 is characterized by: The voltage data includes voltage effective value, voltage fluctuation degree, and voltage deviation value, and the current data includes current effective value and current imbalance degree.

3. The power quality optimization control method for power plants according to claim 1 is characterized by: The specific analysis method of the power supply frequency stability trend analysis is: The first step is to read the power supply frequency stability, divide the plant into several working periods according to the set duration, and analyze the power supply frequency stability of each working period of the plant according to the method of analyzing the power supply frequency stability. Two adjacent working periods are divided into a group, which is recorded as each group of adjacent working periods. A group of adjacent working periods is recorded as the previous working period and the next working period in chronological order, and the power supply frequency stability is recorded as , Indicates The numbers of adjacent working periods of the group, , respectively compare the power supply frequency stability of each group of adjacent working periods of the plant station. If the power supply frequency stability of the next working period of a certain group of adjacent working periods is greater than or equal to that of the previous working period, it means that the power supply frequency stability trend of the adjacent working periods of this group is increasing, and it is recorded as an increasing trend working period group. If the power supply frequency stability of the next working period of a certain group of adjacent working periods is less than that of the previous working period, it means that the power supply frequency stability trend of the adjacent working periods of this group is decreasing, and it is recorded as a decreasing trend working period group; In the second step, the power supply frequency stability difference between the previous working period and the next working period in each upward trend working period group and the previous working period and the next working period in each downward trend working period group is obtained, which is recorded as , Indicates The number of the group of uptrend working periods, , Indicates The number of the downtrend session group, ,and , through the formula Get the average rate of change of power supply frequency stability If the average change rate of the power supply frequency stability is a positive number, it means that the overall trend of the power supply frequency stability of the plant is increasing. If the average change rate of the power supply frequency stability is a negative number, it means that the overall trend of the power supply frequency stability of the plant is decreasing. If the average change rate of the power supply frequency stability is 0, it means that the overall trend of the power supply frequency stability of the plant remains unchanged.

4. The power quality optimization control method for power plants according to claim 1 is characterized by: The specific analysis method for identifying the power quality problem is: The first step is to read the voltage quality evaluation coefficient, current quality evaluation coefficient, harmonic severity, and overall trend of power supply frequency stability of the power plant. The second step is to compare the voltage quality evaluation coefficient with the preset normal range of the voltage quality evaluation coefficient. If the voltage quality evaluation coefficient is not within the preset normal range of the voltage quality evaluation coefficient, it means that there is a voltage problem in the plant, otherwise it means that there is no voltage problem in the plant; The third step is to compare the current quality evaluation coefficient with the preset current quality evaluation coefficient threshold. If the current quality evaluation coefficient is lower than the preset current quality evaluation coefficient threshold, it means that there is a current problem in the plant, otherwise it means that there is no current problem in the plant; The fourth step is to compare the harmonic severity with the preset harmonic severity threshold. If the harmonic severity is greater than or equal to the preset harmonic severity threshold, it means that the plant has a harmonic pollution problem, otherwise it means that the plant does not have a harmonic problem. Step 5: If the overall trend of the power supply frequency stability of the plant station is decreasing, it means that the plant station has a power supply frequency problem; if the overall trend of the power supply frequency stability of the plant station is increasing, it means that the plant station does not have a power supply frequency problem; if the overall trend of the power supply frequency stability of the plant station remains unchanged, execute step 6; The sixth step is to read the power supply frequency stability difference of each upward trend working period group and each downward trend working period group, and compare it with the preset power supply frequency stability difference threshold. If the power supply frequency stability difference of each upward trend working period group and each downward trend working period group is less than or equal to the preset power supply frequency stability difference threshold, it means that there is no power supply frequency problem in the plant. If the power supply frequency stability difference of a certain upward trend working period group or a certain downward trend working period group is greater than the preset power supply frequency stability difference threshold, it means that the power supply frequency stability fluctuation degree of the plant is unqualified and there is a power supply frequency problem.

5. The power quality optimization control method for power plants according to claim 4 is characterized by: The specific analysis method for generating the strategy is as follows: The first step is to generate a corresponding voltage adjustment strategy based on the voltage deviation if there is a voltage problem at the power plant. The voltage adjustment strategy includes adjusting the transformer tap and switching on and off of the reactive compensation device. The second step is to analyze the cause of the abnormal current and generate a corresponding current adjustment strategy if there is a current problem at the plant. The current adjustment strategy includes equipment load adjustment and line optimization. The third step is to install filters according to the severity of harmonic pollution if there is a harmonic pollution problem at the plant. The fourth step is to adjust the operating status of the power generation equipment in the plant to stabilize the power supply frequency if there is a problem with the power supply frequency in the plant.

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