Hybrid control method and system based on distributed power supply electric energy quality treatment

Abstract

The invention relates to the technical field of electric energy management, and discloses a hybrid control method and system based on distributed power supply electric energy quality management, and the method comprises the steps: obtaining a total capacity value needing grid connection and electric energy data of a plurality of distributed power supply stations in an area range; distributing the distributed capacity to the distributed power station according to a first distribution algorithm, and controlling the distributed power station to output electric energy; calculating a current power factor value, calculating a difference value between the current power factor value and a target power factor value as a power factor difference value in real time, and controlling the number of switching intelligent capacitors according to the power factor difference value; adjusting the output of the SVG according to the variation amplitude of the power factor difference value; and calculating a harmonic current step change slope based on a first detection algorithm, calculating a difference value between the harmonic current step change slope and a harmonic distortion target value as a harmonic distortion adjustment value, and adjusting the output of the APF according to the harmonic distortion adjustment value. According to the invention, the electric energy quality of the novel power grid-connected power system can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of power management, and in particular to a hybrid control method and system based on distributed power supply power quality management. Background Art

[0002] At present, distributed power sources represented by wind, solar and storage are gradually integrated into the power system and provide power output at the end of the power system. In particular, the access of a large number of distributed power sources to the distribution network lines has a great impact on the power quality of the original distribution network lines, mainly on the system frequency, system voltage and system power, which causes certain difficulties and pressures on the system power regulation.

[0003] In the existing technology, there are also many related technologies that solve single problems alone. For example, AGC and AVC technologies are used to adjust wind power and photovoltaic input to stabilize the voltage and frequency of the distribution network system to prevent excessive voltage and excessive frequency deviation. Another example is the use of energy storage technology to store the electricity generated by distributed power sources and "charge and discharge" the energy storage device. On the one hand, it can save electricity bills, and on the other hand, it can release electricity in an orderly and controllable manner to ensure the stability of the power quality on the line.

[0004] However, each technology is currently limited to a single line or a regional power grid. Due to the complexity of my country's power distribution network lines, mainly in multiple lines or large areas, each line affects each other. A single line will be affected by other lines in the same distribution system. It relies on its own limited adjustment and does not have a greater ability to change the entire distribution line. Therefore, the problem of the voltage level line will still be extended to the previous voltage level line. The overall power quality is poor. If each level of the power system cannot bear it, it will cause the entire power grid to be overwhelmed. It is necessary to improve the power quality of the electricity generated when the new power source is connected to the grid. Summary of the invention

[0005] In order to improve the power quality of a new type of power grid-connected power system, the present application provides a hybrid control method and system based on distributed power quality management.

[0006] In the first aspect, the present application provides a hybrid control method based on distributed power supply power quality management, which adopts the following technical solutions: A hybrid control method based on distributed power supply power quality management includes the following steps: Obtain the total capacity value that needs to be connected to the grid, and obtain the power data of multiple distributed power stations within the area that needs to be connected to the grid; Allocate distribution capacity to the distributed power station according to a first allocation algorithm, and control the distributed power station to output electric energy; Calculate the current power factor value, obtain the target power factor value, calculate the difference between the current power factor value and the target power factor value in real time as the power factor difference, and control the number of switched smart capacitors according to the positive correlation of the power factor difference; and adjust the output size of the SVG (static var generator) according to the positive correlation of the change amplitude of the power factor difference; Based on the first detection algorithm, the harmonic current step change slope is calculated, the harmonic distortion target value is obtained, the difference between the harmonic current step change slope and the harmonic distortion target value is calculated as the harmonic distortion adjustment value, and the output of the reactive power of the APF (active power filter) is anti-correlatedly adjusted according to the harmonic distortion adjustment value.

[0007] By adopting the above technical solution, according to the total capacity value that needs to be connected to the grid, the information of multiple distributed power stations within the area that needs to be connected to the grid is obtained, including their types, such as wind power, photovoltaic, etc., capacity, location, etc. According to the first allocation algorithm, such as an algorithm based on multiple factors such as capacity, location, stability, etc., the distributed capacity is allocated to each distributed power station. The distributed power station is controlled to output electric energy according to the allocated capacity to ensure the stable operation of the entire system. The number of smart capacitors cut in is controlled according to the power factor difference to compensate for reactive power and improve the power factor. At the same time, the output of SVG (static VAR generator) is adjusted according to the change amplitude of the power factor difference to further stabilize the power factor. The output of APF (active power filter) is adjusted according to the harmonic distortion adjustment value to eliminate or reduce harmonic distortion and improve the power quality.

[0008] Optionally, the method further includes the following steps: If a voltage dispatch instruction is received that requires the voltage to be stabilized at a fixed value; Obtain grid voltage, current and load-side current signals in real time; Calculate the reactive current according to the reactive current detection method; Calculate the average reactive current and the total reactive power that needs to be compensated; According to the reactive power distribution principle, calculate the number of smart capacitors that need to be switched and the reactive current that SVG needs to compensate; Obtain the actual value of the bus voltage on the high-voltage side of the distributed power station in real time; The difference between the actual voltage value and the fixed value is calculated as the voltage difference; According to the voltage difference, the reactive power that needs to be adjusted is calculated through AVC; The output of the photovoltaic inverter is adjusted inversely according to the actual voltage value; the lower the actual voltage value, the greater the reactive power output of the photovoltaic inverter; the higher the actual voltage value, the smaller the reactive power output of the photovoltaic inverter.

[0009] By adopting the above technical solution, the system voltage is adjusted according to the configured SVG (static VAR generator) and smart capacitor; combined with the AVC regulation of the photovoltaic inverter, the amplitude of voltage fluctuation is reduced.

[0010] As the core of the entire power quality management system, the monitoring center is responsible for receiving instructions from the power grid dispatching center. When the dispatching center needs to stabilize the voltage in a certain area to a fixed value, it will send the corresponding dispatching instructions to the monitoring center. After receiving the dispatching instructions, the monitoring center will calculate the voltage value that needs to be adjusted according to the actual situation and configuration of the system. The monitoring center will use this voltage value as the target value and send it to the controller of each distributed power station through the communication network. After receiving the instruction, the controller will respond immediately and adjust the output of SVG (static var generator) and smart capacitor according to the instruction requirements. During the voltage regulation process, SVG (static var generator) and smart capacitors usually work together to achieve more accurate and faster voltage regulation. By adjusting the output of SVG (static var generator) and smart capacitors, the grid voltage can be effectively stabilized at a fixed value and the amplitude of voltage fluctuations can be reduced. Photovoltaic inverters are key equipment in photovoltaic power generation systems. They are responsible for converting the direct current generated by photovoltaic panels into alternating current and transmitting it to the power grid. At the same time, photovoltaic inverters also have reactive power regulation functions, which can adjust the reactive power they output according to the needs of the power grid. AVC (Automatic Voltage Control) is an advanced voltage regulation technology that monitors the grid voltage and reactive power in real time, calculates the amount of reactive power that needs to be adjusted, and controls the photovoltaic inverter to make corresponding adjustments. Through AVC regulation, precise control of the grid voltage can be achieved, further improving voltage stability. During the regulation process, it is necessary to calculate the amount of reactive power that needs to be adjusted based on the actual situation of the grid and the AVC regulation strategy. Then, these parameters are input into the control system of the photovoltaic inverter to control its output of the corresponding reactive power to achieve stable control of the grid voltage. Through the steps of receiving dispatch instructions from the monitoring center, issuing instructions to the controller, SVG (static var generator) and intelligent capacitor to adjust the voltage, and combining the AVC regulation of the photovoltaic inverter, the stable control of the grid voltage and the reduction of the amplitude of voltage fluctuation can be effectively achieved.

[0011] Optionally, the method further includes the following steps: The first detection algorithm is a resonance advance prediction algorithm, and the formula is: ; Among them, T n Moments are a collection of sampling time points, THI n T n The total harmonic current at the moment, the harmonic current step change slope represents the average value of the total harmonic current change rate per unit time in N sections.

[0012] By adopting the above technical solution, by introducing the resonance advance prediction algorithm as the first detection algorithm, and combining it with other control strategies and equipment, it is possible to achieve comprehensive management and optimization of the power quality of distributed power sources after grid connection, and improve the reliability and safety of the power grid.

[0013] Optionally, the method further includes the following steps: Get the harmonic current step change slope in the current area; Get the harmonic current step change slope within the historical set time period; Calculate the change trend value of the harmonic current step change slope within the historical set time period; Obtain the harmonic current step change slopes of multiple surrounding areas and calculate the surrounding average value; Compare the harmonic current step change slope of the current power grid with the surrounding average value and calculate the surrounding difference; The outlier value is calculated based on the change trend value and the surrounding difference value, and the outlier value = a1×change trend value + a2×surrounding difference value; where a1 is the weight corresponding to the change trend value, and a2 is the weight corresponding to the surrounding difference value; If the abnormal value exceeds the set threshold, it is judged that the harmonic current is distorted and an early warning is issued.

[0014] By adopting the above technical solution, historical data and surrounding area data are used to assist in determining whether the harmonic current is distorted.

[0015] Optionally, the method further includes the following steps: Get the harmonic current step change slope in the current area; Performing spectrum analysis on the harmonic current step change slope to obtain the frequency component of the change slope; Within the set frequency range, if the frequency value exceeds the target value, the voltage control strategy is started; The voltage control strategy includes raising the voltage to a set value, maintaining the voltage for a set period of time, and then lowering the voltage to the set value, and then regulating the voltage through a DVR (dynamic voltage restorer).

[0016] By adopting the above technical solution, the voltage and resonance of the power system can be controlled more accurately, thereby improving the stability and reliability of the power system.

[0017] Optionally, the step of controlling the number of smart capacitors to be switched in according to the power factor difference includes: Obtaining a low threshold and a high threshold corresponding to the power factor difference; when the power factor difference is lower than the low threshold, adjusting the number of smart capacitors switched in according to the positive correlation of the power factor difference; when the power factor difference is higher than the high threshold, adjusting the number of smart capacitors switched out according to the positive correlation of the power factor difference; when the power factor difference is between the low threshold and the high threshold, keeping the current number of capacitors switched in unchanged; The step of adjusting the output of SVG (static var generator) according to the variation of the power factor difference comprises: When the change amplitude exceeds the corresponding threshold, the adjustment speed of SVG is adjusted in a positive correlation according to the change amplitude of the power factor difference; the larger the change amplitude, the faster the adjustment speed should be; the smaller the change amplitude, the slower the adjustment speed should be; The step of adjusting the output of reactive power of an APF (active power filter) according to the harmonic distortion adjustment value comprises: If the harmonic distortion adjustment value is positive, the output of the reactive power of the APF (active power filter) is increased in a positive correlation with the harmonic distortion adjustment value; the larger the harmonic distortion adjustment value, the more the output of the reactive power of the APF (active power filter) increases; the smaller the harmonic distortion adjustment value, the less the output of the reactive power of the APF (active power filter) increases; If the harmonic distortion adjustment value is negative, the output of the reactive power of the APF (active power filter) is reduced in an anti-correlated manner according to the harmonic distortion adjustment value; the smaller the harmonic distortion adjustment value, the more the output of the reactive power of the APF (active power filter) is reduced; the larger the harmonic distortion adjustment value, the less the output of the reactive power of the APF (active power filter) is reduced.

[0018] Optionally, the smart capacitor switching logic includes: obtaining a power factor reference value, wherein the power factor reference value is lower than a target power factor value; Adjust the switching logic according to the current power factor value and the target power factor value; When the current power factor value is lower than the power factor reference value, the common compensation is put into operation first, followed by the separate compensation. The large-capacity capacitor is put into operation first, and the capacitor with less number of times is put into operation first. When the current power factor value is higher than the power factor reference value, the common compensation is cut off first and then the separate compensation, the large-capacity capacitors are cut off first, and the capacitors with the most times are cut off first.

[0019] By adopting the above technical solution and utilizing the characteristics of the self-organizing network of intelligent capacitors, the intermittent switching of intelligent capacitors is realized through the switching logic of the controller "first common compensation and then separate compensation, first large capacity and then small capacity, first the ones with fewer switching times and then the ones with more switching times".

[0020] Optionally, the method further includes the following steps: Count the capacitance values ​​of capacitors and calculate the uniformity of distribution; the uniformity is the standard deviation of the capacitance value of each capacitor divided by the total capacitance; Count the switching times of the capacitor and calculate the distribution value of the switching times; the distribution value is the standard deviation of the switching times; Adjust the switching time interval or time difference according to the uniformity and distribution value; Time interval or time difference = basic time interval × (b1 × uniformity + b2 × distribution value); where b1 and b2 are adjustment coefficients, and b1 is less than b2.

[0021] By adopting the above technical solution, in the power compensation system, the switching time interval or time difference is adjusted according to the situation of co-compensation and split compensation, the uniformity of capacity distribution and the distribution of switching times. If the uniformity is high and the distribution value is low, it means that the capacitor works more evenly, and the switching time interval can be appropriately extended or the time difference can be reduced. On the contrary, if the uniformity is low and the distribution value is high, it means that the capacitor works unbalanced, and the switching time interval needs to be shortened or the time difference needs to be increased.

[0022] Optionally, the step of controlling the number of switched intelligent capacitors according to the power factor difference includes: Obtaining a low threshold and a high threshold corresponding to the power factor difference; when the power factor difference is lower than the low threshold, adjusting the number of smart capacitors to be put into operation in a positive correlation according to the size of the power factor difference; when the power factor difference is higher than the high threshold, adjusting the number of smart capacitors to be removed in a positive correlation according to the size of the power factor difference; when the power factor difference is between the low threshold and the high threshold, keeping the current number of capacitors switched in unchanged; The step of adjusting the output of SVG (static var generator) according to the variation of the power factor difference comprises: When the change amplitude exceeds the corresponding threshold, the output size of the SVG is adjusted in a positive correlation according to the change amplitude of the power factor difference; the larger the change amplitude, the larger the SVG output is adjusted; the smaller the change amplitude, the smaller the SVG output is adjusted; The step of adjusting the output of reactive power of an APF (active power filter) according to the harmonic distortion adjustment value comprises: If the actual harmonic distortion rate value is greater than the harmonic distortion rate threshold, the output of the APF (active power filter) is increased in a positive correlation according to the harmonic distortion adjustment value; the larger the harmonic distortion adjustment value, the more the APF (active power filter) output increases; the smaller the harmonic distortion adjustment value, the less the output of the APF (active power filter) reactive power increases; so that the actual harmonic distortion rate is controlled below the harmonic distortion rate threshold.

[0023] By adopting the above technical solution, the smart capacitor, SVG (static var generator) and APF (active power filter) are automatically adjusted according to the power factor difference, the change amplitude of the power factor difference and the harmonic distortion rate.

[0024] Optionally, the first allocation algorithm is a capacity average allocation method, including: Get the total grid load of distributed power stations and the number of distributed power stations, The distributed capacity allocated to the distributed power stations = the total load of the power grid / the number of distributed power stations.

[0025] By adopting the above technical solution, since the power load is evenly distributed, the workload of each power station is also relatively balanced, which helps to extend the service life of the power station and improve the stability of the entire power grid.

[0026] Optionally, the method further includes the following steps: Obtaining power consumption of different areas and calculating the power consumption rate of the power consumption; adjusting capacity allocation according to the power consumption and the power consumption rate; According to the power consumption, the capacity allocation is adjusted in a positive correlation; the greater the power consumption, the more capacity is allocated; the smaller the power consumption, the less capacity is allocated; The capacity allocation is adjusted in a positive correlation according to the power consumption rate; the faster the power consumption rate, the more capacity is allocated; the slower the power consumption rate, the less capacity is allocated.

[0027] By adopting the above technical solutions, since power consumption is not constant, it will fluctuate with changes in various factors such as seasons, weather, and economic activities. Therefore, in order to more accurately adjust the amount of capacity allocation, we need to monitor the dynamic changes in power consumption in each area in real time and conduct in-depth analysis. According to the dynamic changes in power consumption / power consumption in different areas, adjust the amount of capacity allocation; power consumption is an important indicator reflecting the power demand of an area. The power consumption of different areas may vary due to various factors such as population size, economic development level, and industrial structure; therefore, in order to ensure that the allocation of power resources is more accurate and efficient and meet the actual needs of different areas; for areas with large power consumption or rapid growth, their power supply should be prioritized and the amount of capacity allocation should be appropriately increased. This can ensure that these areas can get sufficient power support during peak power demand. For areas with small power consumption or slow growth, the amount of capacity allocation can be flexibly adjusted according to actual conditions. In the case of tight power supply, the capacity allocation of these areas can be appropriately reduced to relieve the pressure on the power grid. In order to better adapt to the dynamic changes in power consumption, a dynamic adjustment mechanism can be established. This mechanism can automatically adjust the amount of capacity allocation based on real-time monitored power consumption data to ensure a real-time balance between power supply and demand.

[0028] In the second aspect, the present application provides a hybrid control system based on distributed power supply power quality management, which adopts the following technical solutions: A hybrid control system based on distributed power supply power quality management includes a processor in which a program of the hybrid control method based on distributed power supply power quality management is run.

[0029] In summary, the present application includes at least one of the following beneficial technical effects: This control system includes the functions of voltage surge and dip control, voltage stability regulation, reactive power compensation, harmonic control, resonance advance prediction and early adjustment. At the same time, the device is equipped with a distributed power supply edge controller (hereinafter referred to as the controller), which has the "four capabilities", namely observable, measurable, adjustable and controllable. It can realize the voltage, frequency, active power and reactive power control of photovoltaic and energy storage inverters, and realize the control of power quality management devices such as PSS, DVR, APF, SVG, and smart capacitors. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a system diagram of hybrid control based on distributed power generation power quality management.

[0031] Figure 2 It is a step diagram of a hybrid control method based on distributed power generation power quality management. DETAILED DESCRIPTION

[0032] Embodiments of the present application are described in detail below, examples of which are shown in the accompanying drawings.

[0033] In the description of this specification, the description with reference to the terms "certain embodiments", "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiments or examples are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0034] The present application embodiment discloses a hybrid control method based on distributed power supply power quality management, referring to Figure 1 and Figure 2 , including the following steps: Obtain the total capacity value that needs to be connected to the grid, and obtain the power data of multiple distributed power stations within the area that needs to be connected to the grid. Distributed photovoltaic power stations such as photovoltaic power stations, wind power stations, etc.; power data includes current, voltage, power factor, etc.

[0035] The distributed capacity is allocated to the distributed power station according to the first allocation algorithm to control the output of electric energy of the distributed power station. The first allocation algorithm, such as an average allocation algorithm or other algorithms, comprehensively considers factors such as the capacity, stability, and reliability of each power station to achieve reasonable capacity allocation and distribution.

[0036] Calculate the current power factor value, obtain the target power factor value, calculate the difference between the current power factor value and the target power factor value in real time as the power factor difference, and control the number of switched smart capacitors according to the positive correlation of the power factor difference. Adjust the output size of the SVG (static var generator) according to the change amplitude of the power factor difference.

[0037] The step of controlling the number of switched intelligent capacitors according to the power factor difference includes: The low threshold and high threshold corresponding to the power factor difference are obtained; when the power factor difference is lower than the low threshold, the number of smart capacitors put into operation is adjusted in a positive correlation according to the size of the power factor difference; when the power factor difference is higher than the high threshold, the number of smart capacitors removed is adjusted in a positive correlation according to the size of the power factor difference; when the power factor difference is between the low threshold and the high threshold, the number of capacitors switched on and off is kept unchanged. The number of smart capacitors switched on and off is automatically adjusted according to the size of the power factor difference, realizing intelligent control of reactive power compensation.

[0038] The step of adjusting the output of the SVG (static VAR generator) according to the variation of the power factor difference includes: When the change amplitude exceeds the corresponding threshold, the output size of the SVG (static VAR generator) is adjusted in a positive correlation according to the change amplitude of the power factor difference; the larger the change amplitude, the larger the SVG (static VAR generator) output is adjusted; the smaller the change amplitude, the smaller the SVG (static VAR generator) output is adjusted.

[0039] Among them, power factor = active power (P) / apparent power (S); among them, active power is the power actually consumed by the equipment and converted into other forms of energy, the unit is watt (W); apparent power is the product of the effective value of voltage and current in the circuit, which represents the total power connected to the circuit, the unit is volt-ampere (VA); power factor is a dimensionless value, usually expressed by the cosine function (cosΦ), where Φ is the phase difference between voltage and current.

[0040] Based on the first detection algorithm, the harmonic current step change slope is calculated to obtain the harmonic distortion target value; the difference between the harmonic current step change slope and the harmonic distortion target value is calculated as the harmonic distortion adjustment value, and the output of the APF (active power filter) reactive power is anti-correlatedly adjusted according to the harmonic distortion adjustment value.

[0041] The steps of adjusting the output of reactive power of the APF (active power filter) according to the harmonic distortion adjustment value include: If the actual harmonic distortion rate value is greater than the harmonic distortion rate threshold, the output of the APF (active power filter) is increased in a positive correlation according to the harmonic distortion adjustment value; the larger the harmonic distortion adjustment value, the more the APF (active power filter) output increases; the smaller the harmonic distortion adjustment value, the less the APF (active power filter) reactive power output increases; so that the actual harmonic distortion rate is controlled below the harmonic distortion rate threshold.

[0042] In summary, the smart capacitor, SVG (static var generator) and APF (active power filter) are automatically adjusted according to the power factor difference, the change amplitude of the power factor difference and the harmonic distortion rate.

[0043] According to the total capacity value that needs to be connected to the grid, obtain the information of multiple distributed power stations within the area that needs to be connected to the grid, including their types, such as wind power, photovoltaic, etc., capacity, location, etc. According to the first allocation algorithm, such as an algorithm based on multiple factors such as capacity, location, stability, etc., the distributed capacity is allocated to each distributed power station. The distributed power station is controlled to output electric energy according to the allocated capacity to ensure the stable operation of the entire system. The number of smart capacitors cut in is controlled according to the power factor difference to compensate for reactive power and improve the power factor. At the same time, the output of the SVG (static VAR generator) is adjusted according to the change amplitude of the power factor difference to further stabilize the power factor. The output of the APF (active power filter) is adjusted according to the harmonic distortion adjustment value to eliminate or reduce harmonic distortion and improve the power quality.

[0044] Among them, the first allocation algorithm has two methods: Method 1: capacity average allocation method, including: Get the total grid load of distributed power stations and the number of distributed power stations, The distribution capacity allocated to distributed power stations = total grid load / number of distributed power stations.

[0045] Since the power load is evenly distributed, the workload of each power station is also relatively balanced, which helps to extend the service life of the power station and improve the stability of the entire power grid.

[0046] Method 2: The first allocation algorithm is a dynamic allocation algorithm; If the distributed power station includes a solar power station, obtaining the intensity of solar radiation of the distributed power station, and performing capacity allocation according to the intensities of multiple solar radiations; If the distributed power station includes a wind power station, the wind data of the distributed power station is obtained, and the capacity allocation is adjusted according to the wind force; the greater the wind force, the more capacity is allocated; the smaller the wind force, the less capacity is allocated; Capacity allocation is carried out according to the peak period and off-peak time of the distributed power station. During the peak period, the closer to the peak value, the more capacity is allocated; during the off-peak period, the closer to the valley value, the less capacity is allocated. Capacity allocation is carried out according to the fault frequency of the distributed power station and the magnitude of the fault frequency. The higher the fault frequency, the less capacity is allocated; the lower the fault frequency, the higher the capacity is allocated.

[0047] If the distributed power station includes solar power stations and wind power stations, the size of the dynamic allocation capacity is comprehensively considered according to the size of solar radiation and wind power; and the capacity allocation is dynamically adjusted in combination with the power consumption time and the frequency of faults.

[0048] When the solar radiation intensity is high or the wind is strong, priority should be given to the generation of renewable energy and its generation capacity should be maximized as much as possible. This can not only improve the utilization rate of renewable energy, but also reduce the dependence on traditional energy. During the peak load period of the power grid, the output power of the power station should be appropriately increased to meet the demand; during the load trough period, the utilization of power resources can be optimized by reducing the output power or using energy storage equipment. By analyzing the historical data of local faults in the power grid, targeted preventive measures can be formulated to reduce the probability and scope of faults. For example, key monitoring and maintenance can be carried out on fault-prone areas, or the grid structure can be adjusted to improve its fault resistance.

[0049] The method further comprises the steps of: If a voltage dispatching instruction is received to stabilize the voltage at a fixed value, the relevant steps of voltage stabilization control are started.

[0050] Real-time acquisition of grid voltage, current and load-side current signals; these signals are the basis for subsequent calculation of reactive current and voltage difference.

[0051] The reactive current is calculated according to the reactive current detection method, such as instantaneous reactive power theory, etc. Reactive current is one of the main causes of voltage fluctuation and loss in the power grid.

[0052] The average reactive current and the total reactive current that needs to be compensated are calculated; these values ​​are used to determine the number of smart capacitors that need to be switched and the reactive current that the SVG needs to compensate.

[0053] According to the reactive power distribution principle, the number of smart capacitors that need to be switched and the reactive current that the SVG needs to compensate are calculated, aiming to stabilize the grid voltage by compensating the reactive current. Among them, the reactive power distribution principles include equal proportion distribution and priority distribution.

[0054] The actual value of the high-voltage bus voltage of the distributed power station is obtained in real time; the actual value of the high-voltage bus voltage is the basis for the subsequent calculation of the voltage difference and the adjustment of the photovoltaic inverter output.

[0055] The difference between the actual voltage value and the fixed value is calculated as the voltage difference; the voltage difference reflects the deviation between the current voltage and the expected voltage.

[0056] According to the voltage difference, the amount of reactive power that needs to be adjusted is calculated through AVC; AVC can automatically adjust the output of reactive power according to the voltage difference to stabilize the grid voltage.

[0057] According to the actual voltage value, the output of the photovoltaic inverter is adjusted in an anti-correlation manner; the lower the actual voltage value, the greater the reactive output of the photovoltaic inverter; the higher the actual voltage value, the smaller the reactive output of the photovoltaic inverter. When the actual voltage value is low, the reactive output of the photovoltaic inverter is increased to increase the voltage; when the actual voltage value is high, the reactive output of the photovoltaic inverter is reduced to reduce the voltage. Anti-correlation regulation helps to achieve stable control of the grid voltage.

[0058] The system voltage is adjusted according to the configured SVG (static var generator) and intelligent capacitors; combined with the AVC regulation of the photovoltaic inverter, the amplitude of voltage fluctuation is reduced.

[0059] As the core of the entire power quality management system, the monitoring center is responsible for receiving instructions from the power grid dispatching center. When the dispatching center needs to stabilize the voltage in a certain area to a fixed value, it will send the corresponding dispatching instructions to the monitoring center. After receiving the dispatching instructions, the monitoring center will calculate the voltage value that needs to be adjusted according to the actual situation and configuration of the system. The monitoring center will use this voltage value as the target value and send it to the controller of each distributed power station through the communication network. After receiving the instruction, the controller will respond immediately and adjust the output of SVG (static var generator) and smart capacitor according to the instruction requirements. During the voltage regulation process, SVG (static var generator) and smart capacitors usually work together to achieve more accurate and faster voltage regulation. By adjusting the output of SVG (static var generator) and smart capacitors, the grid voltage can be effectively stabilized at a fixed value and the amplitude of voltage fluctuations can be reduced. Photovoltaic inverters are key equipment in photovoltaic power generation systems. They are responsible for converting the direct current generated by photovoltaic panels into alternating current and transmitting it to the power grid. At the same time, photovoltaic inverters also have reactive power regulation functions, which can adjust the reactive power they output according to the needs of the power grid. AVC (Automatic Voltage Control) is an advanced voltage regulation technology that monitors the grid voltage and reactive power in real time, calculates the amount of reactive power that needs to be adjusted, and controls the photovoltaic inverter to make corresponding adjustments. Through AVC regulation, precise control of the grid voltage can be achieved, further improving voltage stability. During the regulation process, it is necessary to calculate the amount of reactive power that needs to be adjusted based on the actual situation of the grid and the AVC regulation strategy. Then, these parameters are input into the control system of the photovoltaic inverter to control its output of the corresponding reactive power to achieve stable control of the grid voltage. Through the steps of receiving dispatch instructions from the monitoring center, issuing instructions to the controller, SVG (static var generator) and intelligent capacitor to adjust the voltage, and combining the AVC regulation of the photovoltaic inverter, the stable control of the grid voltage and the reduction of the amplitude of voltage fluctuation can be effectively achieved.

[0060] The method further comprises the steps of: The first detection algorithm is the resonance advance prediction algorithm, and the formula is: ; Among them, T n Moments are a collection of sampling time points, THI n T n Total harmonic current at the moment, THI n+1 Indicates that at the n+1th sampling time point T n+1The total harmonic current at the time. The harmonic current step change slope represents the average value of the total harmonic current change rate per unit time in N sections. If the harmonic current step change slope exceeds the threshold within a certain period of time, it is judged that there is a risk of harmonic amplification and resonance. If the above conditions are met and it is judged that there is a resonance trend, the controller will perform derating control according to the devices that have been put into use, and the control sequence is "PSS-smart capacitor-SVG-APF" to break the conditions for resonance.

[0061] PSS (Power System Stabilizer): Improves the stability of the power system by adjusting the excitation current of the generator.

[0062] Intelligent capacitor: It has functions such as automatic switching and reactive power compensation, which can reduce reactive power loss in the power grid.

[0063] SVG (Static VAR Generator): It can continuously and quickly adjust reactive power to maintain the stability of grid voltage.

[0064] APF (Active Power Filter): can dynamically compensate for harmonic currents in the power grid and improve the power quality of the grid.

[0065] Control purpose: Through derating control, the harmonic current level in the power grid is reduced, thereby breaking the conditions for resonance to occur and ensuring the stable operation of the power grid.

[0066] By introducing the resonance advance prediction algorithm as the first detection algorithm and combining it with other control strategies and equipment, the comprehensive management and optimization of the power quality of distributed power sources after grid connection can be achieved, thereby improving the reliability and safety of the power grid.

[0067] The method further comprises the steps of: Obtain the harmonic current step change slope in the current area; obtain the harmonic current step change slope in the current area within a specific time period through real-time monitoring and calculation.

[0068] Get the harmonic current step change slope within a historical set time period; the historical set time period can be one week, one month, one quarter, etc.

[0069] Calculate the change trend value of the harmonic current step change slope within the historical set time period; the change trend value is such as rising (positive value), falling (negative value) or stable.

[0070] Obtain the harmonic current step change slopes of multiple surrounding areas and calculate the surrounding average value.

[0071] Compare the harmonic current step change slope of the current power grid with the surrounding average value and calculate the surrounding difference.

[0072] The outlier value is calculated based on the change trend value and the surrounding difference value, and the outlier value = a1×change trend value + a2×surrounding difference value; among them, a1 is the weight corresponding to the change trend value, and a2 is the weight corresponding to the surrounding difference value, which can be adjusted according to actual conditions.

[0073] If the abnormal value exceeds the set threshold, it is judged that the harmonic current is distorted and an early warning is issued.

[0074] For example, the weights of the change trend value and the surrounding difference are set, for example, a1=0.6, a2=0.4; and an outlier threshold is set, for example, the threshold is 1.0.

[0075] Combined with historical data, surrounding area data and real-time power factor difference, harmonic current is monitored and analyzed from multiple angles. By calculating the abnormal value and comparing it with the set threshold, it can accurately determine whether the harmonic current is distorted and issue a warning in time.

[0076] The following steps are also included: Get the harmonic current step change slope in the current area; it reflects the change speed and trend of the harmonic current in a short time.

[0077] Perform spectrum analysis on the harmonic current step change slope to obtain the frequency component of the change slope; spectrum analysis can help us understand the distribution of harmonic current at different frequencies, thereby identifying possible harmonic pollution sources or unstable factors.

[0078] Within the set frequency range, if the frequency value exceeds the target value, the voltage control strategy is activated; the voltage control strategy includes raising the voltage to the set value, maintaining it for a set period of time, then lowering the set value, and then adjusting the voltage through the DVR (dynamic voltage restorer). Among them, a frequency range and target value need to be set to determine whether the frequency component of the harmonic current step change slope is abnormal. If a frequency component exceeds the target value, it is considered that there is harmonic pollution or instability in the power grid, and the voltage control strategy needs to be activated.

[0079] By real-time monitoring of the harmonic current step change slope, harmonic pollution or unstable factors in the power grid can be discovered in time, and corresponding voltage control strategies can be adopted.

[0080] For example, the frequency range is set to 50Hz±10% and the target value is 5%. If a frequency component in the spectrum analysis exceeds 55Hz, that is, 50Hz+10%, the voltage control strategy is triggered. The voltage control strategy, for example, increases the voltage by 5% and maintains it for 10 minutes. In order to avoid damage to grid equipment and users caused by excessive voltage, the voltage can be reduced back to within 5% of the original value. In the final stage of the voltage control strategy, the DVR is used to fine-tune the grid voltage. The DVR can quickly respond to changes in grid voltage and provide the necessary reactive power support to maintain the stability of the grid voltage and the quality of power. For example, if the grid voltage fluctuates or becomes unstable during the adjustment process, the DVR can respond quickly and output the corresponding reactive power to stabilize the grid voltage.

[0081] Among them, the intelligent capacitor switching logic includes: A power factor reference value is obtained, wherein the power factor reference value is lower than a target power factor value; the target power factor value is a power factor level expected to be achieved, and the power factor reference value is a threshold value for triggering a capacitor switching operation.

[0082] According to the comparison result of the current power factor value and the target power factor value, the system adjusts the switching logic. If the current power factor value is lower than the power factor reference value, the capacitor needs to be switched on; if the current power factor value is higher than the power factor reference value, the capacitor needs to be switched off.

[0083] When the current power factor value is lower than the power factor reference value, the common compensation is put into operation first, followed by the separate compensation. The large-capacity capacitor is put into operation first, and the capacitor with less number of times is put into operation first. When the current power factor value is higher than the power factor reference value, the common compensation is cut off first and then the separate compensation, the large-capacity capacitors are cut off first, and the capacitors with the most times are cut off first.

[0084] (1) Capacitor input logic: When the current power factor value is lower than the power factor reference value, the system puts capacitors into operation in the following order: First put into common compensation: First put into common compensation capacitors, these capacitors can simultaneously compensate for the reactive power in the system and improve the power factor of the entire system.

[0085] Post-compensation: After the common compensation capacitor is put into use, the separate compensation capacitor can be put into use as needed. The separate compensation capacitor can perform reactive power compensation for specific loads and further improve the power factor.

[0086] First put in large-capacity capacitors: When putting in capacitors, give priority to capacitors with larger capacity. This is because large-capacity capacitors can provide more reactive power compensation, thereby improving the power factor faster.

[0087] Put capacitors that have been used less frequently into use first: When multiple capacitors are available, give priority to those that have been used less frequently to balance the service life of the capacitors.

[0088] (2) Capacitor removal logic: When the current power factor value is higher than the power factor reference value, the system removes the capacitors in the following order: Cut off the common compensation first: First cut off the common compensation capacitors because these capacitors have the greatest impact on the reactive power compensation of the entire system.

[0089] After the common compensation capacitor is removed, the separate compensation capacitor can be removed as needed.

[0090] Cut off the large-capacity capacitors first: When cutting off the capacitors, give priority to cutting off the capacitors with larger capacity. This is to avoid excessive reactive power shortage after the capacitors are cut off.

[0091] Remove capacitors that have been used more often first: When multiple capacitors are available, remove those that have been used more often first to extend the service life of other capacitors.

[0092] Taking advantage of the characteristics of the smart capacitor self-organizing network, the intermittent switching of smart capacitors is achieved through the switching logic of the controller, "first common compensation and then separate compensation, first large capacity and then small capacity, first switching with fewer switching times and then switching with more switching times". Through the above-mentioned smart capacitor switching logic, the system can intelligently switch capacitors according to the current power factor value and the target power factor value, thereby effectively improving the power factor of the power system. This strategy not only improves the power quality, but also optimizes the use efficiency and service life of capacitors.

[0093] The method further comprises the steps of: Count the capacitance values ​​of the capacitors and calculate the uniformity of the distribution; the uniformity is the standard deviation of the capacitance value of each capacitor divided by the total capacitance. Count the capacitance values ​​of each capacitor and calculate the uniformity of the distribution of these capacitance values. The uniformity is obtained by calculating the standard deviation of the capacitance value of each capacitor divided by the total capacitance. The smaller the standard deviation, the more uniform the capacitance distribution of the capacitor.

[0094] The number of switching times of the capacitor is counted, and the distribution value of the switching times is calculated; the distribution value is the standard deviation of the switching times. The smaller the standard deviation, the more uniform the distribution of the switching times of the capacitor is.

[0095] Adjust the switching time interval or time difference according to the uniformity and distribution value; Time interval or time difference = basic time interval × (b1 × uniformity + b2 × distribution value); where b1 and b2 are adjustment coefficients, and b1 is less than b2.

[0096] For example, the basic time interval is set to 10 minutes, that is, in the absence of special adjustments, the default time interval between tasks is 10 minutes; set b1=0.5, b2=1.5.

[0097] Case 1: Uniformity: 0.9 (indicates that the urgency of the task is very high, and the urgency of each task is not much different); Distribution value: 0.3 (indicates that tasks are geographically or logically concentrated); Calculate the time interval: Time interval = 10 minutes × (0.5 × 0.9 + 1.5 × 0.3) = 10 minutes × (0.45 + 0.45) = 10 minutes × 0.9 = 9 minutes. Since the tasks are very urgent and concentrated, the system decides to slightly shorten the time interval between tasks so that they can be processed more quickly.

[0098] Case 2: Uniformity: 0.3 (indicates that the task urgency is low and the urgency of each task varies greatly); Distribution value: 0.7 (indicates that tasks are geographically or logically dispersed); Calculate the time interval: Time interval = 10 minutes × (0.5 × 0.3 + 1.5 × 0.7) = 10 minutes × (0.15 + 1.05) = 10 minutes × 1.2 = 12 minutes. Since the tasks are less urgent and more dispersed, the system decides to slightly extend the time interval between tasks to balance resource allocation and task execution efficiency.

[0099] In the power compensation system, the switching time interval or time difference is adjusted according to the situation of co-compensation and split compensation, the uniformity of capacity distribution, and the distribution of switching times. If the uniformity is high and the distribution value is low, it means that the capacitor works more evenly, and the switching time interval can be appropriately extended or the time difference can be reduced. On the contrary, if the uniformity is low and the distribution value is high, it means that the capacitor works unbalanced, and the switching time interval needs to be shortened or the time difference needs to be increased.

[0100] The method further comprises the steps of: Obtain the power consumption of different areas and calculate the power consumption rate; adjust the capacity allocation according to the power consumption and power consumption rate. The power consumption rate is the rate of change of power consumption per unit time, which helps to understand the growth or decline trend of power demand in each area. Obtain real-time or historical power consumption data for each area from the power grid dispatching center, smart meters or other data sources. To calculate the power consumption rate of each area, you can use the formula "power consumption rate = (current power consumption - power consumption at the previous moment) / time interval".

[0101] The capacity allocation is adjusted in a positive correlation according to the power consumption; the greater the power consumption, the more capacity is allocated; the smaller the power consumption, the less capacity is allocated.

[0102] For example, suppose there are three areas A, B and C; At a certain time point t1, the power consumption of area A is 100 kWh, the power consumption of area B is 150 kWh, and the power consumption of area C is 200 kWh.

[0103] At the next time point t2 (t2 = t1 + 1 hour), the power consumption in area A becomes 110kWh, in area B becomes 160kWh, and in area C becomes 220kWh.

[0104] The rate of change of power consumption in area A is (110kWh - 100kWh) / 1 hour = 10kWh / hour.

[0105] The rate of change in power consumption in area B is (160kWh - 150kWh) / 1 hour = 10kWh / hour.

[0106] The power consumption change rate of area C is (220kWh - 200kWh) / 1 hour = 20kWh / hour.

[0107] Depending on the rate of change in power consumption, it is possible to decide how much capacity to allocate to each area.

[0108] Assuming there is a total available capacity of X kWh, this capacity can be allocated in proportion to the rate of change of power consumption.

[0109] The power consumption change rate of regions A and B is the same, so A, B, and C should get the same capacity allocation ratio, for example, each accounting for 25% of the total capacity.

[0110] Region C has the largest power consumption change rate, so it should get a larger capacity allocation ratio, for example, 50% of the total capacity.

[0111] If the total capacity X is 1000kWh, then areas A and B are allocated 250kWh each, and area C is allocated 500kWh.

[0112] According to the power consumption rate, the amount of capacity allocation is adjusted in a positive correlation; the faster the power consumption rate, the faster the power demand grows, and the more capacity is allocated; the slower the power consumption rate, the less capacity is allocated. According to the adjusted capacity allocation plan, instructions are issued to the distributed power station to adjust its output power or capacity. The allocation method is similar to the above-mentioned method of allocating according to power consumption.

[0113] Since power consumption is not static, it will fluctuate with changes in seasons, weather, economic activities and other factors. Therefore, in order to more accurately adjust the amount of capacity allocation, we need to monitor the dynamic changes in power consumption in each area in real time and conduct in-depth analysis. According to the dynamic changes in power consumption / power consumption in different areas, adjust the amount of capacity allocation; power consumption is an important indicator reflecting the power demand of an area. The power consumption of different areas may vary due to various factors such as population size, economic development level, industrial structure, etc.; therefore, in order to ensure that the allocation of power resources is more accurate and efficient and meet the actual needs of different areas; for areas with large power consumption or rapid growth, their power supply should be prioritized and the amount of capacity allocation should be appropriately increased. This can ensure that these areas can get sufficient power support during peak power demand. For areas with small power consumption or slow growth, the amount of capacity allocation can be flexibly adjusted according to actual conditions. In the case of tight power supply, the capacity allocation of these areas can be appropriately reduced to relieve the pressure on the power grid. In order to better adapt to the dynamic changes in power consumption, a dynamic adjustment mechanism can be established. This mechanism can automatically adjust the amount of capacity allocation based on real-time monitored power consumption data to ensure a real-time balance between power supply and demand.

[0114] In summary, the control principle of this embodiment is as follows: Under normal operating conditions, PSS, DVR, APF, SVG, smart capacitor, PCS and photovoltaic inverter operate independently, that is, off-control operation mode, and each completes its own work task. At the same time, the controller communicates with each device through 485 communication method and standard MODBUS protocol to read the working status and alarm information of each device. At the same time, the Internet of Things technology is used to upload all the information obtained by the controller to the cloud platform, which can be viewed in real time on PC and mobile terminals to achieve observable and measurable functions.

[0115] During this period, if the control center issues a control command (remote control mode operation): 1) Photovoltaic active power and reactive power adjustment instructions: According to the principle of average capacity distribution, the active power and reactive power that each normally working photovoltaic inverter and PCS should send are calculated in real time, and then sent to each photovoltaic inverter and PCS through RS485. After receiving the controller instructions, the photovoltaic inverter and PCS will give priority to the control output according to the controller instructions.

[0116] 2) System reactive power adjustment command: According to the target power factor value issued by the superior control center, the controller allocates capacity according to the linked SVG or smart capacitor, and adopts the allocation principle of "most compensation by smart capacitors, fine adjustment by SVG" to achieve the best compensation effect. At the same time, by utilizing the characteristics of the smart capacitor self-organizing network, the controller's switching logic of "first common compensation and then separate compensation, first large capacity and then small capacity, first switching with fewer times and then switching with more times" is used to achieve intermittent switching of smart capacitors. When the photovoltaic system is reversed, the controller uses the fine compensation algorithm of smart capacitors + SVG to compensate the power factor to above 0.99.

[0117] 3) System harmonic control instructions: If the control center has requirements for the system harmonic distortion rate, after issuing the target value, the APF receives the information and adjusts its own output to control the harmonic distortion rate below the target value.

[0118] 4) System voltage regulation instructions: In automatic operation, if the system voltage rises or falls temporarily, the DVR will automatically adjust the voltage and upload the adjustment information to the monitoring center. If the monitoring center receives a dispatch instruction to stabilize the voltage at a fixed value, the monitoring center will send an instruction to the controller, and the controller will adjust the voltage according to the configured SVG and smart capacitor. At the same time, the AVC adjustment of the photovoltaic inverter can be combined to reduce the amplitude of voltage fluctuations.

[0119] 5) System resonance protection control instructions: through the controller's fast detection algorithm, that is, the resonance advance prediction algorithm, specifically refers to the "1 / 4 cycle detection algorithm": ; The Tn moment is based on the controller DSP fast sampling, such as 256 sampling points distributed within 5ms, THIn is the total harmonic current at the Tn moment, and the harmonic current step change slope represents the average value of the total harmonic current change rate per unit time in N segments. If the harmonic current step change slope exceeds the threshold within a certain period of time, it is judged that there is a risk of harmonic amplification and resonance. If the above conditions are met and it is judged that there is a resonance trend, the controller will perform derating control according to the devices that have been put into use, and the control sequence is "PSS-smart capacitor-SVG-APF" to break the conditions for resonance.

[0120] The technical effects of this application are: Through RS485 communication, the controller cyclically reads the working status and alarm information of PSS, DVR, APF, SVG, smart capacitor, PCS and photovoltaic inverter, which is convenient for users to understand the working status of each device and repair the faulty device in time.

[0121] By sampling the voltage and current of the system, the controller calculates the main power quality data such as voltage, current, active power, reactive power, power factor, voltage distortion rate, current distortion rate, 3-25 odd harmonic voltage, current value in real time. Once the distortion rate exceeds the standard, the distortion rate exceeding standard protection can be triggered to prevent the user's equipment from being damaged due to excessive harmonics.

[0122] In addition to adjusting the active power and reactive power of the photovoltaic inverter and PCS, the controller can also intelligently switch the reactive power compensation device as needed to adjust the voltage of the photovoltaic grid-connected point and improve the power factor.

[0123] This method uses harmonic control equipment to control harmonics, and through monitoring of harmonic amplification and resonance, uses the "resonance advance prediction" model to predict the trend of resonance in advance when harmonics change instantly, and destroys the conditions for resonance by adjusting the power quality control equipment, thereby avoiding the occurrence of harmonic amplification and resonance problems.

[0124] Based on distributed power sources, it is mainly based on PCS and photovoltaic inverters, and covers all the power quality management devices currently on the market. This method is not limited to voltage levels and can be applied to new power systems from 0.4kV to 35kV. It can also realize hybrid compensation systems with multiple voltage levels below 35kV and hybrid control of multi-voltage power grid systems.

[0125] An embodiment of the present application also discloses a hybrid control system based on distributed power supply power quality management, including a processor, in which a program of the above-mentioned hybrid control method based on distributed power supply power quality management is running.

[0126] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A hybrid control method based on distributed power supply power quality management, characterized in that: The steps include: Obtain the total capacity value that needs to be connected to the grid, and obtain the power data of multiple distributed power stations within the area that needs to be connected to the grid; Allocate distribution capacity to the distributed power station according to a first allocation algorithm, and control the distributed power station to output electric energy; Calculate the current power factor value, obtain the target power factor value, calculate the difference between the current power factor value and the target power factor value in real time as the power factor difference, and control the number of switched smart capacitors according to the positive correlation of the power factor difference; and adjust the output size of the SVG (static var generator) according to the positive correlation of the change amplitude of the power factor difference; Based on the first detection algorithm, the harmonic current step change slope is calculated, the harmonic distortion target value is obtained, the difference between the harmonic current step change slope and the harmonic distortion target value is calculated as the harmonic distortion adjustment value, and the output of the reactive power of the APF (active power filter) is anti-correlatedly adjusted according to the harmonic distortion adjustment value.

2. The hybrid control method based on distributed power quality management according to claim 1 is characterized in that: The following steps are also included: If a voltage dispatch instruction is received that requires the voltage to be stabilized at a fixed value; Obtain grid voltage, grid current and load-side current signals in real time; Calculate the reactive current according to the reactive current detection method; Calculate the average reactive current and the total reactive power that needs to be compensated based on the reactive current; According to the reactive power distribution principle, the number of smart capacitors that need to be switched and the reactive current that the SVG (static var generator) needs to compensate are calculated; Obtain the actual voltage value of the high-voltage side bus of the distributed power station in real time; The difference between the actual voltage value and the fixed value is calculated as the voltage difference; Based on the voltage difference, the amount of reactive power that needs to be adjusted is calculated through the AVC (automatic voltage controller); Inversely adjust the output of the photovoltaic inverter according to the actual voltage value; The lower the actual voltage value is, the greater the reactive output of the photovoltaic inverter is; and the higher the actual voltage value is, the smaller the reactive output of the photovoltaic inverter is.

3. The hybrid control method based on distributed power quality management according to claim 1 is characterized in that: The following steps are also included: The first detection algorithm is a resonance advance prediction algorithm, and the formula is: ； Among them, T n Moments are a collection of sampling time points, THI n T n The total harmonic current at the moment, N is the number of unit times in the detection time period; the harmonic current step change slope represents the average value of the total harmonic current change rate per unit time in N sections.

4. The hybrid control method based on distributed power quality management according to claim 3 is characterized in that: The following steps are also included: Get the harmonic current step change slope in the current area; Get the harmonic current step change slope within the historical set time period; Calculate the change trend value of the harmonic current step change slope within the historical set time period; Obtain the harmonic current step change slopes of multiple surrounding areas and calculate the surrounding average value; Compare the harmonic current step change slope of the current power grid with the surrounding average value and calculate the surrounding difference; The outlier value is calculated based on the change trend value and the surrounding difference value, and the outlier value = a1×change trend value + a2×surrounding difference value; where a1 is the weight corresponding to the change trend value, and a2 is the weight corresponding to the surrounding difference value; If the abnormal value exceeds the set threshold, it is judged that the harmonic current is distorted and an early warning is issued.

5. The hybrid control method based on distributed power quality management according to claim 3 is characterized in that: The following steps are also included: Get the harmonic current step change slope in the current area; Performing spectrum analysis on the harmonic current step change slope to obtain the frequency component of the change slope; Within the set frequency range, if the frequency value exceeds the target value, the voltage control strategy is started; The voltage control strategy includes raising the voltage to a set value, maintaining the voltage for a set period of time, and then lowering the voltage to the set value, and then regulating the voltage through a DVR (dynamic voltage restorer).

6. The hybrid control method based on distributed power quality management according to claim 1 is characterized in that: The intelligent capacitor switching logic includes: obtaining a power factor reference value, wherein the power factor reference value is lower than a target power factor value; Adjust the switching logic according to the current power factor value and the target power factor value; When the current power factor value is lower than the power factor reference value, the common compensation is put into operation first, followed by the separate compensation. The large-capacity capacitor is put into operation first, and the capacitor with less number of times is put into operation first. When the current power factor value is higher than the power factor reference value, the common compensation is cut off first and then the separate compensation, the large-capacity capacitors are cut off first, and the capacitors with the most times are cut off first.

7. The hybrid control method based on distributed power quality management according to claim 6 is characterized in that: The following steps are also included: Count the capacitance values ​​of capacitors and calculate the uniformity of distribution; the uniformity is the standard deviation of the capacitance value of each capacitor divided by the total capacitance; Count the switching times of the capacitor and calculate the distribution value of the switching times; the distribution value is the standard deviation of the switching times; Adjust the switching time interval or time difference according to the uniformity and distribution value; Time interval or time difference = basic time interval × (b1 × uniformity + b2 × distribution value); where b1 and b2 are adjustment coefficients, and b1 is less than b2.

8. The hybrid control method based on distributed power quality management according to claim 1 is characterized in that: The step of controlling the number of switched intelligent capacitors according to the power factor difference comprises: Obtaining a low threshold and a high threshold corresponding to the power factor difference; when the power factor difference is lower than the low threshold, adjusting the number of smart capacitors to be put into operation in a positive correlation according to the size of the power factor difference; when the power factor difference is higher than the high threshold, adjusting the number of smart capacitors to be removed in a positive correlation according to the size of the power factor difference; when the power factor difference is between the low threshold and the high threshold, keeping the current number of capacitors switched in unchanged; The step of adjusting the output of SVG (static var generator) according to the variation of the power factor difference comprises: When the change amplitude exceeds the corresponding threshold, the output size of the SVG (static VAR generator) is positively adjusted according to the change amplitude of the power factor difference; the larger the change amplitude, the larger the SVG (static VAR generator) output is adjusted; the smaller the change amplitude, the smaller the SVG (static VAR generator) output is adjusted; The step of adjusting the output of reactive power of an APF (active power filter) according to the harmonic distortion adjustment value comprises: If the actual harmonic distortion rate value is greater than the harmonic distortion rate threshold, the output of the APF (active power filter) is increased in a positive correlation according to the harmonic distortion adjustment value; the larger the harmonic distortion adjustment value, the more the APF (active power filter) output increases; the smaller the harmonic distortion adjustment value, the less the output of the APF (active power filter) reactive power increases; so that the actual harmonic distortion rate is controlled below the harmonic distortion rate threshold.

9. The hybrid control method based on distributed power quality management according to claim 1 is characterized in that: The first allocation algorithm is a capacity average allocation method, including: Obtain the total grid load of distributed power generation stations and the number of distributed power generation stations; Allocate distribution capacity to the distributed power station = total grid load / number of distributed power stations; The method further comprises the steps of: Obtaining power consumption of different areas, and calculating the power consumption rate of the power consumption; adjusting capacity allocation according to the power consumption and the power consumption rate; According to the power consumption, the amount of capacity allocation is positively correlated to be adjusted; the greater the power consumption, the more capacity is allocated; the smaller the power consumption, the less capacity is allocated; The amount of capacity allocation is adjusted in a positive correlation according to the power consumption speed; the faster the power consumption speed, the more capacity is allocated; the slower the power consumption speed, the less capacity is allocated.

10. A hybrid control system based on distributed power supply power quality management, characterized in that: It includes a processor, in which runs a program of a hybrid control method based on distributed power quality management as described in any one of claims 1 to 9.

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