Cooperative method and device for harmonic suppression and reactive power compensation in power distribution network

Abstract

The invention relates to a coordination method and device for harmonic suppression and reactive power compensation in a power distribution network. The method comprises the steps of obtaining power grid operation parameter information of a power distribution network; according to the power grid operation parameter information, the total current harmonic distortion rate, the power factor and each harmonic current information of the power distribution network are detected; detecting to-be-optimized parameters of the power distribution network according to the total current harmonic distortion rate, the power factor and the current information of each harmonic, the to-be-optimized parameters including at least one of each harmonic and reactive power; and according to the to-be-optimized parameters, suppressing each harmonic in the power distribution network and compensating reactive power in the power distribution network. The method can accurately perform cooperative control on harmonic suppression and reactive power compensation in the power distribution network.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of smart grid, and particularly relates to a harmonic suppression and reactive power compensation coordination method and device in a power distribution network. BACKGROUND

[0002] With the rapid growth of power demand in industrial manufacturing, a large number of nonlinear loads (such as frequency converters, electric arc furnaces, etc.) and impact loads are connected to the power grid, resulting in increasingly serious harmonic pollution in the power distribution network, as well as a decrease in power factor. These problems directly affect power quality, and therefore, harmonic suppression and reactive power compensation are needed in the power distribution network.

[0003] In the traditional technology, passive power filters or active power filters can be used to suppress harmonics in the power distribution network, and shunt capacitors or static var compensators can be used to compensate for reactive power in the power distribution network. However, the current harmonic suppression method or reactive power compensation method in the power distribution network has the problem of being unreliable. SUMMARY

[0004] Therefore, it is necessary to provide a reliable harmonic suppression and reactive power compensation coordination method, device, computer equipment, computer readable storage medium and computer program product in the power distribution network in view of the above technical problems.

[0005] In a first aspect, the present application provides a harmonic suppression and reactive power compensation coordination method in a power distribution network, comprising:

[0006] obtaining power grid operation parameter information of the power distribution network;

[0007] detecting total current harmonic distortion rate, power factor, and each harmonic current information of the power distribution network according to the power grid operation parameter information;

[0008] detecting to-be-optimized parameters of the power distribution network according to the total current harmonic distortion rate, the power factor, and the each harmonic current information, wherein the to-be-optimized parameters include at least one of each harmonic and reactive power;

[0009] suppressing each harmonic in the power distribution network and compensating for reactive power in the power distribution network according to the to-be-optimized parameters.

[0010] In a second aspect, the present application further provides a harmonic suppression and reactive power compensation coordination device in a power distribution network, comprising:

[0011] an obtaining module configured to obtain power grid operation parameter information of the power distribution network;

[0012] a detecting module configured to detect total current harmonic distortion rate, power factor, and each harmonic current information of the power distribution network according to the power grid operation parameter information;

[0013] an optimization determining module, configured to detect a to-be-optimized parameter of the power distribution network according to the total current harmonic distortion, the power factor, and the harmonic current information, wherein the to-be-optimized parameter comprises at least one of the harmonics and the reactive power;

[0014] an optimization executing module, configured to suppress the harmonics and compensate the reactive power in the power distribution network according to the to-be-optimized parameter.

[0015] In a third aspect, the present application provides a computer device, comprising a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the above steps.

[0016] In a fourth aspect, the present application provides a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to implement the above steps.

[0017] In a fifth aspect, the present application provides a computer program product, comprising a computer program, and the computer program is executed by a processor to implement the above steps.

[0018] The above-mentioned power distribution network harmonic suppression and reactive power compensation coordination method, device, computer device, computer readable storage medium and computer program product, through the power grid operation parameter information of the power distribution network, detect the total current harmonic distortion, the power factor, and the harmonic current information of the power distribution network, and according to the total current harmonic distortion, the power factor, and the harmonic current information, detect which parameters of the power distribution network need to be optimized, so as to focus on optimizing the to-be-optimized parameter, and the to-be-optimized parameter comprises at least one of the harmonics and the reactive power. Therefore, instead of the independent operation scheme in the prior art, the present application can suppress the harmonics and compensate the reactive power in the power distribution network according to the to-be-optimized parameter, so that the harmonic suppression process and the reactive power compensation process affect each other, and are more reliable. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related art, the drawings needed to be used in the description of the embodiments of the present application or the related art will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can obtain other related drawings without creative labor.

[0020] Figure 1 An application environment diagram of the power distribution network harmonic suppression and reactive power compensation coordination method in an embodiment;

[0021] Figure 2A flowchart of a method for harmonic suppression and reactive power compensation in a power distribution network in an embodiment;

[0022] Figure 3 A topology diagram of a control system of a power distribution network in an embodiment;

[0023] Figure 4 A flowchart of a method for harmonic suppression and reactive power compensation in a power distribution network in another embodiment;

[0024] Figure 5 A schematic diagram of the flow of h-order harmonic current in an embodiment;

[0025] Figure 6 A structural block diagram of a device for harmonic suppression and reactive power compensation in a power distribution network in an embodiment;

[0026] Figure 7 An internal structure diagram of a computer device in an embodiment. DETAILED DESCRIPTION

[0027] In order to make the purposes, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are used to explain the present application and are not used to limit the present application.

[0028] The method for harmonic suppression and reactive power compensation in a power distribution network provided by the embodiments of the present application can be applied in an application environment as shown in Figure 1 . In the application environment, the power distribution network 102 communicates with the control system 104 through a network. The control system 104 detects power grid operation parameter information of the power distribution network 102; detects total current harmonic distortion rate, power factor and each-order harmonic current information of the power distribution network according to the power grid operation parameter information; detects to-be-optimized parameters of the power distribution network according to the total current harmonic distortion rate, the power factor and the each-order harmonic current information, wherein the to-be-optimized parameters include at least one of each-order harmonic and reactive power; suppresses each-order harmonic in the power distribution network 102 and compensates for reactive power in the power distribution network according to the to-be-optimized parameters.

[0029] In an exemplary embodiment, as shown in Figure 2 , a method for harmonic suppression and reactive power compensation in a power distribution network is provided. The method is described below by taking the control system 104 in Figure 1 as an example. In the method, the control system 104 detects power grid operation parameter information of the power distribution network 102; detects total current harmonic distortion rate, power factor and each-order harmonic current information of the power distribution network according to the power grid operation parameter information; detects to-be-optimized parameters of the power distribution network according to the total current harmonic distortion rate, the power factor and the each-order harmonic current information, wherein the to-be-optimized parameters include at least one of each-order harmonic and reactive power; suppresses each-order harmonic in the power distribution network 102 and compensates for reactive power in the power distribution network according to the to-be-optimized parameters.

[0030] S200, obtaining power grid operation parameter information of the power distribution network.

[0031] Specifically, as shown in Figure 3The topology of the control system of a complete power distribution network is shown, and the core acquisition module is a DPSCU (Digital Power Signal Detection Unit). The PAV (Precision Accuracy Sensor for [Target]) is used to monitor the three-phase voltage waveform (U a , U b , U c ) and the respective voltage effective value (380V / 50Hz reference), the three-phase current waveform (I a , I b , I c ) and the respective harmonic component (focusing on h=5 / 7 / 11 / 13 harmonic current I h ), the total active power P and the reactive power Q, and the like. The RS485 (Recommended Standard 485) bus is used to transmit data to the controller at a sampling period.

[0032] In addition, the control system is provided with a harmonic filter subsystem and a reactive compensation subsystem, and is also provided with a main circuit breaker for switching the total power supply, a contactor KM1 for cutting off the harmonic filter subsystem, a contactor KM2 for cutting off the reactive compensation subsystem, and an AC bus voltage U1 as the fundamental voltage of the power distribution network input to the control system. In the harmonic filter subsystem, an electromagnetic coupling reactor, fuses FU 11 , FU 12 ...FU 1m , contactors KM 11 , KM 12 ...KM 1m , and a first capacitor C1 are arranged. The electromagnetic coupling reactor includes a power electronic impedance converter and a primary winding, and the voltage value of the primary inductive winding is U Ln11 . The first capacitor C1 includes a plurality of capacitor groups C 11 , C 12 ...C 1m . In the reactive compensation subsystem, fuses FU 21 , FU 22 ...FU 2m , contactors KM 21 , KM 22 ...KM 2m , and a second capacitor C2 are also arranged. The specific functions of these components will be described in detail later, and will not be described here.

[0033] In one embodiment, the controller implements data monitoring through interrupt service, and when it is monitored that the update flag F u =1, the current grid operation parameter information is acquired and locked, and the grid operation parameter information is analyzed and processed subsequently.

[0034] S400, according to the grid operation parameter information, detecting the total current harmonic distortion rate, power factor, and each harmonic current information of the power distribution network.

[0035] Specifically, through the grid operation parameter information, a mathematical model capable of analyzing harmonic characteristics and reactive power shortage in real time is established, and the model parameters are optimized through historical data training to predict harmonic change trend and reactive power demand, such as total current harmonic distortion rate, power factor, and each harmonic current information. Among them, the total current harmonic distortion rate THD (Total Harmonic Distortion) is a core index for measuring the deviation degree of "harmonic content" and "fundamental signal" in an alternating current circuit, which is used to quantify the pros and cons of power quality; the power factor is a core index for measuring the "electricity utilization efficiency" in an alternating current circuit; each harmonic current is a current component with an integer multiple of the fundamental frequency in an alternating current circuit, which is one of the main reasons for current waveform distortion and power quality decline. The fundamental current is a current component with the same frequency as the grid fundamental frequency, and the harmonic current is generated by the nonlinear load in the circuit (such as frequency converter, rectifier, etc.). Therefore, by detecting the total current harmonic distortion rate, power factor, and each harmonic current information of the power distribution network, it can be accurately determined how to optimize and control the power distribution network subsequently.

[0036] S600, according to the total current harmonic distortion rate, power factor, and each harmonic current information, detecting the to-be-optimized parameters of the power distribution network, wherein the to-be-optimized parameters include at least one of each harmonic and reactive power.

[0037] Specifically, the existing technology has the following problems: the inductance and capacitance parameters of the traditional passive power filter are fixed and cannot be dynamically adjusted according to the harmonic change, resulting in poor filtering effect; after long-term operation, the inductance and capacitance parameters may deviate from the standard value due to temperature change, which may cause resonance point drift or even system resonance, affecting the filtering performance; at the same time, when the harmonic current increases, the filter is easy to overload and damage the electrical elements. In addition, the capacity of the traditional reactive power compensation device is fixed and cannot be adjusted, which is easy to cause parallel resonance with the inductance in the system, resulting in harmonic current amplification. Directly put into the industrial power distribution network with serious harmonic pollution may burn the equipment. More importantly, the existing harmonic filter or reactive power compensation device has single function, which cannot solve the problems of harmonic pollution and low power factor at the same time, making it difficult to comprehensively improve the power quality of the power distribution network.

[0038] Therefore, the application determines the parameters to be optimized in the power distribution network according to the total current harmonic distortion rate, the power factor, and the harmonic current information, determines whether the harmonics need to be suppressed, whether the reactive power needs to be compensated, or whether the harmonics in the power distribution network need to be suppressed and the reactive power in the power distribution network needs to be compensated at the same time, suppresses the harmonics to reduce line loss, reduce power waste, and avoid damage to electrical components, and compensates the reactive power to stabilize the grid voltage, improve power supply quality, and reduce equipment damage. More specifically, whether the parameters to be optimized in the power distribution network include the harmonics can be determined according to the total current harmonic distortion rate and the harmonic current information, and whether the parameters to be optimized in the power distribution network include the reactive power can be determined according to the power factor.

[0039] S800, according to the to-be-optimized parameter, suppressing the harmonics in the power distribution network and compensating the reactive power in the power distribution network.

[0040] Specifically, according to the determined to-be-optimized parameter, when the to-be-optimized parameter is the harmonics, the harmonics in the power distribution network can be suppressed, when the to-be-optimized parameter is the reactive power, the reactive power in the power distribution network is compensated, and when the to-be-optimized parameter is the harmonics and the reactive power, the harmonics in the power distribution network can be suppressed and the reactive power in the power distribution network is compensated.

[0041] In the above-mentioned method for coordinating the harmonic suppression and the reactive power compensation in the power distribution network, the total current harmonic distortion rate, the power factor, and the harmonic current information of the power distribution network are detected according to the grid operation parameter information, and which parameters of the power distribution network need to be optimized is detected according to the total current harmonic distortion rate, the power factor, and the harmonic current information, so that the to-be-optimized parameter is optimized, and the to-be-optimized parameter includes at least one of the harmonics and the reactive power. Therefore, instead of the independent operation scheme in the prior art, the application can suppress the harmonics in the power distribution network and compensate the reactive power in the power distribution network according to the to-be-optimized parameter, so that the harmonic suppression process and the reactive power compensation process affect each other, and are more reliable.

[0042] In an exemplary embodiment, detecting the total current harmonic distortion rate, the power factor, and the harmonic current information of the power distribution network according to the grid operation parameter information includes:

[0043] From the grid operation parameter information, the fundamental current information, the harmonic current information, the total active power, and the reactive power of the power distribution network are obtained, the total current harmonic distortion rate of the power distribution network is detected according to the fundamental current information and the harmonic current information, and the power factor of the power distribution network is detected according to the total active power and the reactive power.

[0044] The power factor essentially reflects the ratio of active power (actual power) to apparent power (total power provided by the power supply) in the circuit, and the value is between 0 and 1. The closer to 1, the higher the utilization efficiency of electric energy.

[0045] Specifically, from the grid operation parameter information, the fundamental current information I1, each harmonic current information (the hth harmonic current information is I h ), total active power P and reactive power Q of the power distribution network are obtained. In practical applications, the harmonic current information is mainly the current information of specific harmonics such as 5th, 7th, 11th, etc.

[0046] At this time, the total current harmonic distortion rate of the power distribution network is , wherein I h represents the amplitude of the hth harmonic current, that is, the current size of the specified harmonic (such as 5th, 7th, 11th, etc.) generated by the nonlinear load. m represents the highest order of odd harmonics or the number of harmonics considered in the filter (dimensionless). When THD> 23.8% (national standard limit), an alarm is triggered. The power factor of the power distribution network is , and the reactive power compensation is to provide or absorb reactive power by installing compensating devices such as capacitors and reactors, to reduce the phase difference and thus improve the power factor.

[0047] In the above embodiment, by obtaining the fundamental current information, each harmonic current information, total active power and reactive power of the power distribution network, the total current harmonic distortion rate, the power factor of the power distribution network, and each harmonic current information can be accurately detected to monitor the operation state of the power grid.

[0048] In an exemplary embodiment, according to the total current harmonic distortion rate, the power factor, and each harmonic current information, the to-be-optimized parameters of the power distribution network are detected, including:

[0049] Obtaining fuzzy logic control rules or threshold control rules; using the fuzzy logic control rules or threshold control rules, the control weights corresponding to the total current harmonic distortion rate, the power factor, and each harmonic current information are obtained; and according to the control weights corresponding to the total current harmonic distortion rate, the power factor, and each harmonic current information, the to-be-optimized parameters of the power distribution network are detected.

[0050] Specifically, the to-be-optimized parameters of the power distribution network detected by the present application are at least two, one is detected by threshold control rules, and the other is detected by fuzzy logic control rules.

[0051] For the threshold control rule, whether the total current harmonic distortion rate, the power factor, and the harmonic current information of each order satisfy the corresponding threshold is judged to obtain the control weight corresponding to the total current harmonic distortion rate, the power factor, and the harmonic current information of each order, and then it is determined which parameter needs to be optimized. For example, when the total current harmonic distortion rate does not satisfy the corresponding threshold, the determined parameter to be optimized is the harmonic of each order, and when the power factor does not satisfy the corresponding threshold, the determined parameter to be optimized is the reactive power.

[0052] For example, one threshold control rule table 1 is as follows:

[0053]

[0054] In addition, a dynamic weight adjustment strategy can also be used, that is, the parameter to be optimized of the power distribution network is set as a multi-objective optimization problem by combining the fuzzy logic control rule, that is, , wherein I h represents the harmonic current information of each order, pf is the power factor, the total current harmonic distortion rate is THD I , w1 is the harmonic suppression weight, w2 is the reactive power compensation weight, w3 is the specific harmonic suppression weight, and the weight constraint is w1+w2+w3=1. Then, the control weight corresponding to the total current harmonic distortion rate, the power factor, and the harmonic current information of each order is obtained by using the fuzzy logic control rule.

[0055] In one embodiment, one fuzzy logic control rule or threshold control rule table is shown in Table 2 as follows:

[0056]

[0057] In one embodiment, the parameters to be optimized obtained by the fuzzy logic control rule or the threshold control rule can be analyzed. If the parameters to be optimized obtained by the two rules are different, manual intervention is needed or the fuzzy logic control rule is used as the reference.

[0058] In the above embodiment, the fuzzy logic control rule or the threshold control rule can accurately detect the parameter to be optimized of the power distribution network according to the control weight corresponding to the total current harmonic distortion rate, the power factor, and the harmonic current information of each order, which is more comprehensive.

[0059] In one exemplary embodiment, as shown in Figure 4 S800 includes:

[0060] S820, when the parameter to be optimized includes a target harmonic of each harmonic, the target harmonic frequency of the target harmonic to be filtered is determined.

[0061] S840, by adjusting the equivalent inductance information of the electromagnetic coupling reactor in the harmonic filtering subsystem of the power distribution network, and switching at least one mode of the first capacitance group of the first filter capacitor in the harmonic filtering subsystem, the resonance frequency of the harmonic filtering subsystem is matched with the target harmonic frequency.

[0062] S860, when the resonance frequency is matched with the target harmonic frequency, the target harmonic is suppressed by using the harmonic filtering subsystem.

[0063] Specifically, when the harmonic suppression flag F rh is "1" and the reactive power compensation flag F rq is "0", the harmonic filtering subsystem HFSS is turned on, and the working state of the HFSS is determined by any one of the following conditions: when I h is greater than the preset harmonic current threshold, the HFSS enters a dynamic tuning state, adjusts the resonance frequency, filters out harmonics, ensures stable operation of the power grid, and until the harmonic current meets the harmonic standard, a symmetrical current waveform is obtained. In addition, it provides a certain amount of reactive power, and sets the harmonic suppression flag F rh to "0"; when I h is less than or equal to the preset harmonic current threshold, the harmonic current meets the harmonic standard, and the HFSS maintains the working state at the previous time; thereafter, the reactive power compensation flag F rq is set to "1".

[0064] The harmonic filtering subsystem is essentially an inductance-capacitance series resonance circuit composed of a power electronic impedance converter (containing thyristors) and a first filter capacitor, and the core filtering logic is based on: when the inherent resonance frequency of the series resonance circuit is consistent with the "target harmonic frequency to be suppressed", the impedance of the circuit to this frequency will be the lowest (ideal state tends to 0). At this time, the target harmonic current in the power distribution network will preferentially flow into this "low impedance" harmonic filtering subsystem loop (rather than the power grid or other loads), and ultimately be consumed / processed through the dissipative elements or feedback devices inside the harmonic filtering subsystem, achieving suppression of the target harmonic. Therefore, when the to-be-optimized parameters include the target harmonic in each harmonic, the controller preferentially starts the harmonic suppression subsystem, adjusts the equivalent inductance information of the electromagnetic coupling reactor in the harmonic filtering subsystem, and switches at least one mode of the first capacitance group of the first filter capacitor in the harmonic filtering subsystem, to form an optimal resonance point so that the resonance frequency of the harmonic filtering subsystem matches the target harmonic frequency of the target harmonic to be filtered, that is, by using the characteristic of the series resonance circuit "presenting low impedance to a specific frequency", the HFSS is resonated at the corresponding harmonic frequency, and the harmonic current is "sucked into" the loop itself, thereby preventing it from flowing into the power distribution network, and thereby suppressing the target harmonic by using the harmonic filtering subsystem.

[0065] In the above embodiments, by adjusting the equivalent inductance information of the electromagnetic coupling reactor in the harmonic filter subsystem and at least one mode of switching the first capacitor group of the first filter capacitor in the harmonic filter subsystem, the resonance frequency of the harmonic filter subsystem is matched with the target harmonic frequency, and then the target harmonic to be filtered is accurately suppressed.

[0066] In one exemplary embodiment, by adjusting the equivalent inductance information of the electromagnetic coupling reactor in the harmonic filter subsystem of the power distribution network and at least one mode of switching the first capacitor group of the first filter capacitor in the harmonic filter subsystem, the resonance frequency of the harmonic filter subsystem is matched with the target harmonic frequency, including:

[0067] By adjusting the trigger angle information of the thyristor of the power electronic impedance converter in the harmonic filter subsystem of the power distribution network, the equivalent inductance information of the electromagnetic coupling reactor in the harmonic filter subsystem is adjusted; the minimum capacitance information of the first filter capacitor in the harmonic filter subsystem is detected, and the first equivalent capacitance information of the first filter capacitor is detected according to the minimum capacitance information; by adjusting the equivalent inductance information and at least one mode of switching the first capacitor group of the first filter capacitor using the first equivalent capacitance information, the resonance frequency of the harmonic filter subsystem is matched with the target harmonic frequency.

[0068] Specifically, still as Figure 3 shown, in the harmonic filter subsystem HFSS, there are an electromagnetic coupling reactor SS, a power electronic impedance converter PEIC (i.e. a secondary impedance conversion circuit of the electromagnetic coupling reactor), a first filter capacitor C1, and a contactor KM connected with each capacitor group in the first filter capacitor C1 11 –KM 1m In this application, first, the first filter capacitor C1 and the electromagnetic coupling reactor SS of the HFSS need to be designed.

[0069] 1) Design of the first filter capacitor C1. In order to reduce the cost of the filter, it is necessary to reduce the capacity of the capacitor as much as possible while meeting the filtering requirements. Therefore, the minimum capacitance information of the first filter capacitor is determined by the minimum capacitance method, and the first equivalent capacitance information of the first filter capacitor is detected according to the minimum capacitance information, which reduces the device cost and overload risk under the premise of meeting the filtering performance. The specific method is as follows: when the HFSS resonates, the inductive reactance is equal to the capacitive reactance, i.e. , where w1 is the fundamental frequency, L 11 and C1 are the inductance of the electromagnetic coupling reactor and the capacitance of the first filter capacitor group respectively. h ​

[0070] Generally, the distortion rate of harmonic voltage of the power distribution system to be processed is small. Therefore, it can be approximately said that the AC bus voltage of the system does not contain harmonic voltage component; that is, the AC bus voltage U1 of the system is equal to the fundamental component U （1） In addition to the h-order harmonic current I f（h） absorbed by the harmonic filtering subsystem, the current in the HFSS branch should also include the fundamental current I （2） caused by the fundamental voltage U f（1） , It is explicitly assumed that the harmonic distortion of the power grid voltage is negligible, that is: the AC bus voltage U1 of the system is equal to its fundamental component U （1） , which means: the total voltage U1 is approximately a pure fundamental U （1） The high-order harmonic voltage components (such as U （2） , U （3） , etc.) are considered to be small and are ignored.

[0071] The fundamental current I f（1） and the harmonic current I f（h） absorbed by the harmonic filtering subsystem will both generate reactive power when flowing through the first filtering capacitor. Therefore, the total installed capacity S （h） of the filtering capacitor bank should be: , wherein S （h） is the total apparent power of the system composed of fundamental and harmonic components, Q （1） is the reactive power component of the fundamental, Q （h） is the reactive power component of the hth harmonic, ω1 is the angular frequency of the fundamental, C1 is the capacitance value, which may be related to the circuit parameters at the fundamental frequency, I f（1） is the current amplitude at the fundamental frequency, I f（h） is the effective value of the current absorbed at the hth harmonic frequency, U （1） is the effective value of the voltage at the fundamental frequency, and h is the harmonic order. f（h） is the current amplitude at the hth harmonic frequency.

[0072] The size of the fundamental reactive capacity Q （1） generated by the branch of the first filtering capacitor under the fundamental voltage U （1） is: , and the meanings of the physical quantities are as follows: Q （1） is the reactive power of the fundamental, U （1） is the effective value of the fundamental voltage, I f（1） is the effective value of the absorbed fundamental current, ω1 is the angular frequency of the fundamental, C1 is the capacitance of the first filtering capacitor, and h is the harmonic order.

[0073] Let the reference installed capacity S （1） = U1I f（h）wherein, , , that is, the total installed capacity S （h） is normalized with respect to the reference installed capacity S （1） , is the normalized S （h） , Q （1） is the fundamental reactive capacity, is the processed Q （1） , U1 is the reference fundamental harmonic voltage effective value, I f（h） is the absorbed hth harmonic current information, and these information are substituted into the equation of the total installed capacity S （h） , to obtain: , Then, the minimum capacity of the HFSS can be obtained Therefore, the fundamental reactive capacity generated by the HFSS is: At this time, the minimum capacity of the HFSS corresponds to the minimum capacitance information wherein w1 is the fundamental angular frequency, U （1） is the fundamental voltage, and I f（h） is the absorbed hth harmonic current information.

[0074] Generally, the standard filter capacitor available on the market has a relatively fixed capacity, and if the calculated capacity of the filter capacitor does not correspond to the standard filter capacitor, a standard capacitor with a capacity slightly larger than the theoretical calculated value can be selected. In addition, the first filter capacitor can be opened / closed in groups, so the capacitor capacity can be flexibly determined. For example, if the total installed capacity is met, two or three groups of capacitors (usually not more than four groups) can be installed. Therefore, under the rated voltage U CN1 of the first filter capacitor, the single-phase capacity of the filter capacitor (the first capacitor group needs to refer to this capacity for configuration) is: wherein Q c1 is the rated reactive power of the capacitor, ceil is the ceiling function, f h is the harmonic frequency, and C 1min is the minimum allowed capacitance value of the capacitor. The capacitance c1 corresponding to Q , and the capacitance C1 at this time is taken as the first equivalent capacitance information. When the HFSS is used for a three-phase system, a three-phase filter capacitor is usually selected, and within the three-phase filter capacitor, the three phases are independent, and a neutral star connection is usually used to improve the operation safety of the HFSS.

[0075] After obtaining the first equivalent capacitance information, the first equivalent capacitance information can be used to switch the first capacitor group of the first filter capacitor, and the first equivalent capacitance information is combined to realize multi-band filtering with the equivalent inductance information of the electromagnetic coupling reactor SS described below.

[0076] 2) Design for electromagnetic coupling reactor SS.

[0077] a) Inductance L of primary reactive winding 11 : According to the first equivalent capacitance information C1 of the first filter capacitor, the hth tuning frequency of the first equivalent capacitance information, and the fundamental frequency f1, the (single-phase) inductance of SS satisfying the resonance condition is L 10 =1 / [(2πhf1) 2 C1], wherein L 10 is the reference inductance value. Considering the manufacturing error, the inductance L of the primary reactive winding of SS is: 11 , wherein L 11 is the adjusted inductance value, k2 is the inductance adjustment coefficient, which refers to the ratio of the actual design inductance to the theoretically calculated inductance, and the range is generally 1.05-1.5. In the engineering design process, the inductance adjustment range of SS should meet the following conditions: (1) the inductance L 1k of SS should be slightly smaller than L 11 when fully open, wherein L 1k is the minimum value of the primary inductance of SS; (2) L 10 is the inductance corresponding to the best adjustment range π / 2≤a<5π / 6, which ensures good adjustment performance; (3) when the first filter capacitor ages or heats up, causing the resonance frequency to increase, L 11 can be increased by increasing the trigger angle information α of the thyristor, so as to restore the resonance frequency to the resonance point; (4) when the controller and HFSS are in parallel resonance, the corresponding parallel resonance impedance modulus is quite large. At this time, smaller harmonic currents will cause larger harmonic voltages, thereby affecting the normal operation of the equipment. Therefore, when determining the parameters of SS, the shift of the parallel resonance point should also be considered, so that the HFSS has a very strong parallel resonance resistance.

[0078] b) Rated voltage of primary and secondary reactive windings: , wherein K is the turns ratio of SS, which is usually set to 4-6, U Ln11 is the reference voltage of the first group of inductors (or filter branches), U Ln12 is the adjusted voltage of the second group of inductors (or filter branches), and U0 is the nominal voltage of the system, and K is the voltage division coefficient.

[0079] c) Rated current: when the harmonic frequency is f h , the inductive reactance and the capacitive reactance are: , wherein X Lh is the inductive reactance under the hth harmonic, X Ch is the capacitive reactance under the hth harmonic, and h is the harmonic number (dimensionless, integer, such as 3, 5, 7…), f​h for the h-th harmonic frequency, f h = hf1, f1 is the fundamental frequency of the power grid, X L11 and X C1 are the fundamental inductive reactance of the primary reactance winding of the SS and the capacitive reactance of the first filter capacitor, respectively. When the primary reactance winding is in series resonance with the first filter capacitor, the imaginary part of the total impedance is zero, and one obtains , the quality factor q h of the HFSS, can be calculated from the resistance of the HFSS branch, where L 10 is the reference inductance value, and q h is typically 30-60 for HFSS. Since the internal resistance of the magnetically coupled reactor can usually be made to meet the requirements, no external resistor is needed. Thus, the impedance Z1 of the primary reactance winding of the SS is equal to its inductive reactance X L11 . Then, the current RMS (root mean square) of the filter branch is:

[0080] , where I f（1） is the effective value of the fundamental (frequency f1) current of the power distribution grid, K u is the voltage fluctuation factor (dimensionless) representing the approximate fluctuation range of the effective voltage during normal operation of the power distribution grid, and its value ranges from 1.05 to 1.15, U1 is the effective value of the fundamental voltage, X c1 is the capacitive reactance at the fundamental frequency, X L11 is the inductive reactance at the fundamental frequency, I IRMS is the total current effective value of the filter branch, and I f（2m+1） is the effective value of the (2m+1)-th harmonic current (such as the 3rd, 5th, 7th, etc. odd harmonic), and m is the number of odd harmonic currents, with m = 0, 1, …, m.

[0081] Typically, the rated current of the primary reactor winding of the SS needs to be higher than the overcurrent during short-circuit (such as short-circuit caused by damage to the filter capacitor). Thus, the rated current I Ln1 of the primary reactor winding is equal to k2 multiplied by I 1RMS , where k2 is the current expansion factor, and its value ranges from 1.1 to 1.3. The rated current I ILn2 of the secondary reactor winding of the SS is equal to k2 multiplied by I Ln1 .

[0082] d) The rated capacity of the magnetically coupled reactor: the three-phase capacity of the SS , where P n is the rated active power of the three-phase system, and U Ln11 is the effective value of the line voltage between the three-phase circuit.Ln11 is the effective value of the line current between the three-phase circuit.

[0083] Further, there is no background harmonic current in the power distribution network to be processed, and the harmonic current in the power distribution network is generated by the nonlinear load, and the amplitude is I h In order to filter out the h-order harmonic current in the power distribution system, the h-order HFSS is installed. Figure 5 The flow of h-order harmonic current is shown, and T1 and T2 are the installation positions of the DPSCU. After passing through the HFSS, the harmonic current injected by the harmonic source load into the power distribution network , wherein according to the impedance frequency characteristic of the HFSS, when it is tuned to the resonance frequency f h , the h-order harmonic current I f absorbed by the HFSS reaches a maximum value, and I s reaches a minimum value. Therefore, the control target is to maximize I f , and the following two constraint conditions need to be met during dynamic tuning: condition 1: the h-order harmonic current I h generated by the nonlinear load is less than or equal to the maximum h-order harmonic current I f（h） that can be filtered by the HFSS, so as to limit the size of the h-order harmonic current generated by the nonlinear load; condition 2: let I ref（h） be the h-order harmonic current allowed to enter the public power grid specified in the harmonic standard, when the h-order harmonic current I s（h） in the power grid is greater than I ref ; otherwise, the HFSS continues to output the control signal Uz(k-1) from the previous moment to avoid continuous tuning of the HFSS. Through the two dynamic constraint conditions, the h-order harmonic current is dynamically filtered, and the stability of the HFSS is improved.

[0084] Assuming that the control signal U z is x, the h-order harmonic current I f（h） to be filtered is the control target, I f（h） and x have a function relationship of I f（h） =f(x), and the tuning process of the HFSS can be regarded as solving the optimal solution x fmax corresponding to I f（h） under the maximum I opt .

[0085] For the HFSS, the first equivalent capacitance information of the first filter capacitor of the harmonic h-order is usually fixed, so its tuning is mainly realized by adjusting the equivalent inductance information L 11 of the SS primary reactance winding. L 11The value of is mainly adjusted by the trigger angle information of the thyristor, and its effective range is α = 30 degrees. Therefore, assuming that the control signal corresponding to α = 30 degrees is x0, the control signal corresponding to α = 150 degrees is x, and the change range of the control signal is [x0, x n ]. During the HFSS running process, the harmonic current generated by the harmonic source load will change with the change of the working condition, the frequency of the power grid will sometimes fluctuate, and the system impedance will occasionally change. After opening the HFSS, the h-order harmonic current flowing into the HFSS branch is l f（h） , and the curve of the harmonic current I f（h） has the characteristics of randomness, time-varying and nonlinearity. It has no single mode, but has multiple extreme points. Therefore, based on the control target of HFSS, that is, the effective value I f（h） of the h-order harmonic current absorbed, a two-step optimization algorithm is used to solve I f（h） The optimal solution x fmax is obtained when I opt is maximum.

[0086] Generally, the principle of the two-step optimization algorithm includes: initial optimization: the optimization interval is [x0, x n ], the optimization step is θ1, and the initial value of the control signal is x0. Then, by continuously increasing θ1, the point (x t , I ft ) at which I t reaches the maximum value is found, wherein x f（h） is the control signal at which I ft reaches the maximum value, and I t-q is the maximum value of the target function corresponding to xt; second self-optimization: the optimization interval is [x t+q , x t-q ], the optimization step is θ2 (θ2 < θ1), and the initial value of the control signal is x f（h） . Then, by continuously increasing θ2, the point (x opt , I fmax ) at which I f（h） reaches the maximum value is found, until I ref（h） > I Ln11 . The point is the best operating point in a certain time.

[0087] In order to calculate the various design parameters of the filter, the parameter design system of HFSS is designed by using the Matlab graphical user interface development environment. The design method is first to add the required components in the development environment according to the needs of parameter design, set the properties of each component, write the callback function program according to the parameter design method of HFSS, and finally complete the debugging and improvement of the program. According to the requirements of HFSS parameter design, the parameter design system mainly consists of five modules: parameter setting module, first filter capacitor design module, electromagnetic coupled reactor inductance design module, capacitor parameter checking module and result output module. The main functions of the five modules are as follows: 1. Parameter setting module: This module is responsible for setting various parameters of the filter, such as harmonic order, size of each harmonic current, line voltage and phase voltage of the system, etc.; 2. First filter capacitor design module: According to the harmonic order, the size of the harmonic current in the system and the minimum capacitance of the filter capacitor, this module calculates the optimal capacitance of the filter capacitor to determine its capacitance. On this basis, the module selects the type of filter capacitor, and then calculates its parameters, including capacitance (uF), nominal voltage (V) and capacitor capacity (kVar); 3. Electromagnetic coupled reactor inductance design module: According to the size of the fundamental current and the capacitance of the filter capacitor, this module calculates the parameters of the electromagnetic coupled reactor, including inductance, current, voltage and capacity; 4. Capacitor parameter checking: This module checks whether the rated voltage and rated current of the filter capacitor meet the requirements; 5. Result output module.

[0088] After determining the inductance of the primary reactive winding, the equivalent inductance information of the electromagnetic coupled reactor will also be dynamically adjusted by adjusting the trigger angle information of the thyristor of the power electronic impedance converter in the harmonic filter subsystem, to adapt to the harmonic changes, avoid the drift of the resonance point, and ensure that the SS has good linear regulation performance within the optimal regulation range. Specifically:

[0089] According to the principle of electromagnetic transformation: , Z1 is the equivalent impedance of the primary winding W1, U Ln11 is the primary winding voltage, usually the system nominal voltage, I1 is the primary winding current, K is the electromagnetic coupling ratio, representing the voltage / current transformation ratio of the secondary to the primary, U Ln12 is the secondary winding voltage, I2 is the secondary winding current, Z g is the equivalent load impedance of the power electronic impedance converter PEIC.

[0090] The voltage across PEIC is set as: , u2 is the instantaneous voltage of the secondary winding, ωt is the control angle, used to adjust the conduction phase. Assuming that Z0 is the equivalent impedance of the secondary winding W2 in the adjusted state, then the positive and negative half waves of the secondary winding W2 current waveform are symmetrical. According to the Fourier transform formula, we get: where i2 is the equivalent current of the secondary winding, obtained by Fourier decomposition, Z g is the equivalent impedance of PEIC: , a is the triggering angle information of the thyristor of the secondary winding, and z is the inductance of the power electronic impedance converter. At this time, the equivalent impedance of the primary winding W1 is: Therefore, the equivalent inductance information of W1 (the primary inductance of SS) is: Based on the above analysis, it can be concluded that: 1. When a = 0°, the thyristor is fully on, and the primary inductance of SS is the smallest, represented by L 1k . 2. When a = 180°, the thyristor is fully off, and the primary inductance of SS is the largest, represented by L 1m . 3. The inductance of SS is in the range of [L 1k , L 1m ]. By adjusting the triggering angle information a of the thyristor, the primary inductance of SS can be continuously adjusted in this range, and its value will increase with the increase of the triggering angle information a. 4. When π / 2≤a<5π / 6, the linearity of the primary inductance is relatively good, so it is the best adjustment range. 5. The change of the stainless steel magnetic circuit is complex and difficult to control quantitatively. In summary, the controller can set the initial triggering angle information to 0 ◦ according to the relationship between the inductance (impedance) and the triggering angle information a, and adjust the triggering angle information according to the required control signal U z to change the equivalent inductance information L 11 of SS, so that HFSS resonates in series with the help of the first equivalent capacitance information C1, thereby realizing dynamic tuning and optimizing the filtering effect.

[0091] In one embodiment, the target of the entire harmonic filter subsystem is to accurately match the series resonance frequency f h of HFSS to the harmonic frequency to be filtered out by dynamically adjusting the equivalent inductance information L 11 of the electromagnetic coupling reactor (SS) and the first equivalent capacitance information C1 of the first filter capacitor. The resonance condition is First, according to the target harmonic frequency f of the target harmonic to be filtered, which is calculated according to the harmonic number h to be filtered out, f1 is the fundamental frequency, and w1 is the fundamental angular frequency, the first capacitor group C1 of the first filter capacitor is designed using the minimum capacitance method, the theoretical inductance L 10 of the electromagnetic coupling reactor is calculated, and the actual inductance L 11 considering the error is calculated, and the actual inductance L 11 is dynamically adjusted by adjusting the triggering angle information a of the thyristor in PEIC. Finally, according to the current maximization principle, the harmonic current I f（h） flowing into HFSS is detected by the controller, and a two-step optimization algorithm is used to dynamically adjust a and C1 to make If（h） reaches the maximum value (i.e. reaches the resonance point). After that, the first capacitor group C1 of the first filter capacitor can also be switched according to the actual demand 11 -C 1m , different C1 values are combined, and L 11 is matched to realize multi-band filtering.

[0092] During the process of switching the first capacitor group of the first filter capacitor by the controller, the contactor KM 11 can be controlled 1M to realize intelligent switching of the filter capacitor group C 11 -C 1m , and form a resonant circuit matched with the inductor L 11 . Specifically, the first capacitor group is composed of multiple independent capacitors (C 11 , C 12 ,..., C 1m ), each group of capacitors is connected to the system through a contactor (KM 11 -KM 1M ), and each group of capacitors has a capacity designed in a binary or equal ratio sequence (such as 5kVar, 10kVar, 20kVar) to realize flexible combination. The digital power signal detection unit DPSCU monitors the harmonic current I h and the reactive power Q in real time, calculates the reactive power Q comp that needs to be compensated by the HFSS according to Q, and then calculates the first capacitor group C1 of the first filter capacitor according to the target harmonic frequency f h and Q comp . Then the closest capacitor combination to C1 is selected to generate a contactor control signal. The controller controls the closing / opening of KM 11 -KM 1M through the contactor control signal to dynamically adjust the capacitor group connected to the system and form the target C1. The application also optimizes the intelligent switching of the first capacitor group: (1) the minimum switching times principle: preferentially switch large-capacity capacitor groups to reduce the number of contactor actions; (2) dynamic tolerance adjustment: if the current I h is close to the limit I ref（h） , a small deviation between the capacitor combination and the theoretical C1 is allowed to avoid frequent switching. (3) Safety protection: pre-charge through a current-limiting resistor before switching to prevent inrush current from damaging the capacitor. (4) Fault isolation: when a capacitor short circuit / overload is detected, the corresponding KM group is immediately disconnected, and a fuse is triggered.

[0093] In one embodiment, the application provides a joint regulation process, i.e. after detecting that the harmonic exceeds I h >I ref（h） , a two-step optimization algorithm is started, step 1: fix the current C1, adjust the inductor L 11Step 2: If the resonance point is still not matched, adjust the switching combination of C1, and re-tune. After switching the capacitor, re-detect I h and Q, and iteratively optimize.

[0094] In the above embodiment, by adjusting the trigger angle information of the thyristor of the power electronic impedance converter in the harmonic filtering subsystem, the equivalent inductance information of the electromagnetic coupling reactor in the harmonic filtering subsystem can be accurately adjusted, and then the first equivalent capacitance information of the first filter capacitor can be accurately obtained by using the minimum capacitance method. At this time, the resonance frequency of the harmonic filtering subsystem can be matched with the target harmonic frequency by at least one of the following ways: adjusting the equivalent inductance information, and switching the first capacitor group of the first filter capacitor by using the first equivalent capacitance information.

[0095] In an exemplary embodiment, according to the to-be-optimized parameter, the suppression of each harmonic in the power distribution network and the compensation of the reactive power in the power distribution network include:

[0096] When the to-be-optimized parameter includes the reactive power, the target power factor of the power distribution network is obtained; according to the power factor and the target power factor, the required reactive power compensation capacity of the reactive compensation subsystem in the power distribution network and the total reactive power capacity provided by the reactive compensation subsystem are detected; according to the reactive power compensation capacity and the total reactive power capacity, the second equivalent capacitance information of the second filter capacitor in the reactive compensation subsystem is detected; and the reactive power in the power distribution network is compensated by using the way of switching the second capacitor group of the second filter capacitor in the reactive compensation subsystem by using the second equivalent capacitance information.

[0097] Specifically, after the reactive compensation subsystem RPCSS is put into operation, the phase angle between the voltage and the current is reduced from φ1 to φ2, and the power loss is reduced. At this time, the target power factor of the power distribution network is obtained, and according to the active power P av , the power factor cosφ1 and the target power factor cosφ2 of the system before compensation, the required reactive power compensation capacity is calculated, and the total reactive power capacity provided by the reactive compensation subsystem is calculated again: in actual engineering application, the capacity of the second capacitor in the reactive compensation subsystem needs to be a multiple of 5, so the total reactive power capacity is calculated, and finally, according to the reactive power compensation capacity and the total reactive power capacity, the second equivalent capacitance information of the second filter capacitor in the reactive compensation subsystem is detected , wherein U CN2 is the rated voltage of the second filter capacitor.

[0098] In one embodiment, the above-mentioned reactive power compensation capacity calculation formula can be a reactive power demand calculation under pure fundamental wave, which is suitable for a simple scenario of "only fundamental wave reactive power deficiency". The application also provides a reactive power compensation capacity calculation method, which is suitable for a complex power grid of "harmonic and reactive power coexistence", i.e., calculating the reactive power compensation capacity based on the instantaneous value of the grid operation parameter information , wherein Q comp is the reactive power compensation capacity provided by the RPCSS, Q load is the total reactive power capacity consumed by the nonlinear load, C1 is the first equivalent capacitance information of the first filter capacitor group, h is the harmonic order, and U (1) is the effective value of the fundamental wave voltage.

[0099] In one embodiment, the second equivalent capacitance information of the second filter capacitor of the RPCSS is adjusted by controlling the on / off of the contactor. If the number of compensator groups of the second filter capacitor is n, the level number n should satisfy the following equation: It can be seen that the n groups of capacitors have a total of 2n-1 levels, which makes up for the disadvantage of single-capacitor passive power filter in the traditional method and expands the compensation range.

[0100] For the switching control of the n groups of compensators, when a single power factor index is selected as the switching standard, the service life of the compensator is easily shortened due to frequent switching of the compensator, switching oscillation is caused, and the operation of other equipment is affected. Therefore, a proper control strategy should be adopted to enable the compensator to be smoothly turned on and off, and the reactive power of the system should be kept within the national standard range. Therefore, the target power factor ph obtained is a range value, at this time, , wherein ph max is the maximum target power factor, ph min is the minimum target power factor which can be selected according to actual requirements, and Δph is a control variable for evaluating the effect of reactive power compensation, which improves the frequent switching caused by a single value as the control standard. The real-time power factor deviation of the distribution network is: , wherein ph0 is the measured real-time power factor. The switching strategy of the compensator is: when 0<Δph0≤Δph 阈值 , the reactive power of the system meets the standard, and the reactive power compensation is maintained; when Δph0>Δph 阈值 , the system is in an under-compensation state; the controller opens the compensators in groups according to the principle that the actual capacity of the compensator should be equal to or slightly higher than the total reactive power capacity provided by the reactive power compensation subsystem.

[0101] Further, the control system will automatically detect the running state of the capacitors in each switching stage to determine whether the voltage U Cpk of the capacitors meets the following safety conditions: Wherein, U1 is the fundamental voltage effective value of the power distribution network, if the detection voltage is out of limit or the capacitor is overloaded, the controller will immediately cut off the fault group, and alarm or link the protection module to prevent overvoltage breakdown and other electrical accidents.

[0102] In one embodiment, the system continuously collects the power factor index during operation, and fine-tunes the second capacitor within the allowed minimum step to achieve real-time optimal maintenance of the power factor. This part can be combined with fuzzy control, proportional-integral-derivative adjustment and other strategies as preferred extension methods.

[0103] In the above embodiment, by the above steps, the harmonic and reactive power changes are dynamically tracked, the harmonics are filtered out, the power factor is improved, and a more symmetrical waveform is generated to avoid frequent power grid problems.

[0104] In one exemplary embodiment, according to the to-be-optimized parameters, the suppression of each harmonic in the power distribution network and the compensation of the reactive power in the power distribution network are performed, including:

[0105] When the to-be-optimized parameters include each harmonic and reactive power, the suppression of each harmonic in the power distribution network is performed first, and then the compensation of the reactive power in the power distribution network is performed.

[0106] Specifically, the present application specifies the principle of HFSS priority operation and RPCSS later input in the control logic, reduces the risk of burning of traditional reactive power compensation equipment caused by direct operation in high harmonic environment, and when the filtering effect of HFSS reaches the national standard (such as THD≤5%), the controller sets the reactive power compensation flag F rq to 1, triggers the input of the reactive power compensation subsystem (RPCSS), intelligently switches the compensation capacitor group according to the real-time calculated reactive power deficiency, dynamically adjusts the compensation capacity, and improves the power factor to above 0.9.

[0107] After collecting and storing the power grid operation data, the controller sets the updated flag F u to "1", the harmonic suppression flag F rh to "2", triggers the input of the reactive power compensation subsystem (RPCSS), and then sets the updated flag F u to "0".

[0108] In one embodiment, the present application sets a shutdown instruction receiving mechanism, that is, when a remote shutdown signal is received through manual operation (such as pressing the stop button) or an external communication interface, the controller sets the stop flag F p= 1, and the start flag bit Fs = 0 is set to trigger the interrupt service program. Before entering the shutdown process, the current running state of the HFSS and the RPCSS is detected, including the opening and closing state of the contactors (KM1, KM2) corresponding to the capacitor bank, the capacitor switching state, the THD, and other running indicators, to ensure that the shutdown operation can be safely implemented.

[0109] In practical applications, the triggering conditions of the shutdown operation can be divided into: 1. Normal shutdown conditions: 1) Harmonic current I h ≤ I ref（h） (consistent with the limit value of IEEE Std519-2014); 2) Power factor pf ≥ 0.9 (satisfies the national standard); 3) Voltage / current waveform symmetry (no significant distortion). 2. Emergency shutdown conditions: 1) Equipment failure: capacitor bank overcurrent (I Cx > 1.35 IIRMS); 2) Reactor overheating or insulation failure; contactor (KM 11 – KM 1m / KM 21 – KM 2n ) fuse action. The abnormal conditions of the system are: 1) Parallel resonance (harmonic voltage amplification) is detected; 2) Grid frequency fluctuation is out of limit (Δf > ± 0.5 Hz).

[0110] In one embodiment, to avoid system impact caused by instantaneous simultaneous power failure, a "delayed step-by-step removal" logic is used: 1) Remove the reactive power compensation subsystem (RPCSS): the controller first disconnects the contactor KM2 to remove each capacitor branch in the RPCSS, preventing overvoltage damage to capacitive elements due to harmonic backflow. 2) Delayed removal of the harmonic suppression subsystem (HFSS): after a delay of 100 milliseconds, the contactor KM1 is disconnected to safely exit the HFSS filter circuit. 3) Total power off: the controller or manually disconnects the main circuit breaker QF to completely disconnect the system from the power distribution network. This shutdown sequence strictly depends on the system topology, ensuring a step-by-step exit process from the source to the end, avoiding equipment damage caused by harmonic impact.

[0111] In the above embodiment, the harmonics in the power distribution network are suppressed first, and then the reactive power in the power distribution network is compensated, reducing the risk of burnout of traditional reactive power compensation equipment due to high harmonic environment. By integrating the harmonic suppression subsystem (HFSS) and the reactive power compensation subsystem (RPCSS) into one system, the dual functions of harmonic filtering and reactive power compensation are realized, a unified controller is used to coordinate the work of the two subsystems, ensuring the synchronous optimization of harmonic suppression and reactive power compensation, and significantly improving the power quality and system symmetry.

[0112] It should be understood that although the steps in the flowcharts involved in the above embodiments are shown in sequence according to the arrows, the steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified herein, the execution of the steps is not strictly limited in sequence, and the steps can be executed in other orders. Moreover, at least some of the steps in the flowcharts involved in the above embodiments can include multiple steps or multiple stages, which are not necessarily executed at the same time, but can be executed at different times, and the execution order of the steps or stages is not necessarily sequential, but can be alternately executed with other steps or steps or stages in at least part of other steps.

[0113] Based on the same inventive concept, the embodiments of the present application also provide a power distribution network harmonic suppression and reactive power compensation coordination device for implementing the above-mentioned power distribution network harmonic suppression and reactive power compensation coordination method. The implementation scheme for solving the problem provided by the device is similar to the implementation scheme described in the above method, so the specific limitations in one or more power distribution network harmonic suppression and reactive power compensation coordination device embodiments provided below can refer to the limitations of the power distribution network harmonic suppression and reactive power compensation coordination method described above, and will not be repeated here.

[0114] In an exemplary embodiment, as shown in Figure 6 a power distribution network harmonic suppression and reactive power compensation coordination device is provided, comprising: an acquisition module 200, a detection module 400, an optimization determination module 600 and an optimization execution module 800, wherein:

[0115] The acquisition module 200 is configured to acquire power grid operation parameter information of the power distribution network.

[0116] The detection module 400 is configured to detect total current harmonic distortion rate, power factor and each harmonic current information of the power distribution network according to the power grid operation parameter information.

[0117] The optimization determination module 600 is configured to detect to-be-optimized parameters of the power distribution network according to the total current harmonic distortion rate, the power factor and the each harmonic current information, wherein the to-be-optimized parameters include at least one of each harmonic and reactive power.

[0118] The optimization execution module 800 is configured to suppress each harmonic in the power distribution network and compensate for reactive power in the power distribution network according to the to-be-optimized parameters.

[0119] In one embodiment, the detection module 400 is further configured to obtain fundamental current information, harmonic current information, total active power and reactive power of the power distribution network from the power grid operation parameter information; detect total current harmonic distortion of the power distribution network according to the fundamental current information and the harmonic current information; and detect power factor of the power distribution network according to the total active power and the reactive power.

[0120] In one embodiment, the optimization determination module 600 is further configured to obtain fuzzy logic control rules or threshold control rules; obtain control weights corresponding to the total current harmonic distortion, the power factor, and the harmonic current information according to the fuzzy logic control rules or the threshold control rules; and detect the to-be-optimized parameter of the power distribution network according to the control weights.

[0121] In one embodiment, the optimization execution module 800 is further configured to, when the to-be-optimized parameter includes a target harmonic in the harmonics, determine a target harmonic frequency of the target harmonic that needs to be filtered; adjust equivalent inductance information of an electromagnetic coupling reactor in a harmonic filtering subsystem of the power distribution network, and switch at least one mode of a first capacitor group of a first filter capacitor in the harmonic filtering subsystem, so that a resonance frequency of the harmonic filtering subsystem matches the target harmonic frequency; and suppress the target harmonic by using the harmonic filtering subsystem when the resonance frequency matches the target harmonic frequency.

[0122] In one embodiment, the optimization execution module 800 is further configured to adjust equivalent inductance information of an electromagnetic coupling reactor in a harmonic filtering subsystem of the power distribution network by adjusting a trigger angle information of a thyristor of a power electronic impedance converter in the harmonic filtering subsystem; detect minimum capacitance information of the harmonic filtering subsystem, and detect first equivalent capacitance information of a first filter capacitor in the harmonic filtering subsystem according to the minimum capacitance information; and adjust the equivalent inductance information, and switch at least one mode of a first capacitor group of the first filter capacitor by using the first equivalent capacitance information, so that a resonance frequency of the harmonic filtering subsystem matches a target harmonic frequency.

[0123] In one embodiment, the optimization execution module 800 is further configured to, when the to-be-optimized parameter includes the reactive power, obtain a target power factor of the power distribution network; detect a reactive power compensation capacity required by a reactive power compensation subsystem in the power distribution network and a total reactive power capacity provided by the reactive power compensation subsystem according to the power factor and the target power factor; detect second equivalent capacitance information of a second filter capacitor in the reactive power compensation subsystem according to the reactive power compensation capacity and the total reactive power capacity; and compensate for the reactive power in the power distribution network by switching a second capacitor group of the second filter capacitor in the reactive power compensation subsystem by using the second equivalent capacitance information.

[0124] In one embodiment, the optimization execution module 800 is further configured to, when the parameters to be optimized include each harmonic and reactive power, first suppress each harmonic in the power distribution network, and then compensate the reactive power in the power distribution network.

[0125] Each module in the above-mentioned harmonic suppression and reactive power compensation coordination device for power distribution network can be implemented by software, hardware, or a combination thereof, in whole or in part. Each module can be embedded in or independent of a processor in a computer device in hardware form, or stored in a memory in a computer device in software form, so as to be called and executed by the processor to perform the operations corresponding to each module.

[0126] In one exemplary embodiment, a computer device, which can be a server, is provided, and an internal structure diagram of the computer device can be as shown in Figure 7 The computer device includes a processor, a memory, an input / output interface (I / O), and a communication interface. The processor, the memory, and the input / output interface are connected through a system bus, and the communication interface is connected to the system bus through the input / output interface. The processor of the computer device is configured to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program, and a database. The internal memory provides an environment for running the operating system and the computer program in the non-volatile storage medium. The database of the computer device is configured to store power grid operation parameter information and other data. The input / output interface of the computer device is configured to exchange information between the processor and external devices. The communication interface of the computer device is configured to communicate with external terminals through a network connection. The computer program is executed by the processor to implement a harmonic suppression and reactive power compensation coordination method for a power distribution network.

[0127] Those skilled in the art can understand that Figure 7 The structure shown in the above-mentioned figure is a block diagram of part of the structure related to the scheme of the present application, and does not constitute a limitation on the computer device to which the scheme of the present application is applied. Specifically, the computer device can include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0128] In one embodiment, a computer device is also provided, which includes a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the steps in each method embodiment described above. In one embodiment, a computer readable storage medium is provided, which stores a computer program. The computer program is executed by the processor to implement the steps in each method embodiment described above.

[0129] In an embodiment, a computer program product is provided, including a computer program which, when executed by a processor, implements the steps of any of the above method embodiments. It is understood by those skilled in the art that all or part of the processes in the above embodiments can be completed by a computer program instructing relevant hardware. The computer program can be stored in a non-volatile computer readable storage medium and, when executed, can include the processes of the above embodiments. Any reference to a memory, database, or other medium used in the embodiments provided by the present application can include at least one of a non-volatile memory and a volatile memory. The non-volatile memory can include a read-only memory (ROM), a tape, a floppy disk, a flash memory, an optical memory, a high-density embedded non-volatile memory, a resistive random access memory (ReRAM), a magnetoresistive random access memory (MRAM), a ferroelectric random access memory (FRAM), a phase change memory (PCM), a graphene memory, and the like. The volatile memory can include a random access memory (RAM) or an external cache memory, and the like. As an illustration but not limitation, the RAM can be in various forms, such as a static random access memory (SRAM) or a dynamic random access memory (DRAM), and the like. The database involved in the embodiments provided by the present application can include at least one of a relational database and a non-relational database. The non-relational database can include a distributed database based on a block chain, and the like, but is not limited thereto. The processor involved in the embodiments provided by the present application can be a general processor, a central processing unit, a graphics processing unit, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, an artificial intelligence (AI) processor, and the like, but is not limited thereto.

[0130] Any technical features in the above embodiments can be combined, and for the sake of brevity, not all possible combinations are described, however, any combination of the technical features is deemed to be within the scope of the present application. The above embodiments merely express several implementation manners of the present application, and the description is relatively specific and detailed, but it should not be construed as a limitation on the patent scope of the present application. It should be noted that, for those skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A coordinated method for harmonic suppression and reactive power compensation in a power distribution network, characterized in that, The method includes: Obtain power grid operation parameter information of the distribution network; Based on the power grid operating parameter information, the total current harmonic distortion rate, power factor, and harmonic current information of the distribution network are detected. Based on the total current harmonic distortion rate, the power factor, and the information of each harmonic current, the parameters to be optimized of the distribution network are detected, wherein the parameters to be optimized include at least one of each harmonic and reactive power. Based on the parameters to be optimized, the harmonics in the distribution network are suppressed and the reactive power in the distribution network is compensated.

2. The method according to claim 1, characterized in that, The step of detecting the total current harmonic distortion rate, power factor, and harmonic current information of the distribution network based on the power grid operating parameter information includes: From the power grid operating parameter information, obtain the fundamental current information, harmonic current information, total active power and reactive power of the distribution network; Based on the fundamental current information and the harmonic current information, the total current harmonic distortion rate of the distribution network is detected. The power factor of the distribution network is detected based on the total active power and the reactive power.

3. The method according to claim 1, characterized in that, The step of detecting the parameters to be optimized in the distribution network based on the total current harmonic distortion rate, the power factor, and the information of each harmonic current includes: Obtain fuzzy logic control rules or threshold control rules; Using fuzzy logic control rules or threshold control rules, the total current harmonic distortion rate, the power factor, and the control weights corresponding to each harmonic current information are obtained. Based on the total current harmonic distortion rate, the power factor, and the control weights corresponding to each harmonic current information, the parameters to be optimized in the distribution network are detected.

4. The method according to claim 1, characterized in that, The step of suppressing harmonics and compensating reactive power in the distribution network based on the parameters to be optimized includes: When the parameter to be optimized includes the target subharmonic in each harmonic, the target subharmonic frequency of the target subharmonic to be filtered is determined. By adjusting the equivalent inductance information of the electromagnetic coupling reactor in the harmonic filtering subsystem of the power distribution network, and by switching at least one of the first capacitor banks of the first filter capacitor in the harmonic filtering subsystem, the resonant frequency of the harmonic filtering subsystem is matched with the target subharmonic frequency. When the resonant frequency matches the target subharmonic frequency, the target subharmonic is suppressed using the harmonic filtering subsystem.

5. The method according to claim 4, characterized in that, The method of matching the resonant frequency of the harmonic filtering subsystem with the target subharmonic frequency by adjusting the equivalent inductance information of the electromagnetic coupling reactor in the harmonic filtering subsystem of the power distribution network and switching at least one of the first capacitor banks of the first filter capacitor in the harmonic filtering subsystem includes: By adjusting the trigger angle information of the thyristor of the power electronic impedance converter in the harmonic filtering subsystem of the power distribution network, the equivalent inductance information of the electromagnetic coupling reactor in the harmonic filtering subsystem is adjusted. The minimum capacitance information of the first filter capacitor in the harmonic filtering subsystem is detected, and the first equivalent capacitance information of the first filter capacitor is detected based on the minimum capacitance information. By adjusting the equivalent inductance information and using at least one method, such as switching the first capacitor bank of the first filter capacitor using the first equivalent capacitance information, the resonant frequency of the harmonic filtering subsystem is matched with the target subharmonic frequency.

6. The method according to claim 1, characterized in that, The step of suppressing harmonics and compensating reactive power in the distribution network based on the parameters to be optimized includes: When the parameter to be optimized includes reactive power, the target power factor of the distribution network is obtained; Based on the power factor and the target power factor, detect the reactive power compensation capacity required by the reactive power compensation subsystem in the distribution network and the total reactive power capacity provided by the reactive power compensation subsystem; Based on the reactive power compensation capacity and the total reactive power capacity, detect the second equivalent capacitance information of the second filter capacitor in the reactive power compensation subsystem; The reactive power in the power distribution network is compensated by switching the second capacitor bank of the second filter capacitor in the reactive power compensation subsystem using the second equivalent capacitance information.

7. The method according to claim 1, characterized in that, The step of suppressing harmonics and compensating reactive power in the distribution network based on the parameters to be optimized includes: When the parameters to be optimized include harmonics and reactive power, the harmonics in the distribution network are first suppressed, and then the reactive power in the distribution network is compensated.

8. A coordinated device for harmonic suppression and reactive power compensation in a power distribution network, characterized in that, The device includes: The acquisition module is used to acquire power grid operation parameter information of the distribution network; The detection module is used to detect the total current harmonic distortion rate, power factor, and harmonic current information of the distribution network based on the power grid operating parameter information. The optimization determination module is used to detect the parameters to be optimized in the distribution network based on the total current harmonic distortion rate, the power factor, and the information of each harmonic current, wherein the parameters to be optimized include at least one of each harmonic and reactive power. The optimization execution module is used to suppress harmonics in the distribution network and compensate reactive power in the distribution network according to the parameters to be optimized.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 7.

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