Reactive compensation optimization method and system for mining frequency conversion system

Abstract

The invention provides a reactive compensation optimization method and system for a mining frequency conversion system, and the method comprises the steps: collecting the multi-dimensional data of the mining frequency conversion system, and carrying out the feature extraction and preprocessing, and obtaining the preprocessing data; the phase fast tracking module accurately obtains phasor parameters according to the preprocessed data, and the phasor parameters serve as input signals and are used for a phase locking ring to achieve phase and frequency locking of the mining frequency conversion system; constructing a multi-parameter fitness function by adopting a particle swarm algorithm, and dynamically calculating and searching an optimal control parameter combination; instantaneous reactive power and harmonic current are detected and analyzed in real time by adopting an instantaneous reactive power detection technology; the instantaneous reactive power and the harmonic current are input into a fuzzy PI controller, and dynamic error compensation is carried out in combination with the optimal control parameter combination; the static synchronous compensator controls output compensation current to complete reactive compensation and harmonic current treatment; compensation verification and feedback are carried out, and the electric energy consumption condition of the mining device is monitored and predicted in real time.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of reactive power compensation, in particular to a mine-used variable frequency system reactive power compensation optimization method and system. BACKGROUND

[0002] With the rapid development of modern industry, mine-used variable frequency systems are widely used in mine hoists, conveyor belt drives, ventilation equipment and other scenarios. However, due to the non-linear load characteristics (such as frequency converters, high-power motors, medium-frequency induction heating furnaces, etc.) in the operation process of mine-used variable frequency systems, a large amount of reactive power and harmonics will be generated, resulting in power grid voltage fluctuation, power factor reduction and increased equipment loss.

[0003] Traditional reactive power compensation methods, such as using shunt capacitor banks for reactive power compensation, can improve power quality to some extent, but have problems such as slow response speed, low compensation accuracy, etc., and when facing frequently changing loads, traditional methods are difficult to achieve real-time and accurate compensation. As a new type of reactive power compensation device, static synchronous compensator (STATCOM) has the advantages of fast response speed, wide compensation range, flexible adjustment, etc., and has gradually become a research hotspot for solving mine-used variable frequency system power quality problems.

[0004] However, the existing STATCOM control strategy has problems such as parameter adjustment lag and insufficient harmonic suppression in complex mine environments. SUMMARY

[0005] The purpose of the present application is to provide a mine-used variable frequency system reactive power compensation optimization method and system that can monitor and predict the power consumption mode of mine-used devices in real time, optimize power use through intelligent adjustment strategies, reduce energy consumption, and improve energy utilization efficiency.

[0006] To achieve the above purpose, the present application provides a mine-used variable frequency system reactive power compensation optimization method, comprising the following steps: S100, collect multi-dimensional data of the mine-used variable frequency system, perform feature extraction and preprocessing, and obtain preprocessed data; S200, a phase fast tracking module accurately acquires phasor parameters according to the preprocessed data, and the phasor parameters are used as input signals for phase-locked loop to lock the phase and frequency of the mine-used variable frequency system; S300, a particle swarm algorithm is used to construct a multi-parameter fitness function to dynamically calculate and find the optimal control parameter combination; S400, instantaneous reactive power detection technology is used to detect and analyze instantaneous reactive power and harmonic current in real time; S500, the instantaneous reactive power and harmonic current are input into a fuzzy PI controller, and the optimal control parameter combination is combined to perform dynamic error compensation; S600, the static synchronous compensator controls output compensation current to complete reactive power compensation and harmonic current treatment. S700, compensation verification and feedback are performed.

[0007] After the technical scheme is adopted, the following technical effects are achieved: through collection of multi-dimensional data of the mine-used frequency conversion system and feature extraction and preprocessing, accurate acquisition of phasor parameters and locking of the phase and frequency of the mine-used frequency conversion system are performed by using a phase fast tracking module, optimal control parameter combinations are dynamically calculated by using a particle swarm algorithm, and instantaneous reactive power detection technology is used to detect and analyze instantaneous reactive power and harmonic current, and a fuzzy PI controller is combined to adjust the compensation strategy in real time, so that the power consumption mode of the mine-used device can be monitored and predicted in real time, the power use is optimized by the intelligent adjustment strategy, the energy consumption is reduced, and the energy utilization efficiency is improved.

[0008] Further, S100 includes the following steps: S110, real-time collection of mine-used frequency conversion system power quality parameters, static synchronous compensator operation parameters and environmental parameters is performed; S120, each harmonic component is extracted by using fast Fourier transform, dynamic calculation of reactive power demand is performed based on a sliding window algorithm, and compensation amount is updated at a period of 10ms; the data collected in S110 is normalized, voltage sag, temporary rise transient interference data is identified and eliminated by abnormal data detection, and a standardized data matrix is constructed; The power quality parameters include bus voltage and current waveforms, power factor, harmonic distortion rate and voltage flicker value; the static synchronous compensator operation parameters include DC side capacitor voltage, insulated gate bipolar transistor module temperature and reactor current effective value; and the environmental parameters include mine humidity, temperature and dust concentration.

[0009] After the technical scheme is adopted, the following technical effects are achieved: multi-dimensional data collection is performed, which not only enhances the real-time monitoring capability of the system, but also provides key data basis for optimizing the compensation strategy, improving the reliability of the mine-used equipment and adapting to complex working conditions. The standardized data matrix constructed based on normalization processing and abnormal data detection effectively filters out transient interference such as voltage sag and temporary rise.

[0010] Further, S300 includes the following steps: S310, a particle swarm is initialized; S320, a fitness function is constructed; S330, the fitness value of each particle is calculated; S340, the individual optimal position and the global optimal position of the particle are updated; S350, judging whether a termination condition is met or not; If yes, S360 is executed, and if no, S370 is executed, and then S330 is repeatedly executed; S360, outputting the optimal control parameter; S370, updating the speed and position of the particle according to a speed and position updating formula.

[0011] The technical effects achieved after adopting the technical scheme are as follows: as a global optimization algorithm, the particle swarm optimization (PSO) has the characteristics of fast convergence speed and strong robustness, and when combined with the static synchronous compensator, the real-time and accurate reactive power compensation and harmonic control of the mine variable frequency system can be realized, the stability and energy efficiency of the mine power supply system are improved, and the particle swarm optimization has important research significance and practical application value.

[0012] Further, S400 comprises the following steps: S410, determining the working frequency of the mine variable frequency system, and determining the harmonic frequency range to be detected, and a phase fast tracking module collects current signals and voltage signals in the mine variable frequency system; S420, amplifying, filtering and digitizing the current signals and the voltage signals; S430, using the phase information output by the phase-locked loop to convert the current signals and the voltage signals from the abc coordinate system to the dq coordinate system, detecting the positive sequence current and the negative sequence current in the dq coordinate system, extracting the harmonic current, and calculating the instantaneous reactive power.

[0013] The technical effects achieved after adopting the technical scheme are as follows: the phase fast tracking module can accurately obtain the amplitude and phase angle of the phasor, and the accurate phasor parameters are crucial for analyzing the operation state of the power system, and the accurate phase angle measurement can help to judge the relationship between the voltage and the current, thereby accurately evaluating the power factor and other parameters of the circuit.

[0014] Further, S500 comprises the following steps: S510, determining the fuzzy variables of input and output; S520, setting the initial values of the proportional gain and the integral gain and the proportional factor; S530, selecting the reactive power to be compensated as the feedback quantity, and comparing the expected reactive power calculated by the instantaneous reactive power theory with the actual compensation reactive power calculated by the mine variable frequency system according to the compensation current to reflect the compensation state of the reactive power of the mine variable frequency system.

[0015] The technical effects achieved after the technical scheme are as follows: the mine frequency conversion system dynamically adjusts proportional gain and integral gain through fuzzy control, significantly improves the reactive power compensation accuracy and response speed of the mine frequency conversion system, calculates expected reactive power in real time through instantaneous reactive power theory, and compares the expected reactive power with actual compensation reactive power in a closed loop, effectively overcomes the compensation lag or over-regulation problem of the traditional fixed parameter fuzzy PI controller caused by working condition fluctuation, and intelligent optimization of fuzzy variables enables the system to adapt to load changes.

[0016] Further, 600 includes the following steps: S610, determine the flow direction and size of the power on both sides of the to-be-parallel point, and reduce and eliminate the voltage difference and phase angle difference on both sides of the to-be-parallel point; S620, when the loop network is parallel, transfer active power from the phase angle leading side to the phase angle lagging side through the static synchronous compensator, reduce the phase angle difference of the two nodes to be parallel, and realize adjustment of the reactive power through the static synchronous compensator to reduce the voltage difference of the two nodes to be parallel; S630, by controlling the operating state of the converter at both ends of the static synchronous compensator, realize the exchange of active power and reactive power between the static synchronous compensator and the alternating current system, and realize bidirectional power transmission.

[0017] The technical effects achieved after the technical scheme are as follows: the static synchronous compensator is used to realize fast and accurate parallel of the loop network, active and reactive power are actively adjusted to dynamically reduce the voltage difference and phase angle difference of the to-be-parallel point, and the system has millisecond-level response, bidirectional power control and high-precision adjustment capability, which can significantly reduce the parallel impact and improve the system stability, and is suitable for complex power grid scenarios and has high efficiency and economy.

[0018] The present application also provides a mine frequency conversion system reactive power compensation optimization system, which is applicable to the mine frequency conversion system reactive power compensation optimization method described above. The mine frequency conversion system reactive power compensation optimization system comprises: The intermediate frequency induction heating furnace is the main load device of the mine frequency conversion system; The static synchronous compensator is used to dynamically compensate the reactive power and harmonics in the mine frequency conversion system; The phase fast tracking module is used to accurately calculate the phasor parameters of the voltage and current of the mine frequency conversion system; The phase-locked loop is used to quickly lock and track the phase change of the mine frequency conversion system; The fuzzy PI controller adjusts the control parameters of the static synchronous compensator based on the instantaneous reactive power and harmonic current.

[0019] The technical effects achieved after the technical scheme are as follows: through the cooperative action of the phase fast tracking module and the phase locked loop, the system can accurately lock the phase change of the mine frequency conversion system, realize millisecond-level dynamic response, and ensure the real-time performance and accuracy of the reactive power compensation; the fuzzy PI controller dynamically adjusts the control parameters of the static synchronous compensator (STATCOM) based on the instantaneous reactive power and the harmonic current, thereby reducing the harmonic pollution of the mine frequency conversion system caused by the nonlinear load such as the medium-frequency induction heating furnace.

[0020] Further, the main circuit of the static synchronous compensator is a composite structure in which two voltage source converters (VSCs) are connected in parallel through a transformer.

[0021] The technical effects achieved after the technical scheme are as follows: the STATCOM structure with the VSCs connected in parallel is simpler, reduces the equipment redundancy rate and cost, and improves the system reliability and dynamic response capability.

[0022] Further, the phase fast tracking module comprises a plurality of multipliers, two quadrature phase shifters, a plurality of adders, and a subtractor.

[0023] The technical effects achieved after the technical scheme are as follows: compared with the traditional software phase locked loop, the phase fast tracking module improves the phase detection reliability of the mine frequency conversion system under complex working conditions such as voltage distortion and frequency mutation through the cooperative action of the plurality of multipliers, the two quadrature phase shifters, the adders, and the subtractor, and provides a high-precision reference phase signal for subsequent reactive power calculation and harmonic compensation.

[0024] Further, the phase fast tracking module adopts a quadrature phase fast delay circuit.

[0025] The technical effects achieved after the technical scheme are as follows: the fast delay circuit is adopted in the phase fast tracking module, and the harmonics of the grid-side current are further reduced.

[0026] Overall, compared with the prior art, the beneficial effects of the present application are as follows: (1) the main circuit of the STATCOM is a composite structure in which two voltage source converters (VSCs) are connected in parallel through a transformer, compared with the traditional series multi-connection scheme, the STATCOM structure with the VSCs connected in parallel is simpler, reduces the equipment redundancy rate and cost, and improves the system reliability and dynamic response capability; (2) the advantages of the STATCOM technology and the particle swarm algorithm are combined, the power quality indexes (such as the harmonic distortion rate, voltage flicker, and STATCOM DC side voltage fluctuation) of the mine frequency conversion system are taken as the optimization targets, a multi-parameter fitness function is constructed, the particle swarm algorithm (PSO) algorithm is used to dynamically adjust the STATCOM control parameters (such as the modulation ratio and the phase angle), and optimal reactive power compensation and harmonic suppression are realized; (3) STATCOM combines the phase fast tracking module with the phase locked loop (PLL), making full use of the module's precise phase calculation and signal processing capabilities to improve the performance of the PLL in the power system. The phase fast tracking module adopts a fast delay circuit to further reduce the harmonics of the grid-side current. (4) Instantaneous reactive power and harmonic current detection and calculation: Using the phase information output by the PLL, the collected signal is transformed from the original coordinate system to a specific coordinate system. In this coordinate system, the positive sequence current and negative sequence current components can be clearly detected. The instantaneous reactive power is calculated using the current and voltage signals in the transformed coordinate system, providing accurate data basis for the power harmonic control and reactive power compensation of the mining system, thereby optimizing the power quality of the mining power grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a flowchart of the steps of the method for optimizing reactive power compensation of a mining frequency conversion system according to an embodiment of the present application; Figure 2 This is a schematic diagram of the principle of a phase fast tracking module according to an embodiment of the present application; Figure 3 This is a flow chart of the particle swarm algorithm according to an embodiment of the present application; Figure 4 This is a schematic diagram of the design principle of instantaneous reactive power harmonic current detection according to an embodiment of the present application; Figure 5 This is a schematic diagram of the STATCOM system structure of an embodiment of the present application; Figure 6 This is a waveform diagram of the A-phase current of the STATCOM according to an embodiment of the present application; Figure 7 This is the reactive power waveform diagram of bus B3 in an embodiment of the present application. DETAILED DESCRIPTION

[0028] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0029] The embodiment of the present application provides a method for optimizing reactive power compensation of a mine frequency conversion system, such as Figure 1 As shown, the specific steps include: S100, collecting multi-dimensional data of the mining frequency conversion system, performing feature extraction and preprocessing to obtain preprocessed data; S200, the phase fast tracking module accurately obtains the sequence parameter according to the preprocessed data, and the sequence parameter is used as an input signal for realizing phase and frequency locking of the mine variable frequency system by a phase-locked loop; S300, a particle swarm algorithm is used to construct a multi-parameter fitness function, and optimal control parameters are dynamically calculated and found; S400, a transient reactive power detection technology is used to detect and analyze the transient reactive power and harmonic current in real time; S500, the transient reactive power and the harmonic current are input into a fuzzy PI controller, and dynamic error compensation is performed in combination with the optimal control parameters; S600, a static synchronous compensator control output compensation current is used to complete reactive power compensation and harmonic current treatment; S700, compensation verification and feedback are performed.

[0030] Specifically, by collecting multi-dimensional data of the mine variable frequency system and performing feature extraction and preprocessing, the phase fast tracking module is used to accurately obtain the sequence parameter and lock the phase and frequency of the mine variable frequency system, the particle swarm algorithm is used to dynamically calculate and find the optimal control parameters, the transient reactive power detection technology is used to detect and analyze the transient reactive power and harmonic current, and the fuzzy PI controller is used to adjust the compensation strategy in real time. Real-time monitoring and prediction of the power consumption mode of the mine device can be realized, power use can be optimized by intelligent adjustment strategy, energy consumption can be reduced, and energy utilization efficiency can be improved.

[0031] Further, S100 includes the following steps: S110, real-time collection of mine variable frequency system power quality parameters, static synchronous compensator operating parameters and environmental parameters; S120, fast Fourier transform is used to extract harmonic components, dynamic calculation of reactive power demand is performed based on a sliding window algorithm, and compensation amount is updated at a period of 10 ms; the data collected in S110 is normalized, and voltage sag, voltage transient disturbance data is identified and removed by abnormal data detection, and a standardized data matrix is constructed; The power quality parameters include bus voltage and current waveform, power factor, harmonic distortion rate and voltage flicker value; the operating parameters of the static synchronous compensator include DC side capacitor voltage, insulated gate bipolar transistor (IGBT) module temperature and reactor current effective value; the environmental parameters include mine humidity, temperature and dust concentration.

[0032] Specifically, real-time acquisition of power quality parameters such as bus voltage and current waveform, power factor, harmonic distortion rate and voltage flicker value of the mine variable frequency system; synchronous acquisition of operating parameters of the STATCOM device, such as DC side capacitor voltage, IGBT module temperature and reactor current effective value; and monitoring of environmental parameters, such as mine humidity, temperature, dust concentration and other environmental variables that may affect the insulation performance and heat dissipation efficiency of the equipment. Fast Fourier transform (FFT) is used to extract each harmonic component, and the dynamic reactive power demand is calculated based on the sliding window algorithm, with the compensation amount updated every 10 ms, and a standardized data matrix is constructed; the original signal is normalized to the [-1, 1] interval to eliminate the dimension effect, and transient disturbance data such as voltage sag and transient rise are identified and removed through abnormal data detection.

[0033] The phase fast tracking module is the premise of reactive power compensation vector control, and the phase of the current phasor calculated by the module is one of the inputs of the PLL phase detector. Through specific circuit design, the module can accurately obtain the amplitude and phase angle of the phasor. Accurate phasor parameters are crucial for analyzing the operating state of the power system, and accurate phase angle measurement can help determine the relationship between voltage and current, thereby accurately evaluating parameters such as power factor of the circuit. The principle diagram of the phase fast tracking module is shown in Figure 2 .

[0034] In some embodiments of the present application, the phase fast tracking module is designed to select a right-angle phase fast delay circuit. The instantaneous value of the sinusoidal quantity is as shown in formula (1): (1) wherein, wherein, is the root mean square value of the sinusoidal quantity, is the phase angle of the sinusoidal quantity lagging behind the reference value, is the angular frequency, is the instantaneous value of the current value of the sinusoidal quantity.

[0035] When the fast delay circuit shifts the phase of by a right angle, the instantaneous value of the sinusoidal quantity can be obtained, as shown in formula (2): (2) wherein, is the root mean square value of the sinusoidal quantity, is the phase angle of the sinusoidal quantity lagging behind the reference value, is the angular frequency, is the instantaneous value of the current value of the sinusoidal quantity when the phase is shifted by a right angle.

[0036] The phase fast tracking module is composed of multiple multipliers, two right-angle phase shifters, multiple adders and one subtractor.

[0037] Set As a unit reference voltage, it is used as a reference in the current signal processing and operation in the module. The unit reference voltage is multiplied by the current signal before and after phase shift, and then operated by the adder and subtractor. Combined with the operation of the trigonometric function, it is obtained as formula (3): (3) Where, is the square root of the sine quantity, indicates the phase angle of the current lagging behind the reference voltage, is the phase angle of the sine quantity lagging behind the reference value, is the angular frequency, is the imaginary unit, is the amplitude of the current after operation and the phase relationship between the reference voltage, is the unit reference unit.

[0038] The phase fast tracking module can accurately obtain the amplitude and phase angle of the phasor. Accurate phasor parameters are crucial for analyzing the operating state of the power system. Accurate phase angle measurement can help determine the relationship between voltage and current, thereby accurately evaluating parameters such as power factor of the circuit.

[0039] In the optimization of reactive power compensation of the mine frequency conversion system, the reasonable design of the fitness function is crucial. In the operation process of the mine frequency conversion system, the power quality is affected by many factors. In some embodiments of the present application, S300 includes the following steps, as shown in Figure 3 : S310, initialize the particle swarm; S320, construct the fitness function; S330, calculate the fitness value of each particle; S340, update the individual optimal position and global optimal position of the particle; S350, judge whether the termination condition is met; If yes, execute S360, if no, execute S370, and then repeat S330; S360, output the optimal control parameter; S370, update the speed and position of the particle according to the speed and position update formula.

[0040] Specifically: in the reactive power compensation optimization of mine frequency conversion system, the reasonable design of fitness function is crucial. In the operation process of mine frequency conversion system, power quality is affected by many factors. First, determine the fitness function, and construct the function with the key parameters such as harmonic content, voltage flicker value, STATCOM capacitor voltage fluctuation and device current effective value of mine frequency conversion system power quality index, aiming to minimize these parameters. Among them, too high harmonic content will lead to distortion of mine frequency conversion system voltage and current waveform, increase line loss and affect the normal operation of other electrical equipment; voltage flicker value reflects the rapid change of voltage amplitude, which will cause light flicker and affect visual perception, and may also cause damage to some devices with high voltage stability requirements; too large STATCOM capacitor voltage fluctuation will affect the effect and stability of reactive power compensation; the device current effective value is closely related to the heating and loss of the equipment. Therefore, minimizing these parameters can effectively improve the power quality of mine frequency conversion system.

[0041] The fitness function can be set as wherein is the harmonic content of current or voltage in mine frequency conversion system, is the voltage flicker value, is the STATCOM capacitor voltage fluctuation, is the device current effective value, is the weight coefficient, is the definition function.

[0042] Initialization of particle swarm is the starting step of particle swarm algorithm. Each particle represents a set of possible control parameter combinations, including STATCOM control parameters (such as modulation ratio, phase angle, etc.), filter parameters (such as filter resistance, inductance, capacitance value, etc.), and different combinations of these parameters will have different effects on the power quality of mine frequency conversion system.

[0043] Particles in the solution space are constantly updated according to their own speed and position. The speed update is shown in formula (4): (4) The position update is shown in formula (5): (5) wherein is the particle speed, is the particle position, is the inertia weight, is the learning factor, is a random number, is the individual optimal position of the particle, is the global optimal position.

[0044] Through multiple iterations of search, the particles constantly adjust their own position and speed, and approach to better solution. In each iteration, the fitness value of each particle is calculated, and the particle individual optimal position is updated and global optimal position . When the termination condition (such as reaching the maximum number of iterations or the fitness value converges to a certain accuracy) is met, the search process ends, and the control parameter combination corresponding to the global optimal position obtained at this time is the optimal control parameter combination sought, which can be used to achieve efficient regulation of the electric energy of the mine variable frequency system. Through multiple iterations of search, the optimal control parameter combination is found, and efficient regulation of the mine variable frequency system is achieved.

[0045] In some embodiments of the present application, S400 includes the following steps: S410, determining the working frequency of the mine variable frequency system, and determining the harmonic number range to be detected, the phase fast tracking module collecting the current signal and the voltage signal in the mine variable frequency system; S420, amplifying, filtering and digitizing the current signal and the voltage signal; S430, using the phase information output by the phase-locked loop, converting the current signal and the voltage signal from the abc coordinate system to the dq coordinate system, detecting the positive sequence current and the negative sequence current in the dq coordinate system, extracting the harmonic current, and calculating the instantaneous reactive power.

[0046] Specifically: the design principle diagram of the instantaneous reactive power harmonic current detection is as shown in Figure 4 The instantaneous reactive power harmonic current detection method uses the reference signal obtained by the phase-locked loop (PLL) to obtain the reference signal. The traditional PLL phase-locked process is complex and will cause detection delay, affecting the real-time performance and detection accuracy. Here, the PLL uses a phase fast tracking module for fast and high-precision detection. The collected signals are amplified, filtered and digitized for subsequent digital signal processing. The PLL can quickly lock and track the phase change of the mine variable frequency system. Through a filter or a spectrum analysis method, the harmonic current component is extracted.

[0047] The instantaneous reactive power is calculated using the current and voltage signals in the coordinate system as shown in equation (6): (6) wherein, are the components of the voltage vector on the d-axis and the q-axis, respectively, are the components of the current vector on the d-axis and the q-axis, respectively.

[0048] In some embodiments of the present application, S500 includes the following steps: S510, determining the fuzzy variables of input and output; S520, set the initial value of the proportional gain and integral gain and the proportional factor; S530, select the reactive power to be compensated as the feedback quantity, and compare the expected reactive power calculated by the instantaneous reactive power theory with the actual compensation reactive power calculated by the mine frequency conversion system according to the compensation current, to reflect the compensation state of the reactive power of the mine frequency conversion system.

[0049] Specifically, the fuzzy PI controller is designed based on a discrete linear PI controller, and the proportional integral part is unchanged, but the gain will change with the change of the input signal. The fuzzy variables of the input and output are determined, the input of the fuzzy PI controller is set as the error and the error change rate , to control the angle; the main factors affecting the fuzzy PI controller are the initial value of the proportional integral coefficient , the proportional factor of the input and output and . The initial value is set to , and the proportional factor of the input and output is set to , , . Select the reactive power to be compensated as the feedback quantity, and compare the reactive power calculated by the control part using the instantaneous reactive power theory with the reactive power calculated by the system according to the compensation current. The comparison result can accurately reflect the compensation state of the system reactive power, and the difference is an important basis for the adjustment of the fuzzy PI controller.

[0050] In some embodiments of the application, further, 600 includes the following steps: S610, determine the flow direction and size of the power on both sides of the parallel point, and reduce and eliminate the voltage difference and phase angle difference on both sides of the parallel point; S620, when the loop network is parallel, transfer active power from the phase angle leading side to the phase angle lagging side through the static synchronous compensator, reduce the phase angle difference between the two nodes to be parallel, and realize the adjustment of the reactive power through the static synchronous compensator, to reduce the voltage difference between the two nodes to be parallel; S630, by controlling the operating state of the converter at both ends of the static synchronous compensator, realize the exchange of active power and reactive power between the static synchronous compensator and the alternating current system, and realize the bidirectional transmission of power.

[0051] Specifically, the STATCOM system structure diagram is as Figure 5As shown, the STATCOM main circuit consists of a composite structure consisting of two voltage source converters (VSCs) connected in parallel via a transformer. Switching control modes through the parallel transformer composite device effectively controls the system short-circuit current and system power flow. It also isolates the fault by decoupling the loop in the event of a fault, eliminating inrush currents and ensuring safe system operation. Switching control modes through the parallel transformer composite device effectively controls the system short-circuit current and system power flow. It also isolates the fault by decoupling the loop in the event of a fault, eliminating inrush currents and ensuring safe system operation. When the ring network is connected in parallel, active power is transferred from the phase-leading side to the phase-lagging side via the grid-connected composite device, reducing the phase angle difference between the two nodes to be connected. Similarly, the grid-connected composite device regulates reactive power and reduces the voltage difference between the two nodes to be connected in parallel.

[0052] The active and reactive power exchanged between the hybrid VSC and the AC system is shown in formula (7): (7) In formula (4), is the fundamental component of the system bus voltage, is the fundamental component of the converter output voltage, for and The phase angle difference between is the reactance value of the commutation reactor, is the active power, Reactive power is the power of the inverter. The operating state of the inverter is determined by the direction of power transmission. If power transmission from the inverter to the grid is defined as the forward direction, power transmission from the grid to the inverter is defined as the reverse direction. By controlling the operating state of the inverters at both ends of the grid-connected hybrid device, active and reactive power can be exchanged between the hybrid device and the AC system, achieving bidirectional power transmission.

[0053] The reactive power compensation optimization method and device for mining frequency conversion system based on particle swarm algorithm, its core component STATCOM plays an extremely important role.

[0054] Next, the compensation verification and feedback of the mine frequency conversion system reactive power compensation S710, the variable load module is set to a constant load; S720. Set the voltage amplitude of the voltage source output to change with time, becoming 1.06 times the rated value at 0.2s, becoming 0.94 times the rated value at 0.3s, and returning to the rated value at 0.4s.

[0055] S730. Observe the changes in three-phase current under the action of STATCOM. Wherein, the A-phase current waveform chart of the STATCOM is as shown in Figure 6 As shown in the figure, under normal circumstances, the STATCOM neither consumes active power nor consumes reactive power, and the current is basically zero, and when the mine frequency conversion system needs reactive power, the STATCOM can quickly output reactive current, and the reactive power flow direction changes around 0.3s, and it can be seen that the current phase can change rapidly and smoothly, and the impact is small.

[0056] S740, the change of the power supply voltage will cause the change of each bus voltage, and under the default working mode of the STATCOM module in the case sequence, the reactive power of the bus B3 can be stabilized, and the reactive power waveform chart of the bus B3 is as shown in Figure 7 As shown in the figure, in the initial stage, the reactive power has a rapid rising process, and then reaches a relatively high value around 0.05-0.1s, and is maintained at a relatively stable level in this stage, and the fluctuation amplitude is small. During 0.1-0.2s, the reactive power is basically maintained stable, and is maintained at a level of about 1.5Mvar; between 0.2-0.3s, a slight downward fluctuation occurs, but soon recovers to be stable; after 0.3s, the reactive power still remains in a relatively stable state, and the overall fluctuation amplitude is small, which indicates that under the action of the STATCOM, the reactive power of the bus B3 can be maintained relatively stable.

[0057] The system adopts a multi-module cooperative closed-loop control process, first, the data acquisition and preprocessing acquires the voltage and current signals of the mine frequency conversion system in real time, then the phase fast tracking module is used to realize accurate phase locking of the mine frequency conversion system frequency, to ensure the synchronization reference, on this basis, the particle swarm optimization algorithm is combined to dynamically optimize the controller parameters, to improve the system response speed, then the instantaneous reactive power detection technology is used to analyze the harmonic and reactive components in real time, then the fuzzy PI control is used to realize dynamic error compensation, finally the STATCOM control output compensation current is used to complete harmonic control, and the whole process forms a closed-loop feedback through verification and adjustment.

[0058] The embodiment of the application also provides a mine frequency conversion system reactive power compensation optimization system, which is suitable for the mine frequency conversion system reactive power compensation optimization method.

[0059] The reactive power compensation optimization system of the mine-used variable frequency system comprises: a medium-frequency induction heating furnace, a static synchronous compensator, a phase fast tracking module, a phase-locked loop and a fuzzy PI controller, wherein the medium-frequency induction heating furnace is used as a main load device of the mine-used variable frequency system; the static synchronous compensator is used for dynamically compensating the reactive power and harmonics in the mine-used variable frequency system; the phase fast tracking module is used for accurately calculating the phasor parameters of the voltage and current of the mine-used variable frequency system; the phase-locked loop is used for quickly locking and tracking the phase change of the mine-used variable frequency system; and the fuzzy PI controller adjusts the control parameters of the static synchronous compensator based on the instantaneous reactive power and harmonic current. Through the cooperative action of the phase fast tracking module and the phase-locked loop, the system can accurately lock the phase change of the mine-used variable frequency system, realize millisecond-level dynamic response, and ensure the real-time performance and accuracy of the reactive power compensation; and the fuzzy PI controller dynamically adjusts the control parameters of the STATCOM based on the instantaneous reactive power and harmonic current, thereby reducing the harmonic pollution of the mine-used variable frequency system caused by the medium-frequency induction heating furnace and other nonlinear loads.

[0060] Further, the main circuit of the static synchronous compensator is a composite structure of two voltage source converters (VSCs) connected in parallel through a transformer, the STATCOM structure adopting the VSCs in parallel is simpler, the equipment redundancy rate and cost are reduced, and the system reliability and dynamic response capability are improved.

[0061] Further, the phase fast tracking module comprises a plurality of multipliers, two quadrature phase shifters, a plurality of adders and a subtractor, compared with the traditional software phase-locked loop, the design significantly improves the phase detection reliability of the mine-used variable frequency system under complex working conditions such as voltage distortion and frequency mutation, and provides a high-precision reference phase signal for subsequent reactive power calculation and harmonic compensation.

[0062] Further, the phase fast tracking module adopts a quadrature phase fast delay circuit, which further reduces the harmonics of the grid-side current.

[0063] The above describes the preferred embodiments of the present application in detail. It should be understood that those skilled in the art can make many modifications and changes to the present application without creative labor based on the concept of the present application. Therefore, any technical solutions obtained by logical analysis, reasoning or limited experiments based on the prior art according to the concept of the present application shall be within the protection scope defined by the claims.

[0064] The specific embodiments of the present application are described above. It should be understood that the present application is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essential content of the present application. In the case of no conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A reactive power compensation optimization method for a mine frequency conversion system, characterized in that: The following steps are involved: S100, collecting multi-dimensional data of the mining frequency conversion system, performing feature extraction and preprocessing to obtain preprocessed data; S200, a phase fast tracking module accurately obtains phasor parameters based on the preprocessed data, and the phasor parameters are used as input signals for a phase-locked loop to achieve phase and frequency locking of the mining frequency conversion system; S300, uses particle swarm optimization to build a multi-parameter fitness function and dynamically calculates and finds the optimal control parameter combination; S400 uses instantaneous reactive power detection technology to detect and analyze instantaneous reactive power and harmonic current in real time; S500, the instantaneous reactive power and the harmonic current are input into a fuzzy PI controller, and dynamic error compensation is performed in combination with the optimal control parameter combination; S600: The static synchronous compensator controls the output compensation current to complete the reactive power compensation and the harmonic current control; S700: Perform compensation verification and feedback.

2. The reactive power compensation optimization method of the mining frequency conversion system according to claim 1 is characterized in that: The S100 includes the following steps: S110, real-time collection of power quality parameters of the mining frequency conversion system, operating parameters of the static synchronous compensator, and environmental parameters; S120, extracting each harmonic component using a fast Fourier transform, dynamically calculating reactive power demand based on a sliding window algorithm, and updating the compensation amount in a 10 ms cycle; normalizing the data collected in S110, and identifying and eliminating transient interference data such as voltage sags and swells through abnormal data detection to construct a standardized data matrix; Among them, the power quality parameters include bus voltage and current waveforms, power factor, harmonic distortion rate and voltage flicker value; the operating parameters of the static synchronous compensator include DC side capacitor voltage, insulated gate bipolar transistor module temperature and effective value of reactor current; the environmental parameters include mine humidity, temperature and dust concentration.

3. The reactive power compensation optimization method of the mine frequency conversion system according to claim 1 is characterized in that: The S300 includes the following steps: S310, initializing the particle swarm; S320, constructing the fitness function; S330, calculating the fitness value of each particle; S340, updating the individual optimal position of the particle and the global optimal position; S350, determining whether a termination condition is satisfied; If yes, execute S360; if no, execute S370 and then repeat S330; S360, outputting optimal control parameters; S370. Update the speed and position of the particle according to the speed and position update formula.

4. The reactive power compensation optimization method of a mine frequency conversion system according to claim 1, characterized in that: The S400 includes the following steps: S410: Determine the operating frequency of the mining frequency conversion system and the harmonic order range to be detected, and the phase fast tracking module collects the current signal and voltage signal in the mining frequency conversion system; S420, amplifying, filtering, and digitally processing the current signal and the voltage signal; S430. Using the phase information output by the phase-locked loop, transform the current signal and the voltage signal from the abc coordinate system to the dq coordinate system. In the dq coordinate system, detect the positive sequence current and the negative sequence current, extract the harmonic current, and calculate the instantaneous reactive power.

5. The reactive power compensation optimization method of a mine frequency conversion system according to claim 1, characterized in that: The S500 includes the following steps: S510, determining input and output fuzzy variables; S520, setting the initial values ​​and proportional factors of the proportional gain and integral gain; S530, selecting the reactive power to be compensated as the feedback quantity, and comparing the expected reactive power calculated by the instantaneous reactive power theory with the actual compensated reactive power calculated by the mining frequency conversion system according to the compensation current, to reflect the compensation status of the reactive power of the mining frequency conversion system.

6. The reactive power compensation optimization method of a mine frequency conversion system according to claim 1, characterized in that: The S600 includes the following steps: S610: Determine the flow direction and magnitude of power on both sides of the point to be paralleled, and reduce and eliminate the voltage difference and phase angle difference on both sides of the point to be paralleled; S620: When the ring networks are connected in parallel, active power is transferred from the phase angle leading side to the phase angle lagging side through the static synchronous compensator to reduce the phase angle difference between the two nodes to be connected in parallel, and reactive power is regulated by the static synchronous compensator to reduce the voltage difference between the two nodes to be connected in parallel; S630: Control the operating states of the converters at both ends of the STATCOM to achieve exchange of the active power and the reactive power between the STATCOM and the AC system, thereby realizing bidirectional power transmission.

7. A reactive power compensation optimization system for a mine frequency conversion system, wherein the reactive power compensation optimization system for a mine frequency conversion system is applicable to the reactive power compensation optimization method for a mine frequency conversion system according to any one of claims 1 to 6, characterized in that: include: Medium frequency induction heating furnace: the medium frequency induction heating furnace serves as the main load equipment of the mining frequency conversion system; Static synchronous compensator: The static synchronous compensator is used to dynamically compensate for reactive power and harmonics in the mining frequency conversion system; Phase fast tracking module: The phase fast tracking module is used to accurately calculate the phasor parameters of the voltage and current of the mining frequency conversion system; Phase-locked loop: The phase-locked loop is used to quickly lock and track the phase changes of the mining frequency conversion system; Fuzzy PI controller: The fuzzy PI controller adjusts the control parameters of the static synchronous compensator based on the instantaneous reactive power and the harmonic current.

8. The reactive power compensation optimization system for a mine frequency conversion system according to claim 7 is characterized in that: The main circuit of the static synchronous compensator is a composite structure in which two voltage source converters are connected in parallel via a transformer.

9. The reactive power compensation optimization system for a mine frequency conversion system according to claim 7, characterized in that: The phase fast tracking module includes a plurality of multipliers, two right-angle phase shifters, a plurality of adders and subtractors.

10. The reactive power compensation optimization system for a mine frequency conversion system according to claim 7, characterized in that: The phase fast tracking module adopts a right-angle phase fast delay circuit.

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