Bidirectional inverter energy conversion method and system for intelligent grid-connected cabinet

Abstract

The present invention relates to the technical field of intelligent grid-connected cabinets, and discloses a bidirectional inverter energy conversion method and system for intelligent grid-connected cabinets, the system comprising a power grid monitoring module, a power adjustment module, an adaptive module, and an inverter control module; wherein: the power grid monitoring module is used to monitor the voltage and frequency of the power grid; the power adjustment module adjusts the active power and reactive power of the inverter through a power adjustment equation based on the voltage and frequency of the power grid; the adaptive module is used to adaptively adjust the equation parameters of the power adjustment equation; the inverter control module generates a control signal for adjusting the inverter output based on the adjusted active power and reactive power of the inverter; the present invention improves the stability and efficiency of the power grid, and enhances the dynamic response capability and adaptive capability of the inverter.

Description

Technical Field

[0001] The present invention relates to the technical field of intelligent grid-connected cabinets, and in particular to a bidirectional inverter energy conversion method and system for an intelligent grid-connected cabinet. Background Art

[0002] Inverters are key devices that connect renewable energy generation devices to the power grid. They are not only responsible for converting DC power to AC power, but also need to ensure the power quality and stability of the inverter so that it meets the grid access standards. In recent years, the requirements for inverters have gone beyond simple power conversion, and more attention has been paid to their support for the grid, especially in maintaining grid frequency and voltage stability. Traditionally, the frequency and voltage of the grid are mainly maintained by large thermal power stations or nuclear power plants by adjusting the speed of generators. However, with the increasing number of distributed energy systems, traditional central control methods can no longer meet the needs of modern power grids. The access of distributed power sources has brought many challenges to the grid, including but not limited to frequency fluctuations, voltage distortion and other problems. These problems not only affect the quality of power, but may also cause stability problems in the power system, leading to power supply interruptions.

[0003] Modern inverters not only need to have efficient energy conversion functions, but also need to be able to provide necessary support services when a grid failure occurs, such as frequency response, voltage support and other functions. Most existing inverter control systems are based on fixed control strategies, lacking flexibility and adaptability, and are difficult to cope with the ever-changing conditions in the grid. When adjusting the grid frequency and voltage, existing control systems often take a long time to respond to changes, which may cause grid instability in some cases.

[0004] For example, a Chinese patent with authorization announcement number CN117713198B discloses a grid-connected inverter control core module and a photovoltaic power exchange cabinet. The photovoltaic power exchange cabinet includes a switch control device and N single-compartment chargers in parallel, as well as a grid-connected inverter control core module, an energy storage battery charger, and an energy storage battery pack. The switch control device is connected to the energy storage battery charger and the N single-compartment chargers, respectively. Each single-compartment charger charges the battery. The output end of the energy storage battery charger is connected to one end of the energy storage battery pack, and the other end of the energy storage battery pack is connected to the input end of the grid-connected inverter control core module. The output end of the grid-connected inverter control core module is connected to the switch control device. After the solar panel converts solar energy into electrical energy, it is stored in the energy storage battery pack, which is used to offset the standby power consumption of the power exchange cabinet itself. On the other hand, the excess electrical energy is sent to the power grid through the grid-connected inverter control core module, thereby reducing the additional electricity bill caused by the standby power consumption of the power exchange cabinet itself and generating power generation income.

[0005] For example, a patent application with authorization announcement number CN114447994B discloses a reactive power compensation grid-connected method and system suitable for new energy intelligent grid-connected cabinets, including: obtaining the active power and reactive power of the new energy intelligent grid-connected cabinet and the grid connection point within a first preset time period to obtain a power sequence, and obtaining the phase shift coefficient of the grid regarding reactive power compensation according to the power sequence; adjusting the first current sinusoidal waveform diagram based on the phase shift coefficient to obtain a second current sinusoidal waveform diagram; comparing the second current sinusoidal waveform diagram with the first current sinusoidal waveform diagram to obtain current compensation information; obtaining dynamic compensation power information of the compensation power unit according to the power outage compensation time, current compensation information, and dynamic compensation offset coefficient; controlling the compensation inverter to continuously perform reactive power compensation on the grid, and when the current power information in the compensation power unit is lower than the compensation power information, controlling the intelligent grid-connected cabinet to supply power to the compensation power unit.

[0006] The above patents all have the problems raised by this background technology: lack of flexibility and adaptability, and difficulty in providing effective frequency response and voltage support for the power grid.

[0007] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgement or any form of suggestion that the information constitutes the prior art already known to ordinary technicians in this field. Summary of the invention

[0008] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a bidirectional inverter energy conversion method and system for an intelligent grid-connected cabinet. The present invention improves the stability and efficiency of the power grid and enhances the dynamic response capability and adaptability of the inverter.

[0009] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0010] On the one hand, the present invention provides a bidirectional inverter energy conversion system for an intelligent grid-connected cabinet, comprising a grid monitoring module, a power adjustment module, an adaptive module, and an inverter control module; wherein:

[0011] The power grid monitoring module is used to monitor the voltage and frequency of the power grid;

[0012] The power adjustment module adjusts the active power and reactive power of the inverter through the power adjustment equation based on the voltage and frequency of the power grid;

[0013] The adaptive module is used for adaptively adjusting the equation parameters of the power adjustment equation;

[0014] The inverter control module generates a control signal for adjusting the inverter output based on the adjusted active power and reactive power of the inverter.

[0015] As a preferred solution of the bidirectional inverter energy conversion system for the intelligent grid-connected cabinet of the present invention, the power adjustment equation includes a first adjustment equation and a second adjustment equation; the power adjustment module includes a first adjustment unit, and the first adjustment unit is configured with a first adjustment equation for adjusting the active power of the inverter according to the frequency of the power grid; the first adjustment equation is specifically as follows:

[0016] ;

[0017] in, Indicates the adjustment value of active power; Indicates the reference active power; represents the frequency control coefficient; Indicates the frequency deviation value, and the calculation formula is as follows:

[0018] ;

[0019] Where, f represents the grid frequency measured by the frequency monitoring unit, Indicates the reference frequency of the power grid.

[0020] As a preferred solution of the bidirectional inverter energy conversion system for the intelligent grid-connected cabinet of the present invention, the power adjustment module further includes a second adjustment unit; the second adjustment unit is configured with a second adjustment equation for adjusting the reactive power of the inverter according to the voltage of the grid; the second adjustment equation is specifically as follows:

[0021] ;

[0022] in, Indicates the adjustment value of reactive power; Indicates the reference reactive power; represents the voltage control coefficient; Indicates the voltage deviation value, and the calculation formula is as follows:

[0023] ;

[0024] Wherein, V represents the grid voltage measured by the voltage monitoring unit; Indicates the reference voltage of the power grid.

[0025] As a preferred solution of the bidirectional inverter energy conversion system for the intelligent grid-connected cabinet described in the present invention, wherein: the adaptive module includes a parameter updating unit; the parameter updating unit is configured with a parameter updating equation, and the values ​​of the frequency control coefficient and the voltage control coefficient are adaptively updated through an adaptive factor; the parameter updating equation is specifically as follows:

[0026] ;

[0027] ;

[0028] in, represents the frequency control coefficient at time t; represents the frequency control coefficient at time t-1; Indicates the adjustment value of active power at time t; Indicates the adjustment value of active power at time t-1; represents the voltage control coefficient at time t; represents the voltage control coefficient at time t-1; Indicates the adjustment value of reactive power at time t; Indicates the adjustment value of reactive power at time t-1; , All are adaptive factors; represents the first adjustment factor, Represents the second adjustment factor, and the value selection rule is as follows: If the grid frequency is higher than the reference frequency at time t, then The value is 1, otherwise, The value is 0; if the grid voltage is higher than the reference voltage at time t, then The value is 1, otherwise, The value is 0.

[0029] As a preferred solution of the bidirectional inverter energy conversion system for the intelligent grid-connected cabinet of the present invention, the parameter updating unit is also configured with a parameter restriction strategy, which is as follows:

[0030] Let the frequency control coefficient range be to ,in Indicates the minimum value of the frequency control coefficient, Represents the maximum value of the frequency control coefficient; the frequency control coefficient at time t is calculated by the parameter update equation ,like Less than , then let The value is equal to ;like Greater than , then let The value is equal to ;

[0031] Let the voltage control coefficient take the range of to ,in Indicates the minimum value of the voltage control coefficient, Represents the maximum value of the voltage control coefficient; the voltage control coefficient at time t is calculated by the parameter update equation ,like Less than , then let The value is equal to ;like Greater than , then let The value is equal to .

[0032] As a preferred solution of the bidirectional inverter energy conversion system for the intelligent grid-connected cabinet of the present invention, the adaptive module further includes an adaptive optimization unit; the adaptive optimization unit is configured with an optimization strategy for optimizing the value of the adaptive factor, and the specific steps are as follows:

[0033] S101: Set the population size, maximum number of iterations, crossover probability, mutation probability, and generate the initial population;

[0034] The primary population contains N individuals, where N is the population size; each individual contains one chromosome, and each chromosome contains two genes, corresponding to the adaptive factors , ;

[0035] S102: Calculate the fitness of each individual;

[0036] Based on N individuals , , construct N groups of parameter update equations, conduct simulation experiments, obtain evaluation factors based on the simulation experiments, and calculate the fitness of individuals corresponding to the N groups of parameter update equations through the corresponding evaluation factors;

[0037] S103: performing selection operation, crossover operation, and mutation operation in sequence, and generating the next generation population;

[0038] S104: Repeat steps S102-S103 until the maximum number of iterations is reached;

[0039] S105: Take the individual with the highest fitness in the last iteration , The value of is taken as the comprehensive optimization result of the adaptive factors.

[0040] As a preferred solution of the bidirectional inverter energy conversion system for the intelligent grid-connected cabinet of the present invention, wherein: the inverter control module includes a reference signal unit; the reference signal unit calculates the reference signal of the inverter based on the adjusted active power and reactive power of the inverter; wherein the amplitude calculation formula of the reference signal is as follows:

[0041] ;

[0042] Where, E represents the amplitude of the reference signal;

[0043] The phase calculation formula of the reference signal is as follows:

[0044] ;

[0045] in, Indicates the phase of the reference signal.

[0046] As a preferred solution of the bidirectional inverter energy conversion system for the intelligent grid-connected cabinet described in the present invention, wherein: the inverter control module also includes a control signal unit; the control signal unit generates a control signal for adjusting the inverter output based on the reference signal of the inverter, specifically as follows: a high-frequency carrier is selected, the control signal is compared point by point with the high-frequency carrier, and a PWM modulation signal is generated as the control signal for adjusting the inverter output.

[0047] In a second aspect, the present invention provides a bidirectional inverter energy conversion method for an intelligent grid-connected cabinet, comprising the following steps:

[0048] S1: Real-time monitoring of the voltage and frequency of the power grid;

[0049] S2: Calculate the adjustment value of the reactive power of the inverter based on the voltage of the power grid, and calculate the adjustment value of the active power of the inverter based on the frequency of the power grid;

[0050] S3: updating the frequency control coefficient and the voltage control coefficient based on the adjustment value of the active power and the adjustment value of the reactive power;

[0051] S4: Correcting the adjustment value of the active power and the adjustment value of the reactive power of the inverter based on the updated frequency control coefficient and the voltage control coefficient;

[0052] S5: Generate a control signal for adjusting the inverter output based on the adjustment value of the active power and the adjustment value of the reactive power of the inverter.

[0053] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0054] The present invention monitors the frequency and voltage of the power grid and adjusts the active power and reactive power of the inverter according to the frequency deviation and the voltage deviation. It helps to stabilize the power grid frequency by increasing or decreasing the active power output when the power grid frequency fluctuates, and stabilize the voltage level by adjusting the reactive power when the voltage fluctuates, thereby improving the overall stability of the power grid.

[0055] By introducing an adaptive mechanism, the system can dynamically adjust the frequency control coefficient and voltage control coefficient according to the actual working conditions of the power grid, so as to achieve a rapid response of the inverter to changes in power grid load and network fluctuations. This adaptive capability enables the system to maintain good performance in the face of unknown disturbances and uncertainties. By optimizing the adaptive factors through genetic algorithms, the system can continuously adjust the control parameters according to the actual situation, ensuring that the inverter can work stably under various conditions and improving the robustness and adaptability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0057] Figure 1 A schematic diagram of the structure of a bidirectional inverter energy conversion system for an intelligent grid-connected cabinet provided by the present invention;

[0058] Figure 2 A flow chart of a bidirectional inverter energy conversion method for an intelligent grid-connected cabinet provided by the present invention;

[0059] Figure 3 A flow chart of the method for optimizing the adaptive factor provided by the present invention. DETAILED DESCRIPTION

[0060] The technical solution of the present invention is described in detail below through the accompanying drawings and specific embodiments. It should be understood that the embodiments of the present invention and the specific features in the embodiments are detailed descriptions of the technical solution of the present invention, rather than limitations on the technical solution of the present invention. The embodiments of the present invention and the technical features in the embodiments may be combined with each other unless there is a conflict.

[0061] Example 1

[0062] This embodiment introduces a bidirectional inverter energy conversion system for an intelligent grid-connected cabinet. Figure 1 The system includes a power grid monitoring module, a power adjustment module, an adaptive module, and an inverter control module; wherein:

[0063] The power grid monitoring module is used to monitor the voltage and frequency of the power grid;

[0064] The power grid monitoring module includes a voltage monitoring unit and a frequency monitoring unit; wherein the voltage monitoring unit is used to monitor the voltage of the power grid; and the frequency monitoring unit is used to monitor the frequency of the power grid;

[0065] Frequency is a key indicator of grid stability. Frequency fluctuations can affect all devices connected to the grid, especially those that rely on constant frequency. The frequency monitoring unit uses a frequency meter or phase-locked loop to accurately measure the grid frequency and transmit the data to the power adjustment module through a communication interface. Voltage that is too high or too low can affect the performance of electrical equipment. By monitoring the grid voltage and adjusting the inverter power in a timely manner, the grid can be helped to maintain the voltage within a safe range. The voltage monitoring unit is equipped with a voltage transformer that can convert the high voltage of the grid into a low voltage signal that is easy to measure, and then convert it into a digital signal through an analog-to-digital converter, and transmit the digital voltage signal to the power adjustment module.

[0066] The power adjustment module adjusts the active power and reactive power of the inverter through the power adjustment equation based on the voltage and frequency of the power grid;

[0067] The power adjustment module includes a first adjustment unit and a second adjustment unit; the power adjustment equation includes a first adjustment equation and a second adjustment equation; wherein the first adjustment unit is configured with a first adjustment equation for adjusting the active power of the inverter according to the frequency of the power grid; the first adjustment equation is specifically as follows:

[0068] ;

[0069] in, Indicates the adjustment value of active power; Indicates the reference active power; represents the frequency control coefficient; Indicates the frequency deviation value, and the calculation formula is as follows:

[0070] ;

[0071] Where, f represents the grid frequency measured by the frequency monitoring unit, Indicates the reference frequency of the power grid. Indicates the standard frequency of the power grid, usually 50HZ.

[0072] The first adjustment equation realizes that when the grid frequency is lower than the reference frequency, the active power of the inverter is increased; when the grid frequency is higher than the reference frequency, the active power of the inverter is reduced. When the grid frequency is lower than the reference frequency, it means that the total load of the grid exceeds the total power generation, that is, the power supply is insufficient to meet the demand. In order to restore the grid frequency, it is necessary to increase the power generation, that is, the inverter should increase the output active power. The increased active power helps to make up for the shortfall in grid power, thereby helping to restore the grid frequency to a normal range. When the grid frequency is higher than the reference frequency, in order to suppress further increases in frequency, the inverter needs to reduce the active power output to the grid. The increase in frequency is usually related to power generation being greater than load demand. By reducing the active power output, the grid frequency can be restored to normal levels.

[0073] Reference active power It is set by technical personnel in this field based on actual needs; technical personnel in this field comprehensively consider the output capacity of the inverter, the specifications of the power grid and the load requirements to set the benchmark active power to ensure the stability and efficiency of the power grid; for example, if the inverter is used for a long time to supply power to a load with a relatively stable load, the active power can be set to the average power requirement of the load.

[0074] Frequency Control Coefficient The value range of is determined by technicians in this field based on a large number of experiments; in order to maintain the frequency stability of the power grid, it is necessary to select a suitable frequency control coefficient so that the inverter can quickly adjust the power output when the frequency changes. Considering the characteristics of the load, if the load changes frequently and the change amplitude is large, a larger frequency control coefficient is required to quickly respond to frequency changes; if the load is relatively stable, a smaller frequency control coefficient can be selected. The maximum output power of the inverter limits the selection range of the frequency control coefficient. If the frequency control coefficient is too large, it may cause the inverter to exceed its maximum output capacity when responding to frequency changes. The dynamic response capability of the inverter will also affect the selection of the frequency control coefficient. Inverters with fast response speed can withstand larger frequency control coefficients. In actual applications, technicians will preliminarily set the frequency control coefficient based on the specifications of the inverter, grid conditions and load requirements. , and then optimize the parameters through simulation and field testing. This method helps ensure that the inverter can work stably under various conditions and meet the performance requirements of the power system. Use simulation tools (such as MATLAB / Simulink, PSCAD, etc.) to simulate, evaluate the performance of the inverter under different frequency control coefficients, and select the appropriate value range of the frequency control coefficient. Then test in the actual power grid environment to observe the performance of the inverter under different frequency control coefficients, and adjust the appropriate value range according to the test results, and finally determine the value range of the frequency control coefficient.

[0075] The second adjustment unit is configured with a second adjustment equation for adjusting the reactive power of the inverter according to the voltage of the power grid; the second adjustment equation is specifically as follows:

[0076] ;

[0077] in, Indicates the adjustment value of reactive power; Indicates the reference reactive power; represents the voltage control coefficient; Indicates the voltage deviation value, and the calculation formula is as follows:

[0078] ;

[0079] Wherein, V represents the grid voltage measured by the voltage monitoring unit; It represents the reference voltage of the power grid, that is, the rated voltage of the power grid. The rated voltage of the power grid for medium and short distance power distribution used by the power connection cabinet involved in this embodiment is 10 kV.

[0080] The second adjustment equation realizes increasing the reactive power of the inverter when the grid voltage is lower than the reference voltage; and reducing the reactive power of the inverter when the grid voltage is higher than the reference voltage. When the grid voltage is lower than the reference voltage, it indicates that there is insufficient reactive power in the grid to maintain the voltage level. In order to restore the voltage, the inverter needs to inject more reactive power into the grid; when the grid voltage is higher than the reference voltage, it indicates that there is too much reactive power in the grid. In order to restore the voltage to normal levels, it is necessary to reduce the reactive power provided by the inverter to the grid.

[0081] Reference reactive power It is set by technicians in this field based on actual needs; and the frequency control coefficient The voltage control coefficient is determined in a similar way. The value range of is determined by those skilled in the art based on a large number of experiments; when selecting the voltage control coefficient, the overall stability of the system needs to be considered. A larger voltage control coefficient may cause the voltage to fluctuate greatly in a short period of time, affecting the stability of the system. A higher voltage control coefficient may also cause harmonic problems, especially when there are many nonlinear loads. Therefore, when selecting the voltage control coefficient, it is also necessary to weigh the impact of harmonics on the power grid.

[0082] The adaptive module is used for adaptively adjusting the equation parameters of the power adjustment equation;

[0083] The adaptive module includes a parameter updating unit and an adaptive optimization unit; the parameter updating unit is configured with a parameter updating equation, and adaptively updates the values ​​of the frequency control coefficient and the voltage control coefficient through an adaptive factor; the parameter updating equation is specifically as follows:

[0084] ;

[0085] ;

[0086] in, represents the frequency control coefficient at time t; represents the frequency control coefficient at time t-1; Indicates the adjustment value of active power at time t; Indicates the adjustment value of active power at time t-1; represents the voltage control coefficient at time t; represents the voltage control coefficient at time t-1; Indicates the adjustment value of reactive power at time t; Indicates the adjustment value of reactive power at time t-1; , All are adaptive factors; represents the first adjustment factor, Represents the second adjustment factor, and the value selection rule is as follows: If the grid frequency is higher than the reference frequency at time t, then The value is 1, otherwise, The value is 0; if the grid voltage is higher than the reference voltage at time t, then The value is 1, otherwise, The value is 0;

[0087] The parameter update unit updates the values ​​of the frequency control coefficient and the voltage control coefficient and then sends a parameter update signal to the power adjustment module; the power adjustment module is configured with a power trimming strategy for correcting the adjustment value of the active power and the adjustment value of the reactive power, and the method is as follows: parsing the parameter update signal, obtaining the updated frequency control coefficient and the voltage control coefficient, and recalculating and updating the adjustment value of the active power and the adjustment value of the reactive power of the inverter.

[0088] The parameter updating unit is also configured with a parameter restriction strategy, which is as follows:

[0089] Let the frequency control coefficient range be to ,in Indicates the minimum value of the frequency control coefficient, Represents the maximum value of the frequency control coefficient; the frequency control coefficient at time t is calculated by the parameter update equation ,like Less than , then let The value is equal to ;like Greater than , then let The value is equal to ;

[0090] Let the voltage control coefficient take the range of to ,in Indicates the minimum value of the voltage control coefficient, Represents the maximum value of the voltage control coefficient; the voltage control coefficient at time t is calculated by the parameter update equation ,like Less than , then let The value is equal to ;like Greater than , then let The value is equal to Based on the above parameter limitation strategy, the values ​​of the frequency control coefficient and the voltage control coefficient are limited to a preset value range to maintain the stability of the inverter and the power grid.

[0091] Based on the above parameter update equation, the frequency control coefficient and voltage control coefficient are adaptively updated. By real-time monitoring of the changes in the active power and reactive power adjustment values, the frequency control coefficient and voltage control coefficient are dynamically adjusted, so that the inverter can quickly respond to the frequency and voltage fluctuations caused by load changes and network fluctuations in the power grid, thereby maintaining the stability of the power grid frequency and voltage. The parameter update equation can dynamically adjust the frequency and voltage control parameters according to the actual working conditions of the power grid, thereby providing a better control effect. For example, when the power grid frequency is abnormally too high and continues to rise, the system will automatically increase the value of the frequency control coefficient, thereby speeding up the adjustment speed of the active power, thereby quickly restoring the stable state of the power grid frequency; when the power grid voltage is abnormally too low and gradually increases to the reference voltage, the system will automatically reduce the value of the voltage control coefficient to reduce system energy consumption and prevent over-regulation from causing overshoot oscillation of the power grid voltage. In short, adaptive control with parameter update equation as the core can improve the robustness and adaptability of the system, enabling it to better cope with changes in various working conditions, and even in the face of unknown disturbances and uncertainties, the system can maintain good performance.

[0092] The adaptive optimization unit is configured with an optimization strategy, and the optimization strategy is used to optimize the value of the adaptive factor, specifically, to use a genetic algorithm to perform comprehensive optimization of the adaptive factor, referring to Figure 3 , the steps are as follows:

[0093] S101: Set the population size, maximum number of iterations, crossover probability, mutation probability, and generate the initial population;

[0094] The primary population contains N individuals, where N is the population size; each individual contains one chromosome, and each chromosome contains two genes, corresponding to the adaptive factors , ;

[0095] S102: Calculate the fitness of each individual;

[0096] Based on N individuals , The value of is used to construct N groups of parameter update equations, and simulation experiments are carried out. Evaluation factors are obtained based on the simulation experiments, and the fitness of the individuals corresponding to the N groups of parameter update equations is calculated by the corresponding evaluation factors. The fitness of any individual is the weighted sum of the evaluation factors corresponding to the individual, and the weights are set by technicians in this field based on actual needs. The evaluation factors include steady-state error, overshoot, and adjustment time. Among them, the steady-state error refers to the average of the difference between the actual output active power and its expected value and the difference between the reactive power and its expected value after the system reaches a steady state in the simulation experiment. A smaller steady-state error indicates that the system has a strong adjustment ability. Overshoot refers to the average of the maximum offset between the active power and its expected value and the maximum offset between the reactive power and its expected value in the simulation experiment. A smaller overshoot means that the system has good stability. Adjustment time refers to the average of the time required for the active power of the inverter to reach its expected value and the time required for the reactive power to reach its expected value in the simulation experiment. A shorter adjustment time indicates that the system responds quickly.

[0097] S103: performing selection operation, crossover operation, and mutation operation in sequence, and generating the next generation population;

[0098] The selection operation is to select a certain proportion of individuals with the highest fitness in the parent population to enter the next generation; the crossover operation is to randomly select two individuals from the parent individuals and exchange any of their genes; the mutation operation is to randomly select several parent individuals and change their , The value of

[0099] S104: Repeat steps S102-S103 until the maximum number of iterations is reached;

[0100] S105: Take the adaptive factor value corresponding to the individual with the highest fitness in the last iteration as the comprehensive optimization result of the adaptive factor (including the adaptive factor , ).

[0101] The inverter control module generates a control signal for adjusting the inverter output based on the adjusted active power and reactive power of the inverter.

[0102] The inverter control module includes a reference signal unit and a control signal unit; the reference signal unit calculates the reference signal of the inverter based on the adjusted active power and reactive power of the inverter; wherein the amplitude calculation formula of the reference signal is as follows:

[0103] ;

[0104] Where, E represents the amplitude of the reference signal;

[0105] The phase calculation formula of the reference signal is as follows:

[0106] ;

[0107] in, Indicates the phase of the reference signal; the phase of the reference signal is the phase difference between the reference signal and the grid voltage; the amplitude of the reference signal determines the amplitude of the inverter output voltage, while the phase of the reference signal determines the phase of the inverter output voltage relative to the AC grid. By adjusting these two parameters, the active power and reactive power of the inverter can be controlled.

[0108] The control signal unit generates a control signal for adjusting the inverter output based on the reference signal of the inverter, specifically as follows: select a high-frequency carrier, compare the control signal with the high-frequency carrier point by point, and generate a PWM modulation signal as the control signal for adjusting the inverter output.

[0109] Select a triangle wave or sawtooth wave with a frequency higher than that of the reference signal as the carrier. Compare the sine wave of the reference signal with the high-frequency triangle wave point by point. When the waveform of the reference signal is higher than the carrier, the corresponding switch tube is turned on; otherwise, it is turned off, and a series of PWM modulation signals with pulse widths varying with time are obtained. The generated PWM modulation signal is used to control the on and off states of the switching devices (such as IGBT or MOSFET) in the inverter, which will cause the inverter to output a series of pulses with widths varying with time, and the average waveform of these pulses is similar to the sine waveform of the reference signal. In order to obtain an output waveform that is closer to the sine wave of the reference signal, a filter (such as an LC filter) is added to the output of the inverter to remove high-frequency components and unnecessary harmonics.

[0110] Example 2

[0111] Based on the same inventive concept as Example 1, refer to Figure 2 This embodiment introduces a bidirectional inverter energy conversion method for an intelligent grid-connected cabinet, comprising the following steps:

[0112] S1: Real-time monitoring of the voltage and frequency of the power grid;

[0113] S2: Calculate the adjusted value of the reactive power of the inverter based on the voltage of the power grid, and calculate the adjusted value of the active power of the inverter based on the frequency of the power grid; calculate the adjusted value of the active power of the inverter by a first adjustment equation and a frequency control coefficient; calculate the adjusted value of the reactive power of the inverter by a second adjustment equation and a voltage control coefficient;

[0114] S3: Based on the adjustment value of the active power and the adjustment value of the reactive power, the frequency control coefficient and the voltage control coefficient are updated; the frequency control coefficient and the voltage control coefficient are updated by using a parameter update equation and an adaptive factor; wherein the adaptive factor is optimized and determined based on a genetic algorithm;

[0115] S4: Correcting the adjustment value of the active power and the adjustment value of the reactive power of the inverter based on the updated frequency control coefficient and the voltage control coefficient;

[0116] S5: Generate a control signal for adjusting the inverter output based on the active power adjustment value and the reactive power adjustment value of the inverter. First, the amplitude and phase of the reference signal of the inverter are calculated based on the active power adjustment value and the reactive power adjustment value, and then a PWM modulation signal is generated as a control signal for adjusting the inverter output by comparing the reference signal with the carrier signal point by point.

[0117] The specific functions of the above modules are realized by referring to the relevant contents of the bidirectional inverter energy conversion system for the intelligent grid-connected cabinet described in Example 1, which will not be elaborated here.

[0118] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0119] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the purpose and scope of protection of the present invention, which are all within the protection of the present invention.

Claims

1. A bidirectional inverter energy conversion system for an intelligent grid-connected cabinet, characterized in that: It includes power grid monitoring module, power adjustment module, adaptive module and inverter control module; among which: The power grid monitoring module is used to monitor the voltage and frequency of the power grid; The power adjustment module adjusts the active power and reactive power of the inverter through the power adjustment equation based on the voltage and frequency of the power grid; The power adjustment equation includes a first adjustment equation and a second adjustment equation; the power adjustment module includes a first adjustment unit, the first adjustment unit is configured with a first adjustment equation, and is used to adjust the active power of the inverter according to the frequency of the power grid; the first adjustment equation is specifically as follows: ； in, Indicates the adjustment value of active power; Indicates the reference active power; represents the frequency control coefficient; Indicates the frequency deviation value, and the calculation formula is as follows: ； Where, f represents the grid frequency measured by the frequency monitoring unit, Indicates the reference frequency of the power grid; The power adjustment module further includes a second adjustment unit; the second adjustment unit is configured with a second adjustment equation for adjusting the reactive power of the inverter according to the voltage of the power grid; the second adjustment equation is specifically as follows: ； in, Indicates the adjustment value of reactive power; Indicates the reference reactive power; represents the voltage control coefficient; Indicates the voltage deviation value, and the calculation formula is as follows: ； Wherein, V represents the grid voltage measured by the voltage monitoring unit; Indicates the reference voltage of the power grid; The adaptive module is used for adaptively adjusting the equation parameters of the power adjustment equation; The adaptive module includes a parameter updating unit; the parameter updating unit is configured with a parameter updating equation, and adaptively updates the values ​​of the frequency control coefficient and the voltage control coefficient through an adaptive factor; the parameter updating equation is specifically as follows: ； ； in, represents the frequency control coefficient at time t; represents the frequency control coefficient at time t-1; Indicates the adjustment value of active power at time t; Indicates the adjustment value of active power at time t-1; represents the voltage control coefficient at time t; represents the voltage control coefficient at time t-1; Indicates the adjustment value of reactive power at time t; Indicates the adjustment value of reactive power at time t-1; , All are adaptive factors; represents the first adjustment factor, Represents the second adjustment factor, and the value selection rule is as follows: If the grid frequency is higher than the reference frequency at time t, then The value is 1, otherwise, The value is 0; if the grid voltage is higher than the reference voltage at time t, then The value is 1, otherwise, The value is 0; The parameter updating unit is also configured with a parameter restriction strategy, which is as follows: Let the frequency control coefficient take the range of to ,in Indicates the minimum value of the frequency control coefficient, Represents the maximum value of the frequency control coefficient; the frequency control coefficient at time t is calculated by the parameter update equation ,like Less than , then let The value is equal to ;like Greater than , then let The value is equal to ; Let the voltage control coefficient take the range of to ,in Indicates the minimum value of the voltage control coefficient, Represents the maximum value of the voltage control coefficient; the voltage control coefficient at time t is calculated by the parameter update equation ,like Less than , then let The value is equal to ;like Greater than , then let The value is equal to ; The inverter control module generates a control signal for adjusting the inverter output based on the adjusted active power and reactive power of the inverter.

2. The bidirectional inverter energy conversion system for the intelligent grid-connected cabinet according to claim 1, characterized in that: The adaptive module further includes an adaptive optimization unit; the adaptive optimization unit is configured with an optimization strategy for optimizing the value of the adaptive factor, and the specific steps are as follows: S101: Set the population size, maximum number of iterations, crossover probability, mutation probability, and generate the initial population; The primary population contains N individuals, where N is the population size; each individual contains one chromosome, and each chromosome contains two genes, corresponding to the adaptive factors , ; S102: Calculate the fitness of each individual; Based on N individuals , , construct N groups of parameter update equations, conduct simulation experiments, obtain evaluation factors based on the simulation experiments, and calculate the fitness of individuals corresponding to the N groups of parameter update equations through the corresponding evaluation factors; S103: performing selection operation, crossover operation, and mutation operation in sequence, and generating the next generation population; S104: Repeat steps S102-S103 until the maximum number of iterations is reached; S105: Take the individual with the highest fitness in the last iteration , The value of is taken as the comprehensive optimization result of the adaptive factors.

3. The bidirectional inverter energy conversion system for the intelligent grid-connected cabinet according to claim 2, characterized in that: The inverter control module includes a reference signal unit; the reference signal unit calculates a reference signal of the inverter based on the adjusted active power and reactive power of the inverter; wherein the amplitude calculation formula of the reference signal is as follows: ； Where, E represents the amplitude of the reference signal; The phase calculation formula of the reference signal is as follows: ； in, Indicates the phase of the reference signal.

4. The bidirectional inverter energy conversion system for the intelligent grid-connected cabinet according to claim 3, characterized in that: The inverter control module also includes a control signal unit; the control signal unit generates a control signal for adjusting the inverter output based on the reference signal of the inverter, specifically as follows: select a high-frequency carrier, compare the control signal with the high-frequency carrier point by point, and generate a PWM modulation signal as the control signal for adjusting the inverter output.

5. A bidirectional inverter energy conversion method for an intelligent power cabinet, implemented based on the bidirectional inverter energy conversion system for an intelligent power cabinet according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1: Real-time monitoring of the voltage and frequency of the power grid; S2: Calculate the adjustment value of the reactive power of the inverter based on the voltage of the power grid, and calculate the adjustment value of the active power of the inverter based on the frequency of the power grid; S3: updating the frequency control coefficient and the voltage control coefficient based on the adjustment value of the active power and the adjustment value of the reactive power; S4: Correcting the adjustment value of the active power and the adjustment value of the reactive power of the inverter based on the updated frequency control coefficient and the voltage control coefficient; S5: Generate a control signal for adjusting the inverter output based on the adjustment value of the active power and the adjustment value of the reactive power of the inverter.

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