Power control system of grid-connected inverter

Abstract

The invention provides a power control system of a grid-connected inverter. The power control system comprises a topological structure module, a reactive power control module, a power regulation module, a switch control module, a voltage and current detection module and a feedback control module. Stable hardware support is constructed through the topological structure module, multiple optimization functions are achieved, other modules perform their own functions, reactive power control is accurate, power adjustment is flexible, switch control is accurate, a basis is provided for voltage and current detection, feedback control and intelligent closed loop are achieved, accurate control and efficient conversion are jointly achieved, and high-efficiency control is achieved. The system performance, reliability and power grid adaptability are improved, and stable and high-quality grid-connected power generation is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of power control of a grid-connected inverter, and in particular to a power control system of a grid-connected inverter. Background Art

[0002] With the widespread application of renewable energy, grid-connected inverters play a key role in distributed power generation systems such as photovoltaic and wind power. The traditional grid-connected inverter power control system topology has low efficiency, poor safety, difficult EMC design, and poor shock resistance. In terms of control strategy, it may be more sensitive to changes in system parameters, slow to respond, large steady-state errors, complex controller design, difficult parameter setting, and difficult to ensure system stability.

[0003] The power control technology of traditional grid-connected inverters has an unreasonable topology structure, cannot achieve bus capacitor voltage balance, leakage current is difficult to attenuate, multiple inductors increase cost, volume and loss, inaccurate reactive power control affects the power quality of the grid, power regulation is not flexible and efficient enough, poor collaboration among modules makes it difficult to give full play to their advantages, and the ability of precise control and efficient conversion is weak, resulting in poor overall system performance and reliability.

[0004] Therefore, it is necessary to design a power control system for a grid-connected inverter to solve the problems of unreasonable topological structure of the power control technology of the existing grid-connected inverter, which causes bus capacitor voltage imbalance, large leakage current, high cost and large loss, inaccurate reactive power control leading to poor power quality of the power grid, poor power regulation that cannot meet demand, and poor module collaboration that weakens the ability of precise control and efficient conversion, resulting in inefficiency, poor stability, and substandard power quality of the power control system of the grid-connected inverter, making it difficult to adapt to changes in the power grid, seriously affecting the normal operation and service life of the system, reducing its reliability and practicality in the power system, increasing maintenance costs and difficulty, and even posing a threat to the safe and stable operation of the power grid. Summary of the invention

[0005] In view of this, the present invention proposes a power control system for a grid-connected inverter, aiming to solve the problems of unreasonable topological structure of the power control technology of the existing grid-connected inverter, inability to achieve bus capacitor voltage balance, difficulty in attenuating leakage current, increased cost, volume and loss due to multiple inductors, inaccurate reactive power control affecting the power quality of the power grid, insufficient flexibility and efficiency in power regulation, poor collaboration among modules making it difficult to give full play to their advantages, weak precise control and efficient conversion capabilities, resulting in poor overall system performance and reliability.

[0006] In one aspect, the present invention provides a power control system for a grid-connected inverter, comprising:

[0007] 1. A power control system for a grid-connected inverter, comprising:

[0008] The topology module is composed of a DC power supply E, two electrolytic capacitors, six power switch tubes, a DC inductor, a filter circuit, an AC power grid and other components, as well as a specific connection method between the various components. Through these connections, the bus capacitor voltage balance, the leakage current attenuation to zero and the buck-boost function of the single DC inductor are achieved;

[0009] The reactive power control module controls the working state of the power switch tube and adjusts the reactive power according to the reactive power demand of the system, the voltage and current state of the grid. When the voltage and current of the grid meet specific conditions, the power switch tubes of different combinations are controlled to conduct at high frequency and complement each other, so that the inverter can provide reactive power support for the grid.

[0010] The power regulation module adjusts the inverter output power by controlling the on-time and off-time ratio of the power switch tube under the topological structure according to the DC power input and AC grid requirements. Under different electrolytic capacitor voltage and grid voltage relationships, the inverter is operated in buck or boost mode, and the working state of the corresponding power switch tube in each half cycle is clearly defined.

[0011] The switch control module accurately controls the on and off operations of the power switch tube according to the instructions of the power regulation module and the reactive power control module. In terms of power regulation, it ensures that the power switch tube works according to the buck or boost mode requirements. In terms of reactive power regulation, it realizes the complementary conduction control of the power switch tube in the inductive or capacitive reactive state, so that the inverter can stably output the required electric energy in different modes;

[0012] The voltage and current detection module monitors the voltage of the electrolytic capacitor on the DC side, the voltage and current of the AC side grid and other parameters in real time. The monitoring data is transmitted to the feedback control module in real time, providing a basis for the system to adjust and optimize according to the actual operation conditions.

[0013] A feedback control module receives the monitoring data of the voltage and current detection module and compares and analyzes it with the preset values ​​to determine whether the DC side capacitor voltage and the AC side voltage and current waveforms meet the requirements. If there is a deviation, an adjustment instruction is generated and sent to the power regulation module and the switch control module to optimize the working parameters;

[0014] The power regulation module formulates a strategy based on the system power demand and topology input and sends a signal to the switch control module. The switch control module controls the power switch tube according to the instructions to achieve power conversion and reactive power regulation. The voltage and current detection module monitors the parameters and feeds back to the feedback control module. The feedback control module optimizes the operation of other modules according to the feedback.

[0015] Furthermore, the topological structure module includes a DC power supply E, a first electrolytic capacitor Ce1 and a second electrolytic capacitor Ce2, a first power switch tube S1 to a sixth power switch tube S6, a first DC inductor L1, a filter circuit (filter inductor Lg and filter capacitor Cg) and an AC power grid Vg, and the connection method of the topological structure module is: the positive electrode of the DC power supply E is connected to the drain of the fifth power switch tube S5 and the positive electrode of the first electrolytic capacitor Ce1, and the negative electrode is connected to the source of the sixth power switch tube S6 and the negative electrode of the second electrolytic capacitor Ce2; the negative electrode of the first electrolytic capacitor Ce1 is connected to the positive electrode of the second electrolytic capacitor Ce2, the second power switch The drain of the gate tube S2, the second end of the filter capacitor Cg, the negative electrode of the AC power grid Vg and the ground; the source of the fifth power switch tube S5 is connected to the drain of the sixth power switch tube S6 and the first end of the DC inductor L1; the second end of the DC inductor L1 is connected to the drain of the first power switch tube S1 and the drain of the fourth power switch tube S4; the source of the first power switch tube S1 is connected to the source of the second power switch tube S2, and the source of the fourth power switch tube S4 is connected to the source of the third power switch tube S3; the drain of the third power switch tube S3 is connected to the first end of the filter capacitor Cg and the first end of the filter inductor Lg, and the second end of the filter inductor Lg is connected to the positive electrode of the AC power grid Vg.

[0016] Furthermore, the reactive power control module accurately controls the working state of the power switch tube according to the reactive power demand of the system to achieve effective regulation of reactive power. When the system operates in an inductive or capacitive reactive state, if the voltage of the AC power grid Vg is greater than zero and the grid-connected current is less than zero, the reactive power control module will make the second power switch tube S2, the third power switch tube S3 and the sixth power switch tube S6 work at high frequency, and ensure that the three switch tubes are complementary. When the voltage of the AC power grid Vg is less than zero and the grid-connected current is greater than zero, the reactive power control module will control the first power switch tube S1, the fourth power switch tube S4 and the fifth power switch tube S5 to work at high frequency and be complementary.

[0017] Furthermore, the power regulation module accurately regulates the inverter output power according to the actual needs of the DC power input and the AC power grid. The power regulation module realizes the power regulation function by controlling the on-time ratio of the power switch tube. In the positive half cycle of the AC voltage, the power regulation module instructs the fifth power switch tube S5 to work at a high frequency, and ensures that the fourth power switch tube S4 is turned on, and the other power switch tubes remain in the off state; in the negative half cycle of the AC voltage, the power regulation module enables the sixth power switch tube S6 to work at a high frequency, the third power switch tube S3 is turned on, and the other switch tubes are turned off. When the first electrolytic capacitor voltage VCE1 or the second electrolytic capacitor voltage VCe2 is less than the absolute value of the AC voltage of the AC grid Vg, the power regulation module controls the inverter to enter the boost mode; in the positive half cycle of the AC voltage, the power regulation module turns on the fifth power switch tube S5 and the fourth power switch tube S4, and at the same time makes the first power switch tube S1 work at high frequency, and the other switch tubes are disconnected; in the negative half cycle of the AC voltage, the power regulation module turns on the sixth power switch tube S6 and the third power switch tube S3, and the second power switch tube S2 works at high frequency, and the other power switch tubes remain disconnected.

[0018] Furthermore, the switch control module accurately controls the on and off operations of each power switch tube according to the instructions of the power regulation module and the control signal of the reactive power control module. The switch control module ensures that the corresponding power switch tube works according to the set timing and frequency according to the requirements of the power regulation module in the buck or boost mode; the switch control module realizes complementary conduction control of the power switch tube in the inductive or capacitive reactive state according to the instructions of the reactive power control module. When the reactive power control module requires the second power switch tube S2, the third power switch tube S3 and the sixth power switch tube S6 to be turned on at high frequency and complementarily, the switch control module will accurately control the drive signals of the three switch tubes so that they work according to the complementary logic to ensure accurate regulation of reactive power.

[0019] Furthermore, the voltage and current detection module accurately measures the voltage across the first electrolytic capacitor Ce1 and the second electrolytic capacitor Ce2, monitors the voltage and current of the AC power grid Vg, and obtains the operating status information of the system and transmits it to the feedback control module in real time.

[0020] Furthermore, the feedback control module receives real-time monitoring data from the voltage and current detection module, and compares and analyzes these data with the target values ​​preset by the system. When there is a deviation between the actual measured value and the preset value, the feedback control module generates corresponding adjustment instructions according to the size and direction of the deviation, and sends the adjustment instructions to the power regulation module and the switch control module respectively.

[0021] Furthermore, the power regulation module formulates a preliminary power conversion strategy according to the power demand of the system and the input conditions of the topology module, and sends a control signal to the switch control module; the switch control module accurately controls the on and off of the power switch tube according to the instructions of the power regulation module and the reactive power control module to achieve power conversion and reactive power regulation; the voltage and current detection module monitors the circuit parameters in real time and feeds back the data to the feedback control module; the feedback control module optimizes and adjusts the work of the power regulation module and the switch control module according to the feedback information.

[0022] Compared with the prior art, the beneficial effect of the present invention is that the power control system of the grid-connected inverter of the present invention provides a stable hardware foundation through the topological structure module, realizes bus capacitor voltage balance, leakage current attenuation and single inductor buck-boost, reduces cost and loss; the reactive power control module accurately adjusts reactive power to improve the power quality of the power grid; the power regulation module flexibly converts power according to demand; the switch control module accurately operates the switch tube; the voltage and current detection module provides a basis for real-time monitoring; the feedback control module intelligently closes the loop for optimization. Each module works closely together to give full play to its own advantages, realize precise control and efficient conversion, improve the overall performance, reliability and adaptability of the system to the power grid, and ensure stable and high-quality grid-connected power generation. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0024] Figure 1 A functional block diagram of a power control system of a grid-connected inverter according to an embodiment of the present invention;

[0025] Figure 2 A circuit diagram of a power control system of a grid-connected inverter according to an embodiment of the present invention;

[0026] Figure 3 It is a voltage and current waveform diagram of the power control system of the grid-connected inverter of the present invention when the voltages of the two electrolytic capacitors VCE1 and VCe2 are greater than the peak value of the grid voltage;

[0027] Figure 4 It is a voltage and current waveform diagram of the power control system of the grid-connected inverter of the present invention when the voltages of the two electrolytic capacitors VCE1 and VCE2 are less than the peak value of the grid voltage;

[0028] Figure 5The power control system of the grid-connected inverter of the present invention is a voltage and current waveform when the two electrolytic capacitor voltages VCE1 and VCE2 suddenly change;

[0029] Figure 6 The voltage and current waveforms of the power control system of the grid-connected inverter of the present invention when a sudden change occurs in the grid voltage;

[0030] Figure 7 The voltage and current waveforms of the power control system of the grid-connected inverter of the present invention when the power factor is 0.9;

[0031] Figure 8 It is the voltage and current waveform of the power control system of the grid-connected inverter of the present invention when energy flows from the AC side to the DC side. DETAILED DESCRIPTION

[0032] The exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to be able to fully convey the scope of the present invention to those skilled in the art. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with the implementation regulations.

[0033] Reference Figure 1 As shown, in some embodiments of the present application, a power control system of a grid-connected inverter includes:

[0034] The topology module is composed of a DC power supply E, two electrolytic capacitors, six power switch tubes, a DC inductor, a filter circuit, an AC power grid and other components, as well as a specific connection method between the various components. Through these connections, the bus capacitor voltage balance, the leakage current attenuation to zero and the buck-boost function of the single DC inductor are achieved;

[0035] The reactive power control module controls the working state of the power switch tube and adjusts the reactive power according to the reactive power demand of the system, the voltage and current state of the grid. When the voltage and current of the grid meet specific conditions, the power switch tubes of different combinations are controlled to conduct at high frequency and complement each other, so that the inverter can provide reactive power support for the grid.

[0036] The power regulation module adjusts the inverter output power by controlling the on-time and off-time ratio of the power switch tube under the topological structure according to the DC power input and AC grid requirements. Under different electrolytic capacitor voltage and grid voltage relationships, the inverter is operated in buck or boost mode, and the working state of the corresponding power switch tube in each half cycle is clearly defined.

[0037] The switch control module accurately controls the on and off operations of the power switch tube according to the instructions of the reactive power control module of the power regulation module. In terms of power regulation, it ensures that the power switch tube works according to the buck or boost mode requirements. In terms of reactive power regulation, it realizes the complementary conduction control of the power switch tube in the inductive or capacitive reactive state, so that the inverter can stably output the required electric energy in different modes;

[0038] The voltage and current detection module monitors the voltage of the electrolytic capacitor on the DC side, the voltage and current of the AC side grid and other parameters in real time. The monitoring data is transmitted to the feedback control module in real time, providing a basis for the system to adjust and optimize according to the actual operation conditions.

[0039] The feedback control module receives the monitoring data of the voltage and current detection module and compares and analyzes it with the preset values ​​to determine whether the DC side capacitor voltage and the AC side voltage and current waveforms meet the requirements. If there is a deviation, an adjustment instruction is generated and sent to the power regulation module and the switch control module to optimize the working parameters;

[0040] The power regulation module formulates a strategy based on the system power demand and topology input and sends a signal to the switch control module. The switch control module controls the power switch tube according to the instructions to achieve power conversion and reactive power regulation. The voltage and current detection module monitors the parameters and feeds back to the feedback control module. The feedback control module optimizes the operation of other modules based on the feedback.

[0041] It can be understood that the topology module realizes multiple functions through specific connections, laying the foundation for the stable operation of the system; the reactive power control module can accurately adjust the reactive power according to the grid status to ensure the power quality of the grid; the power regulation module can flexibly adjust the inverter power according to the input and output requirements to adapt to different working conditions; the switch control module accurately executes control instructions to ensure the accuracy of power conversion and reactive power regulation; the voltage and current detection module monitors parameters in real time to provide key data for system adjustment; the feedback control module analyzes and optimizes based on the detection data, so that the entire system can automatically adjust the working parameters according to the actual situation, improve the stability, reliability and power quality of the system, realize efficient power conversion and reactive power regulation, ensure the stable and reliable operation of the grid-connected inverter under different working conditions, and effectively improve the overall performance of the system.

[0042] Reference Figure 2As shown, specifically, the topology module is the hardware foundation of the entire grid-connected inverter, and its structural design directly affects the system performance. In the present invention, the module includes a DC power supply E, a first electrolytic capacitor Ce1 and a second electrolytic capacitor Ce2 (as DC bus capacitors and equal in size), a first power switch tube S1 to a sixth power switch tube S6 (which can be a metal oxide semiconductor field effect transistor or other replaceable high-frequency power switch tube), a first DC inductor L1, a filter circuit (filter inductor Lg and filter capacitor Cg) and an AC power grid Vg. The connection method is as follows: the positive electrode of the DC power supply E is connected to the drain of the fifth power switch tube S5 and the positive electrode of the first electrolytic capacitor Ce1, and the negative electrode is connected to the source of the sixth power switch tube S6 and the negative electrode of the second electrolytic capacitor Ce2; the negative electrode of the first electrolytic capacitor Ce1 is connected to the positive electrode of the second electrolytic capacitor Ce2, the drain of the second power switch tube S2, the second end of the filter capacitor Cg, the negative electrode of the AC power grid Vg and the ground; the source of the fifth power switch tube S5 is connected to the drain of the sixth power switch tube S6 and the first end of the DC inductor L1; the second end of the DC inductor L1 is connected to the drain of the first power switch tube S1 and the drain of the fourth power switch tube S4; the source of the first power switch tube S1 is connected to the source of the second power switch tube S2, and the source of the fourth power switch tube S4 is connected to the source of the third power switch tube S3; the drain of the third power switch tube S3 is connected to the first end of the filter capacitor Cg and the first end of the filter inductor Lg, and the second end of the filter inductor Lg is connected to the positive electrode of the AC power grid Vg. This topology achieves busbar capacitor voltage balance through unique component layout and connection relationship. The midpoint of the two electrolytic capacitors is grounded so that the electrolytic capacitor voltage is equal to the common mode voltage and constant, thereby effectively attenuating the leakage current to zero. At the same time, only one DC inductor L1 is needed to achieve the boost and buck functions, reducing costs and volume, and the inductor voltage drop in the power circuit is minimized, reducing power loss.

[0043] It can be understood that the ingenious combination of DC power supply E, electrolytic capacitors, power switching tubes, DC inductors, filter circuits and AC power grid achieves bus capacitor voltage balance, ensures system voltage stability, and reduces the adverse effects of voltage fluctuations on the system; it decays the leakage current to zero, greatly improves the safety of the system, and reduces the risk of leakage; at the same time, the step-up and step-down function of a single DC inductor enables the system to flexibly adapt to different voltage input and output requirements, and enhances the system's adaptability to grid voltage changes, thereby providing a solid foundation for the efficient, stable and safe operation of the entire power control system.

[0044] Reference Figure 2As shown, specifically, the reactive power control module is responsible for accurately controlling the working state of the power switch tube according to the reactive power demand of the system to achieve effective regulation of reactive power. When the system works in an inductive or capacitive reactive state, if the voltage of the AC power grid Vg is greater than zero and the grid current is less than zero, the module will make the second power switch tube S2, the third power switch tube S3 and the sixth power switch tube S6 work at high frequency, and ensure that the three switch tubes are complementary to each other, that is, only one switch tube is in the on state at the same time, and the other power switch tubes remain disconnected. When the voltage of the AC power grid Vg is less than zero and the grid current is greater than zero, the reactive power control module will control the first power switch tube S1, the fourth power switch tube S4 and the fifth power switch tube S5 to work at high frequency and complementary conduction. In this way, precise control of reactive power is achieved, so that the inverter can provide inductive or capacitive reactive support according to the grid demand, and the power quality and stability of the grid are improved.

[0045] It can be understood that the reactive power control module can ensure that the inverter provides the required reactive support in real time according to the actual situation of the power grid, effectively maintain the power balance of the power grid, improve the power quality of the power grid, reduce the impact of reactive power fluctuations on the stability of the power grid, enhance the system's adaptability to dynamic changes in the power grid, ensure the safe, stable and efficient operation of the power system, avoid adverse phenomena such as voltage drops and increased harmonics caused by reactive power problems, and improve the operating reliability and economy of the entire power system.

[0046] Reference Figure 2 - Figure 4As shown, specifically, the power regulation module plays a key role in power coordination and conversion in the entire system. It accurately regulates the output power of the inverter according to the actual needs of the DC power input and the AC power grid. Under the topological structure of the present invention, the module realizes the power regulation function by controlling the on-time and off-time ratio of the power switch tube. For example, when the first electrolytic capacitor voltage VCe1 and the second electrolytic capacitor voltage VCe2 are greater than the absolute value of the AC voltage of the AC power grid Vg, the power regulation module will make the inverter work in the buck mode. In the positive half cycle of the AC voltage, it instructs the fifth power switch tube S5 to work at high frequency, while ensuring that the fourth power switch tube S4 is turned on, and the remaining power switch tubes remain disconnected; in the negative half cycle of the AC voltage, the sixth power switch tube S6 is made to work at high frequency, the third power switch tube S3 is turned on, and the remaining switch tubes are disconnected. When the first electrolytic capacitor voltage VCe1 or the second electrolytic capacitor voltage VCe2 is less than the absolute value of the AC voltage of the AC power grid Vg, the power regulation module will control the inverter to enter the boost mode. In the positive half cycle of the AC voltage, the fifth power switch tube S5 and the fourth power switch tube S4 are turned on, and the first power switch tube S1 is operated at high frequency, and the other switch tubes are disconnected; in the negative half cycle of the AC voltage, the sixth power switch tube S6 and the third power switch tube S3 are turned on, the second power switch tube S2 is operated at high frequency, and the other power switch tubes remain disconnected. In this way, the power regulation module can flexibly adjust the working state of the power switch tube according to different voltage conditions, realize efficient power conversion, and meet the power grid's demand for active power.

[0047] It can be understood that based on the DC power input and AC grid demand, the on-time ratio of the power switch tube is flexibly controlled on the basis of the topological structure, and the inverter output power is accurately adjusted, thereby achieving precise power matching and improving the system energy utilization rate; it can automatically switch the inverter working mode according to the relationship between the electrolytic capacitor voltage and the grid voltage, so that it can smoothly switch between the buck or boost mode, effectively respond to grid voltage fluctuations, and ensure the stability of the output power quality; at the same time, it clarifies the working status of the power switch tube in each half cycle, ensures the orderliness and reliability of the power regulation process, and enhances the system's adaptability to complex working conditions, thereby improving the stability, efficiency and adaptability of the entire grid-connected inverter power control system to meet diverse power needs.

[0048] Reference Figure 2As shown, specifically, the switch control module mainly controls the on and off operations of each power switch tube precisely according to the instructions of the power regulation module and the control signal of the reactive power control module. In terms of power regulation, it strictly follows the requirements of the power regulation module in the buck or boost mode to ensure that the corresponding power switch tube works according to the set timing and frequency. For example, in the positive half cycle of the buck mode, when the fifth power switch tube S5 high-frequency working instruction issued by the power regulation module is received, the switch control module will provide a suitable drive signal to make S5 high-frequency conduction and off, while keeping the fourth power switch tube S4 stably turned on, and other switches reliably disconnected. In terms of reactive power regulation, the switch control module implements complementary conduction control of the power switch tube in the inductive or capacitive reactive state according to the instructions of the reactive power control module. When the reactive power control module requires the second power switch tube S2, the third power switch tube S3 and the sixth power switch tube S6 to be high-frequency and complementary, the switch control module will accurately control the drive signals of the three switch tubes so that they work according to the complementary logic to ensure accurate regulation of reactive power. By precisely controlling the power switch tube, the switch control module ensures the normal operation of the entire circuit and the effective conversion of power, enabling the inverter to stably output electrical energy that meets the requirements in different operating modes.

[0049] It is understandable that the switch control module accurately controls the on and off operations of the power switch tube according to the instructions of the power regulation module and the reactive power control module, which is of great significance to the power control system of the grid-connected inverter. During power regulation, it can accurately ensure that the power switch tube works according to the buck or boost mode requirements, realize the precise adjustment of the inverter output power, adapt it to different power inputs and grid requirements, and improve the power adaptability and energy conversion efficiency of the system; in terms of reactive regulation, the complementary conduction control of the power switch tube in the inductive or capacitive reactive state is realized, effectively maintaining the reactive power balance of the grid, stabilizing the grid voltage, reducing the negative impact of reactive current on the system, and ensuring the power quality of the grid. Ultimately, the inverter can stably output the required electric energy under various complex working conditions and different working modes, greatly improving the stability, reliability and power quality of the entire grid-connected inverter power control system, and ensuring the safe and efficient operation of the power system.

[0050] Reference Figure 3 - Figure 8As shown, specifically, the voltage and current detection module is responsible for real-time monitoring of the key voltage and current parameters in the system, providing a basis for the precise control of the system. It mainly measures the voltage on the DC side, that is, the voltage at both ends of the first electrolytic capacitor Ce1 and the second electrolytic capacitor Ce2, because these two voltage values ​​directly reflect the voltage state of the DC bus, which has an important impact on the stability and power conversion efficiency of the system. At the same time, the module closely monitors the voltage (voltage of the AC power grid Vg) and current (grid current) on the AC side. Through real-time monitoring of these voltage and current parameters, the voltage and current detection module can obtain the operating status information of the system in time, such as the fluctuation of the grid voltage, the size and phase of the inverter output current, etc. This information is transmitted to the feedback control module in real time, so that the system can be adjusted and optimized accordingly according to the actual operating conditions, ensuring that the inverter is always running in the best working state, and ensuring the quality and stability of the output electric energy.

[0051] It is understandable that the voltage and current detection module monitors the parameters such as the voltage of the electrolytic capacitor on the DC side, the voltage and current of the AC side grid in the system in real time and transmits them to the feedback control module in real time, which is extremely critical to the power control system of the grid-connected inverter. It is like the "sensory organ" of the system, providing the system with comprehensive and real-time operating status information, so that the system can detect any abnormalities or changes in the operation process in a timely manner based on these accurate data. Based on these monitoring data, the feedback control module can make accurate judgments and then make targeted adjustments and optimizations to the system to ensure that the system always operates in the best working state, effectively improve the stability, reliability and control accuracy of the system, avoid equipment damage and power quality degradation caused by abnormal voltage and current, and ensure that the entire grid-connected inverter power control system outputs high-quality electricity to the grid safely, efficiently and stably.

[0052] Specifically, the feedback control module is the intelligent core of the power control system. It receives real-time monitoring data from the voltage and current detection module, and compares and analyzes these data with the preset target values ​​of the system. For example, the detected DC side capacitor voltage is compared with the preset stable voltage value to determine whether it is within the allowable error range; the voltage and current waveforms on the AC side are analyzed to evaluate whether their sinusoidality meets the grid connection requirements and whether the power factor meets the expected standard. If a deviation is found between the actual measured value and the preset value, the feedback control module will generate corresponding adjustment instructions according to the size and direction of the deviation. These adjustment instructions will be sent to the power regulation module and the switch control module respectively, prompting them to optimize and adjust the working parameters. For example, when it is detected that the grid voltage suddenly rises and causes the inverter output power to fluctuate, the feedback control module will notify the power regulation module to appropriately reduce the output power, and instruct the switch control module to adjust the operating frequency or conduction time of the power switch tube to maintain the stable operation of the system. Through this closed-loop feedback control mechanism, the feedback control module can dynamically adjust the working state of the system in real time to ensure that the power quality output by the inverter meets the grid requirements and realize efficient and stable grid-connected power generation.

[0053] It is understandable that the feedback control module receives the monitoring data of the voltage and current detection module and makes an accurate comparison and analysis with the preset values, and can keenly judge whether the DC side capacitor voltage and the AC side voltage and current waveform meet the requirements. Once a deviation is found, it quickly generates an adjustment instruction and sends it to the power regulation module and the switch control module. This enables the system to optimize power regulation and switch control in a timely and accurate manner, ensuring that the system always maintains an efficient and stable operating state. It effectively avoids a series of problems that may be caused by abnormal voltage and current, such as equipment damage and reduced power quality, greatly improves the reliability, stability and control accuracy of the system, ensures that the grid-connected inverter power control system continuously outputs high-quality electricity to the power grid, and improves the operating performance of the entire power system.

[0054] Specifically, in the entire power control system, each module closely cooperates to form an organic whole. The topology module provides the hardware foundation for other modules, and its stable structure and characteristics ensure the realization of the basic functions of the system. The power regulation module formulates a preliminary power conversion strategy based on the power demand of the system and the input conditions of the topology module, and sends the control signal to the switch control module. The switch control module accurately controls the conduction and shutdown of the power switch tube according to the instructions of the power regulation module and the reactive power control module to achieve power conversion and reactive power regulation. The voltage and current detection module monitors the circuit parameters in real time and feeds the data back to the feedback control module. The feedback control module optimizes and adjusts the work of the power regulation module and the switch control module based on these feedback information to ensure that the system always maintains stable and efficient operation. For example, when the reactive power control module adjusts the working state of the power switch tube according to the reactive power demand of the power grid, the switch control module performs the corresponding operation. During this process, the voltage and current detection module continuously monitors the changes in relevant parameters. The feedback control module determines whether the system has achieved the expected reactive power regulation effect based on the detection data. If not, the working parameters of the power regulation module and the switch control module are further adjusted until the system is stably running in the best state. Through this collaborative working mechanism, each module cooperates with each other to give full play to the innovative advantages of topological structure and reactive power control method, realize precise control and efficient conversion of grid-connected inverter power, and improve the overall performance and reliability of the system.

[0055] It is understandable that the modules work closely together to form an efficient closed-loop control system, which can automatically adjust in real time according to the actual operating conditions of the system, ensure accurate and efficient power conversion, timely and reasonable reactive power regulation, maintain system power balance and stable grid power quality; can quickly adapt to different operating conditions and load changes, effectively improve the system's dynamic response capability, stability and reliability, reduce energy waste, extend equipment life, and ensure that the grid-connected inverter operates continuously, stably and efficiently in a complex and changeable grid environment, providing high-quality electricity for the grid.

[0056] It should be noted that:

[0057] In the description provided herein, a large number of specific details are described. However, it is understood that the embodiments of the present application can be practiced without these specific details. In some instances, well-known structures and technologies are not shown in detail so as not to obscure the understanding of this description.

[0058] Furthermore, those skilled in the art will appreciate that although some embodiments described herein include certain features included in other embodiments but not other features, the combination of features from different embodiments is meant to be within the scope of the present application and to form different embodiments.

[0059] The above is only a preferred specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A power control system for a grid-connected inverter, characterized in that: include: The topology module is composed of a DC power supply E, two electrolytic capacitors, six power switch tubes, a DC inductor, a filter circuit, an AC power grid and other components, as well as a specific connection method between the various components. Through these connections, the bus capacitor voltage balance, the leakage current attenuation to zero and the buck-boost function of the single DC inductor are achieved; The reactive power control module controls the working state of the power switch tube and adjusts the reactive power according to the reactive power demand of the system, the voltage and current state of the grid. When the voltage and current of the grid meet specific conditions, the power switch tubes of different combinations are controlled to conduct at high frequency and complement each other, so that the inverter can provide reactive power support for the grid. The power regulation module adjusts the inverter output power by controlling the on-time and off-time ratio of the power switch tube under the topological structure according to the DC power input and AC grid requirements. Under different electrolytic capacitor voltage and grid voltage relationships, the inverter is operated in buck or boost mode, and the working state of the corresponding power switch tube in each half cycle is clearly defined. The switch control module accurately controls the on and off operations of the power switch tube according to the instructions of the power regulation module and the reactive power control module. In terms of power regulation, it ensures that the power switch tube works according to the buck or boost mode requirements. In terms of reactive power regulation, it realizes the complementary conduction control of the power switch tube in the inductive or capacitive reactive state, so that the inverter can stably output the required electric energy in different modes; The voltage and current detection module monitors the voltage of the electrolytic capacitor on the DC side, the voltage and current of the AC side grid and other parameters in real time. The monitoring data is transmitted to the feedback control module in real time, providing a basis for the system to adjust and optimize according to the actual operation conditions. A feedback control module receives the monitoring data of the voltage and current detection module and compares and analyzes it with the preset values ​​to determine whether the DC side capacitor voltage and the AC side voltage and current waveforms meet the requirements. If there is a deviation, an adjustment instruction is generated and sent to the power regulation module and the switch control module to optimize the working parameters; The power regulation module formulates a strategy based on the system power demand and topology input and sends a signal to the switch control module. The switch control module controls the power switch tube according to the instructions to achieve power conversion and reactive power regulation. The voltage and current detection module monitors the parameters and feeds back to the feedback control module. The feedback control module optimizes the operation of other modules according to the feedback.

2. The power control system of a grid-connected inverter according to claim 1, characterized in that: The topological structure module includes a DC power supply E, a first electrolytic capacitor Ce1 and a second electrolytic capacitor Ce2, a first power switch tube S1 to a sixth power switch tube S6, a first DC inductor L1, a filter circuit (filter inductor Lg and filter capacitor Cg) and an AC power grid Vg. The connection method of the topological structure module is as follows: the positive electrode of the DC power supply E is connected to the drain of the fifth power switch tube S5 and the positive electrode of the first electrolytic capacitor Ce1, and the negative electrode is connected to the source of the sixth power switch tube S6 and the negative electrode of the second electrolytic capacitor Ce2; the negative electrode of the first electrolytic capacitor Ce1 is connected to the positive electrode of the second electrolytic capacitor Ce2, the second power switch tube S5 and the negative electrode of the first electrolytic capacitor Ce2. S2 drain, the second end of the filter capacitor Cg, the negative electrode of the AC power grid Vg and the ground; the source of the fifth power switch tube S5 is connected to the drain of the sixth power switch tube S6 and the first end of the DC inductor L1; the second end of the DC inductor L1 is connected to the drain of the first power switch tube S1 and the drain of the fourth power switch tube S4; the source of the first power switch tube S1 is connected to the source of the second power switch tube S2, and the source of the fourth power switch tube S4 is connected to the source of the third power switch tube S3; the drain of the third power switch tube S3 is connected to the first end of the filter capacitor Cg and the first end of the filter inductor Lg, and the second end of the filter inductor Lg is connected to the positive electrode of the AC power grid Vg.

3. The power control system of a grid-connected inverter according to claim 2, characterized in that: The reactive power control module accurately controls the working state of the power switch tube according to the reactive power demand of the system to achieve effective regulation of reactive power. When the system works in an inductive or capacitive reactive state, if the voltage of the AC power grid Vg is greater than zero and the grid-connected current is less than zero, the reactive power control module will make the second power switch tube S2, the third power switch tube S3 and the sixth power switch tube S6 work at high frequency, and ensure that the three switch tubes are complementary. When the voltage of the AC power grid Vg is less than zero and the grid-connected current is greater than zero, the reactive power control module will control the first power switch tube S1, the fourth power switch tube S4 and the fifth power switch tube S5 to work at high frequency and be complementary.

4. The power control system of a grid-connected inverter according to claim 3, characterized in that: The power regulation module accurately regulates the inverter output power according to the actual needs of the DC power input and the AC power grid. The power regulation module realizes the power regulation function by controlling the on-time and off-time ratio of the power switch tube. In the positive half cycle of the AC voltage, the power regulation module instructs the fifth power switch tube S5 to work at high frequency, and ensures that the fourth power switch tube S4 is turned on, and the other power switch tubes remain disconnected; in the negative half cycle of the AC voltage, the power regulation module enables the sixth power switch tube S6 to work at high frequency, the third power switch tube S3 is turned on, and the other switch tubes are disconnected. When the first electrolytic capacitor voltage VCE1 or the second electrolytic capacitor voltage VCe2 is less than the absolute value of the AC voltage of the AC power grid Vg, the power regulation module controls the inverter to enter the boost mode; in the positive half cycle of the AC voltage, the power regulation module turns on the fifth power switch tube S5 and the fourth power switch tube S4, and at the same time makes the first power switch tube S1 work at high frequency, and the other switch tubes are disconnected; in the negative half cycle of the AC voltage, the power regulation module turns on the sixth power switch tube S6 and the third power switch tube S3, and the second power switch tube S2 works at high frequency, and the other power switch tubes remain disconnected.

5. The power control system of a grid-connected inverter according to claim 4, characterized in that: The switch control module accurately controls the on and off operations of each power switch tube according to the instructions of the power regulation module and the control signal of the reactive power control module. The switch control module ensures that the corresponding power switch tube works according to the set timing and frequency according to the requirements of the power regulation module in the buck or boost mode; the switch control module realizes complementary conduction control of the power switch tube in the inductive or capacitive reactive state according to the instructions of the reactive power control module. When the reactive power control module requires the second power switch tube S2, the third power switch tube S3 and the sixth power switch tube S6 to be turned on at high frequency and complementary, the switch control module will accurately control the driving signals of the three switch tubes so that they work according to the complementary logic to ensure accurate regulation of reactive power.

6. The power control system of a grid-connected inverter according to claim 5, characterized in that: The voltage and current detection module accurately measures the voltage across the first electrolytic capacitor Ce1 and the second electrolytic capacitor Ce2, monitors the voltage and current of the AC power grid Vg, and obtains the operating status information of the system and transmits it to the feedback control module in real time.

7. The power control system of a grid-connected inverter according to claim 6, characterized in that: The feedback control module receives real-time monitoring data from the voltage and current detection module, and compares and analyzes these data with the target values ​​preset by the system. When there is a deviation between the actual measured value and the preset value, the feedback control module generates corresponding adjustment instructions according to the size and direction of the deviation, and sends the adjustment instructions to the power regulation module and the switch control module respectively.

8. The power control system of a grid-connected inverter according to claim 7, characterized in that: The power regulation module formulates a preliminary power conversion strategy according to the power demand of the system and the input conditions of the topology module, and sends a control signal to the switch control module; the switch control module accurately controls the on and off of the power switch tube according to the instructions of the power regulation module and the reactive power control module to achieve power conversion and reactive power regulation; the voltage and current detection module monitors the circuit parameters in real time and feeds back the data to the feedback control module; the feedback control module optimizes and adjusts the work of the power regulation module and the switch control module according to the feedback information.

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