Network construction-network following hybrid electric energy regulator and regulation method

Abstract

The invention discloses a network construction-network following hybrid electric energy regulator and a regulation method. The regulator comprises a magnetic integrated three-winding transformer, a first solid-state power electronic switch, a second solid-state power electronic switch, a first AC / DC bidirectional converter, a second AC / DC bidirectional converter, a DC / DC bidirectional converter, a super capacitor, an energy storage battery, an LC type filter and an LCL type filter. The first AC / DC bidirectional converter and the second AC / DC bidirectional converter respectively adopt network construction type control and network following type control, and the first AC / DC bidirectional converter also has a pre-synchronization control function. And the DC / DC bidirectional converter adopts constant power control. The system disclosed by the invention can realize uninterrupted power supply under the condition of abnormal voltage caused by power grid faults and disturbance, remarkably improves grid-connected compatibility under normal working conditions, and has remarkable advantages in the aspects of cost effectiveness and reliability.

Description

Technical Field

[0001] This invention belongs to the field of urban power distribution networks, specifically relating to a hybrid power regulator and regulation method for grid-connected systems. Background Technology

[0002] In recent years, the rapid development of electric vehicles and new energy sectors has led to a large-scale integration of electric vehicle loads and distributed new energy power generation equipment into urban power distribution networks. Simultaneously, accelerated industrial upgrading has resulted in increased electricity consumption and higher power quality requirements from high-end manufacturing industries. Against this backdrop, urban power distribution networks face several key challenges: 1) Although advanced relay protection systems have reduced large-scale, long-term power outages, user losses due to voltage dips caused by transient faults such as large transformer switching and single-phase motor start-stop have increased significantly; 2) Frequent electric vehicle load surges cause severe overloads in distribution transformers, yet overall utilization remains low, leading to a large demand for dynamic capacity expansion; 3) Backfeeding from new energy sources results in frequent voltage exceedances, increasing the need for local absorption; 4) The mixed connection of single / three-phase loads with active / passive loads causes significant single-phase overloads and three-phase imbalances; 5) Space constraints in urban power distribution stations pose challenges to post-construction expansion and technological upgrades. Therefore, there is an urgent need to explore power distribution network solutions that ensure high power supply reliability, provide flexible adjustment capabilities, and employ compact designs.

[0003] Currently, existing technologies focus on improving the voltage level on the user side of urban power distribution networks, including Static Synchronous Compensators (STATCOMs), Dynamic Voltage Restorers (DVRs), and Uninterruptible Power Supplies (UPSs). STATCOMs indirectly improve the supply voltage and power factor at the point of common coupling by compensating for reactive power, but due to the lack of energy storage units, they cannot support direct voltage control or maintain voltage stability during faults. DVRs are voltage management devices connected in series on the primary side of the power supply, providing instant voltage correction and protecting sensitive industrial equipment from voltage dips and swells; however, their integration with existing power systems is complex, typically requiring specialized maintenance and potentially introducing reliability issues. UPSs are reliable solutions providing continuous operation for critical facilities such as data centers, hospitals, and communication systems; however, because they operate as voltage sources, their output current is uncontrollable, negatively impacting power capacity utilization (note: power electronics-based power supply equipment has extremely limited overload capacity), and battery replacement costs due to aging are high. Furthermore, achieving high-reliability power supply in urban power distribution networks faces challenges such as severe forward and reverse overloads, three-phase imbalance, and low power factor. Therefore, developing a flexible power supply system with high power supply reliability and realizing comprehensive control of medium and low voltage systems has become an urgent technical challenge. Summary of the Invention

[0004] This application provides a grid-connected hybrid power regulator and regulation method to achieve high-reliability power supply and comprehensive regulation of medium and low voltage systems in urban power distribution networks.

[0005] In a first aspect, this application provides a grid-connected hybrid power regulator, which includes a first solid-state power electronic switch, a second solid-state power electronic switch, a magnetically integrated three-winding transformer, a first AC / DC bidirectional converter, a second AC / DC bidirectional converter, a DC / DC bidirectional converter, a supercapacitor, an energy storage battery, an LCL filter, and an LC filter. The first solid-state power electronic switch is connected in series between the power grid and the three-winding transformer. The second solid-state power electronic switch is connected in series between the magnetically integrated three-winding transformer and the first AC / DC bidirectional converter. The first AC / DC bidirectional converter is connected to the load through the LC filter and then through the magnetically integrated three-winding transformer. The second AC / DC bidirectional converter is connected to the load through the LCL filter. The supercapacitor is connected to the common DC bus of the first AC / DC bidirectional converter and the second AC / DC bidirectional converter through the DC / DC bidirectional converter. The energy storage battery is directly connected to the DC bus of the first AC / DC bidirectional converter and the second AC / DC bidirectional converter.

[0006] Preferably, one end of the first AC / DC bidirectional converter is connected to the low-voltage side of the magnetically integrated three-winding transformer, and the other end is connected to one end of the second AC / DC bidirectional converter; the other end of the second AC / DC bidirectional converter is connected to an LCL filter.

[0007] Preferably, the output filter inductor of the first AC / DC bidirectional converter is integrated into the low-voltage winding of the magnetically integrated three-winding transformer.

[0008] Preferably, the LCL filter includes a first inductor, a second inductor, and a filter capacitor. One end of the first inductor is connected to a second AC / DC bidirectional converter, and the other end is connected to the second inductor and the filter capacitor. The second inductor is also connected to a magnetically integrated three-winding transformer and the load.

[0009] Preferably, the first inductor is used as the inverter-side inductor, and the second inductor is used as the grid-side filter inductor; the filter capacitor is connected in series between the first inductor and the second inductor.

[0010] Secondly, this application provides a grid-connected hybrid power regulation method, comprising: under normal grid conditions, turning on the thyristor in the first solid-state power electronic switch to enable the grid to supply power to the load; using a supercapacitor energy storage branch as a backup power source to draw energy from the load side to maintain sufficient energy storage and ensure emergency operation capability; coordinating the energy storage battery, the second AC / DC bidirectional converter, and the LCL filter to absorb energy from the grid during off-peak periods and release it during peak periods to reduce load fluctuations and optimize the load curve; and increasing the capacity or number of batteries as needed to perform reactive power compensation and three-phase imbalance management in real time.

[0011] Preferably, in the event of a power grid anomaly, after completing the pre-synchronization function, the thyristor in the first solid-state power electronic switch is immediately turned off, and power is supplied through the first AC / DC bidirectional converter, the supercapacitor energy storage branch, and the energy storage battery. The first AC / DC bidirectional converter is controlled by a virtual synchronous generator to simulate generator characteristics. The second AC / DC bidirectional converter and the LCL filter are coordinated to provide power supply support, reactive power compensation, harmonic suppression, and phase-to-phase balancing functions in real time according to the battery status.

[0012] Preferably, when the grid voltage is restored, the first solid-state power electronic switch is reactivated to restore grid-connected operation, the operation of the first AC / DC bidirectional converter is suspended, and the functions of the grid under normal conditions are restored by using the energy storage battery, supercapacitor and second AC / DC bidirectional converter.

[0013] The grid-connected hybrid power regulator and regulation method provided by this invention, compared with the prior art, innovatively proposes a grid-connected hybrid power regulation mode and discloses the specific topology of the power regulator, thereby achieving the goal of supporting direct voltage control or maintaining voltage stability during faults, and simplifying the power system structure; it solves the challenges faced by urban distribution networks in achieving high-reliability power supply, such as severe forward and reverse overloads, three-phase imbalance, and low power factor; at the same time, it has the characteristics of high-reliability power supply for urban distribution networks and comprehensive regulation of medium and low voltage systems. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 A detailed topology diagram of the grid-connected hybrid power conditioner provided by the present invention; Figure 2A schematic diagram of the system-level control architecture of the grid-connected hybrid power conditioner provided by the present invention; Figure 3 Schematic diagrams of four operating modes of the grid-connected hybrid power conditioner provided by the present invention; Figure 4 The control block diagram of the first AC / DC bidirectional converter and the second AC / DC bidirectional converter of the grid-connected hybrid power regulator provided by the present invention; Figure 5 The block diagram of reactive power-voltage and active power-frequency control for achieving seamless switching of the grid-connected hybrid power regulator provided by this invention; Figure 6 A schematic diagram of the pre-synchronization control structure of the grid-connecting hybrid power regulator provided by the present invention; Figure 7 The control block diagram of the supercapacitor for the grid-connected hybrid power conditioner provided by this invention; Figure 8 a is a graph showing the grid voltage results of the grid-connected hybrid power regulator provided by the present invention in emergency mode; Figure 8 b is a graph showing the load voltage results of the grid-connected hybrid power regulator provided by the present invention in emergency mode; Figure 8 c is a power result diagram of the grid-connected hybrid power regulator provided by the present invention operating in emergency mode; Figure 8 d is a graph showing the grid current results of the grid-connected hybrid power regulator provided by the present invention in emergency mode; Figure 9 a is a graph showing the grid voltage results of the grid-connected hybrid power regulator provided by the present invention operating in power compensation mode; Figure 9 b is a power result diagram of the grid-connected hybrid power conditioner provided by the present invention operating in power compensation mode; Figure 9 c is a graph showing the grid current results of the grid-connected hybrid power regulator provided by the present invention operating in power compensation mode. Detailed Implementation

[0016] To facilitate a clearer understanding of the objectives, technical solutions, and advantages of this invention, the invention will be further described below in conjunction with the accompanying drawings and specific embodiments. Those skilled in the art can easily understand other advantages and effects of this invention from the content disclosed in this specification.

[0017] This invention can also be implemented or applied through other different specific examples, and various details in this specification can also be modified and changed based on different viewpoints and applications without departing from the spirit of this invention.

[0018] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0019] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Secondly, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0020] Figure 1 The specific topology diagram of the grid-connected hybrid power conditioner (GFM / L-HPR) provided by the present invention includes: a first solid-state power electronic switch. S 1. Second solid-state power electronic switch S 2. Magnetic integrated three-winding transformer, first AC / DC bidirectional converter, second AC / DC bidirectional converter, DC / DC bidirectional converter, supercapacitor, energy storage battery, LCL filter, LC filter.

[0021] The first solid-state power electronic switch S 1 is connected in series between the public power grid and the three-winding transformer; the second solid-state power electronic switch S 2 is connected in series between the magnetically integrated three-winding transformer and the first AC / DC bidirectional converter; the first AC / DC bidirectional converter is connected to the load through an LC filter and then through the magnetically integrated three-winding transformer; the second AC / DC bidirectional converter is connected to the load through an LCL filter.

[0022] The supercapacitor is connected to the common DC bus of the first AC / DC bidirectional converter and the second AC / DC bidirectional converter via a DC / DC bidirectional converter; the energy storage battery is directly connected to the DC bus of the first AC / DC bidirectional converter and the second AC / DC bidirectional converter.

[0023] The first AC / DC bidirectional converter integrates the filter inductor of its LC filter into the magnetically integrated transformer through non-orthogonal decoupling technology.

[0024] The first AC / DC bidirectional converter adopts a grid-based control mode and includes a power module, a sampling unit, a pre-synchronization control module, a virtual synchronous generator (VSG) control module, a voltage and current inner loop controller, and a pulse width modulation (PWM) generator.

[0025] The second AC / DC bidirectional converter operates in grid-connected control mode and includes a power module, a sampling unit, a phase-locked loop (PLL), an outer loop power controller, an inner loop current controller, and a PWM generator.

[0026] The DC / DC bidirectional converter is connected in series with the supercapacitor to form a supercapacitor energy storage branch.

[0027] The DC / DC bidirectional converter operates in power control mode and includes a power module, a sampling unit, an outer loop power (voltage) controller, an inner loop current controller, and a PWM generator.

[0028] The supercapacitor energy storage branch is connected in parallel with the energy storage branch to the common DC bus of the first AC / DC bidirectional converter and the second AC / DC bidirectional converter. The energy storage battery provides stable DC voltage support for the two AC / DC converters.

[0029] The first AC / DC bidirectional converter is connected to the second solid-state power electronic switch. S One end is connected to the compensation winding of the magnetically integrated transformer, and the other end is connected to the second AC / DC bidirectional converter. The other end of the second AC / DC bidirectional converter is connected to the LCL filter. The magnetically integrated transformer integrates the output filter inductance of the LC filter into its compensation winding.

[0030] The LCL filter includes a first inductor serving as the converter-side inductor, a second inductor serving as the grid / load-side inductor, and a filter capacitor positioned between the two inductors. One end of the first inductor is connected to the second AC / DC bidirectional converter, and the other end is connected to the second inductor and the filter capacitor; the second inductor is simultaneously connected to the magnetic integrated transformer and the load.

[0031] The first inductor serves as the inverter-side inductor, and the second inductor serves as the grid-side filter inductor; the filter capacitor is connected in series between the first inductor and the second inductor. Figure 1 In this process, the corrected three-phase current can be obtained by extracting the zero-sequence component from the load current.

[0032] in, Indicates the load current; Represents the zero-order component; , These represent the positive and negative sequence components of the corrected load current, respectively. , These are the magnitudes of the positive and negative order components, respectively; , These are the phase angles of the positive and negative sequence components, respectively; This represents the system's angular frequency.

[0033] Figure 1 In this case, the current balance equation holds true:

[0034] in, and These represent the first solid-state power electronic switch. S 1 and second solid-state power electronic switches S The state of 2; when (or When ), corresponding to the first solid-state power electronic switch S 1 or second solid-state power electronic switch S 2 is in a closed state; conversely, when (or When ), corresponding to the first solid-state power electronic switch S 1 or second solid-state power electronic switch S 2 is in the disconnected state; and This indicates the turns ratio coefficient between different windings of a transformer.

[0035] Therefore, the current flowing out of the transformer load side It can be represented as:

[0036] In this context, the superscripts d and q represent the direct and quadrature components of the dq coordinate system, respectively.

[0037] Combining formulas (3), (4), and (5), it can be seen that the grid-side current only contains the fundamental positive-sequence active component. This means that by implementing appropriate control through a grid-connected hybrid power regulator in both normal and emergency power supply modes, the three-phase imbalance and reactive power problems can be effectively solved.

[0038] Figure 1 In this context, the active power balance equation holds true:

[0039] in, Indicates the active power output of the power grid; This indicates the active power consumed by the load; and These represent the output active power of the energy storage battery section and the supercapacitor energy storage branch, respectively. and These represent the output active power of the first and second AC / DC bidirectional converters, respectively.

[0040] To achieve the above objectives, the present invention also provides a grid-connected hybrid power regulation method, referring to... Figure 1 and Figure 2 As shown, the method includes: Under normal grid conditions, the first solid-state power electronic switch is activated. S The thyristors in section 1 enable the grid to supply power to the load; the supercapacitor energy storage branch serves as a backup power source, drawing energy from the load side to maintain sufficient energy storage and ensure emergency operation capability; the energy storage battery, the second AC / DC bidirectional converter, and the LCL filter coordinate to absorb energy from the grid during off-peak hours and release it during peak hours to reduce load fluctuations and optimize the load curve; the battery capacity or number can be increased as needed to perform reactive power compensation and three-phase imbalance management in real time; and in abnormal grid conditions, the first solid-state power electronic switch is immediately turned off after completing the pre-synchronization function. S The thyristor in 1 is powered by the first AC / DC bidirectional converter, the supercapacitor energy storage branch and the energy storage battery. The first AC / DC bidirectional converter adopts virtual synchronous generator control to simulate generator characteristics. It coordinates the second AC / DC bidirectional converter and LCL filter to provide power supply support, reactive power compensation, harmonic suppression and phase-to-phase balance functions in real time according to the battery status. When the grid voltage recovers, the first solid-state power electronic switch is reactivated. S 1. To restore grid-connected operation, the operation of the first AC / DC bidirectional converter is suspended, and the functions of the grid under normal conditions are restored by using energy storage batteries, supercapacitors and the second AC / DC bidirectional converter. Figure 2 This is a schematic diagram of the system-level control architecture of the grid-connected hybrid power conditioner provided by the present invention; based on the detected effective value of the grid voltage, the grid state can be divided into the following two types, corresponding to different functions of GFM / L-HPR: Under normal power grid conditions ( V g ∈[0.9,1] pu), the first solid-state power electronic switch S 1. Closed (Γ) g =1), the second solid-state power electronic switch S 2 Disconnect (Γ) m =0), the load is powered by the grid; In case of abnormal power grid conditions ( V g [0.9,1] pu), the first solid-state power electronic switch S 1 Disconnect (Γ)g =0), the second solid-state power electronic switch S 2 Closed (Γ) m =1), the load is powered by the energy storage battery system.

[0041] Under these two conditions, based on the load conditions and HESS state of charge (SoC), the operation mode of the grid-connected hybrid power conditioner is further divided into four working modes: charging mode, discharging mode, power compensation mode, and emergency mode.

[0042] Figure 3 This is a schematic diagram of four operating modes of the grid-connected hybrid power regulator provided by the present invention. The charging mode is as follows: if the total active power demand... Below the valley filling threshold GFM / L-HPR operates in charging mode under the following three conditions: When the state of charge of both the supercapacitor (SC) and the battery (BAT) is below the upper limit ( and ); When the state of charge of the supercapacitor is below the upper limit, while the state of charge of the battery is above the upper limit ( and ); When the state of charge of the battery is below the upper limit, while the state of charge of the supercapacitor is above the upper limit ( and At this point, the power reference value of the supercapacitor energy storage branch must meet the following requirements:

[0043] in, This indicates the output active power of the energy storage battery; and These represent the apparent power and output power of the second AC / DC bidirectional converter, respectively. Defined as (The difference between real-time load power and valley filling threshold). This indicates the constant charging power of the supercapacitor; This indicates the rated output active power of the supercapacitor energy storage system.

[0044] Under the premise of ensuring stable active power transmission, the residual apparent power capacity of the second AC / DC bidirectional converter can be used for reactive power compensation:

[0045] in, This indicates the reactive power of the second AC / DC bidirectional converter; This indicates the reactive power referenced by the second AC / DC bidirectional converter; and These represent the apparent power and output power of the second AC / DC bidirectional converter, respectively.

[0046] The discharge mode is as follows: if the total active power demand is... Exceeding the peak shaving threshold GFM / L-HPR operates in discharge mode under the following two conditions: When the state of charge of both the supercapacitor and the battery is higher than the lower limit ( and When the state of charge of the battery is higher than the lower limit and the state of charge of the supercapacitor is lower than the upper limit (); and At this point, the power reference value of the supercapacitor energy storage branch must meet the following requirements:

[0047] in, Defined as (The difference between real-time load power and peak shaving threshold); This indicates the rated output active power of the supercapacitor energy storage system. and These represent the apparent power and output power of the second AC / DC bidirectional converter, respectively.

[0048] The power compensation mode is as follows: GFM / L-HPR operates in power compensation mode under the following three conditions: When the total active power demand It falls between the preset thresholds for peak shaving and valley filling, i.e. And when the state of charge of the supercapacitor (SC) exceeds the upper limit ( ); When total active power demand When the peak reduction threshold is exceeded and the battery state of charge is below the lower limit ( ); When the total active power demand When the state of charge is below the valley filling threshold, and both the battery and the supercapacitor exceed their respective upper limits ( In this mode, the power of the second AC / DC bidirectional converter (GFL), representing the grid-connected transformation, and the power reference values ​​of the supercapacitor energy storage branch must meet the following requirements:

[0049] in, This indicates the output power of the second AC / DC bidirectional converter; This indicates the rated output active power of the supercapacitor energy storage system.

[0050] The emergency mode is used when a power grid fault or disturbance causes a voltage dip ( V g When [0.9,1]pu), the first solid-state power electronic switch S 1 Disconnect (Γ) g =0), second solid-state power electronic switch S 2 Closed (Γ) m =1), the grid-connected hybrid power regulator operates in emergency mode. At this time, the power reference values ​​of the energy storage battery and the supercapacitor energy storage branch must meet the following:

[0051] in, This indicates the output power of the first AC / DC bidirectional converter; This indicates the rated output active power of the supercapacitor energy storage system. This indicates the active power consumed by the load.

[0052] Figure 4 The control block diagrams of the first and second AC / DC bidirectional converters of the grid-connected hybrid power regulator provided by the present invention illustrate the specific control method of the AC / DC bidirectional converter in the grid-connected hybrid power regulator. The second AC / DC converter feeds the compensation component obtained by separating the positive and negative sequences and the output of the DC link voltage regulation proportional-integral (PI) controller into the current control loop to achieve power / current regulation.

[0053] Under normal grid voltage conditions, the first AC / DC converter adopts a pre-synchronization control strategy to maintain synchronization between its output voltage and the output voltage of the transformer compensation winding.

[0054] In emergency mode, the first AC / DC converter adopts a virtual synchronous generator (VSG) control strategy.

[0055] Figure 5 The block diagram of reactive power-voltage and active power-frequency control for seamless switching in the grid-connected hybrid power regulator provided by this invention illustrates the reactive power-voltage and active power-frequency control mechanism for achieving seamless switching. The control and regulation processes of Pf and QV are as follows:

[0056] in, J Indicates the moment of inertia; D This represents the corresponding damping coefficient; and These represent mechanical power and reference active power, respectively. ω 0 is the rated angular frequency. ω m This is the actual angular frequency; The active power-frequency droop factor is... The reactive power-voltage coefficient; KRepresents the time constant of the integral term; and These represent the actual reactive power and the reference reactive power, respectively. and These represent the reference voltage amplitude and the output voltage amplitude, respectively. E m and θ m The internal electromotive force amplitude and phase angle; Δ V and Δ θ This indicates the amplitude and frequency disturbances generated by pre-synchronization control.

[0057] To achieve pre-synchronization of the VSG, a virtual impedance is introduced between the grid-type converter voltage and the converter secondary side voltage. The formula for calculating its virtual current is as follows:

[0058] in, and This indicates the amplitude and phase angle of the VSG output voltage; and This indicates the amplitude and phase angle of the voltage in the transformer's compensation winding; and This represents the magnitude difference and phase angle difference of the voltage across the virtual impedance.

[0059] q-axis component of virtual current This reflects the phase relationship between the VSG voltage and the transformer secondary voltage; similarly, the d-axis component... This characterizes the magnitude relationship between the two voltages. Therefore, by transforming the virtual current to the dq coordinate system and controlling... and This allows for pre-synchronization control.

[0060] in, The reference angular frequency representing the coordinate transformation; , and This represents the components of the virtual current in the abc coordinate system; This represents the phase angle difference between the voltages across the virtual impedance.

[0061] Through the Perform differentiation and redefine the new variables of the phase controller. Y The control process can be expressed as shown in equations (17) and (18). It should be noted that only when the phase angle difference... or 2π Y =0, thus ensuring the accuracy of phase angle adjustment.

[0062]

[0063] in, express The differential value; express Reference value; and This represents the magnitude difference and phase angle difference of the voltage across the virtual impedance.

[0064] A virtual synchronous generator (VSG) generates voltage phase and amplitude reference values ​​through active-frequency and reactive-voltage control. Its output voltage reference value can be expressed as:

[0065] The regulation method employs a dual-loop voltage-current control scheme to achieve virtual impedance and fault current limiting functions, while providing a drive modulation signal for the converter.

[0066] Figure 7 The control block diagram of the supercapacitor in the grid-connected hybrid power regulator provided by this invention illustrates the structure of the hybrid energy storage system.

[0067] Under normal power grid conditions ( V g Under the condition ∈[0.9,1] pu), the DC / DC converter adopts an outer-loop power control and inner-loop current control strategy. The converter adjusts its operating state according to the load demand and the state of charge of the supercapacitor, and works in conjunction with the battery: providing power support during peak load periods and absorbing energy during low load periods to achieve power supply balance.

[0068] In abnormal power grid conditions ( V g Under [0.9,1] pu), the HESS controller adopts a frequency division control strategy to decompose the DC voltage deviation into high-frequency and low-frequency components. The high-frequency component is compensated by the supercapacitor energy storage branch, and the generated high-frequency power reference value is sent to the converter controller to achieve accurate power point tracking; the low-frequency component is processed by the battery energy storage system to maintain the stability of the DC side voltage.

[0069] To further illustrate the present invention, a specific embodiment of the system operation is provided, in which a hardware-in-the-loop experimental system is used to test a typical 200kVA distribution network system integrating GFM / L-HPR. Two typical operating conditions are set up: condition IFM / L-HPR operates in emergency mode; condition IIGFM / L-HPR operates in power compensation mode.

[0070] Table I: HIL System Main Circuit Parameters

[0071] Table I shows the specific parameters of the main circuit of its HIL system.

[0072] When Condition I occurs, GFM / L-HPR is running in emergency mode. Figure 8 The experimental results of GFM / L-HPR operating in emergency mode are presented. In this test case, the load power is: , ; , ; , .

[0073] Figure 8 Figure a shows the grid voltage results when GFM / L-HPR is operating in emergency mode. Figure 8 c shows the power results of GFM / L-HPR operating in emergency mode, by Figure 8 a and Figure 8 c can be derived; In scenario I, the grid voltage is normal, and the first solid-state power electronic switch... S 1. Keep closed ( =1), the load is powered by the grid.

[0074] In Scenario II, a voltage dip occurs in the power grid, and the GFM / L-HPR enters emergency mode.

[0075] Figure 8 c displays the first solid-state power electronic switch S 1. Rapidly respond to isolate the upstream power grid ( =0), while the hybrid energy storage system is based on a frequency division control strategy, using the fast power response characteristics of supercapacitors to compensate for high-frequency components and batteries to compensate for low-frequency components, providing fast and stable power support for the load.

[0076] Figure 8 Figure b shows the load voltage results of the GFM / L-HPR operating in emergency mode, demonstrating that the load voltage remains essentially constant during the switching process. Simultaneously, the second AC / DC bidirectional converter performs reactive power compensation and three-phase imbalance mitigation, ensuring that the output current of the first AC / DC bidirectional converter is balanced and contains only a power component (peak current approximately 209.5A), significantly improving the capacity utilization of the first AC / DC bidirectional converter. In contrast, if the GFM / L-HPR only uses grid-based control (equivalent to a traditional grid-based energy storage device), the peak output current reaches 270.2A.

[0077] In Scenario III, after the grid voltage returns to normal, the first solid-state power electronic switch... S 1. Close quickly ( =1), the load is restored to power from the grid. Figure 8b also demonstrates that the load voltage remained stable during the transition from an emergency state to a normal grid state.

[0078] When operating condition II occurs, the GFM / L-HPR is running in power compensation mode. Figure 9 Experimental results of the GFM / L-HPR operating in power compensation mode are presented. In this test case, the load power is: , ; , ; ,

[0079] Figure 9 Figure a shows the grid voltage results when GFM / L-HPR is operating in power compensation mode. Figure 9 b shows the power results of GFM / L-HPR operating in power compensation mode. Figure 9 c shows the grid current results for GFM / L-HPR operating in power compensation mode, by Figure 9 a, Figure 9 b and Figure 9 c leads to the conclusion that: In Scenario I, when the total active power demand is between 50kW and 100kW (i.e., below the valley filling threshold) P low The GFM / L-HPR operates in charging mode. The supercapacitor energy storage branch and the battery energy storage branch absorb power from the grid at 20kW and 40kW respectively, increasing the grid output power from 50kW to 110kW. Figure 9 As shown in b.

[0080] In Scenario II, when the total active power demand remains between 50kW and 100kW, but the battery state of charge... ≥0.9 (i.e., reaching the upper limit) And the state of charge of the supercapacitor ≥0.9 (i.e., reaching the upper limit) At this point, the GFM / L-HPR switches to power compensation mode. The load is powered by the grid, and the second AC / DC bidirectional converter performs reactive power compensation and three-phase imbalance control.

[0081] from Figure 9 As can be seen, when the total active power demand increases to 225kW in Scenario III, it exceeds 150kW (i.e., it exceeds the peak shaving threshold). The GFM / L-HPR switches to discharge mode. The battery energy storage branch provides power support to the load through the second AC / DC converter (Note: at this time...). =110kW, =115kW). Furthermore, through Figure 9 c shows that the proposed strategy can effectively achieve reactive power compensation and three-phase imbalance management.

[0082] Based on hardware-in-the-loop experimental results, it is demonstrated that the grid-connected hybrid power conditioner can effectively improve the power supply reliability of the distribution network.

[0083] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A grid-connected hybrid power regulator, characterized in that, include: First solid-state power electronic switch, second solid-state power electronic switch, magnetically integrated three-winding transformer, first AC / DC bidirectional converter, second AC / DC bidirectional converter, DC / DC bidirectional converter, supercapacitor, energy storage battery, LCL filter, LC filter; The first solid-state power electronic switch is connected in series between the magnetically integrated three-winding transformer and the power grid; The second solid-state power electronic switch is connected in series between the magnetically integrated three-winding transformer and the first AC / DC bidirectional converter; The first AC / DC bidirectional converter is connected to the load via an LC filter and a magnetically integrated three-winding transformer. The second AC / DC bidirectional converter is connected to the load via an LCL filter; The supercapacitor is connected to the DC bus of the first AC / DC bidirectional converter and the second AC / DC bidirectional converter via a DC / DC bidirectional converter. The energy storage battery is directly connected to the DC bus of the first AC / DC bidirectional converter and the second AC / DC bidirectional converter.

2. The regulator according to claim 1, characterized in that, The first AC / DC bidirectional converter adopts a grid-based control mode; the second AC / DC bidirectional converter adopts a grid-following control mode.

3. The regulator according to claim 1, characterized in that, The DC / DC bidirectional converter is connected in series with the supercapacitor to form a supercapacitor energy storage branch. The supercapacitor energy storage branch and the energy storage battery are connected in parallel to the DC bus of the first AC / DC bidirectional converter and the second AC / DC bidirectional converter.

4. The regulator according to claim 1, characterized in that: One end of the first AC / DC bidirectional converter is connected to the low-voltage side of the magnetically integrated three-winding transformer, and the other end is connected to one end of the second AC / DC bidirectional converter; the other end of the second AC / DC bidirectional converter is connected to an LCL filter.

5. The regulator according to claim 4, characterized in that, The output filter inductor of the first AC / DC bidirectional converter is integrated into the low-voltage winding of the magnetically integrated three-winding transformer.

6. The regulator according to claim 4, characterized in that, The LCL filter includes a first inductor, a second inductor, and a filter capacitor. One end of the first inductor is connected to a second AC / DC bidirectional converter, and the other end is connected to the second inductor and the filter capacitor. The second inductor is also connected to a magnetically integrated three-winding transformer and the load.

7. The regulator according to claim 6, characterized in that, The first inductor serves as the inverter-side inductor, and the second inductor serves as the grid-side filter inductor; the filter capacitor is connected in series between the first inductor and the second inductor.

8. A grid-connected hybrid power regulation method, characterized in that, include: Under normal grid operation, the thyristor in the first solid-state power electronic switch is turned on to supply power to the load; the supercapacitor energy storage branch is used as a backup power source to draw energy from the load side to maintain sufficient energy storage; the energy storage battery, the second AC / DC bidirectional converter and the LCL filter are coordinated to absorb energy from the grid during off-peak hours and release it during peak hours; the capacity or number of batteries is increased as needed to perform reactive power compensation and three-phase imbalance management in real time.

9. The method according to claim 8, characterized in that, Also includes: In the event of a grid anomaly, after completing the pre-synchronization function, the thyristor in the first solid-state power electronic switch is immediately turned off, and power is supplied through the first AC / DC bidirectional converter, the supercapacitor energy storage branch, and the energy storage battery. The first AC / DC bidirectional converter is controlled by a virtual synchronous generator to simulate generator characteristics. The second AC / DC bidirectional converter and the LCL filter are coordinated to provide power supply support, reactive power compensation, harmonic suppression, and phase-to-phase balancing functions in real time according to the battery status.

10. The method according to claim 9, characterized in that, Also includes: When the grid voltage is restored, the first solid-state power electronic switch is reactivated to restore grid-connected operation, the operation of the first bidirectional AC / DC converter is suspended, and the functions of the grid under normal conditions are restored by using energy storage batteries, supercapacitors and the second bidirectional AC / DC converter.

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