Regulation and control method and device of energy storage type hybrid power flow controller

Abstract

The invention provides a regulation and control method and device for an energy storage type hybrid power flow controller, and belongs to the technical field of power grid control. The method is applied to a multi-level control loop of the energy storage type hybrid power flow controller, the energy storage type hybrid power flow controller comprises an energy storage unit and a hybrid power flow controller, and the hybrid power flow controller comprises a cascaded H bridge; the energy storage unit is connected with the cascaded H bridge through a capacitor and an inductor; the method comprises the following steps: acquiring output power and reference power of a target line, total power of an energy storage unit and reference power of the energy storage unit; inputting the output power, the reference power, the total power of the energy storage unit and the reference power of the energy storage unit module into a multi-level regulation and control loop to obtain a modulation signal; and regulating and controlling the energy storage type hybrid power flow controller based on the modulation signal. According to the invention, basic functions of the hybrid power flow controller can be realized, accurate management of the battery can be realized, and mutual influence among multiple functions is effectively avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of power grid control, and in particular to a control method and device for an energy storage type hybrid power flow controller. Background Art

[0002] With the access of a large number of renewable energy sources to the power grid, the power system faces problems such as volatility and intermittency, which leads to prominent problems in grid stability and power quality. At present, the mainstream power flow regulation devices in the power grid include two categories: mechanical electromagnetic devices and flexible alternating current transmission systems (FACTS). The former is typically represented by the phase-shifting transformer (PST), which has a large regulation capacity but low accuracy and cannot be adjusted continuously; the latter is typically represented by the unified power flow controller (UPFC). FACTS has high regulation accuracy, but the structure is complex and the cost is high, which is not conducive to the promotion of engineering applications. PST and UPFC can form a hybrid unified power flow controller (HUPFC), which can achieve both high-power regulation and high-precision power regulation.

[0003] However, the existing HUPFC cannot be connected to the battery system, and the battery system cannot effectively utilize the isolation transformer and converter that already exist in the HUPFC. If you want to add a battery energy storage system, you need to separately add isolation transformers, energy storage converters and other equipment, which increases the construction cost of the entire system. Summary of the invention

[0004] The embodiments of the present invention provide a control method and device for an energy storage type hybrid power flow controller to solve the problem that adding a battery energy storage system to a hybrid power flow controller will increase the construction cost at this stage.

[0005] In a first aspect, an embodiment of the present invention provides a control method of an energy storage type hybrid power flow controller, which is applied to a multi-level control loop of the energy storage type hybrid power flow controller, wherein the energy storage type hybrid power flow controller includes an energy storage unit and a hybrid power flow controller, and the hybrid power flow controller includes a cascade H-bridge; the energy storage unit is connected to the cascade H-bridge through a capacitor and an inductor; the method includes:

[0006] Obtain the output power, reference power, total power of the energy storage unit and reference power of the energy storage unit of the target line;

[0007] The output power, the reference power, the total power of the energy storage unit and the reference power of the energy storage unit module are input into a multi-level control loop to obtain a modulation signal;

[0008] The energy storage hybrid power flow controller is regulated based on the modulation signal.

[0009] In a possible implementation, the multi-level control loop includes an outer gear control loop, a middle charge and discharge control loop, and an inner load state balancing loop;

[0010] The output power, reference power, total power of the energy storage unit and reference power of the energy storage unit are input into a multi-level control loop to obtain a modulation signal, including:

[0011] The output power and the reference power are input into the outer gear control loop to determine and output the d-axis reference voltage of the cascaded H-bridge inverter;

[0012] The d-axis reference voltage, the total power of the energy storage unit and the reference power of the energy storage unit are input into the middle-layer charge and discharge control loop to determine and output the basic modulation signal of the cascaded H-bridge inverter;

[0013] The basic modulation signal is input into the inner load state balancing loop to determine and output the modulation signal.

[0014] In a possible implementation, the hybrid power flow controller includes a phase-shifting transformer, which is connected to a cascaded H-bridge;

[0015] The output power and reference power are input into the outer gear control loop to determine and output the d-axis reference voltage of the cascaded H-bridge inverter, including:

[0016] If the output power is less than the reference power, the d-axis voltage of the cascaded H-bridge inverter is increased until the output power is equal to the reference power, and the corresponding d-axis voltage is output as the d-axis reference voltage;

[0017] If the d-axis voltage of the cascaded H-bridge inverter increases to an upper limit value and the output power is less than the reference power, the gear of the phase-shifting transformer is increased and the d-axis voltage is reset; the reset d-axis voltage is output as the d-axis reference voltage.

[0018] In a possible implementation, the output power and the reference power are input into the outer gear control loop to determine and output the d-axis reference voltage of the cascaded H-bridge inverter, including:

[0019] In the outer gear control loop, if the output power is greater than the reference power, the d-axis voltage of the cascaded H-bridge inverter is reduced until the output power is equal to the reference power, and the corresponding d-axis voltage is output as the d-axis reference voltage;

[0020] If the d-axis voltage of the cascaded H-bridge inverter decreases to a lower limit value and the output power is greater than the reference power, the gear of the phase-shifting transformer is reduced and the d-axis voltage is reset; the reset d-axis voltage is output as the d-axis reference voltage.

[0021] In a possible implementation, the d-axis reference voltage, the total power of the energy storage unit, and the reference power of the energy storage unit are input into the middle-layer charge and discharge control loop to determine and output the basic modulation signal of the cascaded H-bridge inverter, including:

[0022] In the middle-level charge and discharge control loop, the average DC voltage reference value is determined according to the total power of the energy storage unit and the reference power of the energy storage unit;

[0023] A basic modulation signal of the cascaded H-bridge inverter is determined according to the average DC voltage reference value and the d-axis reference voltage.

[0024] In a possible implementation, determining an average DC voltage reference value according to the total power of the energy storage unit and the reference power of the energy storage unit includes:

[0025] In the middle layer charge and discharge control loop,

[0026] The difference between the reference power of the energy storage unit and the total power of the energy storage unit is passed through a proportional loop to obtain an additional voltage component of the DC voltage;

[0027] The sum of the additional voltage component and the average voltage of each energy storage unit is used as the average DC voltage reference value; wherein the average voltage of each energy storage unit is determined based on the total power of the energy storage unit.

[0028] In a possible implementation, determining a basic modulation signal of a cascaded H-bridge inverter according to an average DC voltage reference value and a d-axis reference voltage includes:

[0029] Obtaining the voltage of the capacitor and the phase angle of the secondary voltage of the excitation transformer in the phase-shifting transformer;

[0030] In the middle-level charge and discharge control loop, the q-axis reference voltage is determined according to the capacitor voltage and the average DC voltage reference value;

[0031] A basic modulation signal of each phase of the cascaded H-bridge inverter is determined according to a q-axis reference voltage, a d-axis reference voltage and a phase angle.

[0032] In a possible implementation, the basic modulation signal is input into the inner load state balancing loop, and the modulation signal is determined and output, including:

[0033] Obtaining the remaining power ratio of each energy storage unit in the energy storage unit;

[0034] In the inner load state balancing loop, the average DC voltage of each phase in the three-phase line and the average DC voltage of the target line are calculated according to the output power;

[0035] Determine a modulation signal reference value for each phase according to an average DC voltage of each phase, an average DC voltage of the target line, a phase angle of the phase-shifting transformer, and a basic modulation signal of each phase;

[0036] The modulation signal of each phase is determined according to the remaining power ratio of each energy storage unit and the modulation signal reference value of each phase.

[0037] In a possible implementation, determining a modulation signal reference value of each phase according to an average DC voltage of each phase, an average DC voltage of a target line, a phase angle of a phase-shifting transformer, and a basic modulation signal of each phase includes:

[0038] In the inner load state balancing loop, the difference between the average value of the DC voltage of each phase and the average value of the DC voltage of the target line is input into the first regulator, and the output value of the first regulator is multiplied by the phase angle of the phase-shifting transformer to obtain a first additional modulation signal of each phase;

[0039] The first additional modulation signal of each phase is added to the corresponding basic modulation signal to obtain a modulation signal reference value of each phase;

[0040] According to the remaining power ratio of each energy storage unit and the modulation signal reference value of each phase, the modulation signal of each phase is determined, including:

[0041] In the inner load state balancing loop, the average remaining power ratio of the energy storage unit is calculated according to the remaining power ratio of each energy storage unit;

[0042] Inputting the difference between the remaining power ratio of each energy storage unit and the average remaining power ratio into the second regulator to obtain a compensation amount;

[0043] Multiplying the compensation amount by the phase angle of the phase-shifting transformer respectively to obtain a second additional modulation signal of each energy storage unit in each phase;

[0044] The second additional modulation signal of each module in each phase is added to its corresponding modulation signal reference value to obtain the modulation signal of each energy storage unit in each phase.

[0045] In a second aspect, an embodiment of the present invention provides a control device of an energy storage type hybrid power flow controller, which is applied to a multi-level control loop of the energy storage type hybrid power flow controller, wherein the energy storage type hybrid power flow controller includes an energy storage unit and a hybrid power flow controller, and the hybrid power flow controller includes a cascade H-bridge; the energy storage unit is connected to the cascade H-bridge through a capacitor and an inductor; the device includes:

[0046] An acquisition module, used to acquire the output power, reference power, total power of the energy storage unit and reference power of the energy storage unit of the target line;

[0047] A modulation module is used to input the output power and reference power, the total power of the energy storage unit and the reference power of the module battery into a multi-level control loop to obtain a modulation signal;

[0048] The control module is used to control the energy storage hybrid power flow controller based on the modulation signal.

[0049] The embodiment of the present invention provides a control method and device for an energy storage hybrid power flow controller, which connects the hybrid power flow controller to the energy storage unit through capacitors and inductors, and can synchronously realize line power flow control and battery charge and discharge control by sharing power modules and isolation transformers, without adding additional isolation transformers, energy storage converters, etc., thereby reducing investment costs. In addition, through a multi-level control loop, both the power of the target line and the battery load status are taken into account, which can realize the basic functions of the hybrid power flow controller and the precise management of the battery, effectively avoiding the mutual influence between multiple functions. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0051] Figure 1 It is a structural schematic diagram of an energy storage type hybrid power flow controller provided by an embodiment of the present invention;

[0052] Figure 2 It is a flow chart of the implementation of the control method of the energy storage type hybrid power flow controller provided by the embodiment of the present invention;

[0053] Figure 3 It is a control schematic diagram of a control method of an energy storage type hybrid power flow controller provided by an embodiment of the present invention;

[0054] Figure 4 It is a structural schematic diagram of a control device of an energy storage type hybrid power flow controller provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0055] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present invention. However, it should be clear to those skilled in the art that the present invention may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present invention.

[0056] In order to make the purpose, technical solutions and advantages of the present invention more clear, specific embodiments will be described below in conjunction with the accompanying drawings.

[0057] Figure 1 is a schematic diagram of the structure of an energy storage hybrid power flow controller provided by an embodiment of the present invention, such as Figure 1 shown.

[0058] In this embodiment, the energy storage type hybrid power flow controller includes at least one energy storage unit and a hybrid power flow controller; the hybrid power flow controller includes a phase shifting transformer PST and at least one cascaded H bridge (cascaded HB, CHB), that is, a single-phase full-bridge converter. The PST includes an excitation transformer and a series transformer.

[0059] The DC side of each H-bridge converter in the cascaded H-bridge is connected in parallel with a capacitor and is connected to the energy storage unit through an inductor; the capacitor is used to smooth the secondary power fluctuations of the H-bridge, and the inductor is used to smooth the charging and discharging current of the battery pack in the energy storage unit to ensure the safety of the battery.

[0060] The output side of the cascade H-bridge is connected in series with the excitation transformer in the PST and then connected to the series transformer, which is connected to the three-phase line. The excitation transformer has the function of adjustable gears. After being connected in series with the cascade H-bridge, it can realize continuous voltage adjustment, and finally connected to the line through the series transformer, it can realize voltage phase adjustment, thereby realizing flexible adjustment of line power.

[0061] In order to regulate the energy storage type hybrid power flow controller, the embodiment of the present invention provides a regulation method applied to the multi-level control loop of the energy storage type hybrid power flow controller. Figure 2 This method will be described.

[0062] Figure 2 is a flow chart of the implementation of the control method of the energy storage type hybrid power flow controller provided by the embodiment of the present invention, such as Figure 2 As shown, the method includes:

[0063] Step 110: Obtain the output power of the target line, the reference power, the total power of the energy storage unit, and the reference power of the energy storage unit.

[0064] In this embodiment, the output power of the target line can be calculated from its output voltage and output current, or can be directly determined by instantaneous power calculation.

[0065] Step 120: input the output power, the reference power, the total power of the energy storage unit and the reference power of the energy storage unit module into a multi-level control loop to obtain a modulation signal.

[0066] Figure 3 The schematic diagram of the control method of the energy storage hybrid power flow controller provided by the embodiment of the present invention is shown below. Figure 3 This embodiment is described.

[0067] In this embodiment, the multi-level control loop may include an outer gear control loop, a middle charge and discharge control loop, and an inner load state balancing loop. Among them, the outer gear control loop includes a PST gear control module and a CHB collaborative control module; the middle charge and discharge control loop may include a battery charge and discharge control module, a DC voltage average value control module, and a PLL phase-locked module; the inner load state balancing loop may include a three-phase DC voltage average value control module and a remaining power (State of Charge, SOC) balancing control module of each bridge arm. Among them, the outer gear control loop can adjust the gear of the PST and the d-axis reference voltage of the cascaded H-bridge to achieve the regulation of the current. The middle charge and discharge control loop can flexibly control the charge and discharge power of the entire system. The inner load state balancing loop can achieve the balance of the battery SOC, and can also adjust the SOC value of each battery pack as needed to ensure the safety of the system.

[0068] Accordingly, in an optional embodiment, in step 120, the output power, the reference power, the total power of the energy storage unit, and the reference power of the energy storage unit module are input into a multi-level control loop to obtain a modulation signal, which may include:

[0069] Step 121: input the output power and the reference power into the outer gear control loop, determine and output the d-axis reference voltage of the cascaded H-bridge inverter.

[0070] Step 122: Input the d-axis reference voltage, the total power of the energy storage unit and the reference power of the energy storage unit into the middle-layer charge and discharge control loop to determine and output the basic modulation signal of the cascaded H-bridge inverter.

[0071] Step 123: Input the basic modulation signal into the inner load state balancing loop, determine and output the modulation signal.

[0072] In this embodiment, in step 121, the function performed by the PST gear position control module and the CHB collaborative control module is to adjust the gear position D of the PST according to the output power and the reference power. PST and CHB d-axis reference voltage Vd .

[0073] Specifically, in step 121, inputting the output power and the reference power into the outer gear control loop, determining and outputting the d-axis reference voltage of the cascaded H-bridge inverter may include:

[0074] If the output power is less than the reference power, the d-axis voltage of the cascaded H-bridge inverter is increased until the output power is equal to the reference power, and the corresponding d-axis voltage is output as the d-axis reference voltage.

[0075] If the d-axis voltage of the cascaded H-bridge inverter increases to an upper limit value and the output power is less than the reference power, the gear of the phase-shifting transformer is increased and the d-axis voltage is reset; the reset d-axis voltage is output as the d-axis reference voltage.

[0076] If the output power is greater than the reference power, the d-axis voltage of the cascaded H-bridge inverter is reduced until the output power is equal to the reference power, and the corresponding d-axis voltage is output as the d-axis reference voltage.

[0077] If the d-axis voltage of the cascaded H-bridge inverter decreases to a lower limit value and the output power is greater than the reference power, the gear of the phase-shifting transformer is reduced and the d-axis voltage is reset; the reset d-axis voltage is output as the d-axis reference voltage.

[0078] In this embodiment, if Figure 3 As shown, after the output power and the reference power are input into the outer gear control loop, the outer gear control loop compares the output power and the reference power. If the output power is less than the reference power, the d-axis voltage of the cascaded H-bridge inverter is increased; wherein, it is necessary to control the d-axis voltage of the cascaded H-bridge inverter within the control range, and the control range can be set to -1 to 1. The step size increased each time can be determined according to actual needs, for example, it can be increased by 0.05 each time.

[0079] When the d-axis voltage of the cascaded H-bridge inverter is increased and the output power is equal to the reference power, the corresponding d-axis voltage at this time is output as the d-axis reference voltage. When the d-axis voltage of the cascaded H-bridge inverter increases to the upper limit value, that is, 1, and the output power is still less than the reference power, the gear of the phase-shifting transformer is increased and the d-axis voltage is reset to 0; the reset d-axis voltage is output as the d-axis reference voltage.

[0080] Similarly, if the output power is greater than the reference power, the d-axis voltage of the cascaded H-bridge inverter is reduced until the output power is equal to the reference power, and the corresponding d-axis voltage is output as the d-axis reference voltage.

[0081] If the d-axis voltage of the cascaded H-bridge inverter decreases to the lower limit value, that is, -1, and the output power is still greater than the reference power, the gear of the phase-shifting transformer is reduced and the d-axis voltage is reset to 0; the reset d-axis voltage is output as the d-axis reference voltage.

[0082] It can be seen that this embodiment gives full play to the precise adjustment capability of CHB and the wide range adjustment capability of PST. In terms of precise adjustment, if the line power is less than the power reference value, the d-axis voltage is increased, and if the line power is greater than the power reference value, the d-axis voltage is reduced. In terms of wide range adjustment, the gear position of PST is used to make up for the lack of CHB adjustment range.

[0083] In an optional embodiment, in step 122, the d-axis reference voltage, the total power of the energy storage unit, and the reference power of the energy storage unit are input into the middle-layer charge and discharge control loop to determine and output the basic modulation signal of the cascaded H-bridge inverter, which may include:

[0084] Step 122.1: In the middle-level charge and discharge control loop, determine the average DC voltage reference value according to the total power of the energy storage unit and the reference power of the energy storage unit.

[0085] Step 122.2: Determine a basic modulation signal of the cascaded H-bridge inverter according to the average DC voltage reference value and the d-axis reference voltage.

[0086] In an optional embodiment, step 122.1 may be implemented in the following manner:

[0087] The difference between the reference power of the energy storage unit and the total power of the energy storage unit is passed through a proportional loop to obtain an additional voltage component of the DC voltage.

[0088] The sum of the additional voltage component and the average voltage of each energy storage unit is used as the average DC voltage reference value; wherein the average voltage of each energy storage unit is determined based on the total power of the energy storage unit.

[0089] In an optional embodiment, step 122.2 may be implemented in the following manner:

[0090] Obtaining the voltage of the capacitor and the phase angle of the secondary voltage of the excitation transformer in the phase-shifting transformer;

[0091] In the middle-level charge and discharge control loop, the q-axis reference voltage is determined according to the capacitor voltage and the average DC voltage reference value;

[0092] A basic modulation signal of each phase of the cascaded H-bridge inverter is determined according to a q-axis reference voltage, a d-axis reference voltage and a phase angle.

[0093] In this embodiment, refer to Figure 3The battery charge and discharge control module in the middle charge and discharge control loop is used to subtract the total power of the energy storage unit from the reference power of the energy storage unit, and pass the obtained difference through the proportional loop to obtain the additional voltage component of the DC voltage. According to the total power of the energy storage unit, the average voltage of each energy storage unit is determined. Then the additional voltage component is added to the average voltage of each energy storage unit to obtain the average DC voltage reference value.

[0094] That is:

[0095] V B_ref =V B_avg +V B_add

[0096] V B_add =K B (P B_ref -P B_tol )

[0097] Among them, V B_ref is the average DC voltage reference value; V B_avg is the average voltage of each energy storage unit; V B_add is the additional voltage component; K B is the proportionality coefficient; P B_ref is the reference power of the energy storage unit; P B_tol is the total power of the energy storage unit.

[0098] The DC voltage average value control module receives the average DC voltage reference value V B_ref and the capacitor voltage V C , the average DC voltage reference value V B_ref and the capacitor voltage V C Subtract the difference and output the q-axis reference voltage V through the PI regulator. q , so that it is finally input into the dq / abc conversion module. At the same time, a closed-loop control loop is constructed to convert V C Control to V B_ref .

[0099] The PLL phase-locked module collects the secondary voltage of the excitation transformer, and based on the secondary voltage of the excitation transformer, obtains the positive sequence component phase angle of the secondary voltage of the excitation transformer in real time. Based on the q-axis reference voltage, d-axis reference voltage and phase angle, and using the dq / abc conversion module, the basic modulation signal for each phase of the cascaded H-bridge inverter is determined, that is, V a_ref0 、V b_ref0 、V c_ref0 .

[0100] In an optional embodiment, in step 123, inputting the basic modulation signal into the inner load state balancing loop, determining and outputting the modulation signal may include:

[0101] Step 123.1: Obtain the remaining power ratio of each energy storage unit in the energy storage unit.

[0102] Step 123.2: In the inner load state balancing loop, the average DC voltage of each phase in the three-phase line and the average DC voltage of the target line are calculated according to the output power.

[0103] Step 123.3: Determine a modulation signal reference value for each phase according to the average value of the DC voltage of each phase, the average value of the DC voltage of the target line, the phase angle of the phase-shifting transformer, and the basic modulation signal of each phase.

[0104] Step 123.4: Determine the modulation signal of each phase according to the remaining power ratio of each energy storage unit and the modulation signal reference value of each phase.

[0105] In an optional embodiment, determining the modulation signal reference value of each phase according to the average DC voltage of each phase, the average DC voltage of the target line, the phase angle of the phase-shifting transformer and the basic modulation signal of each phase in step 123.3 may include:

[0106] In the inner load state balancing loop, the difference between the average DC voltage of each phase and the average DC voltage of the target line is input into the first regulator, and the output value of the first regulator is multiplied by the phase angle of the phase-shifting transformer to obtain the first additional modulation signal of each phase.

[0107] The first additional modulation signal of each phase is added to the corresponding basic modulation signal to obtain a modulation signal reference value of each phase.

[0108] In an optional embodiment, determining the modulation signal of each phase according to the remaining power ratio of each energy storage unit and the modulation signal reference value of each phase in step 123.4 may include:

[0109] In the inner load state balancing loop, the average remaining power ratio of the energy storage units is calculated according to the remaining power ratio of each energy storage unit.

[0110] The difference between the remaining power ratio of each energy storage unit and the average remaining power ratio is input into the second regulator to obtain the compensation amount.

[0111] The compensation amount is multiplied by the phase angle of the phase-shifting transformer to obtain a second additional modulation signal for each energy storage unit in each phase.

[0112] The second additional modulation signal of each module in each phase is added to its corresponding modulation signal reference value to obtain the modulation signal of each energy storage unit in each phase.

[0113] In this embodiment, the three-phase DC voltage average value control module in the inner load state balancing ring calculates the average value of the DC voltage of each phase in the ABC three-phase line and the average value of the DC voltage of the target line according to the output power. That is, the target line can be a three-phase line, and the output power of the target line is the output power of the three-phase line. According to the output power of the A-phase line, the average value of the DC voltage in the A-phase line is calculated, according to the output power of the B-phase line, the average value of the DC voltage in the B-phase line is calculated, and according to the output power of the C-phase line, the average value of the DC voltage in the C-phase line is calculated. According to the total output power of the three-phase line, the average value of the DC voltage of the target line is calculated.

[0114] The three-phase DC voltage average value control module subtracts the average DC voltage of each phase from the average DC voltage of the target line, that is, the average DC voltage in the A phase line minus the average DC voltage of the target line, the average DC voltage in the B phase line minus the average DC voltage of the target line, and the average DC voltage in the C phase line minus the average DC voltage of the target line. The obtained difference is input into the first regulator, that is, the PI regulator, and the output value of the first regulator is multiplied by the cosine value of the phase angle of the phase-shifting transformer to obtain the first additional modulation signal of each phase.

[0115] That is:

[0116] V a_bal =V a_bal_PI ×cos(θ)

[0117] V b_bal =V b_bal_PI ×cos(θ-120°)

[0118] V c_bal =V c_bal_PI ×cos(θ-240°)

[0119] Among them, V a_bal 、V b_bal 、V c_bal are the first additional modulation signals of each phase respectively; V a_bal_PI 、V b_bal_PI 、V c_bal_PI are the output values ​​of each phase of the first regulator respectively; θ is the phase angle.

[0120] The first additional modulation signal of each phase is added to the corresponding basic modulation signal to obtain a modulation signal reference value of each phase.

[0121] That is:

[0122] V a_ref =V a_ref0 +V a_bal

[0123] V b_ref =V b_ref0 +V b_bal

[0124] V c_ref =V c_ref0 +V c_bal

[0125] In this embodiment, each bridge arm SOC balancing control module calculates the average remaining power ratio of the energy storage unit according to the remaining power ratio of each energy storage unit in the inner load state balancing loop, that is, the average SOC value of all energy storage units is calculated according to the SOC value of each energy storage unit. The SOC value of each energy storage unit is compared with the average SOC value of all energy storage units to obtain a difference, and the difference is input to the second regulator, that is, the proportional regulator, to obtain a compensation amount. The compensation amount is multiplied by the cosine of the phase angle of the phase-shifting transformer to obtain a second additional modulation signal for each energy storage unit in each phase. Among them, the number of second additional modulation signals is determined according to the number of energy storage units in each phase line. For example, if the A phase line includes two energy storage units, the second additional modulation signal in the A phase line can be V a_1_soc 、V a_2_soc .

[0126] The second additional modulation signal of each module in each phase is added to its corresponding modulation signal reference value to obtain the modulation signal of each energy storage unit in each phase. For example, the second additional modulation signal V in the A phase line a_1_soc The modulation signal reference value V corresponding to the A phase line a_ref Add, V a_2_soc With V a_ref Add together to get the modulation signal V of the two energy storage units in the A phase line a_1_ref and V a_2_ref The calculation process of the other two phases can refer to the calculation process of phase A, which will not be repeated here.

[0127] Specific:

[0128] V a_1_soc =K soc (SOC avg -SOC a_1 )×cos(θ)

[0129] V a_2_soc =K soc (SOC avg -SOC a_2 )×cos(θ)

[0130] V b_1_soc =K soc (SOC avg -SOCb_1 )×cos(θ-120°)

[0131] V b_2_soc =K soc (SOC avg -SOC b_2 )×cos(θ-120°)

[0132] V c_1_soc =K soc (SOC avg -SOC c_1 )×cos(θ-240°)

[0133] V c_2_soc =K soc (SOC avg -SOC c_2 )×cos(θ-240°)

[0134] Among them, SOC avg is the average SOC value of the energy storage unit, SOC a_1 is the SOC value of the first energy storage unit of phase A, and the definition rules of other variables are the same. K soc It is the proportional coefficient of the proportional regulator in this layer control.

[0135] Step 130: regulating the energy storage hybrid power flow controller based on the modulation signal.

[0136] In this embodiment, the modulation signal of each energy storage unit in each phase is shift modulated to obtain a corresponding pulse width modulation (PWM) signal, and the power semiconductor device in the energy storage hybrid power flow controller is driven based on the PWM signal.

[0137] In summary, the embodiments of the present invention can be applied to power transmission lines with power flow control requirements, and can realize economical electric energy storage at the same time. The embodiments of the present invention can also be applied to medium and low voltage distribution circuits, which can not only flexibly control line power, but also assist in the consumption of new energy. Compared with the traditional method, the embodiments of the present invention combine the energy storage unit (battery) with the hybrid power flow controller, and synchronously realize line power flow control and battery charge and discharge control by sharing power modules and isolation transformers, thereby reducing investment costs. By constructing multi-layer control, it is possible to realize the basic functions of the hybrid power flow controller and the precise management of the battery, effectively avoiding the mutual influence between multiple functions.

[0138] It should be understood that the order of execution of the steps in the above embodiment does not necessarily mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present invention.

[0139] The following is an embodiment of the device of the present invention. For details not described in detail therein, reference may be made to the corresponding method embodiment described above.

[0140] Figure 4 The structure diagram of the control device of the energy storage type hybrid power flow controller provided by the embodiment of the present invention is shown. For the convenience of explanation, only the part related to the embodiment of the present invention is shown, which is described in detail as follows:

[0141] like Figure 4 As shown, the control device 4 of the energy storage type hybrid power flow controller is applied to the multi-level control loop of the energy storage type hybrid power flow controller, the energy storage type hybrid power flow controller includes an energy storage unit and a hybrid power flow controller, the hybrid power flow controller includes a cascade H bridge; the energy storage unit is connected to the cascade H bridge through a capacitor and an inductor; the control device 4 of the energy storage type hybrid power flow controller includes:

[0142] An acquisition module 41 is used to acquire the output power, reference power, total power of the energy storage unit and reference power of the energy storage unit of the target line;

[0143] The modulation module 42 is used to input the output power and the reference power, the total power of the energy storage unit and the reference power of the module battery into a multi-level control loop to obtain a modulation signal;

[0144] The control module 43 is used to control the energy storage hybrid power flow controller based on the modulation signal.

[0145] In a possible implementation, the multi-level control loop includes an outer gear control loop, a middle charge and discharge control loop, and an inner load state balancing loop;

[0146] The modulation module 42 is specifically used for:

[0147] The output power and the reference power are input into the outer gear control loop to determine and output the d-axis reference voltage of the cascaded H-bridge inverter;

[0148] The d-axis reference voltage, the total power of the energy storage unit and the reference power of the energy storage unit are input into the middle-layer charge and discharge control loop to determine and output the basic modulation signal of the cascaded H-bridge inverter;

[0149] The basic modulation signal is input into the inner load state balancing loop to determine and output the modulation signal.

[0150] In a possible implementation, the hybrid power flow controller includes a phase-shifting transformer, which is connected to a cascaded H-bridge;

[0151] The modulation module 42 is specifically used for:

[0152] If the output power is less than the reference power, the d-axis voltage of the cascaded H-bridge inverter is increased until the output power is equal to the reference power, and the corresponding d-axis voltage is output as the d-axis reference voltage;

[0153] If the d-axis voltage of the cascaded H-bridge inverter increases to an upper limit value and the output power is less than the reference power, the gear of the phase-shifting transformer is increased and the d-axis voltage is reset; the reset d-axis voltage is output as the d-axis reference voltage.

[0154] In a possible implementation, the modulation module 42 is specifically configured to:

[0155] In the outer gear control loop, if the output power is greater than the reference power, the d-axis voltage of the cascaded H-bridge inverter is reduced until the output power is equal to the reference power, and the corresponding d-axis voltage is output as the d-axis reference voltage;

[0156] If the d-axis voltage of the cascaded H-bridge inverter decreases to a lower limit value and the output power is greater than the reference power, the gear of the phase-shifting transformer is reduced and the d-axis voltage is reset; the reset d-axis voltage is output as the d-axis reference voltage.

[0157] In a possible implementation, the modulation module 42 is specifically configured to:

[0158] In the middle-level charge and discharge control loop, the average DC voltage reference value is determined according to the total power of the energy storage unit and the reference power of the energy storage unit;

[0159] A basic modulation signal of the cascaded H-bridge inverter is determined according to the average DC voltage reference value and the d-axis reference voltage.

[0160] In a possible implementation, the modulation module 42 is specifically configured to:

[0161] In the middle-level charge and discharge control loop, the difference between the reference power of the energy storage unit and the total power of the energy storage unit is passed through a proportional loop to obtain an additional voltage component of the DC voltage;

[0162] The sum of the additional voltage component and the average voltage of each energy storage unit is used as the average DC voltage reference value; wherein the average voltage of each energy storage unit is determined based on the total power of the energy storage unit.

[0163] In a possible implementation, the modulation module 42 is specifically configured to:

[0164] Obtaining the voltage of the capacitor and the phase angle of the secondary voltage of the excitation transformer in the phase-shifting transformer;

[0165] In the middle-level charge and discharge control loop, the q-axis reference voltage is determined according to the capacitor voltage and the average DC voltage reference value;

[0166] A basic modulation signal of each phase of the cascaded H-bridge inverter is determined according to a q-axis reference voltage, a d-axis reference voltage and a phase angle.

[0167] In a possible implementation, the modulation module 42 is specifically configured to:

[0168] Obtaining the remaining power ratio of each energy storage unit in the energy storage unit;

[0169] In the inner load state balancing loop, the average DC voltage of each phase in the three-phase line and the average DC voltage of the target line are calculated according to the output power;

[0170] Determine a modulation signal reference value for each phase according to an average DC voltage of each phase, an average DC voltage of the target line, a phase angle of the phase-shifting transformer, and a basic modulation signal of each phase;

[0171] The modulation signal of each phase is determined according to the remaining power ratio of each energy storage unit and the modulation signal reference value of each phase.

[0172] In a possible implementation, the modulation module 42 is specifically configured to:

[0173] In the inner load state balancing loop, the difference between the average value of the DC voltage of each phase and the average value of the DC voltage of the target line is input into the first regulator, and the output value of the first regulator is multiplied by the phase angle of the phase-shifting transformer to obtain a first additional modulation signal of each phase;

[0174] The first additional modulation signal of each phase is added to the corresponding basic modulation signal to obtain a modulation signal reference value of each phase.

[0175] In a possible implementation, the modulation module 42 is specifically configured to:

[0176] In the inner load state balancing loop, the average remaining power ratio of the energy storage unit is calculated according to the remaining power ratio of each energy storage unit;

[0177] Inputting the difference between the remaining power ratio of each energy storage unit and the average remaining power ratio into the second regulator to obtain a compensation amount;

[0178] Multiplying the compensation amount by the phase angle of the phase-shifting transformer respectively to obtain a second additional modulation signal of each energy storage unit in each phase;

[0179] The second additional modulation signal of each module in each phase is added to its corresponding modulation signal reference value to obtain the modulation signal of each energy storage unit in each phase.

[0180] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0181] Those of ordinary skill in the art will appreciate that the templates, units, and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0182] If the module / unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present invention implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by the processor, it can implement the steps of the above-mentioned various energy storage hybrid power flow controller control method embodiments. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may include: any entity or device that can carry the computer program code, recording medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory, random access memory, electrical carrier signal, telecommunication signal and software distribution medium.

[0183] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A control method for an energy storage type hybrid power flow controller, characterized in that: Applied to a multi-level control loop of an energy storage type hybrid power flow controller, the energy storage type hybrid power flow controller includes an energy storage unit and a hybrid power flow controller, the hybrid power flow controller includes a cascade H bridge; the energy storage unit is connected to the cascade H bridge through a capacitor and an inductor; the method includes: Obtaining the output power, reference power, total power and single reference power of the energy storage unit of the target line; Inputting the output power, the reference power, the total power of the energy storage unit and the reference power of the energy storage unit module into the multi-level control loop to obtain a modulation signal; The energy storage hybrid power flow controller is regulated based on the modulation signal.

2. The control method of the energy storage type hybrid power flow controller according to claim 1, characterized in that: The multi-level control loop includes an outer gear control loop, a middle charge and discharge control loop and an inner load state balancing loop; The step of inputting the output power, the reference power, the total power of the energy storage unit and the reference power of the energy storage unit into the multi-level control loop to obtain a modulation signal comprises: Inputting the output power and the reference power into the outer gear control loop, determining and outputting the d-axis reference voltage of the cascaded H-bridge inverter; Inputting the d-axis reference voltage, the total power of the energy storage unit and the reference power of the energy storage unit into the middle-layer charge and discharge control loop, determining and outputting the basic modulation signal of the cascaded H-bridge inverter; The basic modulation signal is input into the inner load state balancing loop to determine and output the modulation signal.

3. The control method of the energy storage type hybrid power flow controller according to claim 2 is characterized in that: The hybrid power flow controller includes a phase-shifting transformer, and the phase-shifting transformer is connected to the cascade H-bridge; The step of inputting the output power and the reference power into the outer gear position control loop to determine and output a d-axis reference voltage of the cascaded H-bridge inverter comprises: If the output power is less than the reference power, increasing the d-axis voltage of the cascaded H-bridge inverter until the output power is equal to the reference power, and outputting the corresponding d-axis voltage as the d-axis reference voltage; If the d-axis voltage of the cascaded H-bridge inverter increases to an upper limit value and the output power is less than the reference power, the gear of the phase-shifting transformer is increased and the d-axis voltage is reset; the reset d-axis voltage is output as the d-axis reference voltage.

4. The control method of the energy storage type hybrid power flow controller according to claim 1, characterized in that: The step of inputting the output power and the reference power into the outer gear position control loop to determine and output a d-axis reference voltage of the cascaded H-bridge inverter comprises: In the outer gear control loop, if the output power is greater than the reference power, the d-axis voltage of the cascaded H-bridge inverter is reduced until the output power is equal to the reference power, and the corresponding d-axis voltage is output as the d-axis reference voltage; If the d-axis voltage of the cascaded H-bridge inverter decreases to a lower limit value and the output power is greater than the reference power, the gear of the phase-shifting transformer is reduced and the d-axis voltage is reset; the reset d-axis voltage is output as the d-axis reference voltage.

5. The control method of the energy storage type hybrid power flow controller according to claim 2, characterized in that: The step of inputting the d-axis reference voltage, the total power of the energy storage unit and the reference power of the energy storage unit into the middle-layer charge and discharge control loop, and determining and outputting the basic modulation signal of the cascaded H-bridge inverter comprises: In the middle-layer charge and discharge control loop, an average DC voltage reference value is determined according to the total power of the energy storage unit and the reference power of the energy storage unit; A basic modulation signal of the cascaded H-bridge inverter is determined according to the average DC voltage reference value and the d-axis reference voltage.

6. The control method of the energy storage type hybrid power flow controller according to claim 5, characterized in that: The step of determining the average DC voltage reference value according to the total power of the energy storage unit and the reference power of the energy storage unit comprises: In the middle-layer charge and discharge control loop, the difference between the reference power of the energy storage unit and the total power of the energy storage unit is passed through a proportional loop to obtain an additional voltage component of the DC voltage; The sum of the additional voltage component and the average voltage of each energy storage unit is used as an average DC voltage reference value; wherein the average voltage of each energy storage unit is determined based on the total power of the energy storage unit.

7. The control method of the energy storage type hybrid power flow controller according to claim 5, characterized in that: Determining the basic modulation signal of the cascaded H-bridge inverter according to the average DC voltage reference value and the d-axis reference voltage includes: Obtaining the voltage of the capacitor and the phase angle of the secondary side voltage of the excitation transformer in the phase-shifting transformer; In the middle-layer charge and discharge control loop, a q-axis reference voltage is determined according to the voltage of the capacitor and the average DC voltage reference value; A basic modulation signal of each phase of the cascaded H-bridge inverter is determined according to the q-axis reference voltage, the d-axis reference voltage and the phase angle.

8. The control method of the energy storage type hybrid power flow controller according to claim 2, characterized in that: The step of inputting the basic modulation signal into the inner load state balancing loop, and determining and outputting the modulation signal comprises: Obtaining the remaining power ratio of each energy storage unit in the energy storage unit; In the inner load state balancing loop, the average value of the DC voltage of each phase in the three-phase line and the average value of the DC voltage of the target line are calculated according to the output power; Determine a modulation signal reference value of each phase according to the average value of the DC voltage of each phase, the average value of the DC voltage of the target line, the phase angle of the phase-shifting transformer and the basic modulation signal of each phase; The modulation signal of each phase is determined according to the remaining power ratio of each energy storage unit and the modulation signal reference value of each phase.

9. The control method of the energy storage type hybrid power flow controller according to claim 8, characterized in that: The step of determining a modulation signal reference value of each phase according to the average value of the DC voltage of each phase, the average value of the DC voltage of the target line, the phase angle of the phase-shifting transformer and the basic modulation signal of each phase comprises: In the inner load state balancing loop, the difference between the average value of the DC voltage of each phase and the average value of the DC voltage of the target line is input into a first regulator, and the output value of the first regulator is multiplied by the phase angle of the phase-shifting transformer to obtain a first additional modulation signal of each phase; The first additional modulation signal of each phase is added to the corresponding basic modulation signal to obtain a modulation signal reference value of each phase; Determining the modulation signal of each phase according to the remaining power ratio of each energy storage unit and the modulation signal reference value of each phase includes: In the inner load state balancing loop, according to the remaining power ratio of each energy storage unit, the average remaining power ratio of the energy storage unit is calculated; Inputting the difference between the remaining power ratio of each energy storage unit and the average remaining power ratio into the second regulator to obtain a compensation amount; Multiplying the compensation amount by the phase angle of the phase-shifting transformer respectively to obtain a second additional modulation signal of each energy storage unit in each phase; The second additional modulation signal of each module in each phase is added to its corresponding modulation signal reference value to obtain the modulation signal of each energy storage unit in each phase.

10. A control device for an energy storage type hybrid power flow controller, characterized in that: Applicable to a multi-level control loop of an energy storage type hybrid power flow controller, the energy storage type hybrid power flow controller includes an energy storage unit and a hybrid power flow controller, the hybrid power flow controller includes a cascade H bridge; the energy storage unit is connected to the cascade H bridge through a capacitor and an inductor; the device includes: An acquisition module, used to acquire the output power, reference power, total power of the energy storage unit and reference power of the energy storage unit of the target line; A modulation module, used for inputting the output power and the reference power, the total power of the energy storage unit and the reference power of the module battery into the multi-level control loop to obtain a modulation signal; A control module is used to control the energy storage hybrid power flow controller based on the modulation signal.

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