Direct-current bus voltage control method and system for energy router

Abstract

The invention provides a direct-current bus voltage control method and system for an energy router, and the method comprises the steps: dividing the operation of the energy router to a corresponding control layer based on the voltage variation of a direct-current bus in the energy router; for a control layer corresponding to the energy router, determining a converter operating as a voltage source in the energy router; a control strategy of the control layer is utilized to perform operation control on a plurality of converters including the converter operating as the voltage source in the energy router, thereby realizing regulation and control on the voltage of the direct current bus and maintaining the voltage and power balance of the direct current bus; the control layer where the energy router is located is switched through the voltage variable quantity of the direct-current bus, the operation mode of each converter is adjusted based on the control strategy of each control layer, it is guaranteed that one converter works in the voltage source mode at any time, stable operation of the direct-current bus is maintained, and the reliability of the energy router is improved. And the control is simplified, and the stable work in the system can be ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of energy routers, and in particular to a DC bus voltage control method and system for an energy router. Background Art

[0002] Energy router is an energy conversion and energy management device based on power electronics technology and information technology. It can monitor the operation status of the power grid in real time through an intelligent control unit, and dynamically adjust the transmission and distribution of energy according to the needs of power-consuming equipment and the supply of the power grid. In the energy router system, the DC bus is the key link to connect different energy sources and loads, so the stability of the DC bus voltage is crucial to the normal operation of the entire energy router system.

[0003] The voltage of the DC bus is affected by many factors, such as the fluctuation of the power generated by the renewable energy connected to the DC bus due to environmental factors, the changes in various load demands, and the power constraints of the power grid. The stability of the DC bus voltage represents the power balance in the energy router system. Improper control of the DC bus voltage will affect the stability of the DC bus voltage, and further affect the power balance of the entire energy router system, resulting in the inability of multiple converters in the energy router system to work in coordination. Summary of the invention

[0004] In order to overcome the above-mentioned deficiencies of the prior art, the present invention proposes a DC bus voltage control method for an energy router, comprising:

[0005] Based on the voltage variation of the DC bus in the energy router, the operation of the energy router is divided into corresponding control layers;

[0006] For a control layer corresponding to the energy router, determining a converter operating as a voltage source in the energy router;

[0007] The control strategy of the control layer is used to control the operation of multiple converters in the energy router, including the converter operating as a voltage source, so as to regulate the voltage of the DC bus and maintain the voltage and power balance of the DC bus.

[0008] Optionally, the energy router includes: a grid-connected unit converter, an energy storage converter, a photovoltaic converter and a load unit converter;

[0009] The energy router is connected to the power grid through the grid-connected unit converter, and the load unit, photovoltaic unit and energy storage unit are connected to the DC bus through the load unit converter, the photovoltaic converter and the energy storage converter respectively.

[0010] Optionally, dividing the operation of the energy router into corresponding control layers based on the voltage variation of the DC bus in the energy router includes:

[0011] If the voltage variation of the DC bus is within the first layer voltage interval, the energy converter is divided into the grid dominant control layer for operation;

[0012] If the voltage variation of the DC bus is within the second layer voltage interval, the energy converter is divided into the energy storage dominant control layer for operation;

[0013] If the voltage variation of the DC bus is within the third layered voltage interval, the energy converter is divided into the photovoltaic dominant control layer for operation.

[0014] Optionally, before dividing the operation of the energy router to the corresponding control layer based on the voltage change of the DC bus in the energy router, the method further includes:

[0015] Voltage hysteresis loops are respectively added to the interval boundary values ​​of the first layer voltage interval, the second layer voltage interval and the third layer voltage interval to avoid frequent switching of the energy router between different control layers.

[0016] Optionally, for a control layer corresponding to the energy router, determining a converter operating as a voltage source in the energy router includes:

[0017] If the control layer corresponding to the energy router is the grid-dominant control layer, the grid-connected unit converter is operated as a voltage source, and other converters other than the grid-connected unit converter are operated as current sources;

[0018] If the control layer corresponding to the energy router is the energy storage dominant control layer, the energy storage converter is operated as a voltage source, and other converters other than the energy storage converter are operated as current sources;

[0019] If the control layer corresponding to the energy router is the photovoltaic dominant control layer, the photovoltaic converter is operated as a voltage source, and converters other than the photovoltaic converter are operated as current sources.

[0020] Optionally, for the grid dominant control layer, using the control strategy of the control layer to control the operation of multiple converters in the energy router including the converter operating as a voltage source includes:

[0021] When the operation mode of the energy router is a free networking mode, an outer loop with a droop characteristic in a control loop of the grid-connected unit converter is used to perform voltage control, and the output of the voltage control is used as an input of the current control in the inner loop, and a PWM signal is generated by the current control to control the operation of the grid-connected unit converter;

[0022] Based on the charging instruction of the battery in the energy storage unit and the current reference value of the energy storage converter, the energy storage converter is current controlled, and the PWM signal output by the current control is combined with the charge state of the battery to perform logic control to output a driving signal, and the energy storage converter is controlled based on the driving signal, and the energy storage unit is charged by the DC bus;

[0023] The terminal voltage reference value output by the maximum power point tracking control link in the control loop of the photovoltaic converter is combined with the output voltage of the photovoltaic unit to input the controller to obtain a PWM signal, and the photovoltaic converter is driven to operate in the maximum power point tracking mode based on the PWM signal to input the electric energy generated by the photovoltaic unit into the DC bus;

[0024] The load unit converter is controlled by a double closed-loop control loop of a voltage outer loop and a current inner loop to provide stable direct current for the load unit.

[0025] Optionally, before the current control of the energy storage converter based on the charging instruction of the battery in the energy storage unit and the current reference value of the energy storage converter is performed, the method further includes:

[0026] A state of charge threshold interval of the battery is set. If the state of charge of the battery exceeds the state of charge threshold interval, the PWM signal is blocked, and the DC bus is stopped from charging the energy storage unit.

[0027] Optionally, for the energy storage leading control layer, using the control strategy of the control layer to control the operation of multiple converters in the energy router including the converter operating as a voltage source includes:

[0028] When the operation mode of the energy router is the networking current limiting mode, the outer loop with droop characteristics in the control loop of the energy storage converter is used for voltage control, and the output of the voltage control is input into the current control in the inner loop after passing through the current limiting link, and the PWM signal is generated by the current control to control the operation of the energy storage converter;

[0029] The terminal voltage reference value output by the maximum power point tracking control link in the control loop of the photovoltaic converter is combined with the output voltage of the photovoltaic unit to input the controller to obtain a PWM signal, and the photovoltaic converter is driven to operate in the maximum power point tracking mode based on the PWM signal to input the electric energy generated by the photovoltaic unit into the DC bus;

[0030] The load unit converter is controlled by a double closed-loop control loop of a voltage outer loop and a current inner loop to provide stable direct current for the load unit.

[0031] Optionally, for the photovoltaic dominant control layer, the control strategy of the control layer corresponding to the energy router is used to control the operation of multiple converters in the energy router including the converter operating as a voltage source, including:

[0032] When the operation mode of the energy router is the abandoned light operation mode, the terminal voltage reference value of the photovoltaic unit is obtained by using the maximum power point tracking control link and the voltage bias link in the control loop of the photovoltaic converter, the terminal voltage reference value and the output voltage of the photovoltaic unit are input into the controller to obtain a PWM signal, and the photovoltaic converter is driven to operate in a constant voltage mode based on the PWM signal, and the electric energy generated by the photovoltaic unit is input into the DC bus;

[0033] The load unit converter is controlled by a double closed-loop control loop of a voltage outer loop and a current inner loop to provide stable direct current for the load unit.

[0034] Based on the same inventive concept, the present invention proposes a DC bus voltage control system for an energy router, comprising:

[0035] A control layer division module, used for dividing the operation of the energy router into corresponding control layers based on the voltage change of the DC bus in the energy router;

[0036] A voltage source mode converter determination module, for determining a converter operating as a voltage source in the energy router for a control layer corresponding to the energy router;

[0037] A DC bus voltage control module is used to utilize the control strategy of the control layer to control the operation of multiple converters in the energy router, including the converter operating as a voltage source, to control the voltage of the DC bus and maintain the voltage and power balance of the DC bus.

[0038] Optionally, the energy router includes: a grid-connected unit converter, an energy storage converter, a photovoltaic converter and a load unit converter;

[0039] The energy router is connected to the power grid through the grid-connected unit converter, and the load unit, photovoltaic unit and energy storage unit are connected to the DC bus through the load unit converter, the photovoltaic converter and the energy storage converter respectively.

[0040] Optionally, the control layer division module is specifically used to:

[0041] If the voltage variation of the DC bus is within the first layer voltage interval, the energy converter is divided into the grid dominant control layer for operation;

[0042] If the voltage variation of the DC bus is within the second layer voltage interval, the energy converter is divided into the energy storage dominant control layer for operation;

[0043] If the voltage variation of the DC bus is within the third layered voltage interval, the energy converter is divided into the photovoltaic dominant control layer for operation.

[0044] Optionally, the control layer division module is further used for:

[0045] Voltage hysteresis loops are respectively added to the interval boundary values ​​of the first layer voltage interval, the second layer voltage interval and the third layer voltage interval to avoid frequent switching of the energy router between different control layers.

[0046] Optionally, the voltage source mode converter determination module is specifically used to:

[0047] If the control layer corresponding to the energy router is the grid-dominant control layer, the grid-connected unit converter is operated as a voltage source, and other converters other than the grid-connected unit converter are operated as current sources;

[0048] If the control layer corresponding to the energy router is the energy storage dominant control layer, the energy storage converter is operated as a voltage source, and other converters other than the energy storage converter are operated as current sources;

[0049] If the control layer corresponding to the energy router is the photovoltaic dominant control layer, the photovoltaic converter is operated as a voltage source, and converters other than the photovoltaic converter are operated as current sources.

[0050] Optionally, for the grid leading control layer, the DC bus voltage regulation module is specifically used to:

[0051] When the operation mode of the energy router is a free networking mode, an outer loop with a droop characteristic in a control loop of the grid-connected unit converter is used to perform voltage control, and the output of the voltage control is used as an input of the current control in the inner loop, and a PWM signal is generated by the current control to control the operation of the grid-connected unit converter;

[0052] Based on the charging instruction of the battery in the energy storage unit and the current reference value of the energy storage converter, the energy storage converter is current controlled, and the PWM signal output by the current control is combined with the charge state of the battery to perform logic control to output a driving signal, and the energy storage converter is controlled based on the driving signal, and the energy storage unit is charged by the DC bus;

[0053] The terminal voltage reference value output by the maximum power point tracking control link in the control loop of the photovoltaic converter is combined with the output voltage of the photovoltaic unit to input the controller to obtain a PWM signal, and the photovoltaic converter is driven to operate in the maximum power point tracking mode based on the PWM signal to input the electric energy generated by the photovoltaic unit into the DC bus;

[0054] The load unit converter is controlled by a double closed-loop control loop of a voltage outer loop and a current inner loop to provide stable direct current for the load unit.

[0055] Optionally, for the grid leading control layer, the DC bus voltage regulation module is further used to:

[0056] A state of charge threshold interval of the battery is set. If the state of charge of the battery exceeds the state of charge threshold interval, the PWM signal is blocked, and the DC bus is stopped from charging the energy storage unit.

[0057] Optionally, for the energy storage dominant control layer, the DC bus voltage regulation module is specifically used to:

[0058] When the operation mode of the energy router is the networking current limiting mode, the outer loop with droop characteristics in the control loop of the energy storage converter is used for voltage control, and the output of the voltage control is input into the current control in the inner loop after passing through the current limiting link, and the PWM signal is generated by the current control to control the operation of the energy storage converter;

[0059] The terminal voltage reference value output by the maximum power point tracking control link in the control loop of the photovoltaic converter is combined with the output voltage of the photovoltaic unit to input the controller to obtain a PWM signal, and the photovoltaic converter is driven to operate in the maximum power point tracking mode based on the PWM signal to input the electric energy generated by the photovoltaic unit into the DC bus;

[0060] The load unit converter is controlled by a double closed-loop control loop of a voltage outer loop and a current inner loop to provide stable direct current for the load unit.

[0061] Optionally, for the photovoltaic dominant control layer, the DC bus voltage regulation module is specifically used to:

[0062] When the operation mode of the energy router is the abandoned light operation mode, the terminal voltage reference value of the photovoltaic unit is obtained by using the maximum power point tracking control link and the voltage bias link in the control loop of the photovoltaic converter, the terminal voltage reference value and the output voltage of the photovoltaic unit are input into the controller to obtain a PWM signal, and the photovoltaic converter is driven to operate in a constant voltage mode based on the PWM signal, and the electric energy generated by the photovoltaic unit is input into the DC bus;

[0063] The load unit converter is controlled by a double closed-loop control loop of a voltage outer loop and a current inner loop to provide stable direct current for the load unit.

[0064] In another aspect, the present application further provides an electronic device, comprising: at least one processor and a memory; the memory and the processor are connected via a bus;

[0065] The memory is used to store one or more programs;

[0066] When the one or more programs are executed by the at least one processor, a DC bus voltage control method for an energy router as described above is implemented.

[0067] On the other hand, the present application further provides a computer-readable storage medium having an execution program stored thereon, and when the execution program is executed, a DC bus voltage control method for an energy router as described above is implemented.

[0068] Compared with the closest prior art, the present invention has the following beneficial effects:

[0069] The present invention provides a DC bus voltage control method and system for an energy router, comprising: dividing the operation of the energy router into corresponding control layers based on the voltage variation of the DC bus in the energy router; determining a converter operating as a voltage source in the energy router for the control layer corresponding to the energy router; using the control strategy of the control layer, controlling the operation of multiple converters in the energy router including the converter operating as a voltage source, so as to regulate the voltage of the DC bus and maintain the voltage and power balance of the DC bus; in the present invention, the voltage signal of the DC bus is used as a reference, the control layer where the energy router is located is switched according to the voltage variation of the DC bus, and the operation mode of each converter is adjusted based on the control strategy of each control layer, so as to ensure that at any time there is a converter operating in the voltage source mode, maintain the stable operation of the DC bus, and then maintain the power balance of the entire energy router system, so that multiple converters in the energy router system can operate stably; in the present invention, communication between converters is not required, so it has good compatibility, and can ensure the stable operation of the system while simplifying the control, and can improve the management efficiency of system operation and maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Figure 1 A schematic flow chart of a DC bus voltage control method for an energy router provided by the present invention;

[0071] Figure 2 It is a schematic diagram of the structure of the power system where the energy router is located;

[0072] Figure 3 It is a schematic diagram of dividing the control layer where the energy router is located based on voltage;

[0073] Figure 4 It is the control schematic diagram of superimposed droop control;

[0074] Figure 5 It is a schematic diagram of the control loop of the grid-connected unit converter in the grid dominant control layer;

[0075] Figure 6 It is a schematic diagram of the control loop of the energy storage converter in the dominant control layer of the power grid;

[0076] Figure 7 It is a schematic diagram of the control loop of the photovoltaic converter;

[0077] Figure 8 It is a schematic diagram of the control loop of the energy storage converter in the energy storage dominant control layer;

[0078] Fig. 9 It is the voltage layered droop control characteristic diagram;

[0079] Fig.10It is the power waveform diagram of the DC bus and each unit during the simulation process in the free networking mode;

[0080] Fig.11 It is the output waveform diagram of the energy storage unit during the simulation process under the network current limiting mode;

[0081] Fig.12 It is the power waveform diagram of the DC bus and each unit during the simulation process under the network current limiting mode;

[0082] Fig.13 It is the power waveform diagram of the DC bus and each unit during the simulation process under the abandoned light operation mode;

[0083] Fig.14 It is the voltage waveform diagram of each unit in the system operation process in the energy storage dominant control layer;

[0084] Fig.15 It is the current waveform diagram of each unit in the system operation process in the energy storage dominant control layer;

[0085] Fig.16 The waveforms of the voltage Uc and current Ic of the inverter AC side phase C in the energy storage dominant control layer;

[0086] Fig.17 The voltage and current waveforms of each unit in the energy router during the loading process;

[0087] Fig.18 A schematic structural diagram of a DC bus voltage control system for an energy router provided by the present invention;

[0088] Fig.19 The present invention provides a schematic diagram of the structure of an electronic device. DETAILED DESCRIPTION

[0089] The specific implementation modes of the present invention are further described in detail below with reference to the accompanying drawings.

[0090] Example 1

[0091] The present invention provides a DC bus voltage control method for an energy router, such as Figure 1 As shown, including:

[0092] S1. Based on the voltage change of the DC bus in the energy router, the operation of the energy router is divided into corresponding control layers;

[0093] S2. for the control layer corresponding to the energy router, determining a converter operating as a voltage source in the energy router;

[0094] S3. Utilize the control strategy of the control layer to control the operation of multiple converters in the energy router, including the converter operating as a voltage source, to regulate the voltage of the DC bus and maintain the voltage and power balance of the DC bus.

[0095] like Figure 2 As shown, the energy router includes: a grid-connected unit converter, an energy storage converter, a photovoltaic converter and a load unit converter; the energy router is connected to the power grid through the grid-connected unit converter, and the load unit, the photovoltaic unit and the energy storage unit are respectively connected to the DC bus through the load unit converter, the photovoltaic converter and the energy storage converter.

[0096] Specifically, the topological structure of the power system where the energy router is located in this embodiment mainly includes four units, such as Figure 2 As shown, they are a photovoltaic unit, a grid-connected unit, a load unit and an energy storage unit, respectively. The converters in the four units together constitute the energy router. The No. 1 converter (i.e., the grid-connected unit converter) in the grid-connected unit is a bidirectional AC / DC converter (Alternating Current / Direct Current), which is responsible for the power interaction between the energy router and the power grid, and the PCC (Point of Common Coupling) is the grid-connected switch on the AC side of the power grid; the No. 2 converter (i.e., the load unit converter) in the load unit is a single-phase step-down converter, and in this embodiment, a Buck circuit is used to convert the intermediate DC bus voltage of 750V into DC 220V for use by the DC load; the No. 3 converter (i.e., the photovoltaic converter) in the photovoltaic unit is responsible for boosting the low-voltage DC power emitted by the photovoltaic to the DC bus, and controlling the power output of the photovoltaic unit during operation; the No. 4 converter (i.e., the energy storage converter) of the energy storage unit is a bidirectional DC / DC converter (Current / Direct Current), and the energy storage unit includes the energy storage converter and an energy storage battery, which is used to store and release energy during operation.

[0097] In step S1, based on the voltage variation of the DC bus in the energy router, the operation of the energy router is divided into corresponding control layers.

[0098] If the voltage variation of the DC bus is within the first layer voltage interval, the energy converter is divided into the grid dominant control layer for operation;

[0099] If the voltage variation of the DC bus is within the second layer voltage interval, the energy converter is divided into the energy storage dominant control layer for operation;

[0100] If the voltage variation of the DC bus is within the third layered voltage interval, the energy converter is divided into the photovoltaic dominant control layer for operation.

[0101] like Figure 3 As shown, the operation of the system is divided into three layers according to the voltage change of the DC bus. vt1 and vt2 are the threshold voltages of the switching points in the hierarchical control. In this embodiment, the values ​​selected for vt1 and vt2 are 0.02 and 0.05 (unit value), respectively. dc *Indicates the reference value of voltage change, v dc Indicates the DC bus voltage. S=1, 2, 3 means that the energy router works in the first, second, and third control layers respectively. ΔV dc Indicates the voltage change. Specifically, when the voltage change range of the DC bus |△U dc |When the voltage is within ±2%, i.e., the first layer voltage range, the energy router operates in the first layer, i.e., the grid dominant control layer;

[0102] When the voltage variation range of DC bus|△U dc |2%≤|△U dc |≤5%, that is, in the second layer voltage interval, the energy router operates in the second layer, that is, the energy storage dominant control layer, ΔU dc Indicates the voltage change of the DC bus;

[0103] When the voltage variation range of DC bus|△U dc |in|△U dc |>5%, that is, the third layer voltage interval, the energy router operates in the third layer, that is, the photovoltaic dominant control layer.

[0104] Before dividing the operation of the energy router into corresponding control layers based on the voltage variation of the DC bus in the energy router, the method further includes:

[0105] Voltage hysteresis loops are respectively added to the interval boundary values ​​of the first layer voltage interval, the second layer voltage interval and the third layer voltage interval to avoid frequent switching of the energy router between different control layers.

[0106] In step S2, for a control layer corresponding to the energy router, a converter operating as a voltage source is determined in the energy router.

[0107] In different control layers, one converter in each layer needs to operate as a voltage source to control the relative stability of the DC bus voltage. Other converters operate as current sources to absorb power from the DC bus or directly feed power to the DC bus. The converter operating as a voltage source can absorb or release power according to the power conditions of other converters operating as current sources. Under this hierarchical control method, there is no communication connection between the converters, which avoids various control problems caused by communication delays and simplifies the control complexity of the system.

[0108] Specifically, if the control layer corresponding to the energy router is the grid-dominant control layer, the grid-connected unit converter is operated as a voltage source, and other converters other than the grid-connected unit converter (i.e., the energy storage converter, the photovoltaic converter, and the load unit converter) are operated as current sources;

[0109] If the control layer corresponding to the energy router is the energy storage dominant control layer, the energy storage converter is operated as a voltage source, and other converters other than the energy storage converter (i.e., the grid-connected unit converter, the photovoltaic converter, and the load unit converter) are operated as current sources;

[0110] If the control layer corresponding to the energy router is the photovoltaic dominant control layer, the photovoltaic converter is operated as a voltage source, and other converters other than the photovoltaic converter (i.e., the energy storage converter, the grid-connected unit converter, and the load unit converter) are operated as current sources.

[0111] In step S3, the control strategy of the control layer is used to control the operation of multiple converters in the energy router, including the converter operating as a voltage source, so as to regulate the voltage of the DC bus and maintain the voltage and power balance of the DC bus.

[0112] S3-1, Power grid dominant control layer:

[0113] When the energy router operates in the grid-dominated control layer, the operation mode of the energy router is the free networking mode. In this layer of control, the grid plays a leading role, and the system DC bus voltage is controlled by the grid-connected inverter (i.e., the grid-connected unit converter) for rectification operation, and the grid-connected inverter undertakes the task of balancing the system power; the energy storage unit is charged and the electric energy is stored in the energy storage battery for backup; the photovoltaic unit operates in MPPT (Maximum Power Point Tracking) mode to capture solar energy and connect pollution-free solar energy to the energy router.

[0114] The grid-connected inverter is a DC voltage control terminal that can be used to control the voltage of the DC bus to be constant. The outer loop of the control loop of the grid-connected inverter uses DC voltage control to operate as a voltage source to ensure the stability of the DC side voltage, and the inner loop uses current control.

[0115] Specifically, the outer loop with droop characteristics in the control loop of the grid-connected unit converter is used to perform voltage control, the output of the voltage control is used as the input of the current control in the inner loop, and a PWM (Pulse Width Modulation) signal is generated through the current control to control the operation of the grid-connected unit converter;

[0116] Superimposing voltage droop control in the outer loop of the control loop can realize automatic power distribution, dynamically balance the power generation in the energy router and the power consumption of the load unit, while maintaining the DC bus voltage in a relatively constant range, and can achieve smooth switching between control layers. The basic principle of droop control is to introduce a current feedback link in the control loop of the converter. The feedback current value is multiplied by the droop coefficient as a voltage offset and works together with the original given voltage to become a new voltage setting. Figure 4 As shown in the figure, it is a control diagram of superimposed droop control, U i0 is the initial given voltage command of the converter, that is, the initial expected voltage value, K i is the droop coefficient of the converter, I i Indicates the feedback current value, U dcrefi is the new expected voltage value after the initial expected voltage value and droop control work together, U dci is the output voltage of the converter.

[0117] After superimposing droop control, the control loop of the grid-connected unit converter operating as a voltage source is as follows: Figure 5 As shown, It represents the initial given voltage instruction of the grid-connected unit converter in the grid dominant control layer, that is, the initial voltage reference value. In this embodiment, the initial voltage reference value 750V, U dcref_G Indicates the voltage reference value after superimposing droop control, K G Indicates the droop coefficient of the grid-connected unit converter, K G =0.02 / I G_max , I G_max Indicates the maximum value of the DC side current of the grid-connected unit converter; I G_min Indicates the minimum value of the DC side current of the grid-connected unit converter; I dc_G Indicates the feedback current value of the grid-connected unit converter, that is, the output current; U dc_G Indicates the output voltage of the grid-connected unit converter.

[0118] In the grid dominant control layer, the energy storage battery (battery) in the energy storage unit is in a charging state. Specifically, Figure 6 As shown, the battery energy management system gives a current charging instruction based on the charging instruction of the battery in the energy storage unit and the current reference value of the energy storage converter. And the output current I of the energy storage converter dc_B The energy storage converter is current controlled, and a PWM signal output by the current control is combined with the state of charge (SOC) of the battery to perform logic control to output a drive signal, the energy storage converter is controlled based on the drive signal, and the DC bus is used to charge the energy storage battery in the energy storage unit.

[0119] Before the energy storage converter is current controlled, the method further includes: setting a state of charge threshold interval of the battery, and if the state of charge of the battery exceeds the state of charge SOC threshold interval, blocking the PWM signal and stopping the DC bus from charging the energy storage battery in the energy storage unit. In this embodiment, the SOC threshold interval is set to 20% to 80%, that is, the upper limit of the battery charging SOC is 80%, and the lower limit of the discharge SOC is 20%. When the SOC is higher than 80%, the PWM signal is blocked to stop charging.

[0120] In the grid-dominated control layer, the photovoltaic converter in the photovoltaic unit works in MPPT mode, converting solar energy into electrical energy to the DC bus of the input system to the greatest extent. Figure 7 As shown, the terminal voltage reference value output by the maximum power point tracking control link in the control loop of the photovoltaic converter is combined with the output voltage of the photovoltaic unit to input the controller to obtain a PWM signal, and the photovoltaic converter is driven to operate in the maximum power point tracking mode based on the PWM signal, and the electric energy generated by the photovoltaic unit is input into the DC bus.

[0121] Specifically, during the operation of the energy router, the output voltage and current of the photovoltaic unit are collected. The voltage U PV and current I PV Through the maximum power point tracking MPPT link in the control loop of the photovoltaic converter, the output voltage command signal V MPPT and the voltage bias signal ΔV calculated by the voltage bias link PvAfter superposition, the terminal voltage reference value of the photovoltaic cell is obtained. After comparison with the output voltage of the photovoltaic unit, the difference is passed through the PI controller (Proportional-Integral Controller) to generate a duty cycle signal, and the drive signal is generated through the PWM link to control the operation of the photovoltaic converter. Since the photovoltaic converter needs to operate in the MPPT mode in the dominant control layer of the power grid, the voltage bias signal ΔV in the voltage bias link at this time PV is zero, ensuring that the system works in normal MMPT mode. PV The DC bus voltage V collected in real time dc The DC bus voltage is set to a preset value V dcref After comparison, it is obtained through PI controller.

[0122] The load unit converter is controlled by a double closed-loop control loop of a voltage outer loop and a current inner loop to provide stable direct current for the direct current load in the load unit.

[0123] S3-2, energy storage dominant control layer:

[0124] In the energy storage-dominant control layer, the operation mode of the energy router is the network-connected current limiting mode. The current output capacity of the converter is limited. When the power is too large, the converter needs to limit the power to avoid damage during operation. Therefore, a current limiting link is usually set in the control loop to ensure that when the power is too large, the converter can automatically enter the current limiting mode. In the network-connected current limiting mode, the grid-connected unit converter reaches the current output or absorption limit and loses the ability to maintain a constant bus voltage. In this layer of control, the photovoltaic unit still operates in the MPPT mode, absorbing solar energy, and the DC bus voltage is controlled by the energy storage unit. The energy storage converter in the energy storage unit is converted from a current source to a voltage source mode to control the DC bus side voltage stability.

[0125] Specifically, Figure 8 As shown, the outer loop with droop characteristics in the control loop of the energy storage converter is used for voltage control, and the droop control output is used as a given value of the voltage controller. The output of the voltage control is input into the current control in the inner loop after passing through the current limiting link, and the PWM signal is generated by the current control to control the operation of the energy storage converter. Among them, represents the initial voltage reference value of the energy storage converter in the energy storage dominant control layer. In this embodiment, or U dcref_B Indicates the voltage reference value after superimposing droop control, K B Represents the droop coefficient of the energy storage converter. In this embodiment, K G =0.03 / I B_max , IB_max It represents the maximum value of the DC side current of the energy storage converter. According to the characteristics of droop control, in order to increase the energy storage capacity of the system, when there are multiple groups of energy storage batteries in the system, the droop coefficient corresponding to the group of energy storage units can be designed according to the power distribution of different energy storage units, so as to control the DC bus voltage more finely. B_min Indicates the minimum value of the DC side current of the energy storage converter; I dc_B Indicates the feedback current value of the energy storage converter, that is, the output current; U dc_B Represents the output voltage of the energy storage converter.

[0126] In the energy storage dominant control layer, the terminal voltage reference value output by the maximum power point tracking control link in the control loop of the photovoltaic converter is combined with the output voltage of the photovoltaic unit to input the controller to obtain a PWM signal, and the photovoltaic converter is driven to operate in the maximum power point tracking mode based on the PWM signal, and the electric energy generated by the photovoltaic unit is input into the DC bus;

[0127] The load unit converter is controlled by a double closed-loop control loop of a voltage outer loop and a current inner loop to provide stable direct current for the direct current load of the load unit.

[0128] In the present invention, the grid-connected unit converter and the energy storage converter in the grid-dominant control layer and the energy storage-dominant control layer respectively adopt a control method with droop characteristics, such as Fig. 9 As shown in the figure, it is a voltage layered droop control characteristic diagram, which respectively represents the power supply external characteristics of the grid-connected unit converter and the energy storage converter at different layers, where the horizontal axis represents the output current of the converter, and the vertical axis represents the voltage change of the DC bus. The voltage change is marked in the form of per unit value, I dc_B Represents the output current of the energy storage converter, I dc_G Represents the output current of the grid-connected unit converter; I G_max Indicates the maximum value of the DC side current of the grid-connected unit converter; I G_min Indicates the minimum value of the DC side current of the grid-connected unit converter; I B_min Indicates the minimum value of the DC side current of the energy storage converter, I B_max Indicates the maximum value of the DC side current of the energy storage converter, U dc_B Represents the output voltage of the energy storage converter, U d c G Represents the output voltage of the grid-connected unit converter. The positive direction of the output current indicates that the grid-connected unit converter and the energy storage converter transmit electric energy to the DC bus of the energy router, and the negative direction of the output current indicates that the grid-connected unit converter and the energy storage converter absorb electric energy from the DC bus.

[0129] S3-3, Photovoltaic dominant control layer:

[0130] In the photovoltaic dominant control layer, the operation mode of the energy router is the abandoned light operation mode. At this time, the battery SOC of the energy storage unit has reached the upper limit value specified by the system, or the energy storage unit is charging the battery at the maximum charging current, and the photovoltaic power is relatively large; at this time, the voltage of the DC bus will continue to increase. In order to ensure the stability of the DC bus voltage in the system, the photovoltaic unit needs to exit the MPPT mode and switch to the constant voltage operation mode.

[0131] The maximum power point tracking control link and the voltage bias link in the control loop of the photovoltaic converter are used to obtain a terminal voltage reference value of the photovoltaic unit, the terminal voltage reference value and the output voltage of the photovoltaic unit are input into a controller to obtain a PWM signal, and the photovoltaic converter is driven to operate in a constant voltage mode based on the PWM signal, and the electric energy generated by the photovoltaic unit is input into the DC bus.

[0132] Specifically, Figure 7 As shown, the output voltage and current of the photovoltaic unit are collected, and the voltage U PV and current I Pv Through the maximum power point tracking MPPT link in the control loop of the photovoltaic converter, the output voltage command signal V MPPT and the voltage bias signal ΔV calculated by the voltage bias link PV After superposition, the terminal voltage reference value V of the photovoltaic cell is obtained. PVref In the voltage bias link, the DC bus voltage V is collected in real time dc And with the preset value of the DC bus voltage V dcref By comparison, the PI controller adjusts and controls the difference between the actual voltage and the preset voltage, and the PI controller of the voltage bias link outputs ΔV PV The limit processing is done and the lower limit value is set. When the actual voltage value of the DC bus voltage is lower than the preset value of the DC bus voltage, △V PV is zero, ensuring that the system works in normal MPPT mode; in the photovoltaic-dominated control layer, the photovoltaic power is high, the system power consumption is small, the bus power is unbalanced, resulting in voltage increase, and the real-time collected DC bus voltage V dc >V dcref At this time, the photovoltaic power needs to be reduced. That is, when the actual value of the DC bus voltage is higher than the preset bus voltage value, the output of the PI controller is positive, which will control the photovoltaic array to work in the downhill area and reduce the photovoltaic output power, so that the system can deviate from the maximum power point and work in the constant voltage mode, and control the voltage of the DC bus in the system at V dcref Value place.

[0133] After the terminal voltage reference value obtained after the voltage bias link is superimposed is compared with the output voltage of the photovoltaic unit, the difference is passed through the PI controller (Proportional-Integral Controller) to generate a duty cycle signal, and the PWM link generates a drive signal to control the photovoltaic converter to operate in a constant voltage mode. In this embodiment, the preset value V of the DC bus voltage is set dcref =1.075pu. When the voltage of the DC bus rises to 1.075pu, the system's abandoned light operation threshold is triggered. To ensure system safety, the photovoltaic converter needs to deviate from the original working state MPPT mode, reduce the output power, and work in the constant voltage mode to control the voltage of the DC bus in the system at 1.075pu.

[0134] The photovoltaic abandoned operation can ensure the power balance of the system and become a new power balance node. At this time, when the system DC bus decreases with the decrease of photovoltaic output power and light intensity, the energy storage unit is in a saturated state, so the DC bus voltage is controlled by the grid-connected inverter.

[0135] The load unit converter is controlled by a double closed-loop control loop of a voltage outer loop and a current inner loop to provide stable direct current for the direct current load of the load unit.

[0136] In this scheme, there are many types of power electronic converters in the energy router, and the voltage variation range of different converters is also relatively wide. Combined with the relationship between the DC bus voltage and the system power balance, the operation of the energy router is hierarchically controlled according to the DC voltage. According to the voltage, the system operation is divided into different control layers. In each layer, there needs to be a converter operating as a voltage source to control the relative stability of the DC bus voltage. Other converters operate as current sources to absorb power from the DC bus or feed power to the DC bus. The converter operating as a voltage source can absorb or release power according to the power conditions of other converters operating as current sources. In this hierarchical control mode, there is no communication connection between the converters, which avoids various control problems caused by communication delays and simplifies the control complexity of the system.

[0137] In a multi-port energy router, the power balance of the system can be directly reflected by the DC bus voltage. In the corresponding control layer, droop control is adopted for the energy storage converter and the grid-connected unit converter. According to the voltage signal of the DC bus, the converter automatically switches its own working state to ensure that only one converter in the system works in the voltage source mode at any time, so as to maintain the DC bus voltage and power balance of the system. At the same time, MPPT control and constant voltage control are adopted for the photovoltaic converter. When the photovoltaic power is too large, the photovoltaic converter can work in the abandoned light operation mode to ensure that the DC bus voltage of the system is maintained at a higher level.

[0138] In this solution, each converter can automatically switch its own working mode according to the DC bus voltage, realizing smooth switching between control layers without the need for communication between converters. This simplifies control while ensuring stable operation within the system.

[0139] Example 2

[0140] In order to verify the DC bus voltage control method for an energy router provided by the present invention and the effectiveness of the hierarchical coordinated control adopted by the energy router, a simulation model of the power system where the energy router is located is built. In the simulation model, a grid-connected unit converter, an energy storage converter, a photovoltaic converter and a DC step-down converter (load unit converter) are included. The topological structure of the connection between the converters is as follows: Figure 2 shown.

[0141] In the simulation system of this embodiment, the DC bus voltage is 750V, the rated voltage of the DC load is 220V, and a resistive load is used to simulate the load.

[0142] 101-Simulation analysis of the free networking mode of the power grid dominant control layer:

[0143] At the beginning of the simulation, the grid-connected unit inverter (grid-connected unit converter) starts to establish a DC bus voltage of 750V. At t1 = 0.5s, the energy storage unit starts. At this time, the battery SOC is lower than 80%. The bidirectional energy storage converter starts to charge the battery, and the battery SOC begins to gradually increase. Fig.10As shown, at this time, the DC bus voltage begins to decrease under the droop control. At t2=1s, the load unit starts to start without load, establishes an output voltage of 220V, and the DC bus voltage remains basically unchanged. At t3=1.5s, the load unit suddenly increases by 0.5kW, the DC bus voltage drops slightly, and the battery charging power decreases. At t4=2s, the photovoltaic unit starts MPPT control and begins to convert solar energy into electrical energy to the system DC bus. The bus voltage rises and the battery charging power increases. At t5=2.435s, the battery SOC reaches 80%, the energy storage unit is turned off, stops charging the battery, and the energy storage unit power drops to 0. At t6=3s, the light intensity in the environment increases, the photovoltaic power gradually increases, and the bus voltage increases. At t7=3.2s, the light intensity increases to the maximum and remains constant, the bus voltage remains stable, and the inverter grid-connected power increases. At t8=4s, the light intensity in the environment suddenly drops, and the photovoltaic current and photovoltaic power drop accordingly. Affected by the fluctuation of photovoltaic output, the bus voltage and the power fed back by the inverter to the grid drop. At t9=4.5s, the load unit is loaded, the photovoltaic power remains unchanged, and the grid-connected power of the grid-connected unit inverter decreases. At t10=5s, the light intensity in the environment recovers, the photovoltaic output recovers, the power consumed by the load remains unchanged, the bus voltage rises, and the grid-connected power increases. At t11=5.5s, the load unit suddenly increases the load again, and the grid-connected power decreases. Fig.10 a, b, c, d, and e in the figure represent the waveforms of the system DC bus voltage Vbus, photovoltaic power Ppv, inverter power Pinv, load power Pload, and battery power Pbat in the free interconnection mode, respectively.

[0144] from Fig.10 It can be seen that during the entire change process of the system, the change of the bus voltage remains within ±2%, the photovoltaic output is constantly fluctuating, and the load unit power is also constantly changing. The grid-connected unit inverter adjusts the energy exchange between the energy router and the grid according to the droop control to maintain the system bus voltage within a relatively constant range. Charging stops when the battery SOC reaches 80% to prevent overcharging.

[0145] 102-Simulation analysis of the network current limiting mode of the energy storage dominant control layer:

[0146] At the beginning of the simulation, the grid-connected unit inverter starts up and establishes a DC bus voltage of 750V. At t1=0.5s, the energy storage unit starts up. At this time, the battery SOC is lower than 80%. The energy storage converter starts to charge the battery, and the battery SOC begins to gradually increase. Fig.11 As shown, Fig.11a, b, c, and d in the figure represent the waveforms of the battery SOC, battery current Ibat, battery voltage Vbat, and battery power Pbat in the grid-connected current limiting mode, respectively. At this time, the DC bus voltage decreases under the droop control. At t2=1s, the DC load unit starts with a load of 5kW, the DC bus voltage decreases, and the simulation system receives a dispatch instruction to limit the power. At this time, the maximum power that the grid-connected unit can absorb from the grid is 5kW, the battery charging power drops to 0, and the grid-connected unit absorbs 5kW of power from the grid. At 1.088s, the power of the grid-connected unit inverter reaches the power limit value of 5kW, and the bus voltage is 731V at this time. The DC bus voltage in the system enters the second layer, and the energy storage converter begins to dominate the stable control of the system bus voltage. The battery SOC begins to decrease, as shown in Fig.11 shown.

[0147] At t3 = 1.5s, the DC load is loaded with 1.25kW. Since the grid-connected unit inverter is limited in power, the power absorbed from the grid is insufficient to meet the power demand of the load. At this time, the power shortage is provided by the energy storage unit. Fig.12 It can be seen that the energy storage unit begins to input power to the DC bus. At t4=2s, the photovoltaic unit starts to work. At this time, the light intensity is relatively low. The work of the photovoltaic unit can reduce the power burden of the energy storage unit, and the output of the energy storage unit is reduced. At t5=2.5s and t6=3s, the load unit is loaded with 1.25kW respectively. During the loading process, the DC bus voltage is further reduced. At t7=4s, the load unit is unloaded by 2.5kW. At t8=5s, the output power of the photovoltaic unit increases with the increase of light intensity. At t9=5.5s, the light intensity and photovoltaic output power both reach peak values. As the light intensity gradually increases, the DC bus voltage also gradually recovers. At 5.115s, the DC bus voltage enters the range of ±2%, and the grid-connected unit inverter re-controls the DC bus voltage. The energy storage unit begins to switch from discharge to charging again, the battery SOC begins to recover, and the power flow direction of the grid-connected unit inverter changes, and begins to transmit power to the grid. When t10=6s and t11=7s, the load unit gradually reduces the load. When t11=7s, the load unit becomes no-load. At this time, the power units in the system are only the grid-connected unit, the energy storage unit and the photovoltaic unit. Since the photovoltaic output is relatively large, the energy storage unit charges the battery at full power at this time, and the surplus power is transmitted to the grid through the inverter.

[0148] Under the action of droop control, the grid-connected unit inverter and the energy storage unit converter can achieve seamless switching, and the DC bus voltage always remains in a relatively stable state without any major mutations. When the DC bus voltage variation range is in the second layered voltage interval, the energy storage unit can smoothly switch from charging or standby mode to voltage source mode to control the DC bus voltage. At the same time, during the switching process, the inverter and the bidirectional energy storage converter can achieve the conversion of working modes without communication.

[0149] 103-Simulation analysis of photovoltaic dominant control layer under abandoned light operation mode:

[0150] At the beginning of the simulation, the grid-connected unit inverter starts up and establishes a DC bus voltage of 750V. At t1 = 0.5s, the energy storage unit starts up. At this time, the battery SOC is lower than 80%. The bidirectional energy storage converter starts to charge the battery, and the battery SOC begins to gradually increase. Fig.13 As shown, Fig.13 In the figure, a, b, c, d, and e respectively represent the waveforms of the DC bus voltage Vbus, photovoltaic power Ppv, inverter power Pinv, load power Pload, and battery power Pbat in the system under the abandoned light operation mode. At this time, the DC bus voltage decreases under the droop control. At t2=1s, the DC load unit starts with a load of 2.5kW and begins to establish a stable DC 220V output to supply power to the DC load. At the same time, the photovoltaic unit starts MPPT control and begins to convert solar energy into electrical energy and input it into the system. At this time, due to the weak light intensity, the power of the photovoltaic unit is relatively low. At t3=1.1s, the light intensity begins to rise, and the photovoltaic output power also increases accordingly. At t4=1.32s, the battery charging SOC reaches 80%, the energy storage unit stops working, and the battery stops charging. At t5=1.4s, the light intensity reaches the maximum, and the output power of the photovoltaic unit also reaches the maximum. In the process of increasing the photovoltaic output power, the power flow direction of the grid-connected unit inverter also gradually changes, from absorbing power from the grid to feeding power to the grid. Since the output power of the photovoltaic unit is relatively large, the grid-connected power of the grid-connected unit inverter gradually increases to the power limit value and remains unchanged. At this time, the power transmitted by the photovoltaic unit to the DC bus is greater than the power value absorbed by each converter from the DC bus, and the DC bus voltage rises.

[0151] At t6, when the bus voltage rises to 1.075pu, the system's abandoned light operation threshold is triggered. To ensure system safety, the photovoltaic needs to deviate from the original working state, reduce the output power, work in constant voltage mode, and control the system DC bus at 1.075pu. The photovoltaic abandoned light operation ensures the power balance of the system and becomes a new power balance node. At t7 = 2.6s, the system DC bus decreases with the decrease of photovoltaic output power and light intensity. At this time, the energy storage unit is in a saturated state, so the DC bus voltage is controlled by the grid-connected inverter. At t10 = 3.75s, the light intensity is restored, the grid-connected power is restored to the maximum value, and the photovoltaic unit is converted to voltage source mode. At t11 ​​= 4s, the load unit is loaded. At this time, the load required power and grid-connected power are still less than the maximum output power of the photovoltaic unit, so the photovoltaic still works in constant voltage mode to ensure the power balance of the system and the stability of the bus voltage.

[0152] When the output of the photovoltaic unit is too large, the photovoltaic unit can seamlessly switch to the constant voltage control mode and abandon the light operation to ensure the power balance of the system. At the same time, when the power demand of the system increases or the environmental conditions deteriorate and the photovoltaic output decreases, it can automatically work in the MPPT mode, and the two modes can be seamlessly switched. At the same time, during the simulation process, the grid-connected unit inverter and photovoltaic converter can change their own working state according to the size of the DC bus voltage of the system, ensuring the stable operation of the system without communication.

[0153] Example 3

[0154] In order to verify the coordinated control strategy based on DC bus voltage proposed in the present invention, experiments were conducted using an actually constructed energy router. Limited by experimental conditions, this embodiment only conducted an operating condition experiment of energy storage-dominated control.

[0155] During the experiment, a bidirectional energy storage converter was used to establish the bus voltage. Affected by the converter performance, the DC bus voltage was set to 600V. The photovoltaic converter worked in MPPT mode, the grid-connected unit converter fed energy to the grid, and the load unit converter provided a stable 220V voltage to the DC load.

[0156] During the experiment, the maximum power point of the photovoltaic unit was set to 2kW, the grid-connected inverter was set to 3.3kW, and the DC 220V port was running at no load. Fig.14 As shown in the figure, Ubus, Upv, Ubat and Uload are the voltage waveforms of the DC bus, photovoltaic unit, energy storage unit and load unit during the operation of the system. It can be seen from the figure that the voltages in the system remain stable at this time, indicating that the power of the system remains balanced and stable. Fig.15is the current waveform of the system, Ibat, Iinv_dc, Ipv and Iload are the low-voltage side current of the energy storage converter, the DC side voltage of the inverter, the output current of the photovoltaic simulator and the output current of the DC 220V port, respectively. Fig.14 The voltage of each channel in Fig.15 The current of each channel corresponds to the power of the corresponding port. The data can be read and calculated from the figure to prove that the power of the system is balanced at this time.

[0157] As shown in Table 1, the parameter table of the photovoltaic simulator in the energy router, the maximum power point voltage VMP is set to 250V, the current IMP is 8A, and the actual operation voltage is 251.46V and the current is 7.8515A. The reason for the voltage deviation is the photovoltaic simulator itself. When the set parameters are different, the simulated photovoltaic characteristics are inconsistent, which will affect its output results. According to the parameters of the photovoltaic simulator, the photovoltaic unit has been tracking the maximum power point operation normally at this time, and the system inputs 2kW power EQ_PMP operation.

[0158] Table 1 Parameters of photovoltaic simulator

[0159]

[0160] like Fig.16 The figure shows the waveforms of the voltage Uc and current Ic of the inverter AC side phase C. The voltage and current in the system maintain sinusoidal operation, which reflects the power stability of the system. The inverter voltage and current have the same phase, and the system is transmitting power to the AC grid.

[0161] In order to further verify the stability of the system, Fig.17 This is the voltage and current waveform diagram of the 220V port loading process during system operation. Fig.17 The left side shows the voltage waveform of each unit of 220V port 3 with no load and 494W load. Fig.17 The right side shows the current waveform of each unit when the 220V port is loaded with 494W. It can be seen from the dynamic change process of loading that the DC bus voltage remains stable with little fluctuation. The voltage of the 220V port drops significantly when it changes from no-load to loaded. This is because the current inside the converter is relatively small during the no-load process, and the voltage control performance is poor compared to when loaded. When the 220V port voltage is restored, it can still maintain stable operation.

[0162] Example 4

[0163] Based on the same inventive concept, the present invention proposes a DC bus voltage control system for an energy router, such as Fig.18 As shown, including:

[0164] A control layer division module, used for dividing the operation of the energy router into corresponding control layers based on the voltage change of the DC bus in the energy router;

[0165] A voltage source mode converter determination module, for determining a converter operating as a voltage source in the energy router for a control layer corresponding to the energy router;

[0166] A DC bus voltage control module is used to utilize the control strategy of the control layer to control the operation of multiple converters in the energy router, including the converter operating as a voltage source, to control the voltage of the DC bus and maintain the voltage and power balance of the DC bus.

[0167] The energy router includes: a grid-connected unit converter, an energy storage converter, a photovoltaic converter and a load unit converter;

[0168] The energy router is connected to the power grid through the grid-connected unit converter, and the load unit, photovoltaic unit and energy storage unit are connected to the DC bus through the load unit converter, the photovoltaic converter and the energy storage converter respectively.

[0169] The control layer division module is specifically used for:

[0170] If the voltage variation of the DC bus is within the first layer voltage interval, the energy converter is divided into the grid dominant control layer for operation;

[0171] If the voltage variation of the DC bus is within the second layer voltage interval, the energy converter is divided into the energy storage dominant control layer for operation;

[0172] If the voltage variation of the DC bus is within the third layered voltage interval, the energy converter is divided into the photovoltaic dominant control layer for operation.

[0173] The control layer division module is also used for:

[0174] Voltage hysteresis loops are respectively added to the interval boundary values ​​of the first layer voltage interval, the second layer voltage interval and the third layer voltage interval to avoid frequent switching of the energy router between different control layers.

[0175] The voltage source mode converter determination module is specifically used for:

[0176] If the control layer corresponding to the energy router is the grid-dominant control layer, the grid-connected unit converter is operated as a voltage source, and other converters other than the grid-connected unit converter are operated as current sources;

[0177] If the control layer corresponding to the energy router is the energy storage dominant control layer, the energy storage converter is operated as a voltage source, and other converters other than the energy storage converter are operated as current sources;

[0178] If the control layer corresponding to the energy router is the photovoltaic dominant control layer, the photovoltaic converter is operated as a voltage source, and converters other than the photovoltaic converter are operated as current sources.

[0179] For the grid leading control layer, the DC bus voltage control module is specifically used for:

[0180] When the operation mode of the energy router is a free networking mode, an outer loop with a droop characteristic in a control loop of the grid-connected unit converter is used to perform voltage control, and the output of the voltage control is used as an input of the current control in the inner loop, and a PWM signal is generated by the current control to control the operation of the grid-connected unit converter;

[0181] Based on the charging instruction of the battery in the energy storage unit and the current reference value of the energy storage converter, the energy storage converter is current controlled, and the PWM signal output by the current control is combined with the charge state of the battery to perform logic control to output a driving signal, and the energy storage converter is controlled based on the driving signal, and the energy storage unit is charged by the DC bus;

[0182] The terminal voltage reference value output by the maximum power point tracking control link in the control loop of the photovoltaic converter is combined with the output voltage of the photovoltaic unit to input the controller to obtain a PWM signal, and the photovoltaic converter is driven to operate in the maximum power point tracking mode based on the PWM signal to input the electric energy generated by the photovoltaic unit into the DC bus;

[0183] The load unit converter is controlled by a double closed-loop control loop of a voltage outer loop and a current inner loop to provide stable direct current for the load unit.

[0184] For the grid leading control layer, the DC bus voltage regulation module is also used for:

[0185] A state of charge threshold interval of the battery is set. If the state of charge of the battery exceeds the state of charge threshold interval, the PWM signal is blocked, and the DC bus is stopped from charging the energy storage unit.

[0186] With respect to the energy storage dominant control layer, the DC bus voltage regulation module is specifically used for:

[0187] When the operation mode of the energy router is the networking current limiting mode, the outer loop with droop characteristics in the control loop of the energy storage converter is used for voltage control, and the output of the voltage control is input into the current control in the inner loop after passing through the current limiting link, and the PWM signal is generated by the current control to control the operation of the energy storage converter;

[0188] The terminal voltage reference value output by the maximum power point tracking control link in the control loop of the photovoltaic converter is combined with the output voltage of the photovoltaic unit to input the controller to obtain a PWM signal, and the photovoltaic converter is driven to operate in the maximum power point tracking mode based on the PWM signal to input the electric energy generated by the photovoltaic unit into the DC bus;

[0189] The load unit converter is controlled by a double closed-loop control loop of a voltage outer loop and a current inner loop to provide stable direct current for the load unit.

[0190] With respect to the photovoltaic dominant control layer, the DC bus voltage regulation module is specifically used for:

[0191] When the operation mode of the energy router is the abandoned light operation mode, the terminal voltage reference value of the photovoltaic unit is obtained by using the maximum power point tracking control link and the voltage bias link in the control loop of the photovoltaic converter, the terminal voltage reference value and the output voltage of the photovoltaic unit are input into the controller to obtain a PWM signal, and the photovoltaic converter is driven to operate in a constant voltage mode based on the PWM signal, and the electric energy generated by the photovoltaic unit is input into the DC bus;

[0192] The load unit converter is controlled by a double closed-loop control loop of a voltage outer loop and a current inner loop to provide stable direct current for the load unit.

[0193] Example 5

[0194] like Fig.19 As shown, the present invention also provides an electronic device, which may be a computer device, a single-chip device, an intelligent mobile device, etc. The electronic device in this embodiment may include a processor, a memory, a transceiver component, etc. The memory, the processor, and the transceiver component are connected via a bus; the memory may be used to store an execution program, and an exemplary execution program may include instructions; the processor is used to execute the instructions stored in the memory. The memory may also be used to store data, which may be called and / or modified when the instructions are executed.

[0195] The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, which is suitable for implementing one or more instructions, and is specifically suitable for loading and executing one or more instructions in a storage medium to implement a corresponding method flow or a corresponding function, so as to implement the steps of a DC bus voltage control method for an energy router in the above embodiment.

[0196] Example 6

[0197] Based on the same inventive concept, the present invention also provides a readable storage medium, specifically an electronic device readable storage medium (Memory), which is a memory device in an electronic device for storing programs and data. It can be understood that the storage medium here can include both built-in storage media in electronic devices and, of course, extended storage media supported by electronic devices. The storage medium provides a storage space, which stores the operating system of the terminal. In addition, one or more instructions suitable for being loaded and executed by a processor are also stored in the storage space, and these instructions can be one or more execution programs (including program codes). It should be noted that the storage medium here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk memory. The processor loads and executes one or more instructions stored in the storage medium, which can implement the steps of a DC bus voltage control method for an energy router in the above embodiment.

[0198] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit its protection scope. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that after reading the present invention, those skilled in the art can still make various changes, modifications or equivalent substitutions to the specific implementation methods of the application, but these changes, modifications or equivalent substitutions are all within the protection scope of the claims to be approved.

Claims

1. A DC bus voltage control method for an energy router, characterized in that: include: Based on the voltage variation of the DC bus in the energy router, the operation of the energy router is divided into corresponding control layers; For a control layer corresponding to the energy router, determining a converter operating as a voltage source in the energy router; The control strategy of the control layer is used to control the operation of multiple converters in the energy router, including the converter operating as a voltage source, so as to regulate the voltage of the DC bus and maintain the voltage and power balance of the DC bus.

2. The method according to claim 1, characterized in that The energy router includes: a grid-connected unit converter, an energy storage converter, a photovoltaic converter and a load unit converter; The energy router is connected to the power grid through the grid-connected unit converter, and the load unit, photovoltaic unit and energy storage unit are connected to the DC bus through the load unit converter, the photovoltaic converter and the energy storage converter respectively.

3. The method according to claim 2, characterized in that The operation of the energy router is divided into corresponding control layers based on the voltage variation of the DC bus in the energy router, including: If the voltage variation of the DC bus is within the first layer voltage interval, the energy converter is divided into the grid dominant control layer for operation; If the voltage variation of the DC bus is within the second layered voltage interval, the energy converter is divided into the energy storage dominant control layer for operation; If the voltage variation of the DC bus is within the third layered voltage interval, the energy converter is divided into the photovoltaic dominant control layer for operation.

4. The method according to claim 3, characterized in that Before dividing the operation of the energy router into corresponding control layers based on the voltage variation of the DC bus in the energy router, the method further includes: Voltage hysteresis loops are respectively added to the interval boundary values ​​of the first layer voltage interval, the second layer voltage interval and the third layer voltage interval to avoid frequent switching of the energy router between different control layers.

5. The method according to claim 3, characterized in that For the control layer corresponding to the energy router, a converter operating as a voltage source is determined in the energy router, including: If the control layer corresponding to the energy router is the grid-dominant control layer, the grid-connected unit converter is operated as a voltage source, and other converters other than the grid-connected unit converter are operated as current sources; If the control layer corresponding to the energy router is the energy storage dominant control layer, the energy storage converter is operated as a voltage source, and other converters other than the energy storage converter are operated as current sources; If the control layer corresponding to the energy router is the photovoltaic dominant control layer, the photovoltaic converter is operated as a voltage source, and converters other than the photovoltaic converter are operated as current sources.

6. The method according to claim 5, characterized in that For the grid-dominant control layer, the control strategy of the control layer is used to control the operation of multiple converters in the energy router, including the converter operating as a voltage source, including: When the operation mode of the energy router is a free networking mode, an outer loop with a droop characteristic in a control loop of the grid-connected unit converter is used to perform voltage control, and the output of the voltage control is used as an input of the current control in the inner loop, and a PWM signal is generated by the current control to control the operation of the grid-connected unit converter; Based on the charging instruction of the battery in the energy storage unit and the current reference value of the energy storage converter, the energy storage converter is current controlled, and the PWM signal output by the current control is combined with the charge state of the battery to perform logic control to output a driving signal, and the energy storage converter is controlled based on the driving signal, and the energy storage unit is charged by the DC bus; The terminal voltage reference value output by the maximum power point tracking control link in the control loop of the photovoltaic converter is combined with the output voltage of the photovoltaic unit to input the controller to obtain a PWM signal, and the photovoltaic converter is driven to operate in the maximum power point tracking mode based on the PWM signal to input the electric energy generated by the photovoltaic unit into the DC bus; The load unit converter is controlled by a double closed-loop control loop of a voltage outer loop and a current inner loop to provide stable direct current for the load unit.

7. The method according to claim 6, characterized in that Before the current control of the energy storage converter is performed based on the charging instruction of the battery in the energy storage unit and the current reference value of the energy storage converter, the method further includes: A state of charge threshold interval of the battery is set. If the state of charge of the battery exceeds the state of charge threshold interval, the PWM signal is blocked, and the DC bus is stopped from charging the energy storage unit.

8. The method according to claim 5, characterized in that For the energy storage dominant control layer, the control strategy of the control layer is used to control the operation of multiple converters in the energy router including the converter operating as a voltage source, including: When the operation mode of the energy router is the networking current limiting mode, the outer loop with droop characteristics in the control loop of the energy storage converter is used for voltage control, and the output of the voltage control is input into the current control in the inner loop after passing through the current limiting link, and the PWM signal is generated by the current control to control the operation of the energy storage converter; The terminal voltage reference value output by the maximum power point tracking control link in the control loop of the photovoltaic converter is combined with the output voltage of the photovoltaic unit to input the controller to obtain a PWM signal, and the photovoltaic converter is driven to operate in the maximum power point tracking mode based on the PWM signal to input the electric energy generated by the photovoltaic unit into the DC bus; The load unit converter is controlled by a double closed-loop control loop of a voltage outer loop and a current inner loop to provide stable direct current for the load unit.

9. The method according to claim 5, characterized in that For the photovoltaic dominant control layer, the control strategy of the control layer corresponding to the energy router is used to control the operation of multiple converters in the energy router including the converter operating as a voltage source, including: When the operation mode of the energy router is the abandoned light operation mode, the terminal voltage reference value of the photovoltaic unit is obtained by using the maximum power point tracking control link and the voltage bias link in the control loop of the photovoltaic converter, the terminal voltage reference value and the output voltage of the photovoltaic unit are input into the controller to obtain a PWM signal, and the photovoltaic converter is driven to operate in a constant voltage mode based on the PWM signal, and the electric energy generated by the photovoltaic unit is input into the DC bus; The load unit converter is controlled by a double closed-loop control loop of a voltage outer loop and a current inner loop to provide stable direct current for the load unit.

10. A DC bus voltage control system for an energy router, characterized in that: include: A control layer division module, used for dividing the operation of the energy router into corresponding control layers based on the voltage change of the DC bus in the energy router; A voltage source mode converter determination module, for determining a converter operating as a voltage source in the energy router for a control layer corresponding to the energy router; A DC bus voltage control module is used to utilize the control strategy of the control layer to control the operation of multiple converters in the energy router, including the converter operating as a voltage source, to control the voltage of the DC bus and maintain the voltage and power balance of the DC bus.

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