Power scheduling device and method for energy storage grid-connected system

Abstract

The application discloses a power scheduling device and method of energy storage grid-connected system, and relates to the field of power grid power scheduling. The power scheduling device comprises a slow calculation unit and a fast calculation unit. The slow calculation unit is used for calculating bus voltage setting value, grid-side reactive power setting value or power factor setting value and grid-side active power setting value according to detection signal, grid-connected regulation, preset working mode, reading of the electric meter, maximum allowed charging current of the battery and maximum allowed discharging current of the battery. The fast calculation unit is used for calculating inverter PWM driving signal according to bus voltage setting value, grid-side reactive power setting value or power factor setting value and grid-side active power setting value. In the embodiment of the application, the fast calculation unit and the slow calculation unit are adopted, so that the stability, precision and response delay of power control of the energy conversion device can be improved.

Description

Technical Field

[0001] This invention relates to the field of power grid dispatching, and in particular to a power dispatching device and method for energy storage grid-connected systems. Background Technology

[0002] Power dispatching of energy storage grid-connected systems needs to meet several constraints in order to ensure that the active power on the grid side reaches the value required by the customer. This value is a constantly changing value. The constraints include maximizing the utilization of photovoltaic power and avoiding waste of green energy; ensuring that the charging and discharging current of the battery does not exceed the required values; and ensuring that the delay time does not exceed the required values.

[0003] Figure 1 This is a schematic diagram of an existing energy storage grid-connected system. (Example:) Figure 1As shown, the energy storage grid-connected system includes at least one single-unit energy storage inverter, a load 6, and an electricity meter 4. The single-unit energy storage inverter 1 includes at least one solar panel (PV) module 11, an energy conversion device 12, and at least one battery 13. The energy conversion device 12 is connected to at least one PV 11, at least one battery 13, and the electricity meter 4. The load 6 is connected to the connection line between the energy conversion device 12 and the electricity meter 4, and the electricity meter 4 is connected to the power grid 5. The at least one single-unit energy storage inverter includes multiple single-unit energy storage inverters 1, 2, and 3, which are connected in parallel. Based on the mandatory requirements of local grid connection regulations and the pre-specified operating modes such as self-consumption, generation priority, peak shaving and valley filling, and forced charging arising from the customer's own economic needs regarding electricity prices, the energy conversion device 12 continuously adjusts the active and reactive power on the grid side to complete power dispatch while satisfying the aforementioned constraints. Existing power dispatch methods can be implemented through a calculation module within the controller of the energy conversion device. This module can be a single slow calculation module or a single fast calculation module. When power dispatch is implemented in the slow calculation module, the PV power output from the solar panel modules experiences instantaneous changes. The battery current setpoint and grid-side active power setpoint calculated by this slow calculation module cannot maintain the stability of the bus voltage (the voltage across the DC bus capacitor connected to the inverter input). Typically, excess or insufficient PV power is temporarily transferred to the grid side. When the next calculation cycle arrives, the battery current setpoint and grid-side active power setpoint are recalculated based on the new PV power. This slow calculation module indirectly controls the grid-side active power, resulting in deficiencies in the stability, accuracy, and response delay of the AC-side power control of the energy conversion device. When power dispatch is implemented within the fast calculation module, it can keep up with the instantaneous changes in PV power and quickly recalculate new battery current setpoints and grid-side active power setpoints. It can make full use of the battery power and the energy buffering effect of the bus capacitor, ensuring battery safety and ensuring that the grid-side active power setpoints are not affected. However, some values ​​do not need to be calculated quickly, which will waste computing resources and increase the burden on the controller in the energy conversion device.

[0004] Therefore, the industry urgently needs to develop a power scheduling device and method that can improve the stability and accuracy of AC power control in energy conversion devices and reduce response delay. Summary of the Invention

[0005] As mentioned above, indirectly controlling the active power on the grid side through a calculation module to achieve power dispatch will result in poor stability, accuracy, and response delay of the AC power control of the energy conversion device.

[0006] This application proposes a power dispatching device for an energy storage grid-connected system, the energy storage grid-connected system including...

[0007] The system comprises at least one stand-alone energy storage inverter, a load, and an electricity meter; the at least one stand-alone energy storage inverter is connected to the load and the electricity meter; characterized in that the power dispatching device for the energy storage grid-connected system includes:

[0008] The slow calculation unit is used to calculate the bus voltage setting value, the grid-connected power setting value or power factor setting value to be issued by the at least one single-unit energy storage inverter, and the grid-side active power setting value based on the detection signal, grid connection regulations, preset working mode, the meter reading, the maximum allowable charging current of the battery and the maximum allowable discharging current of the battery.

[0009] A fast calculation unit is used to calculate and obtain an inverter PWM drive signal based on the bus voltage setting value, the grid-side reactive power setting value or the power factor setting value and the grid-side active power setting value, so as to control the operation of the at least one single-unit energy storage inverter device.

[0010] Optionally, the slow calculation unit includes: an MPPT calculation unit, a bus voltage setpoint calculation unit, a grid-side reactive power setpoint calculation unit, and a slow power dispatch calculation unit; the detection signals include digital PV voltage signals, digital PV current signals, digital PV power signals, digital battery voltage signals, and digital grid-side voltage signals.

[0011] The MPPT calculation unit is used to calculate the PV voltage setpoint based on the digital PV voltage signal, the digital PV current signal, and the digital PV power signal;

[0012] The bus voltage setpoint calculation unit is used to calculate the bus voltage setpoint based on the digital PV voltage signal, the digital battery voltage signal, and the digital grid-side voltage signal.

[0013] The grid-side reactive power setpoint calculation unit is used to calculate the grid-side reactive power setpoint or power factor setpoint that the at least one single-unit energy storage inverter should issue according to the grid connection regulations and the preset working mode.

[0014] The slow power scheduling calculation unit is used to calculate the active power setting value on the grid side based on the preset working mode, the meter reading, the maximum allowable charging current of the battery, and the maximum allowable discharging current of the battery.

[0015] Optionally, the fast calculation unit includes: a voltage loop unit, a current loop unit, and a PWM signal output unit;

[0016] The voltage loop unit is used to calculate the PV current loop setting value, battery current loop setting value, and inverter current loop setting value based on the PV voltage setting value, the bus voltage setting value, the grid-side reactive power setting value or the power factor setting value and the grid-side active power setting value.

[0017] The current loop unit is used to generate a first duty cycle indication signal, a second duty cycle indication signal, and a third duty cycle indication signal according to the PV current loop setting value, the battery current loop setting value, and the inverter current loop setting value, respectively.

[0018] The PWM signal output unit is used to generate a first PWM drive signal, a second PWM drive signal, and the inverter PWM drive signal according to the first duty cycle indication signal, the second duty cycle indication signal, and the third duty cycle indication signal, respectively.

[0019] Optionally, the current loop unit includes a PV current loop, a battery current loop, and an inverter current loop;

[0020] The PV current loop is used to generate the first duty cycle indication signal according to the PV current loop set value;

[0021] The battery current loop is used to generate the second duty cycle indication signal according to the battery current loop set value;

[0022] The inverter current loop is used to generate the third duty cycle indication signal according to the inverter current loop set value.

[0023] Optionally, the voltage loop unit includes a PV voltage loop, a first adder unit, a second adder unit, a bus voltage loop, a fast power dispatch calculation unit, a battery power to current conversion unit, a grid-side power to current conversion unit, and a comparison unit; the bus voltage loop includes a first bus voltage loop and a second bus voltage loop.

[0024] The PV voltage loop is used to generate a first PV current target value based on the PV voltage set value;

[0025] The first addition unit is used to add the bus voltage set value and the bus voltage upward floating value to generate the bus voltage target value;

[0026] The first bus voltage loop is used to generate a second PV current target value based on the bus voltage target value;

[0027] The comparison unit is used to compare the first PV current target value and the second PV current target value, and take the smaller of the first PV current target value and the second PV current target value as the PV current loop setting value.

[0028] Optionally, the second bus voltage loop is used to generate a target power value based on the bus voltage setpoint;

[0029] The second addition unit is used to superimpose the target power value with the instantaneous PV power to generate the total power value to be received;

[0030] The fast power dispatch calculation unit is used to calculate the battery power value and the grid power value based on the total power to be received, the grid-side active power setting, the maximum allowable charging power of the battery, the maximum allowable discharging power of the battery, and the grid-side active power limit.

[0031] The battery power to current conversion unit is used to generate the battery current loop setting value based on the battery power carrying value;

[0032] The grid-side power-to-current conversion unit is used to generate the inverter current loop setting value based on the grid-side reactive power setting value or the power factor setting value and the grid-side power carrying value.

[0033] Optionally, the total power to be received is the sum of the battery power received and the grid-side power received.

[0034] Optionally, the maximum allowable charging power of the battery is denoted as Pc, the maximum allowable discharging power of the battery is denoted as Pd, the total power to be received is denoted as Po, the active power setting value on the grid side is denoted as Pa, the active power limit value on the grid side is denoted as Pm, the battery power received value is denoted as Py, and the power received value on the grid side is denoted as Px.

[0035] The fast power scheduling calculation unit determines whether Po is greater than Pa + Pc. If so, it determines whether Pa + Pc is greater than or equal to 0. If so, it further determines whether Po - Pc is less than Pm. If so, then Py = Pc and Px = Po - Pc; otherwise, then Py = Pc and Px = Pm.

[0036] The fast power scheduling calculation unit determines whether Po is greater than Pa + Pc. If so, it determines whether Pa + Pc is greater than or equal to 0. If not, it determines whether Po - Pc is less than 0. If so, Py = Pc and Px = Po - Pc. If not, Py = Pc and Py = 0.

[0037] The fast power scheduling calculation unit determines whether Po is greater than Pa + Pc. If not, it then determines whether Po is less than Pa + Pd. If yes, then Py = Pd and Px = Po - Pd; otherwise, then Py = Po - Pa and Px = Pa.

[0038] Optionally, the at least one stand-alone energy storage inverter includes a stand-alone energy storage inverter. The slow calculation unit and the fast calculation unit in the power dispatching device are both located in the controller of the stand-alone energy storage inverter. The controller is connected to the electricity meter, and the slow calculation unit is used to receive the reading of the electricity meter.

[0039] Optionally, the controller includes a communication microprocessor and a control microprocessor, with the slow calculation unit disposed on the communication microprocessor and the fast calculation unit disposed on the control microprocessor, and the electricity meter connected to the communication microprocessor for providing the electricity meter reading; or both the slow calculation unit and the fast calculation unit are disposed on the control microprocessor, and the electricity meter is connected to the control microprocessor for providing the electricity meter reading.

[0040] Optionally, the at least one stand-alone energy storage inverter includes multiple stand-alone energy storage inverters, the energy storage grid-connected system includes an energy management system, the energy management system is connected to the electricity meter, the slow calculation unit in the power dispatching device is set in the energy management system for receiving the reading of the electricity meter, and the fast calculation unit in the power dispatching device is respectively set in the controller of the multiple stand-alone energy storage inverters.

[0041] This application also proposes a power dispatching method for an energy storage grid-connected system, the energy storage grid-connected system including at least one single-unit energy storage inverter, a load, and an electricity meter; the at least one single-unit energy storage inverter is connected to the load and the electricity meter; characterized in that the power dispatching method includes:

[0042] The bus voltage setting value, the grid connection regulation, the preset operating mode, the meter reading, the maximum allowable charging current of the battery, and the maximum allowable discharging current of the battery are calculated based on the detection signal, grid connection regulations, preset operating mode, the meter reading, the maximum allowable charging current of the battery, and the maximum allowable discharging current of the battery. The grid-side reactive power setting value or power factor setting value and the grid-side active power setting value that the at least one single-unit energy storage inverter should output are also calculated.

[0043] The inverter PWM drive signal is calculated based on the bus voltage setting value, the grid-side reactive power setting value or the power factor setting value and the grid-side active power setting value to control the operation of the at least one single-unit energy storage inverter device.

[0044] Optionally, the bus voltage setting value, the grid-connected reactive power setting value or power factor setting value to be issued by the at least one single-unit energy storage inverter, and the grid-side active power setting value are calculated based on the detection signal, grid connection regulations, preset operating mode, meter reading, maximum allowable charging current of the battery, and maximum allowable discharging current of the battery. Specifically, this includes:

[0045] The detection signals include digital PV voltage signal, digital PV current signal, digital PV power signal, digital battery voltage signal, and digital grid-side voltage signal;

[0046] The PV voltage setpoint is calculated based on the digital PV voltage signal, the digital PV current signal, and the digital PV power signal.

[0047] The bus voltage setpoint is calculated based on the digital PV voltage signal, the digital battery voltage signal, and the digital grid-side voltage signal.

[0048] The setpoint value of reactive power or power factor that the at least one standalone energy storage inverter should output on the grid side is calculated based on the grid connection regulations and the preset operating mode; and

[0049] The active power setting value on the grid side is calculated based on the preset working mode, the meter reading, the maximum allowable charging current of the battery, and the maximum allowable discharging current of the battery.

[0050] Optionally, an inverter PWM drive signal is calculated based on the bus voltage setting value, the grid-side reactive power setting value or the power factor setting value and the grid-side active power setting value to control the operation of the at least one single-unit energy storage inverter, specifically including:

[0051] The PV current loop setting value, battery current loop setting value, and inverter current loop setting value are calculated based on the PV voltage setting value, the bus voltage setting value, the grid-side reactive power setting value or the power factor setting value and the grid-side active power setting value.

[0052] Based on the PV current loop setting value, the battery current loop setting value, and the inverter current loop setting value, a first duty cycle indication signal, a second duty cycle indication signal, and a third duty cycle indication signal are generated respectively; and

[0053] The first PWM drive signal, the second PWM drive signal, and the inverter PWM drive signal are generated according to the first duty cycle indication signal, the second duty cycle indication signal, and the third duty cycle indication signal, respectively.

[0054] Optionally, the PV current loop setting value, battery current loop setting value, and inverter current loop setting value are calculated based on the PV voltage setting value, the bus voltage setting value, the grid-side reactive power setting value or the power factor setting value, and the grid-side active power setting value, specifically including:

[0055] A first PV current target value is generated based on the PV voltage setting value;

[0056] The bus voltage setpoint and the upward fluctuation value of the bus voltage are superimposed to generate the target value of the bus voltage;

[0057] A second PV current target value is generated based on the bus voltage target value;

[0058] Compare the first PV current target value and the second PV current target value, and take the smaller of the two PV current target values ​​as the PV current loop setting value;

[0059] The target power value is generated based on the bus voltage setpoint.

[0060] The target power value is superimposed with the instantaneous PV power to generate the total power value to be received;

[0061] The battery power and grid power are calculated based on the total power to be received, the grid-side active power setting, the battery maximum allowable charging power, the battery maximum allowable discharging power, and the grid-side active power limit.

[0062] The battery current loop setting value is generated based on the battery power carrying capacity value;

[0063] The inverter current loop setting value is generated based on the grid-side reactive power setting value or the power factor setting value and the grid-side power receiving value.

[0064] Optionally, the maximum allowable charging power of the battery is denoted as Pc, the maximum allowable discharging power of the battery is denoted as Pd, the total power to be received is denoted as Po, the active power setting value on the grid side is denoted as Pa, the active power limit value on the grid side is denoted as Pm, the battery power received value is denoted as Py, and the power received value on the grid side is denoted as Px.

[0065] Determine if Po is greater than Pa + Pc. If so, determine if Pa + Pc is greater than or equal to 0. If so, determine if Po - Pc is less than Pm. If so, then Py = Pc and Px = Po - Pc; otherwise, Py = Pc and Px = Pm.

[0066] Determine if Po is greater than Pa + Pc. If yes, then determine if Pa + Pc is greater than or equal to 0. If no, then determine if Po - Pc is less than 0. If yes, then Py = Pc and Px = Po - Pc. If no, then Py = Pc and Py = 0.

[0067] Determine if Po is greater than Pa + Pc. If not, then determine if Po is less than Pa + Pd. If yes, then Py = Pd and Px = Po - Pd; otherwise, then Py = Po - Pa and Px = Pa.

[0068] This application can achieve at least one of the following beneficial effects:

[0069] 1) The power dispatching device of this application includes a fast calculation unit and a slow calculation unit. The slow calculation unit completes the calculation of the active power setpoint on the grid side and remains relatively unchanged. The fast power dispatching calculation unit in the fast calculation unit, based on the fluctuation of PV power, makes full use of the energy buffering effect of battery power and bus voltage, and continuously adjusts the setpoint of battery current to transfer excess or insufficient PV power to the battery. This ensures both battery safety and that the actual active power on the grid side is not affected. Therefore, the active power on the grid side still belongs to the direct control method, which performs better in terms of stability, accuracy and response delay of AC power control in the energy conversion device. The fast calculation unit is deeply integrated with the controller in the energy conversion device, while the slow calculation unit is not deeply integrated with the controller in the energy conversion device. The location of the slow calculation unit is more flexible, which is conducive to making full use of computing resources and improving the computing efficiency of the controller.

[0070] 2) When the communication delay between the controller in the energy conversion device and the energy management system is small enough, the slow computing unit can be moved out to the energy management system for centralized and unified execution. This is beneficial for the energy management system to perform complex overall power grid scheduling, such as communicating and controlling the loads that can be commanded, making the setting of the power scheduling device more flexible.

[0071] The features and technical advantages of this application have been broadly outlined above to facilitate a better understanding of the following detailed description. Additional features and advantages of this application, which form the subject matter of the claims, will be described below. Those skilled in the art will understand that the disclosed concepts and specific embodiments can be readily utilized as the basis for modifying or designing other structures or processes to achieve the same purpose as this application. Those skilled in the art will also recognize that such equivalent constructions do not depart from the spirit and scope of this application as set forth in the appended claims. Attached Figure Description

[0072] To gain a more comprehensive understanding of this application and its advantages, the following description is now taken in conjunction with the accompanying drawings, in which:

[0073] Figure 1 A schematic diagram of an existing energy storage grid-connected system is shown;

[0074] Figure 2 A schematic diagram of the power scheduling device according to an embodiment of this application is shown;

[0075] Figure 3 A schematic diagram of the energy conversion device according to an embodiment of this application is shown.

[0076] Figure 4 A schematic diagram of the specific structure of the power scheduling device according to an embodiment of this application is shown;

[0077] Figure 5 A partial structural schematic diagram of the fast computing unit according to an embodiment of this application is shown;

[0078] Figure 6 This illustration shows a schematic diagram of the structure of an energy storage grid-connected system according to an embodiment of the present application, in which the electricity meter, load, energy management system and controller in the energy conversion device communicate with each other when multiple stand-alone energy storage inverters are included.

[0079] Figure 7 This illustration shows a schematic diagram of the structure of an energy storage grid-connected system according to an embodiment of the present application, which includes a single-unit energy storage inverter, an electricity meter, and a controller in an energy conversion device communicating with each other.

[0080] Figure 8 The flowchart illustrating the process of the fast power scheduling calculation unit of this application obtaining the battery power capacity value and the grid power capacity value is shown.

[0081] Unless otherwise indicated, corresponding numbers and symbols in different figures generally refer to corresponding parts. The accompanying drawings are provided to clearly illustrate relevant aspects of various embodiments and are not necessarily drawn to scale. Implementation

[0082] Various exemplary embodiments, features, and aspects of the present invention will now be described in detail with reference to the accompanying drawings. The same reference numerals in the drawings denote elements that have the same or similar functions. Although various aspects of the embodiments are shown in the drawings, they are not necessarily drawn to scale unless specifically indicated otherwise.

[0083] The term "exemplary" as used herein means "serving as an example, embodiment, or illustration." Any embodiment illustrated herein as "exemplary" is not necessarily to be construed as superior to or better than other embodiments. The terms "first," "second," "third," etc. (if present) in the specification, claims, and drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a particular order or sequence.

[0084] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "coupled," "connected," and "linked" should be interpreted broadly. For example, they can refer to electrical connection or mutual communication; they can be a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0085] Furthermore, to better illustrate the present invention, numerous specific details are provided in the following detailed embodiments. Those skilled in the art should understand that the present invention can be practiced without certain specific details. In some instances, methods, means, elements, and circuits well known to those skilled in the art have not been described in detail in order to highlight the spirit of the invention.

[0086] Figure 2 A schematic diagram of the power scheduling device according to an embodiment of this application is shown. Figure 2 The power dispatching device shown is used in an energy storage grid-connected system. The structure of this energy storage grid-connected system is similar to... Figure 1 The illustrated energy storage grid-connected system includes at least one standalone energy storage inverter, a load 6, and an electricity meter 4. The at least one standalone energy storage inverter is connected to the load 6 and the electricity meter 4, and the electricity meter 4 is connected to the power grid 5. The at least one standalone energy storage inverter includes a standalone energy storage inverter 1, which includes at least one solar panel (PV) module 11, at least one battery 13, and an energy conversion device 12. The input terminals of the energy conversion device 12 are connected to at least one PV module 11 and at least one battery 13, respectively, and the output terminals of the energy conversion device 12 are connected to the load 6 and the electricity meter 4. The at least one standalone energy storage inverter includes multiple standalone energy storage inverters 1, 2, and 3, which are connected in parallel. The multiple standalone energy storage inverters 1, 2, and 3 can be applied to a three-phase energy storage grid-connected system with a neutral wire, a three-phase energy storage grid-connected system without a neutral wire, or a single-phase energy storage grid-connected system. Figure 3 A schematic diagram of the energy conversion device according to an embodiment of this application is shown. Figure 3 As shown, the energy conversion device 12 includes a first DC / DC converter 121, a second DC / DC converter 122, an inverter 123, and a controller 124. The input terminal of the first DC / DC converter 121 is connected to at least one PV module 11, and its output terminal is connected to a DC bus 125. The input terminal of the second DC / DC converter 122 is connected to at least one battery 13, and its output terminal is connected to the DC bus 125. The input terminal of the inverter 123 is connected to the DC bus 125, and its output terminal is used to connect a meter 4 and a load 6. The controller 124 controls the operation of the first DC / DC converter 121, the second DC / DC converter 122, and the inverter 123. Note that the bus mentioned above or subsequently refers to the DC bus 125.

[0087] Combination Figure 3 and Figure 2As shown, the power dispatching device for the energy storage grid-connected system includes a slow calculation unit 43 and a fast calculation unit 42. The slow calculation unit 43 calculates the bus voltage setting, the grid-side reactive power setting or power factor setting, and the grid-side active power setting based on the detection signal, grid connection regulations, preset operating mode, meter readings, maximum allowable charging current, and maximum allowable discharging current of the battery. The fast calculation unit 42 calculates the inverter PWM drive signal based on the bus voltage setting, the grid-side reactive power setting or the power factor setting, and the grid-side active power setting, to control the operation of the at least one single-unit energy storage inverter, i.e., to control the operation of the inverter 123 of the energy conversion device 12. In this embodiment, the detection signal includes a digital PV voltage signal, a digital PV current signal, a digital PV power signal, a digital battery voltage signal, and a digital grid-side voltage signal.

[0088] Figure 4 A schematic diagram of the specific structure of a power scheduling device according to an embodiment of this application is shown. (In conjunction with...) Figure 3 and Figure 4 As shown, the energy storage grid-connected system also includes a sampling input unit 41, which is used to sample the voltage and current signals output by the corresponding PV module 11, the voltage and current signals of the corresponding battery 13, and the voltage and current signals of the grid side, and convert these voltage and current signals into detection signals respectively. The detection signals include digital PV voltage signals, digital PV current signals, digital battery voltage signals, digital battery current signals, digital grid-side voltage signals, and digital grid current signals.

[0089] The slow calculation unit 43 includes an MPPT calculation unit 431, a bus voltage setpoint calculation unit 432, a grid-side reactive power setpoint calculation unit 433, and a slow power dispatch calculation unit 434. The MPPT calculation unit 431 calculates the PV voltage setpoint based on the digital PV voltage signal, the digital PV current signal, and the digital PV power signal. The bus voltage setpoint calculation unit 432 calculates the bus voltage setpoint based on the digital PV voltage signal, the digital battery voltage signal, and the digital grid-side voltage signal. The grid-side reactive power setpoint calculation unit 433 calculates the grid-side reactive power setpoint or power factor setpoint that the at least one single-unit energy storage inverter should output, according to the grid connection regulations and the preset operating mode. The slow power dispatch calculation unit 434 is used to calculate the active power setting value on the grid side based on the preset working mode, the meter reading, the maximum allowable charging current of the battery, and the maximum allowable discharging current of the battery. The preset working modes include self-consumption, power generation priority, peak shaving and valley filling, and forced charging. The maximum allowable charging current and maximum allowable discharging current of the battery are calculated comprehensively based on relevant information from the Battery Management System (BMS) and other conditions. The slow power dispatch calculation unit 434 in the slow calculation unit 43 only calculates the active power setting value on the grid side and does not calculate the battery current setting value. Instead, the calculation of the battery current setting value is completed in the fast calculation unit 42. The slow power dispatch calculation unit 434 is not deeply integrated with the controller in the energy conversion device 12, allowing the slow calculation unit 43 to be flexibly set within the controller of the energy conversion device 12 or within the Energy Management System (EMS) of the energy storage grid-connected system, thus fully utilizing computing resources. The EMS is the control system of the energy storage grid-connected system. In this embodiment, the slow calculation unit 43 is used to calculate non-real-time changes, and is generally updated once per cycle. Specifically, the slow calculation unit 43 is executed in the task of the operating system of the controller of the energy conversion device 12, and the calculation cycle is usually 10-500ms.

[0090] In this embodiment, the power output or received by the power grid 5 is the reading displayed by the meter 4 (i.e., power). For this energy storage grid-connected system, the load 6 is not controllable. Whether the power grid 5 outputs or receives power is according to the agreement. Therefore, the power dispatching device of this application satisfies the agreement value between at least one single-unit energy storage inverter and the power grid, which is the power output or received by the power grid, i.e., the power displayed by the meter, under the circumstances of load changes and uncertainty of the energy of PV components and batteries.

[0091] The fast calculation unit 42 includes a voltage loop unit 421, a current loop unit 422, and a PWM signal output unit 44. The voltage loop unit 421 calculates the PV current loop setting value, battery current loop setting value, and inverter current loop setting value based on the PV voltage setting value, the bus voltage setting value, the grid-side reactive power setting value or the power factor setting value, and the grid-side active power setting value. The current loop unit 422 generates a first duty cycle indication signal, a second duty cycle indication signal, and a third duty cycle indication signal based on the PV current loop setting value, the battery current loop setting value, and the inverter current loop setting value, respectively. The PWM signal output unit 44 is used to generate a first PWM drive signal, a second PWM drive signal, and an inverter PWM drive signal according to the first duty cycle indication signal, the second duty cycle indication signal, and the third duty cycle indication signal. The first PWM drive signal is used to control the operation of the first DC / DC converter connected between the PV module 11 and the energy conversion device 12; the second PWM drive signal is used to control the operation of the second DC / DC converter connected between the battery 13 and the energy conversion device 12; and the inverter PWM drive signal is used to control the operation of the energy conversion device 12 to achieve power scheduling and power control to meet customer needs. In this embodiment, the fast calculation unit 42 is used to calculate instantaneous changes. The calculation speed is fast; that is, the fast calculation unit 42 is usually executed in the interrupt routine of the controller of the energy conversion device 12, and the typical calculation cycle is 50µs.

[0092] In this example, the current loop unit 422 includes a PV current loop 4221, a battery current loop 4222, and an inverter current loop 4223. The PV current loop 4221 generates a first duty cycle indication signal based on a PV current loop setpoint. The battery current loop 4222 generates a second duty cycle indication signal based on a battery current loop setpoint. The inverter current loop 4223 generates a third duty cycle indication signal based on an inverter current loop setpoint.

[0093] In the example, the voltage loop unit 421 includes: a PV voltage loop 4211, a bus voltage loop 4212, a grid-side power-to-current conversion unit 4213, and a fast power dispatch calculation unit 4214. The PV voltage loop 4211 receives the PV voltage setpoint. The bus voltage loop 4212 receives the bus voltage setpoint. The fast power dispatch calculation unit 4214 receives the grid-side active power setpoint. The grid-side power-to-current conversion unit 4213 receives the grid-side reactive power setpoint or the power factor setpoint. The PV voltage loop 4211 and the bus voltage loop 4212 generate the PV current loop setpoint based on the PV voltage setpoint, the bus voltage upward fluctuation value, and the bus voltage setpoint. The bus voltage loop 4212, the fast power dispatch calculation unit 4214, and the grid-side power-to-current conversion unit 4213 are used to generate the battery current loop setting value and the inverter current loop setting value based on the bus voltage setting value, the grid-side active power setting value, the battery maximum allowable charging power, the battery maximum allowable discharging power, the grid active power limit value, and the grid-side reactive power setting value or the power factor setting value. The fast calculation unit employs a floating bus voltage control strategy. The fast power dispatch calculation unit 4214 can continuously adjust the actual active power without being affected by fluctuations in PV power, fully utilizing the energy buffering effect of the battery power and the bus capacitor power. Therefore, the grid-side active power is still controlled directly. The fast power dispatch calculation unit 4214 is deeply integrated with the controller of the energy conversion device 12, resulting in better stability, accuracy, and response delay in the power control received by the grid.

[0094] In the example, the power dispatching device also includes an RMS and average value accumulation and calculation unit. The RMS and average value accumulation unit receives digital PV voltage signals, digital PV current signals, digital battery voltage signals, digital battery current signals, digital grid-side voltage signals, and digital grid current signals, and calculates and stores the corresponding RMS and average values ​​for each of these detected signals. The RMS and average value calculation unit reads the corresponding data from the RMS and average value accumulation unit and performs RMS and average value calculations periodically. The typical calculation cycle is one power frequency cycle of the power grid to obtain the average PV voltage, average PV current, PV power, average battery voltage, average battery current, battery power, RMS grid-side voltage, RMS grid-side current, grid-side active power, grid-side reactive power, and grid-side power factor.

[0095] Figure 6This illustration shows a schematic diagram of the communication structure between the electricity meter, load, energy management system, and controller in the energy conversion device when the energy storage grid-connected system includes multiple single-unit energy storage inverters according to an embodiment of this application. The at least one single-unit energy storage inverter includes multiple single-unit energy storage inverters 1, 2, and 3. The energy storage grid-connected system includes an energy management system 8, which is connected to the electricity meter 4. The slow calculation unit 43 in the power dispatching device is located within the energy management system 8 and is used to receive the readings from the electricity meter 4. The fast calculation units 42 in the power dispatching devices 1, 2, and 3 are respectively located within the controllers of the multiple single-unit energy storage inverters 1, 2, and 3. Figure 6 As shown, the controller in each standalone energy storage inverter 1, 2, and 3 includes a control microprocessor 121 and a communication microprocessor 122. Battery 13 includes a battery management system 131. Each control microprocessor 121 communicates with its corresponding communication microprocessor 122, and each battery management system communicates with its corresponding communication microprocessor 122 to provide relevant information about the battery management system. Load 6 includes non-directable loads or directable loads, such as heat pump system 61 and charging pile system 62. Energy management system 8 is interconnected with meter 4, heat pump system 61, charging pile system 62, and each communication microprocessor 122 to achieve mutual communication. A fast calculation unit 42 is located within each control microprocessor 121, meaning it is deeply integrated with the control microprocessor 121, exhibiting superior performance in terms of power control stability, accuracy, and response delay. A slow calculation unit 43 is located within energy management system 8. The communication delay between the control microprocessor 121, the communication microprocessor 122, and the energy management system 8 is sufficiently small compared to the computation cycle of the slow computing unit 43. The slow computing unit 43 can be centrally and uniformly executed within the energy management system 8, controlling the on / off state of loads and power consumption, which is beneficial for the energy management system 8 to perform complex overall grid-side power dispatching. In other embodiments, the meter 4 can be directly connected to one of the control microprocessors 121 or one of the communication microprocessors 122 in the single-unit energy storage inverter devices 1, 2, and 3. The fast computing unit 42 is located within each control microprocessor 121, i.e., deeply integrated with the control microprocessor 121, exhibiting better performance in terms of power control stability, accuracy, and response delay. The slow computing unit 43 is located in one of the control microprocessors 121 or one of the communication microprocessors 122.

[0096] Figure 7This diagram illustrates the structure of an energy storage grid-connected system according to an embodiment of this application, where the electricity meter and the controller in the energy conversion device communicate with each other. Both the slow calculation unit 43 and the fast calculation unit 42 are located within the controller of the single-unit energy storage inverter. The controller is connected to the electricity meter 4, and the slow calculation unit 43 receives the reading from the electricity meter 4. Figure 7 As shown, the energy conversion device 12 in the standalone system 1 includes a control microprocessor 121 and a communication microprocessor 122. The battery 13 includes a battery management system 131. The meter 4 can be connected to either the communication microprocessor 122 or the control microprocessor 121. The slow calculation unit 43 is located in the communication microprocessor 122, and the fast calculation unit 42 is located in the control microprocessor 121. The meter 4 is connected to the communication microprocessor 122 to provide the meter reading; or both the slow calculation unit 43 and the fast calculation unit 42 are located in the control microprocessor 121, and the meter is connected to the control microprocessor 121 to provide the meter reading. The fast calculation unit 42 is deeply integrated with the control microprocessor 121, resulting in better performance in terms of power control stability, accuracy, and response delay.

[0097] Figure 5 A partial structural schematic diagram of the fast computing unit according to an embodiment of this application is shown. (In conjunction with...) Figure 4 and Figure 5 The voltage loop unit includes a PV voltage loop 4211, a first adder unit 514, a second adder unit 519, a bus voltage loop 4212, a fast power dispatch calculation unit 4214, a battery power-to-current conversion unit 522, a grid-side power-to-current conversion unit 4213, and a comparison unit 512. The bus voltage loop 4212 includes a first bus voltage loop 515 and a second bus voltage loop 518. The PV voltage loop 4211 is used to generate a first PV current target value based on the PV voltage setpoint. The first adder unit 514 is used to superimpose the bus voltage setpoint and the bus voltage upward floating value to generate the bus voltage target value. The first bus voltage loop 515 is used to generate a second PV current target value based on the bus voltage target value. The comparison unit 512 is used to compare the first PV current target value and the second PV current target value, and take the smaller of the two as the PV current loop setpoint.

[0098] The second bus voltage loop 518 is used to generate a target power value based on the bus voltage setpoint. The second adder unit 519 is used to superimpose the target power value with the instantaneous PV power to generate a total power to be received value. This total power to be received value indicates how much power the bus should release outward to maintain the bus voltage stable near the bus voltage setpoint; releasing outward is positive, and absorbing inward is negative. The fast power dispatch calculation unit 4214 is used to calculate the battery power receiving value and the grid-side power receiving value based on the total power to be received value, the grid-side active power setpoint, the maximum allowable charging power of the battery, the maximum allowable discharging power of the battery, and the grid-side active power limit. The battery power to current conversion unit 522 is used to generate the battery current loop setpoint based on the battery power receiving value. The grid-side power to current conversion unit 4213 is used to generate the inverter current loop setpoint based on the grid-side reactive power setpoint or the power factor setpoint and the grid-side power receiving value.

[0099] In the example, the total power to be received is the sum of the battery power received and the grid power received.

[0100] Figure 8 A flowchart illustrating how the fast power dispatch calculation unit of this application obtains the battery's load capacity value and the grid's load capacity value is shown. Figure 8 As shown, the maximum allowable charging power of the battery is denoted as Pc (a positive number representing charging power, with a minimum value of zero), the maximum allowable discharging power of the battery is denoted as Pd (a negative number representing discharging power, with a maximum value of zero), the total power to be received is denoted as Po, the active power setpoint on the grid side is denoted as Pa (a positive number represents power generation to the grid, a negative number represents power intake from the grid), the active power limit on the grid side is denoted as Pm, the battery's power receiving value is denoted as Py, and the power receiving value on the grid side is denoted as Px. Normally, Pc ≥ 0 ≥ Pd; under forced charging conditions, Pc ≥ Pd ≥ 0. The active power limit on the grid side, denoted as Pm, is either positive or zero, and Pa ≤ Pm is always true.

[0101] When the energy storage grid-connected system is operating normally, under ideal conditions, the power received by the battery is Py=Po-Pa, and the power received by the grid is Px=Pa. That is, the battery receives the fluctuation of PV power, while the grid side remains unchanged.

[0102] The fast power scheduling calculation unit determines whether Po is greater than Pa + Pc. If so, it further determines whether Pa + Pc is greater than or equal to 0. If so, it further determines whether Po - Pc is less than Pm. If so, then Py = Pc and Px = Po - Pc; if not, then Py = Pc and Px = Pm. The fast power scheduling calculation unit determines whether Po is greater than Pa + Pc. If so, it further determines whether Pa + Pc is greater than or equal to 0; if not, it further determines whether Po - Pc is less than 0. If so, then Py = Pc and Px = Po - Pc; if not, then Py = Pc and Py = 0. Specifically, when Po > Pa + Pc, if Pa >= 0, then there must be Pa + Pc ≥ 0; if Pa < 0, then it is possible that Pa + Pc ≥ 0 or Pa + Pc < 0. When Po ≥ Pa + Pc ≥ 0, it indicates that the PV power is severely excessive. At this time, the bus voltage automatically floats upward and is controlled by the first bus voltage loop 515, and it can be obtained that Py = Pc and Px = Pa. To prevent the PV power from getting stuck in some cases, such as in the self-use mode, the battery is fully charged, the load is very light, the total power limit for grid-connected power generation is very high, and the PV power is very sufficient. At this time, a free upward tracking space needs to be given to the PV power, and recalculation gives Py = Pc and Px = MIN(Po - Pc, Pm), that is, Px is the smaller value between Po - Pc and Pm. At this time, Po - Pc < Pa ≤ Pm. When Pa + Pc < 0, it must be that Pa < 0. Even if the PV power is completely zero, the bus voltage may still rise out of control. At this time, Py = Pc and Px = Po - Pc. Because the target is Pa and Pa < 0, it is necessary to ensure that Px ≤ 0, and recalculation gives Py = Pc and Px = MIN(Po - Pc, 0), that is, Px is the smaller value between Po - Pc and 0.

[0103] The fast power scheduling calculation unit determines whether Po is less than Pa + Pc. If not, it further determines whether Po is less than Pa + Pd. If so, then Py = Pd and Px = Po - Pd; if not, then Py = Po - Pa and Px = Pa. Specifically, Po < Pa + Pd indicates that the PV power is severely insufficient, and even if the battery discharges at the maximum allowable discharge power, it still cannot meet the requirements of the grid side, and Py = Pd and Px = Po - Pd are obtained. Po ≥ Pa + Pd means that the PV power may be relatively sufficient and can charge the battery while meeting the requirements of the grid side; or it may be slightly insufficient, but it can be supplemented by the battery to meet the requirements of the grid side. Py = Po - Pa and Px = Pa are obtained. At this time, Pc ≥ Py ≥ Pd.

[0104] The slow calculation unit in the aforementioned power dispatching device calculates the active power setpoint on the grid side and keeps it relatively constant. In contrast, the fast power dispatching calculation unit in the fast calculation unit continuously adjusts the battery current setpoint based on the fluctuations in PV power, making full use of the energy buffering effect of battery power and bus voltage. This transfers excess or insufficient PV power to the battery, ensuring both battery safety and that the actual active power on the grid side is not affected. This results in better performance in terms of power control stability, accuracy, and response delay. The fast calculation unit is deeply integrated with the controller in the energy conversion device, while the slow calculation unit is not deeply integrated with the controller in the energy conversion device. This allows for more flexible placement of the slow calculation unit and full utilization of computing resources.

[0105] Combination Figure 2 , Figure 4 and Figure 5 A power dispatching method for an energy storage grid-connected system is disclosed. The energy storage converter system includes at least one single-unit energy storage inverter, a load 6, and an electricity meter 4. The at least one single-unit energy storage inverter is connected to the load 6 and the electricity meter 4, and the electricity meter 4 is connected to the power grid 5. The at least one single-unit energy storage inverter includes a single-unit energy storage inverter 1, which includes at least one solar panel (PV) module 11, at least one battery 13, and an energy conversion device 12. The input terminals of the energy conversion device 12 are connected to at least one PV module 11 and at least one battery 13, respectively, and the output terminals of the energy conversion device 12 are connected to the load 6 and the electricity meter 4. The at least one single-unit energy storage inverter also includes multiple single-unit energy storage inverters 1, 2, and 3, which are connected in parallel. The power dispatching method includes: calculating the bus voltage setting value based on the digital PV voltage signal, digital battery voltage signal, digital grid-side voltage signal, grid connection regulations, preset working mode, meter readings, maximum allowable charging current of the battery, and maximum allowable discharging current of the battery; the grid-side reactive power setting value or power factor setting value to be issued by the at least one single-unit energy storage inverter; and the grid-side active power setting value.

[0106] Specifically, the slow calculation unit 43 is used to calculate the bus voltage setting value, the grid-connected power setting value or power factor setting value to be issued by the at least one single-unit energy storage inverter, and the grid-side active power setting value based on the detection signal, grid connection regulations, preset working mode, the meter reading, the maximum allowable charging current of the battery and the maximum allowable discharging current of the battery.

[0107] The inverter PWM drive signal is calculated based on the bus voltage setting value, the grid-side reactive power setting value or the power factor setting value and the grid-side active power setting value to control the operation of the at least one single-unit energy storage inverter device.

[0108] Specifically, the fast calculation unit 42 is used to calculate and obtain the inverter PWM drive signal based on the bus voltage setting value, the grid-side reactive power setting value or the power factor setting value and the grid-side active power setting value, so as to control the operation of the at least one single-unit energy storage inverter device, that is, to control the operation of the energy conversion device 123 of the energy conversion device 12.

[0109] like Figure 2 and Figure 4 As shown, the bus voltage setting value, the grid-side reactive power setting value or power factor setting value to be issued by the at least one single-unit energy storage inverter device, and the grid-side active power setting value are calculated based on the detection signal, grid connection regulations, preset working mode, meter reading, maximum allowable charging current of the battery, and maximum allowable discharging current of the battery. Specifically, the detection signal includes digital PV voltage signal, digital PV current signal, digital PV power signal, digital battery voltage signal, and digital grid-side voltage signal.

[0110] Specifically, the energy storage grid-connected system also includes a sampling input unit, which is used to sample the voltage and current signals output by the corresponding PV module 11, the voltage and current signals of the corresponding battery 13, and the voltage and current signals of the grid side, and convert the sampled voltage and current signals into detection signals, including digital PV voltage signals, digital PV current signals, digital battery voltage signals, digital battery current signals, digital grid-side voltage signals, and digital grid current signals.

[0111] The PV voltage setting value is calculated based on the digital PV voltage signal, digital PV current signal, and digital PV power signal.

[0112] Specifically, the MPPT calculation unit 431 is used to calculate the PV voltage setpoint based on the digital PV voltage signal, digital PV current signal and digital PV power signal.

[0113] The bus voltage setpoint is calculated based on the digital PV voltage signal, the digital battery voltage signal, and the digital grid-side voltage signal.

[0114] Specifically, the bus voltage setpoint calculation unit 432 is used to calculate the bus voltage setpoint based on the digital PV voltage signal, the digital battery voltage signal, and the digital grid side voltage signal.

[0115] The setpoint value of reactive power or power factor that the at least one standalone energy storage inverter should output on the grid side is calculated based on the grid connection regulations and the preset working mode.

[0116] Specifically, the grid-side reactive power setting value calculation unit 433 is used to calculate the grid-side reactive power setting value or power factor setting value that the at least one single-unit energy storage inverter should issue according to the grid connection regulations and the preset working mode.

[0117] The active power setting value on the grid side is calculated based on the preset working mode, the meter reading, the maximum allowable charging current of the battery, and the maximum allowable discharging current of the battery.

[0118] Specifically, the slow power dispatch calculation unit 434 is used to calculate the active power setting value on the grid side based on the preset working mode, the meter reading, the maximum allowable charging current of the battery, and the maximum allowable discharging current of the battery. The preset working mode includes self-consumption, power generation priority, peak shaving and valley filling, forced charging, etc. The maximum allowable charging current of the battery and the maximum allowable discharging current of the battery are calculated based on the relevant information of the battery management system (BMS) in the battery and other conditions.

[0119] Refer to Figure 2 , Figure 3 and Figure 4 The inverter PWM drive signal is calculated based on the bus voltage setting value, the grid-side reactive power setting value or the power factor setting value and the grid-side active power setting value to control the operation of the at least one single-unit energy storage inverter device, specifically including:

[0120] The PV current loop setting value, battery current loop setting value, and inverter current loop setting value are calculated based on the PV voltage setting value, the bus voltage setting value, the grid-side reactive power setting value or the power factor setting value and the grid-side active power setting value.

[0121] Specifically, the voltage loop unit 421 is used to calculate and obtain the PV current loop setting value, the battery current loop setting value, and the inverter current loop setting value based on the PV voltage setting value, the bus voltage setting value, the grid-side reactive power setting value or the power factor setting value and the grid-side active power setting value.

[0122] A first duty cycle indication signal, a second duty cycle indication signal, and a third duty cycle indication signal are generated based on the PV current loop setting value, the battery current loop setting value, and the inverter current loop setting value, respectively.

[0123] Specifically, the PV current loop 4221 is used to generate a first duty cycle indication signal based on the PV current loop set value. The battery current loop 4222 is used to generate a second duty cycle indication signal based on the battery current loop set value. The inverter current loop 4223 is used to generate a third duty cycle indication signal based on the inverter current loop set value.

[0124] The first PWM drive signal, the second PWM drive signal, and the inverter PWM drive signal are generated according to the first duty cycle indication signal, the second duty cycle indication signal, and the third duty cycle indication signal, respectively.

[0125] Specifically, the PWM signal output unit 44 is used to generate a first PWM drive signal, a second PWM drive signal, and an inverter PWM drive signal according to the first duty cycle indication signal, the second duty cycle indication signal, and the third duty cycle indication signal. The first PWM drive signal is used to control the operation of the first DC / DC converter connected between the PV module 11 and the energy conversion device 12; the second PWM drive signal is used to control the operation of the second DC / DC converter connected between the battery 13 and the energy conversion device 12; and the inverter PWM drive signal is used to control the operation of the energy conversion device 12 to achieve power scheduling and power control to meet customer needs.

[0126] Combination Figure 4 and Figure 5 The PV current loop setting value, battery current loop setting value, and inverter current loop setting value are calculated based on the PV voltage setting value, the bus voltage setting value, the grid-side reactive power setting value or the power factor setting value, and the grid-side active power setting value, specifically including:

[0127] A first PV current target value is generated based on the PV voltage setting value.

[0128] Specifically, the PV voltage loop 4211 is used to generate a first PV current target value based on the PV voltage set value.

[0129] The bus voltage setpoint and the bus voltage upward fluctuation value are superimposed to generate the target bus voltage value.

[0130] Specifically, the first addition unit 514 is used to superimpose the bus voltage set value and the bus voltage upward floating value to generate the bus voltage target value.

[0131] A second PV current target value is generated based on the bus voltage target value.

[0132] Specifically, the first bus voltage loop 515 is used to generate a second PV current target value based on the target bus voltage value.

[0133] The first PV current target value and the second PV current target value are compared, and the smaller of the two PV current target values ​​is taken as the PV current loop setting value.

[0134] Specifically, the comparison unit 512 is used to compare the first PV current target value and the second PV current target value, and take the smaller of the first PV current target value and the second PV current target value as the PV current loop setting value.

[0135] The target power value is generated based on the bus voltage setting value.

[0136] Specifically, the second bus voltage loop 518 is used to generate a target power value based on the bus voltage setpoint.

[0137] The target power value and the instantaneous PV power are superimposed to generate the total power value to be received.

[0138] Specifically, the second addition unit 519 is used to superimpose the target power value with the instantaneous PV power to generate a total power value to be received. This total power value to be received indicates how much power the bus should release to the outside in order to maintain the bus voltage stable near the bus voltage set value. Releasing to the outside is positive, and absorbing to the inside is negative.

[0139] The battery power and grid power are calculated based on the total power to be received, the grid-side active power setting, the battery maximum allowable charging power, the battery maximum allowable discharging power, and the grid-side active power limit.

[0140] Specifically, the fast power dispatch calculation unit 4214 is used to calculate the battery power value and the grid power value based on the total power to be received, the grid-side active power setting, the maximum allowable charging power of the battery, the maximum allowable discharging power of the battery, and the grid-side active power limit.

[0141] The battery current loop setting value is generated based on the battery's power carrying capacity.

[0142] Specifically, the battery power to current conversion unit 522 is used to generate the battery current loop setting value based on the battery power carrying value.

[0143] The inverter current loop setting value is generated based on the grid-side reactive power setting value or the power factor setting value and the grid-side power receiving value.

[0144] Specifically, the grid-side power conversion to current unit 4213 is used to generate the inverter current loop setting value based on the grid-side reactive power setting value or the power factor setting value and the grid-side power receiving value.

[0145] In the example, the total power to be received is the sum of the battery power received and the grid power received.

[0146] like Figure 8 As shown, the maximum allowable charging power of the battery is denoted as Pc (a positive number representing charging power, with a minimum value of zero), the maximum allowable discharging power of the battery is denoted as Pd (a negative number representing discharging power, with a maximum value of zero), the total power to be received is denoted as Po, the active power setpoint on the grid side is denoted as Pa (a positive number represents generating power to the grid, a negative number represents drawing power from the grid), the active power limit on the grid side is denoted as Pm, the battery's power receiving value is denoted as Py, and the grid's power receiving value is denoted as Px. Normally, Pc ≥ 0 > Pd; under forced charging conditions, Pc ≥ Pd ≥ 0. The active power limit on the grid side, denoted as Pm, is either positive or zero, and Pa ≤ Pm is always true.

[0147] When the energy storage grid-connected system is operating normally, under ideal conditions, the power received by the battery is Py=Po-Pa, and the power received by the grid is Px=Pa. That is, the battery receives the fluctuation of PV power, while the grid side remains unchanged.

[0148] Determine whether Po is greater than Pa + Pc. If so, then determine whether Pa + Pc is greater than or equal to 0. If so, further determine whether Po - Pc is less than Pm. If so, then Py = Pc and Px = Po - Pc; if not, then Py = Pc and Px = Pm. Determine whether Po is greater than Pa + Pc. If so, then determine whether Pa + Pc is greater than or equal to 0; if not, then determine whether Po - Pc is less than 0. If so, then Py = Pc and Px = Po - Pc; if not, then Py = Pc and Px = 0. Specifically, when Po > Pa + Pc, if Pa >= 0, then it must be that Pa + Pc ≥ 0; if Pa < 0, then it is possible that Pa + Pc ≥ 0 or Pa + Pc < 0. When Po ≥ Pa + Pc ≥ 0, it indicates that the PV power is severely excessive. At this time, the bus voltage automatically floats upward and is controlled by the first bus voltage loop 515, and we can obtain Py = Pc and Px = Pa. To prevent situations where, for example, in the self-consumption mode, the battery is fully charged, the load is very light, the total power limit for grid-connected power generation is very high, and the PV power is very sufficient, the PV power may get stuck. At this time, a free upward tracking space needs to be given to the PV power, and recalculation gives Py = Pc and Px = MIN(Po - Pc, Pm), that is, Px is the smaller value between Po - Pc and Pm. At this time, Po - Pc < Pa ≤ Pm. When Pa + Pc < 0, it must be that Pa < 0. Even if the PV power is completely zero, the bus voltage may still rise out of control. At this time, Py = Pc and Px = Po - Pc. Because the target is Pa and Pa < 0, it is necessary to ensure that Px ≤ 0, and recalculation gives Py = Pc and Px = MIN(Po - Pc, 0), that is, Px is the smaller value between Po - Pc and 0.

[0149] Determine whether Po is greater than Pa + Pc. If not, then determine whether Po is less than Pa + Pd. If so, then Py = Pd and Px = Po - Pd; if not, then Py = Po - Pa and Px = Pa. Specifically, Po < Pa + Pd indicates that the PV power is severely insufficient, and even if the battery discharges at the maximum allowable discharge power, it still cannot meet the requirements of the grid side, obtaining Py = Pd and Px = Po - Pd. Po ≥ Pa + Pd means that the PV power may be relatively sufficient, and in addition to meeting the requirements of the grid side, it can also charge the battery; or it may be slightly insufficient, but it can be supplemented by the battery to meet the requirements of the grid side. Obtaining Py = Po - Pa and Px = Pa, at this time Pc ≥ Py ≥ Pd.

[0150] In the aforementioned power dispatching method, the slow calculation unit calculates the active power setpoint on the grid side, which remains relatively constant. In contrast, the fast power dispatching calculation unit in the fast calculation unit continuously adjusts the battery current setpoint based on PV power fluctuations, fully utilizing the energy buffering effect of battery power and bus voltage. This transfers excess or insufficient PV power to the battery, ensuring both battery safety and that the actual active power on the grid side is not affected. This results in better performance in terms of power control stability, accuracy, and response delay. The fast calculation unit is deeply integrated with the controller in the energy conversion device, while the slow calculation unit is not deeply integrated with the controller in the energy conversion device, allowing for more flexible placement of the slow calculation unit.

[0151] Although embodiments of the present application and their advantages have been described in detail, it should be understood that various changes, substitutions and alterations may be made herein without departing from the spirit and scope of the present application as defined by the appended claims.

[0152] Furthermore, the scope of this application is not limited to the specific embodiments of the processes, machines, manufactures, compositions of matter, methods, and steps described herein. Those skilled in the art will readily understand from the disclosure of this application that, according to this application, currently existing or to be developed processes, machines, manufactures, compositions of matter, methods, or steps that perform substantially the same function or achieve substantially the same results as the corresponding embodiments described herein can be utilized. Therefore, it is intended that the appended claims encompass such processes, machines, manufactures, compositions of matter, methods, or steps within their scope.

Claims

1. A power dispatching device for an energy storage grid-connected system, the energy storage grid-connected system comprising at least one single-unit energy storage inverter, a load, and an electricity meter; the at least one single-unit energy storage inverter being connected to the load and the electricity meter; characterized in that, The power scheduling device includes: The slow calculation unit is used to calculate the bus voltage setting value, the grid-connected power setting value or power factor setting value to be issued by the at least one single-unit energy storage inverter, and the grid-side active power setting value based on the detection signal, grid connection regulations, preset working mode, the meter reading, the maximum allowable charging current of the battery and the maximum allowable discharging current of the battery. A fast calculation unit is used to calculate and obtain an inverter PWM drive signal based on the bus voltage setting value, the grid-side reactive power setting value or the power factor setting value and the grid-side active power setting value, so as to control the operation of the at least one single-unit energy storage inverter device. The slow calculation unit includes: an MPPT calculation unit, a bus voltage setpoint calculation unit, a grid-side reactive power setpoint calculation unit, and a slow power dispatch calculation unit; the detection signals include digital PV voltage signal, digital PV current signal, digital PV power signal, digital battery voltage signal, and digital grid-side voltage signal. The MPPT calculation unit is used to calculate the PV voltage setpoint based on the digital PV voltage signal, the digital PV current signal, and the digital PV power signal; The bus voltage setpoint calculation unit is used to calculate the bus voltage setpoint based on the digital PV voltage signal, the digital battery voltage signal, and the digital grid-side voltage signal. The grid-side reactive power setpoint calculation unit is used to calculate the grid-side reactive power setpoint or power factor setpoint that the at least one single-unit energy storage inverter should issue according to the grid connection regulations and the preset working mode. The slow power scheduling calculation unit is used to calculate the active power setting value on the grid side based on the preset working mode, the meter reading, the maximum allowable charging current of the battery, and the maximum allowable discharging current of the battery. The fast calculation unit includes: a voltage loop unit, a current loop unit, and a PWM signal output unit; The voltage loop unit is used to calculate the PV current loop setting value, battery current loop setting value, and inverter current loop setting value based on the PV voltage setting value, the bus voltage setting value, the grid-side reactive power setting value or the power factor setting value and the grid-side active power setting value. The current loop unit is used to generate a first duty cycle indication signal, a second duty cycle indication signal, and a third duty cycle indication signal according to the PV current loop setting value, the battery current loop setting value, and the inverter current loop setting value, respectively. The PWM signal output unit is used to generate a first PWM drive signal, a second PWM drive signal, and the inverter PWM drive signal according to the first duty cycle indication signal, the second duty cycle indication signal, and the third duty cycle indication signal, respectively.

2. The power dispatching device for an energy storage grid-connected system according to claim 1, characterized in that, The current loop unit includes a PV current loop, a battery current loop, and an inverter current loop. The PV current loop is used to generate the first duty cycle indication signal according to the PV current loop set value; The battery current loop is used to generate the second duty cycle indication signal according to the battery current loop set value; The inverter current loop is used to generate the third duty cycle indication signal according to the inverter current loop set value.

3. The power dispatching device for an energy storage grid-connected system according to claim 1, characterized in that, The voltage loop unit includes a PV voltage loop, a first adder unit, a second adder unit, a bus voltage loop, a fast power dispatch calculation unit, a battery power to current conversion unit, a grid-side power to current conversion unit, and a comparison unit; the bus voltage loop includes a first bus voltage loop and a second bus voltage loop. The PV voltage loop is used to generate a first PV current target value based on the PV voltage set value; The first addition unit is used to add the bus voltage set value and the bus voltage upward floating value to generate the bus voltage target value; The first bus voltage loop is used to generate a second PV current target value based on the bus voltage target value; The comparison unit is used to compare the first PV current target value and the second PV current target value, and take the smaller of the first PV current target value and the second PV current target value as the PV current loop setting value; The second bus voltage loop is used to generate a target power value based on the bus voltage setpoint; The second addition unit is used to superimpose the target power value with the instantaneous PV power to generate the total power value to be received; The fast power dispatch calculation unit is used to calculate the battery power value and the grid power value based on the total power to be received, the grid-side active power setting, the maximum allowable charging power of the battery, the maximum allowable discharging power of the battery, and the grid-side active power limit. The battery power to current conversion unit is used to generate the battery current loop setting value based on the battery power carrying value; The grid-side power-to-current conversion unit is used to generate the inverter current loop setting value based on the grid-side reactive power setting value or the power factor setting value and the grid-side power carrying value.

4. The power dispatching device for an energy storage grid-connected system according to claim 3, characterized in that, The total power to be received is the sum of the battery power received and the grid power received.

5. The power dispatching device for an energy storage grid-connected system according to claim 4, characterized in that, The maximum allowable charging power of the battery is denoted as Pc, the maximum allowable discharging power of the battery is denoted as Pd, the total power to be received is denoted as Po, the active power setting value on the grid side is denoted as Pa, the active power limit value on the grid side is denoted as Pm, the battery power received value is denoted as Py, and the power received value on the grid side is denoted as Px. The fast power scheduling calculation unit determines whether Po is greater than Pa + Pc. If so, it determines whether Pa + Pc is greater than or equal to 0. If so, it further determines whether Po - Pc is less than Pm. If so, then Py = Pc and Px = Po - Pc; otherwise, then Py = Pc and Px = Pm. The fast power scheduling calculation unit determines whether Po is greater than Pa + Pc. If so, it determines whether Pa + Pc is greater than or equal to 0. If not, it determines whether Po - Pc is less than 0. If so, Py = Pc and Px = Po - Pc. If not, Py = Pc and Px = 0. The fast power scheduling calculation unit determines whether Po is greater than Pa + Pc. If not, it then determines whether Po is less than Pa + Pd. If yes, then Py = Pd and Px = Po - Pd; otherwise, then Py = Po - Pa and Px = Pa.

6. The power dispatching device for an energy storage grid-connected system according to claim 1, characterized in that, The at least one stand-alone energy storage inverter includes a stand-alone energy storage inverter. The slow calculation unit and the fast calculation unit in the power dispatching device are both located in the controller of the stand-alone energy storage inverter. The controller is connected to the electricity meter. The slow calculation unit is used to receive the reading of the electricity meter.

7. The power dispatching device for an energy storage grid-connected system according to claim 6, characterized in that, The controller includes a communication microprocessor and a control microprocessor. The slow calculation unit is located on the communication microprocessor, and the fast calculation unit is located on the control microprocessor. The electricity meter is connected to the communication microprocessor and is used to provide the reading of the electricity meter. Alternatively, both the slow calculation unit and the fast calculation unit can be located in the control microprocessor, and the electricity meter is connected to the control microprocessor to provide the electricity meter reading.

8. The power dispatching device for an energy storage grid-connected system according to claim 1, characterized in that, The at least one stand-alone energy storage inverter includes multiple stand-alone energy storage inverters. The energy storage grid-connected system includes an energy management system. The energy management system is connected to the electricity meter. The slow calculation unit in the power dispatching device is located in the energy management system and is used to receive the reading of the electricity meter. The fast calculation unit in the power dispatching device is respectively located in the controller of the multiple stand-alone energy storage inverters.

9. A power dispatching method for an energy storage grid-connected system, the energy storage grid-connected system comprising at least one single-unit energy storage inverter, a load, and an electricity meter; the at least one single-unit energy storage inverter being connected to the load and the electricity meter; characterized in that, The power scheduling method includes: The bus voltage setting value, the grid connection regulation, the preset operating mode, the meter reading, the maximum allowable charging current of the battery, and the maximum allowable discharging current of the battery are calculated based on the detection signal, grid connection regulations, preset operating mode, the meter reading, the maximum allowable charging current of the battery, and the maximum allowable discharging current of the battery. The grid-side reactive power setting value or power factor setting value and the grid-side active power setting value that the at least one single-unit energy storage inverter should output are also calculated. The inverter PWM drive signal is calculated based on the bus voltage setting value, the grid-side reactive power setting value or the power factor setting value and the grid-side active power setting value to control the operation of the at least one single-unit energy storage inverter device. Specifically, the bus voltage setting value, the grid-side reactive power setting value or power factor setting value to be issued by the at least one single-unit energy storage inverter, and the grid-side active power setting value are calculated based on the detection signal, grid connection regulations, preset operating mode, meter reading, maximum allowable charging current of the battery, and maximum allowable discharging current of the battery. The detection signals include digital PV voltage signal, digital PV current signal, digital PV power signal, digital battery voltage signal, and digital grid-side voltage signal; The PV voltage setpoint is calculated based on the digital PV voltage signal, the digital PV current signal, and the digital PV power signal. The bus voltage setpoint is calculated based on the digital PV voltage signal, the digital battery voltage signal, and the digital grid-side voltage signal. The setpoint value of reactive power or power factor that the at least one standalone energy storage inverter should output on the grid side is calculated based on the grid connection regulations and the preset operating mode; and The active power setting value on the grid side is calculated based on the preset working mode, the meter reading, the maximum allowable charging current of the battery, and the maximum allowable discharging current of the battery. The inverter PWM drive signal is calculated based on the bus voltage setting value, the grid-side reactive power setting value or the power factor setting value and the grid-side active power setting value to control the operation of the at least one single-unit energy storage inverter device, specifically including: The PV current loop setting value, battery current loop setting value, and inverter current loop setting value are calculated based on the PV voltage setting value, the bus voltage setting value, the grid-side reactive power setting value or the power factor setting value and the grid-side active power setting value. Based on the PV current loop setting value, the battery current loop setting value, and the inverter current loop setting value, a first duty cycle indication signal, a second duty cycle indication signal, and a third duty cycle indication signal are generated respectively; and The first PWM drive signal, the second PWM drive signal, and the inverter PWM drive signal are generated according to the first duty cycle indication signal, the second duty cycle indication signal, and the third duty cycle indication signal, respectively.

10. The power dispatching method for an energy storage grid-connected system according to claim 9, characterized in that, The PV current loop setting value, battery current loop setting value, and inverter current loop setting value are calculated based on the PV voltage setting value, the bus voltage setting value, the grid-side reactive power setting value or the power factor setting value, and the grid-side active power setting value, specifically including: A first PV current target value is generated based on the PV voltage setting value; The bus voltage setpoint and the upward fluctuation value of the bus voltage are superimposed to generate the target value of the bus voltage; A second PV current target value is generated based on the bus voltage target value; Compare the first PV current target value and the second PV current target value, and take the smaller of the two PV current target values ​​as the PV current loop setting value; The target power value is generated based on the bus voltage setpoint. The target power value and the instantaneous PV power are superimposed to generate the total power value to be received; The battery power and grid power are calculated based on the total power to be received, the grid-side active power setting, the battery maximum allowable charging power, the battery maximum allowable discharging power, and the grid-side active power limit. The battery current loop setting value is generated based on the battery power carrying capacity value; The inverter current loop setting value is generated based on the grid-side reactive power setting value or the power factor setting value and the grid-side power receiving value.

11. The power dispatching method for an energy storage grid-connected system according to claim 10, characterized in that, The maximum allowable charging power of the battery is denoted as Pc, the maximum allowable discharging power of the battery is denoted as Pd, the total power to be received is denoted as Po, the active power setting value on the grid side is denoted as Pa, the active power limit value on the grid side is denoted as Pm, the battery power received value is denoted as Py, and the power received value on the grid side is denoted as Px. Determine if Po is greater than Pa + Pc. If so, determine if Pa + Pc is greater than or equal to 0. If so, determine if Po - Pc is less than Pm. If so, then Py = Pc and Px = Po - Pc; otherwise, Py = Pc and Px = Pm. Determine if Po is greater than Pa + Pc. If yes, then determine if Pa + Pc is greater than or equal to 0. If no, then determine if Po - Pc is less than 0. If yes, then Py = Pc and Px = Po - Pc. If no, then Py = Pc and Px = 0. Determine if Po is greater than Pa + Pc. If not, then determine if Po is less than Pa + Pd. If yes, then Py = Pd and Px = Po - Pd; otherwise, then Py = Po - Pa and Px = Pa.

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