CN112803437A - Power battery charging/discharging control system for power grid frequency regulation - Google Patents

Power battery charging/discharging control system for power grid frequency regulation Download PDF

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CN112803437A
CN112803437A CN202110187886.5A CN202110187886A CN112803437A CN 112803437 A CN112803437 A CN 112803437A CN 202110187886 A CN202110187886 A CN 202110187886A CN 112803437 A CN112803437 A CN 112803437A
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current
signal
voltage
battery
output signal
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CN112803437B (en
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李秉宇
杜旭浩
曾四鸣
芮月晨
肖国春
常征
刘宏亮
郭小凡
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State Grid Corp of China SGCC
Electric Power Research Institute of State Grid Hebei Electric Power Co Ltd
Xian Jiaotong University
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State Grid Corp of China SGCC
Electric Power Research Institute of State Grid Hebei Electric Power Co Ltd
Xian Jiaotong University
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
    • H02J3/241—The oscillation concerning frequency
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/70—Energy storage systems for electromobility, e.g. batteries

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  • Power Engineering (AREA)
  • Charge And Discharge Circuits For Batteries Or The Like (AREA)
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Abstract

The invention is suitable for the technical field of power battery charging/discharging, and provides a power battery charging/discharging control system for power grid frequency regulation, and the power battery charging/discharging control system for power grid frequency regulation comprises: the constant current control module comprises a constant current frequency adjusting unit, a first battery current control unit and a first signal generator which are sequentially connected; the constant voltage control module comprises a constant voltage frequency adjusting unit, a battery voltage control unit, a second battery current control unit and a second signal generator which are sequentially connected; the constant voltage frequency adjusting unit and the battery voltage control unit are also respectively connected with the signal acquisition module and the signal giving module. The invention greatly improves the stability of the operation of the power grid.

Description

Power battery charging/discharging control system for power grid frequency regulation
Technical Field
The invention belongs to the technical field of power battery charging/discharging, and particularly relates to a power battery charging/discharging control system for power grid frequency adjustment.
Background
In recent years, Electric Vehicles (EVs) are expected to become important vehicles in the future due to the advantages of cleanliness and environmental protection. With the development of high-capacity power battery technology and electric vehicle technology and the reduction of cost, the number of electric vehicles will increase dramatically. However, the random and intermittent charging behaviors of the electric vehicle bring important influences on the operation of the power grid, and the large-scale access of the electric vehicle to the power grid charging brings challenges to the safe and stable operation of the power system. The popularization of electric vehicles in the future becomes a trend, the charging/discharging control of the electric vehicles becomes an important means for controlling the operation of a power system, the adverse effect of charging load can be limited, load peak clipping and valley filling can be realized, the absorption of renewable energy sources is promoted, and the load dispatching effect is played. Through proper charging/discharging control, particularly Vehicle-to-Grid interaction (V2G), the negative influence of a charging load on a system can be effectively controlled, and the operation and control means of a power system can be enriched.
The power of the high-power quick charging of the electric automobile is getting larger and larger, and reaches hundreds of kW to hundreds of kW or even 1MW at present, and especially, the power battery of the electric automobile as a load may have a large influence on the frequency of a power grid in the charging and discharging process, so that more pressure is brought to the safe and stable operation of the power grid. At present, the influence on the frequency of a power grid is not considered in the charge and discharge control of most of the conventional power batteries, and hidden danger is brought to the stable operation of the power grid.
Disclosure of Invention
In view of this, the embodiment of the present invention provides a power battery charging/discharging control system for adjusting a power grid frequency, so as to solve the problem in the prior art that the charging/discharging control of most power batteries does not consider the influence on the power grid frequency, which may cause hidden troubles to the stable operation of the power grid.
The embodiment of the invention provides a power battery charging/discharging control system for adjusting the frequency of a power grid, which comprises a constant current control module, a constant voltage control module, a signal acquisition module and a signal giving module, wherein the constant current control module is used for controlling the constant voltage control module;
the constant current control module comprises a constant current frequency adjusting unit, a first battery current control unit and a first signal generator which are sequentially connected; the constant current frequency adjusting unit and the first battery current control unit are also respectively connected with the signal acquisition module and the signal giving module;
the constant voltage control module comprises a constant voltage frequency adjusting unit, a battery voltage control unit, a second battery current control unit and a second signal generator which are sequentially connected; the constant voltage frequency adjusting unit and the battery voltage control unit are also respectively connected with the signal acquisition module and the signal giving module; the second current control unit is also connected with the signal acquisition module; the first signal generator and the second signal generator are both connected with a DC/DC conversion module of the power battery charging and discharging circuit.
In some embodiments of the present invention, the constant current frequency adjustment unit includes a first phase locked loop, a first subtractor, a first dead band controller, and an angular frequency current controller;
the first phase-locked loop, the first subtracter, the first dead zone controller, the angular frequency current controller and the first battery current control unit are sequentially connected; the first phase-locked loop is also connected with the signal acquisition module; the first subtracter is also connected with the signal giving module;
the first phase-locked loop takes the three-phase voltage of the power grid sent by the signal acquisition module as an input signal, and outputs a signal to the first subtracter; wherein, the output signal of the first phase-locked loop is the actual angular frequency of the power grid;
the first subtractor takes the output signal of the first phase-locked loop and the rated angular frequency of the power grid sent by the signal giving module as input signals, and the output signal is sent to the first dead zone controller; wherein, the output signal of the first subtracter is the angular frequency deviation of the power grid;
the first dead zone controller takes an output signal of the first subtracter as an input signal, and the output signal is sent to the angular frequency current controller;
the angular frequency current controller takes an output signal of the first dead zone controller as an input signal, and the output signal is sent to the first battery current control unit; the output signal of the angular frequency current controller is the output signal of the constant current frequency adjusting unit;
the first battery current control unit takes an actual battery current value sent by the signal acquisition module, a first reference battery current value sent by the signal given module and an output signal sent by the angular frequency current controller as input signals, and the output signals are sent to the first signal generator;
the first signal generator generates a first PWM wave and a second PWM wave according to an output signal of the first battery current control unit, and transmits the first PWM wave and the second PWM wave to the DC/DC conversion module.
In some embodiments of the present invention, the first battery current control unit includes a first operator, a first current PI controller, and a first current limiter;
the constant current frequency adjusting unit, the first arithmetic unit, the first current PI controller, the first current amplitude limiter and the first signal generator are sequentially connected; the first arithmetic unit is also connected with the signal acquisition module and the signal given module respectively;
the first arithmetic unit takes the actual battery current value sent by the signal acquisition module, the first reference battery current value sent by the signal setting module and the output signal of the constant current frequency adjusting unit as input signals, and the output signals are sent to the first current PI controller and are used for summing the difference value obtained by subtracting the actual battery current value from the first reference battery current value and the output signal of the constant current frequency adjusting unit to obtain the output signal of the first arithmetic unit;
the first current PI controller takes an output signal of the first arithmetic unit as an input signal, and the output signal is sent to the first current amplitude limiter;
the first current amplitude limiter takes an output signal of the first current PI controller as an input signal, and the output signal is sent to the first signal generator; wherein, the output signal of the first current limiter is the output signal of the first battery current control unit.
In some embodiments of the present invention, the constant voltage frequency adjustment unit includes a second phase locked loop, a second subtractor, a second dead band controller, and an angular frequency voltage controller;
the second phase-locked loop, the second subtracter, the second dead zone controller, the angular frequency voltage controller and the battery voltage control unit are sequentially connected; the second phase-locked loop is also connected with the signal acquisition module; the second subtracter is also connected with the signal giving module;
the second phase-locked loop takes the three-phase voltage of the power grid sent by the signal acquisition module as an input signal, and outputs a signal to the second subtracter; the output signal of the second phase-locked loop is the actual angular frequency of the power grid;
the second subtracter takes an output signal of the second phase-locked loop and the rated angular frequency of the power grid sent by the signal given module as input signals, and the output signal is sent to the second dead zone controller; the output signal of the second subtracter is the angular frequency deviation of the power grid;
the second dead zone controller takes the output signal of the second subtracter as an input signal, and the output signal is sent to the angular frequency voltage controller;
the angular frequency voltage controller takes the output signal of the second dead zone controller as an input signal and sends the output signal to the battery voltage control unit;
the battery voltage control unit takes a battery reference voltage value sent by the signal given module, an actual battery voltage value sent by the signal acquisition module and an output signal of the angular frequency voltage controller as input signals, and the output signal is sent to the second battery current control unit; the output signal of the battery voltage control unit is a second reference battery current value;
the second battery current control unit takes the output signal of the battery voltage control unit and the actual battery current value sent by the signal acquisition module as input signals, and the output signals are sent to the second signal generator;
the second signal generator generates a third PWM wave and a fourth PWM wave according to an output signal of the first current limiter, and sends the third PWM wave and the fourth PWM wave to the DC/DC conversion module.
In some embodiments of the present invention, the battery voltage control unit includes a second operator, a voltage PI controller, and a second current limiter;
the constant voltage frequency adjusting unit, the second arithmetic unit, the voltage PI controller, the second current limiter and the second battery current control unit are sequentially connected; the second arithmetic unit is also respectively connected with the signal acquisition module and the signal given module;
the second arithmetic unit takes the battery reference voltage value sent by the signal setting module, the actual battery voltage value sent by the signal acquisition module and the output signal of the constant voltage frequency adjusting unit as input signals, and the output signals are sent to the voltage PI controller and are used for summing the difference value obtained by subtracting the actual battery voltage value from the battery reference voltage value and the output signal of the constant voltage frequency adjusting unit to obtain the output signal of the second arithmetic unit;
the voltage PI controller takes the output signal of the second arithmetic unit as an input signal, and the output signal is sent to the second current amplitude limiter;
the second current limiter takes the output signal of the voltage PI controller as an input signal, and the output signal is sent to the second battery current control unit; the output signal of the second current limiter is the output signal of the battery voltage control unit and is also the second reference battery current value.
In some embodiments of the present invention, the second battery current control unit includes a third subtractor, a second current PI controller, and a third current limiter;
the battery voltage control unit, the third subtracter, the second current PI controller, the third current amplitude limiter and the second signal generator are sequentially connected; the third subtracter is also connected with the signal acquisition module;
the third subtracter takes an output signal of the battery voltage control unit and an actual battery current value sent by the signal acquisition module as input signals, and the output signal is sent to the second current PI controller;
the second current PI controller takes the output signal of the third subtracter as an input signal, and the output signal is sent to the third current amplitude limiter;
the third current amplitude limiter takes the output signal of the second current PI controller as an input signal, and the output signal is sent to the second signal generator; wherein, the output signal of the third current limiter is the output signal of the second battery current control unit.
In some embodiments of the present invention, the power battery charging/discharging control system for grid frequency adjustment further comprises a Load Virtual Synchronous Machine (LVSM) control module based on an analog Synchronous motor, the Load Virtual Synchronous Machine (LVSM) control module being used for controlling an AC/DC conversion module of the power battery charging/discharging circuit;
the LVSM control module comprises an active power control unit and a reactive power control unit;
the active power control unit takes an actual direct current bus voltage value sent by the signal acquisition module and a direct current bus reference voltage value sent by the signal given module as input signals.
In some embodiments of the present invention, the calculation formula of the moment of inertia and the damping coefficient of the active power control unit is:
Figure BDA0002943835230000051
wherein J is rotational inertia, D is damping coefficient, ElFor the effective value of the virtual internal potential, V, of each phase of the LVSM control modulesFor the effective value, X, of the network phase voltagesBeing the impedance of the filter inductor, omega0For rating the angular frequency, omega, of the gridpcFor active power controlOpen loop cut-off angular frequency, ζ, of the system looppThe damping ratio of the active power control loop.
In some embodiments of the present invention, the loop gain of the dc bus voltage loop of the active power control unit is:
Figure BDA0002943835230000061
where s is the Laplace operator, Tvdc(s) is the loop gain of the DC bus voltage loop, J is the moment of inertia, D is the damping coefficient, ElFor the effective value of the virtual internal potential, V, of each phase of the LVSM control modulesFor the effective value, X, of the network phase voltagesBeing the impedance of the filter inductor, omega0For rating the angular frequency, K, of the gridpIs the proportional regulation coefficient, K, of a DC bus voltage PI regulator in an active power control unitiIs the integral regulation coefficient, G, of a DC bus voltage PI regulator in an active power control unitmIs the amplitude margin of the DC bus voltage, CdcIs a DC bus capacitance value, VdcAnd the voltage between the positive electrode and the negative electrode of the direct current bus.
In a second aspect, the embodiment of the present invention provides a power battery charging/discharging control method for grid frequency regulation, which is used in the power battery charging/discharging control system for grid frequency regulation as described in any one of the above, and the control method includes:
if the absolute value of the difference value between the rated angular frequency of the power grid and the actual angular frequency of the power grid is larger than the preset difference value, the constant-current frequency adjusting unit and the constant-voltage frequency adjusting unit both output first gain signals; wherein, the first gain signal is used for leading the constant current frequency regulating unit to the constant current charging/discharging control and leading the constant voltage frequency regulating unit to the constant voltage charging/discharging control;
if the absolute value of the difference value between the rated angular frequency of the power grid and the actual angular frequency of the power grid is not larger than the preset difference value, the constant-current frequency adjusting unit and the constant-voltage frequency adjusting unit both output second gain signals; wherein the second gain signal is used to disable the constant current frequency adjusting unit and the constant voltage frequency adjusting unit during the battery charging/discharging process.
Compared with the prior art, the embodiment of the invention has the following beneficial effects: the power battery charging/discharging control system for adjusting the power grid frequency comprises a constant current control module, a constant voltage control module, a signal acquisition module and a signal giving module; the constant current control module comprises a constant current frequency adjusting unit, a first battery current control unit and a first signal generator which are sequentially connected; the constant current frequency adjusting unit and the first battery current control unit are also respectively connected with the signal acquisition module and the signal giving module; the constant voltage control module comprises a constant voltage frequency adjusting unit, a battery voltage control unit, a second battery current control unit and a second signal generator which are sequentially connected; the constant voltage frequency adjusting unit and the battery voltage control unit are also respectively connected with the signal acquisition module and the signal giving module; the second current control unit is also connected with the signal acquisition module; the first signal generator and the second signal generator are both connected with a DC/DC conversion module of the power battery charging and discharging circuit. The invention adds the frequency of the power grid into the charge/discharge control of the power battery, thereby not only improving the charge efficiency of the power battery, but also improving the stability of the operation of the power grid.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.
Fig. 1 is a schematic structural diagram of a power battery charging and discharging circuit according to an embodiment of the present invention;
fig. 2 is a schematic diagram of connection between a plurality of chargers/charging piles and a power grid and an electric vehicle at a charging station according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a constant current control module of a power battery charging/discharging control system for grid frequency regulation according to an embodiment of the present invention;
fig. 4 is a schematic structural diagram of a constant voltage control module of a power battery charging/discharging control system for grid frequency regulation according to an embodiment of the present invention;
fig. 5 is a schematic connection diagram of a constant current control according to an embodiment of the present invention;
fig. 6 is a schematic control diagram of a DC/DC conversion module during constant current charging according to an embodiment of the present invention;
FIG. 7 is a schematic diagram of the connection of a constant voltage control according to an embodiment of the present invention;
fig. 8 is a schematic control diagram of the DC/DC conversion module during constant voltage charging according to the embodiment of the present invention;
fig. 9 is a schematic structural diagram of an LVSM control system according to an embodiment of the present invention;
FIG. 10 is a power grid frequency dynamic response process provided by an embodiment of the invention;
FIG. 11 illustrates an LVSM DC bus voltage dynamic response process provided by an embodiment of the present invention;
fig. 12 is a dynamic response process of the charging current provided by the embodiment of the invention.
Detailed Description
In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular system structures, techniques, etc. in order to provide a thorough understanding of the embodiments of the invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.
Generally, a charging/discharging (charging/charging pile) device of an electric vehicle mainly comprises an input (front stage) Pulse Width Modulation (PWM) rectifier and an output (rear stage) DC/DC conversion module, and a main circuit of a power battery charging/discharging system is a typical power electronic device (system) as shown in fig. 1. In fig. 1, a preceding AC/DC converter is connected to an AC power grid to rectify or invert AC to DC; the rear-stage DC/DC is connected with a power battery of the electric automobile, and outputs adjustable direct-current voltage to charge the power battery or discharge the power battery. The power battery charging generally includes two modes, i.e., Constant Current (CC) charging and Constant Voltage (CV) charging. A schematic diagram of the connection between the multiple chargers/charging piles and the power grid and the electric vehicle at the charging station is shown in fig. 2.
Referring to fig. 1, a schematic diagram of a main circuit of a power battery charging/discharging control system for grid frequency regulation according to an embodiment of the present invention is shown.
In FIG. 1, esa、esb、escIs the three-phase voltage of the grid, which can also be denoted as esabc；
isa、isb、iscThree-phase current, LVSM, also denoted as isabc；
Power electronic devices (such as IGBT (insulated gate bipolar transistor) with anti-parallel diodes) V1, V2, V3, V4, V5 and V6 form a three-phase PWM rectifier/inverter, V1 and V2 form a first bridge arm of the rectifier/inverter, a midpoint is connected with a second end of a filter inductor La, and the midpoint voltage is VlaThe first end of the filter inductor La and the grid voltage esaV3 and V4 form a second leg of the rectifier/inverter, the midpoint is connected to the second end of the filter inductance Lb, and the midpoint voltage is VlbThe first end of the filter inductance Lb and the grid voltage esbV5 and V6 form a third leg of the rectifier/inverter, the midpoint is connected to the second end of the filter inductor Lc, and the midpoint voltage is VlcThe first end of the filter inductor Lc and the grid voltage escIs connected to a three-phase power supply esa、esb、escThe first ends of the first and second power supply are connected together to form a midpoint of a power grid power supply;
vdc is the voltage between the positive electrode P and the negative electrode N of the direct current bus, and Cdc is the capacitance of the direct current bus;
power electronic switching devices (such as IGBT, including anti-parallel diode) V7 and V8 form a DC/DC (voltage rising/falling) bidirectional converter for charging/discharging a battery of an electric automobile, and the actual battery current value IbThe voltage of the battery E is Vb；
Ldc is the filter inductance of the DC/DC conversion module;
v7 and V8 form a bridge arm of the DC/DC conversion module, and the midpoint O of the bridge arm is connected with the first end of the filter inductor Ldc; the second end of the filter inductor Ldc is connected with the E-stage of the battery;
actual battery current value IbThe reference direction is positive when the direction shown in the figure is the same, i.e. the battery is charged; actual battery current value IbThe reference direction of (a) is opposite to the direction shown in the figure, i.e. the battery is discharged.
In order to explain the technical means of the present invention, the following description will be given by way of specific examples.
Referring to fig. 3 and fig. 4, a schematic structural diagram of a power battery charging/discharging control system for grid frequency regulation and a schematic structural diagram of a constant voltage control module of the power battery charging/discharging control system for grid frequency regulation according to an embodiment of the present invention are respectively shown.
In some embodiments of the present invention, a power battery charging/discharging control system for grid frequency regulation may include a constant current control module 1, a constant voltage control module 2, a signal acquisition module 3, and a signal giving module 4;
the constant current control module 1 comprises a constant current frequency adjusting unit 11, a first battery current control unit 12 and a first signal generator 13 which are connected in sequence; the constant current frequency adjusting unit 11 and the first battery current control unit 12 are also respectively connected with the signal acquisition module 3 and the signal given module 4;
the constant voltage control module 2 comprises a constant voltage frequency adjusting unit 21, a battery voltage control unit 22, a second battery current control unit 23 and a second signal generator 24 which are connected in sequence; the constant voltage frequency adjusting unit 21 and the battery voltage control unit 22 are also respectively connected with the signal acquisition module 3 and the signal given module 4; the second current control unit 23 is also connected with the signal acquisition module 3; the first signal generator 13 and the second signal generator 24 are both connected with the DC/DC conversion module 5 of the power battery charging and discharging circuit.
The invention provides a power battery charging/discharging control system for adjusting the frequency of a power grid, which comprises a constant current control module, a constant voltage control module, a signal acquisition module and a signal giving module, wherein the constant current control module is used for controlling the constant voltage control module; the constant current control module comprises a constant current frequency adjusting unit, a first battery current control unit and a first signal generator which are sequentially connected; the constant current frequency adjusting unit and the first battery current control unit are also respectively connected with the signal acquisition module and the signal giving module; the constant voltage control module comprises a constant voltage frequency adjusting unit, a battery voltage control unit, a second battery current control unit and a second signal generator which are sequentially connected; the constant voltage frequency adjusting unit and the battery voltage control unit are also respectively connected with the signal acquisition module and the signal giving module; the second current control unit is also connected with the signal acquisition module; the first signal generator and the second signal generator are both connected with a DC/DC conversion module of the power battery charging and discharging circuit. The invention adds the frequency of the power grid into the charge/discharge control of the power battery, thereby not only improving the charge efficiency of the power battery, but also improving the stability of the operation of the power grid.
Referring to fig. 5, a connection diagram of constant current control according to an embodiment of the present invention is shown.
In some embodiments of the present invention, the constant current frequency adjusting unit 11 includes a first phase locked loop 111, a first subtractor 112, a first dead zone controller 113, and an angular frequency current controller 114;
the first phase-locked loop 111, the first subtractor 112, the first dead zone controller 113, the angular frequency current controller 114 and the first battery current control unit 12 are connected in sequence; the first phase-locked loop 111 is also connected with the signal acquisition module 3; the first subtractor 112 is also connected with the signal giving module 4;
a first phase-locked loop 111, a three-phase voltage e of the power grid transmitted by the signal acquisition module 3sabcThe output signal is sent to the first subtractor 112 as an input signal; wherein, the output signal of the first phase-locked loop is the actual angular frequency omega of the power gridg；
A first subtracter 112 for setting the rated angular frequency omega of the power grid transmitted by the module 4 according to the output signal of the first phase-locked loop 111 and the signal0The output signal is sent to the first dead band controller 113 as an input signal; wherein, the output signal of the first subtractor 112 is the angular frequency deviation Δ ω of the power gridg；
A first dead zone controller 113 which takes the output signal of the first subtractor 112 as an input signal and sends the output signal to an angular frequency current controller 114;
an angular frequency current controller 114 that takes the output signal of the first dead zone controller 113 as an input signal and sends the output signal to the first battery current control unit 12; wherein, the output signal of the angular frequency current controller 114 is the output signal of the constant current frequency adjusting unit 11;
a first battery current control unit 12 for controlling the actual battery current value I transmitted by the signal acquisition module 3bA first reference battery current value sent by the signal given module 4
Figure BDA0002943835230000112
The output signal sent by the sum-frequency current controller 114 is an input signal, and the output signal is sent to the first signal generator 13;
the first signal generator 13 generates a first PWM wave and a second PWM wave according to an output signal of the first battery current control unit 12, and transmits the first PWM wave and the second PWM wave to the DC/DC conversion module 5.
Optionally, the current control coefficient of the angular frequency current controller 114 is KibRated angular frequency omega of the grid0Corresponding to the rated frequency f of the grid0Actual angular frequency omega of the gridgCorresponding to the actual frequency f of the gridgAngular frequency deviation of the grid, Δ ωgCorresponding to grid frequency deviation delta fg。
Optionally, the first PWM wave is sent to the power electronic switching device V7 in the DC/DC conversion module 5, for controlling the on/off of the V7; the second PWM wave is sent to the power electronic switching device V8 in the DC/DC conversion module 5 for controlling the switching on and off of V8.
In some embodiments of the present invention, the first battery current control unit 12 includes a first operator 121, a first current PI controller 122, and a first current limiter 123;
the constant current frequency adjusting unit 11, the first arithmetic unit 121, the first current PI controller 122, the first current limiter 123 and the first signal generator 13 are connected in sequence; the first arithmetic unit 121 is also connected with the signal acquisition module 3 and the signal given module 4 respectively;
a first arithmetic unit 121 for calculating the actual battery current value I sent by the signal acquisition module 3bA first reference battery current value sent by the signal given module 4
Figure BDA0002943835230000111
And the output signal of the constant current frequency adjusting unit 11 is an input signal, which is sent to the first current PI controller 122 for providing the first reference battery current value
Figure BDA0002943835230000121
Subtracting the actual battery current value IbThe obtained difference is summed with the output signal of the constant current frequency adjusting unit 11 to obtain the output signal of the first operator 121;
a first current PI controller 122, which takes the output signal of the first arithmetic unit 121 as an input signal, and sends the output signal to a first current limiter 123;
a first current limiter 123, which takes the output signal of the first current PI controller 122 as an input signal, and sends the output signal to the first signal generator 13; wherein, the output signal of the first current limiter 123 is the output signal of the first battery current control unit 12.
For example, fig. 6 shows a control schematic diagram of the DC/DC conversion module during constant current charging according to the embodiment of the present invention.
The State of Charge (SOC) of the power Battery is derived from a Battery Management System (BMS), and the SOC is used for monitoring the operating State of the Battery and protecting the Battery.
Referring to fig. 7, it shows a schematic connection diagram of constant voltage control according to an embodiment of the present invention
In some embodiments of the present invention, the constant voltage frequency adjusting unit includes a second phase locked loop 211, a second subtractor 212, a second dead band controller 213, and an angular frequency voltage controller 214;
the second phase-locked loop 211, the second subtractor 212, the second dead zone controller 213, the angular frequency voltage controller 214 and the battery voltage control unit 22 are connected in sequence; the second phase-locked loop 211 is also connected with the signal acquisition module 3; the second subtractor 212 is also connected to the signal providing module 4;
a second phase-locked loop 211 for receiving the three-phase voltage e of the grid from the signal acquisition module 3sabcThe output signal is sent to the second subtractor 212 as an input signal; wherein the output signal of the second phase-locked loop 211 is the actual angular frequency ω of the power gridg；
A second subtractor 212 for determining the nominal angular frequency ω of the grid transmitted by the module 4, based on the output signal of the second phase-locked loop 211 and the signal0The output signal is sent to the second dead band controller 213 for input; wherein, the output signal of the second subtractor 212 is the angular frequency deviation Δ ω of the power gridg；
A second dead band controller 213 that takes the output signal of the second subtractor 212 as an input signal and sends the output signal to the angular frequency voltage controller 214;
an angular frequency voltage controller 214 that takes the output signal of the second dead zone controller 213 as an input signal and sends the output signal to the battery voltage control unit 22;
a battery voltage control unit 22 for signaling the battery reference voltage value sent by the module 4
Figure BDA0002943835230000131
Actual battery voltage value V sent by signal acquisition module 3bThe output signal of the sum-frequency voltage controller 214 is an input signal, and the output signal is sent to the second battery current control unit 23; wherein the output signal of the battery voltage control unit 22 is the second reference battery current value
Figure BDA0002943835230000132
Optionally, the second reference battery current value
Figure BDA0002943835230000133
And a first reference battery current value
Figure BDA0002943835230000134
The current limiting device can be the same or different, and both can be arranged according to actual requirements for preventing the current from being overlarge.
A second battery current control unit 23 for controlling the actual battery current value I sent by the signal acquisition module 3 and the output signal of the battery voltage control unit 22bThe output signal is sent to the second signal generator 24 as an input signal;
the second signal generator 24 generates a third PWM wave and a fourth PWM wave according to the output signal of the first current limiter and transmits the third PWM wave and the fourth PWM wave to the DC/DC conversion module 5.
Optionally, the third PWM wave is sent to the power electronic switching device V7 in the DC/DC conversion module 5, for controlling the on/off of V7; the fourth PWM wave is sent to the power electronic switching device V8 in the DC/DC conversion module 5 for controlling the switching on and off of V8.
In some embodiments of the present invention, the battery voltage control unit 22 includes a second operator 221, a voltage PI controller 222, and a second current limiter 223;
the constant voltage frequency adjustment unit 21, the second arithmetic unit 221, the voltage PI controller 222, the second current limiter 223, and the second battery current control unit 23 are sequentially connected; the second arithmetic unit 221 is also connected with the signal acquisition module 3 and the signal given module 4 respectively;
a second arithmetic unit 221 for signaling the battery reference voltage value sent by the module 4
Figure BDA0002943835230000135
Actual battery voltage value V sent by signal acquisition module 3bAnd the output signal of the constant voltage frequency adjusting unit 21 is an input signal, which is sent to the voltage PI controller 222 for referencing the battery voltage value
Figure BDA0002943835230000136
Minus the actual battery voltage value VbThe obtained difference is summed with the output signal of the constant voltage frequency adjusting unit 21 to obtain the output signal of the second operator 221;
a voltage PI controller 222, which takes the output signal of the second arithmetic unit 221 as an input signal, and sends the output signal to a second current limiter 223;
a second current limiter 223, which takes the output signal of the voltage PI controller 222 as an input signal, and sends the output signal to the second battery current control unit 23; wherein, the output signal of the second current limiter 223 is the output signal of the battery voltage control unit 22, and is also the second reference battery current value
Figure BDA0002943835230000141
In some embodiments of the present invention, the second battery current control unit 23 includes a third subtractor 231, a second current PI controller 232, and a third current limiter 233;
the battery voltage control unit 22, the third subtractor 231, the second current PI controller 232, the third current limiter 233 and the second signal generator 24 are connected in sequence; the third subtractor 231 is also connected with the signal acquisition module 3;
a third subtracter 231 for calculating the actual battery current value I sent by the signal acquisition module 3 according to the output signal of the battery voltage control unit 22bThe output signal is sent to the second current PI controller 232 as an input signal;
a second current PI controller 232 which takes an output signal of the third subtractor 231 as an input signal and transmits the output signal to a third current limiter 233;
a third current limiter 233, which takes the output signal of the second current PI controller 232 as an input signal, and sends the output signal to the second signal generator 24; wherein the output signal of the third current limiter 233 is the output signal of the second battery current control unit 23.
For example, fig. 8 shows a control schematic diagram of the DC/DC conversion module during constant voltage charging according to the embodiment of the present invention.
Wherein the battery is referenced to a voltage
Figure BDA0002943835230000142
Is controlled by using a battery referenceVoltage of
Figure BDA0002943835230000143
Is an outer loop, a second reference battery current value
Figure BDA0002943835230000144
Is a double closed loop control structure of an inner loop.
In some embodiments of the present invention, the power battery charging/discharging control system for grid frequency regulation further comprises an LVSM control module based on an analog synchronous motor for controlling an AC/DC conversion module of the power battery charging/discharging circuit;
the LVSM control module comprises an active power control unit and a reactive power control unit;
the active power control unit takes an actual direct current bus voltage value sent by the signal acquisition module and a direct current bus reference voltage value sent by the signal given module as input signals.
Optionally, referring to fig. 9, which shows a schematic structural diagram of an LVSM control system provided in the embodiment of the present invention, relevant parameters are described as follows:
the LVSM model adopts an LVSM model based on a synchronous inverter/synchronous converter (synchronous converter) simulation synchronous motor, and is mainly divided into two parts, namely reactive power control and active power control.
Optionally, the reactive power control parameter may include:
Qrefis a given value of LVSM reactive power, Q is a feedback value of LVSM reactive power, Vsp(nom)Is the voltage rating, V, of the Common node (PCC) of the gridspIs the actual value of the voltage of the grid common node (PCC), DqIs a reactive sag factor, KqFor adjusting the coefficient of excitation flux linkage, Mfif0For LVSM excitation flux linkage initial value, MfifFor the given value of the LVSM excitation flux linkage,
Figure BDA0002943835230000151
for LVSM DC bus voltage set value, VdcFor LVSM DC bus voltageThe feedback value PI is a direct-current bus voltage PI (proportional-integral) regulator (controller).
Optionally, the reactive power control process may include:
voltage rating V of a grid common node (PCC)sp(nom)And the actual value VspIs subjected to reactive droop control (the reactive droop coefficient is D)q) Its output, and LVSM reactive power setpoint QrefSubtracting the deviation of the feedback value Q, and using the subtracted result as the input of the excitation flux linkage regulator (controller) (the excitation flux linkage regulation coefficient is K)q) The output of the flux linkage regulator (controller) is used as the input of the integrator 1, the output of the integrator 1 is used as the initial value M of the LVSM flux linkagefif0Added as LVSM excitation flux linkage given value MfifLVSM excitation flux linkage given value MfifThe signal multiplied by the three-phase synchronous signal through the multiplier 1 is further multiplied with the three-phase current i of the LVSMsa、isb、iscMultiplying by a multiplier 2 and summing to obtain the electromagnetic torque T output by the LVSMeLVSM bus voltage setpoint
Figure BDA0002943835230000153
And a feedback value VdcThe output of the PI (proportional integral) regulator (controller) is a mechanical power command P of LVSMm。
Wherein, the reactive power feedback value Q is:
Figure BDA0002943835230000152
electromagnetic torque TeComprises the following steps:
Te＝Mfif[isasinθ+isbsin(θ-2π/3)+iscsin(θ+2π/3)]
optionally, the active power control parameter may include:
ω0for rating the angular frequency of the grid (corresponding to a frequency f0)，ωmIs the actual angular frequency of LVSM (corresponding to frequency f)m)，Δω＝ωm-ω0Is the deviation of the rated angular frequency and the actual angular frequency of the power grid (corresponding to a frequency deviation of deltaf), D is the virtual damping of the LVSM, J is the virtual inertia of the LVSM, and i is the virtual inertia of the LVSM for simplificationsabcRepresenting three-phase current i flowing through LVSMsa、isb、isc，elabcrefRepresenting three-phase PWM rectifier/inverter three-phase midpoint voltage control reference signal elaref、elbref、elcref。
Optionally, the active power control process may include:
mechanical power command PmActual angular frequency ω from LVSMmThe output of the divider is LVSM mechanical torque TmElectromagnetic torque TeWith mechanical torque TmAnd damping torque TdThe deviation of (a) is input to a virtual inertia controller (virtual inertia coefficient of LVSM J), the output of the virtual inertia controller is input to an integrator 2, and the output of the integrator 2 is Δ ω ═ ωm-ω0Is the actual angular frequency omegamRated angular frequency omega of power grid0Deviation of (LVSM) actual angular frequency omegamRated angular frequency omega of power grid0As an input to the LVSM virtual damping controller (the virtual damping coefficient of the LVSM is D), and the output of the LVSM virtual damping controller is the damping torque TdLVSM actual angular frequency ωmRated angular frequency omega of power grid0The sum of the deviation delta omega and the rated angular frequency of the power grid is LVSM actual angular frequency omegamLVSM actual angular frequency ωmThe output of the integrator 3 is a three-phase synchronization signal (phase a is θ, phase B is (θ -2 π/3), and phase C is (θ +2 π/3)) as the input of the integrator 3, and the actual angular frequency ω of the LVSM ismThe output signal of the multiplier 1 is used as the input signal of the multiplier 3, and the output signal of the multiplier 3 is a three-phase PWM rectifier/inverter three-phase bridge arm midpoint PWM (pulse width modulation) voltage control reference signal elaref、elbref、elcrefThree-phase PWM rectifier/inverter controlling reference signal e according to PWM (pulse width modulation) voltagelaref、elbref、elcrefControlling power electronics (e.g. IGBT inclusion)Anti-parallel diode) switching of V1, V2, V3, V4, V5 and V6 causes the output of the three-phase PWM rectifier/inverter to track the reference signal elaref、elbref、elcrefAnd realizing the control of the LVSM system.
Wherein e islaref、elbref、elcrefRespectively as follows:
elaref＝ωmMfifsinθ
elbref＝ωmMfifsin(θ-2π/3)
elcref＝ωmMfifsin(θ+2π/3)
the virtual synchronous machine of the electric automobile participates in dynamic adjustment of the frequency of the power grid by utilizing the stored energy of the electric automobile and properly controlling the charging and discharging processes of a power battery of the electric automobile, so that the adaptability of the power grid to large-scale electric automobile access can be improved, and the influence of the load of the high-power electric automobile on the power grid can be reduced.
In some embodiments of the present invention, the calculation formula of the moment of inertia and the damping coefficient of the active power control unit is:
Figure BDA0002943835230000171
wherein J is rotational inertia, D is damping coefficient, ElFor the effective value of the virtual internal potential, V, of each phase of the LVSM control modulesFor the effective value, X, of the network phase voltagesBeing the impedance of the filter inductor, omega0For rating the angular frequency, omega, of the gridpcFor open loop cut-off angular frequency, ζ, of active power control looppThe damping ratio of the active power control loop, where XsThe impedance of any one of the filter inductors La, Lb, and Lc may be used, and in general, the three filter inductors have equal impedance.
Exemplary, ζp0.707, namely the optimal damping ratio of the second-order system;
usually will be ωpcThe design is far less than 2 times of power frequency to inhibit the pulsation in the instantaneous active power; when ω ispcWhen 54.7rad/s is used, J is 0.1kg m2、D＝12W·s2/rad2(ii) a When ω ispcWhen 24.5rad/s is taken, the J value is 0.5kg m2、D＝27W·s2/rad2。
In some embodiments of the present invention, the loop gain of the dc bus voltage loop of the active power control unit is:
Figure BDA0002943835230000172
where s is the Laplace operator, Tvdc(s) is the loop gain of the DC bus voltage loop, J is the moment of inertia, D is the damping coefficient, ElFor the effective value of the virtual internal potential, V, of each phase of the LVSM control modulesFor the effective value, X, of the network phase voltagesBeing the impedance of the filter inductor, omega0For rating the angular frequency, K, of the gridpIs the proportional regulation coefficient, K, of a DC bus voltage PI regulator in an active power control unitiIs the integral regulation coefficient, G, of a DC bus voltage PI regulator in an active power control unitmIs the amplitude margin of the DC bus voltage, CdcIs a DC bus capacitance value, VdcAnd the voltage between the positive electrode and the negative electrode of the direct current bus.
Optional, free-running frequency of active power control loop
Figure BDA0002943835230000181
Zero point of direct current bus voltage PI regulator is positioned at omegaPI＝Ki/KpTo make T(vds)Obtaining proper amplitude margin and phase angle margin T(vds)To cross the line 0dB, selecting ωPI<ωpnOpen loop cut-off angular frequency omega of DC bus voltagevdccIs located at omegaPIAnd ωpnIn the meantime.
Exemplarily, when J is 0.1kg m2、D＝12W·s2/rad2When it is used, Kp is 80W/V, Ki＝300W/(V·s)，T(vds)Open loop cut-off ofAngular frequency omegavdc11.9rad/s, a phase angle margin γ of 61.1 °, and a magnitude margin Gm＝19.9dB；
When J is 0.5kg m2、D＝27W·s2/rad2If Kp is still 80W/V, Ki300W/(V · s), the phase angle margin γ is 46.4 °, and the amplitude margin G ism＝19.9dB；
If Kp is 60W/V, Ki100W/(V · s), the phase angle margin γ is 60.3 °, and the amplitude margin G ism＝15.4dB。
In some embodiments of the present invention, the present invention further provides a power battery charging/discharging control method for grid frequency regulation, which is applied to the power battery charging/discharging control system for grid frequency regulation in any one of the above embodiments, and the control method includes:
if the absolute value of the difference value between the rated angular frequency of the power grid and the actual angular frequency of the power grid is larger than the preset difference value, the constant-current frequency adjusting unit and the constant-voltage frequency adjusting unit both output first gain signals; wherein, the first gain signal is used for leading the constant current frequency regulating unit to the constant current charging/discharging control and leading the constant voltage frequency regulating unit to the constant voltage charging/discharging control;
if the absolute value of the difference value between the rated angular frequency of the power grid and the actual angular frequency of the power grid is not larger than the preset difference value, the constant-current frequency adjusting unit and the constant-voltage frequency adjusting unit both output second gain signals; wherein the second gain signal is used to disable the constant current frequency adjusting unit and the constant voltage frequency adjusting unit during the battery charging/discharging process.
Optionally, the electric vehicle power battery is charged in a Constant Current (CC) (control) mode, and when the SOC is greater than 80%, the charging is switched to a Constant Voltage (CV) (control) mode.
Optionally, an angular frequency current controller (angular frequency (deviation) current control coefficient is K) is used during charging or discharging in a Constant Current (CC) modeib) And controlling the magnitude of the constant current charging or discharging current to participate in the dynamic regulation of the frequency of the power grid.
Optionally, the principle that the electric vehicle load virtual synchronous machine participates in the dynamic adjustment of the power grid frequency during Constant Current (CC) charging is as follows:
fluctuations in the grid load may cause changes in the grid angular frequency (or frequency) that will decrease when the grid load increases and conversely increase when the grid load decreases.
When the grid load fluctuation causes the actual angular frequency omega of the grid voltageg(corresponding to a frequency fg) Rated angular frequency omega of power grid0(corresponding to a frequency f0) Deviation Δ ω of (a)g(corresponding to a frequency deviation of Δ fg) When the frequency deviation exceeds the range set by the frequency dead zone controller (such as the frequency deviation limit value specified by the national power grid standard or the respective power grid standard +/-0.2 Hz or +/-0.1 Hz), the gain (amplification factor) of the frequency deviation dead zone controller, namely the first dead zone controller is 1.0, and the actual angular frequency omega of the power grid voltage is omegagRated angular frequency omega of power grid0Deviation Δ ω of (a)gBy means of an angular frequency current controller (angular frequency (deviation) current control coefficient of Kib) The constant current charging control is introduced, the charging power of the electric automobile is reduced or increased by properly reducing or increasing the current of the constant current charging, so that the reduction rate or the rising rate of the angular frequency (or frequency) of the power grid is slowed down, and the frequency of the power grid is stabilized.
When the grid load fluctuation causes the actual angular frequency omega of the grid voltageg(corresponding to a frequency fg) Rated angular frequency omega of power grid0(corresponding to a frequency f0) Deviation Δ ω of (a)g(corresponding to a frequency deviation of Δ fg) When the frequency deviation of the frequency dead zone controller does not exceed the set range of the frequency dead zone controller (such as the frequency deviation limit value +/-0.2 Hz or +/-0.1 Hz specified by national grid standard or respective grid standard), the gain (amplification factor) of the frequency deviation dead zone controller, namely the first dead zone controller is 0, the angular frequency current controller does not work, the electric automobile charges a power battery of the electric automobile according to the set reference current value, and at the moment, other characteristics (such as damping, inertia and the like) controlled by the electric automobile charging system as a Load Virtual Synchronous Machine (LVSM) are not changed.
The frequency deviation dead zone controller is combined with the regulation (national standard) requirement of power grid frequency regulation, so that the flexibility of the charging of the power battery of the electric automobile for participating in the dynamic regulation and control of the power grid frequency is improved, the frequency of charging current regulation during the constant current charging of the power battery of the electric automobile is reduced, and the service life of the power battery of the electric automobile is prolonged.
The principle that the electric automobile is used as a virtual synchronous generator to participate in dynamic adjustment of the power grid frequency when the electric automobile discharges at a Constant Current (CC) is similar to the principle that the electric automobile is used as a load virtual synchronous generator to participate in dynamic adjustment of the power grid frequency when the electric automobile charges at the Constant Current (CC).
Optionally, the principle that the electric vehicle load virtual synchronous machine participates in the dynamic adjustment of the power grid frequency during Constant Voltage (CV) charging is as follows:
when the grid load fluctuation causes the actual angular frequency omega of the grid voltageg(corresponding to a frequency fg) Rated angular frequency omega of power grid0(corresponding to a frequency f0) Deviation Δ ω of (a)g(corresponding to a frequency deviation of Δ fg) When the frequency deviation exceeds the range set by the frequency dead zone controller (such as the frequency deviation limit value specified by the national grid standard or the respective grid standard +/-0.2 Hz or +/-0.1 Hz), the gain (amplification factor) of the second frequency deviation dead zone controller, namely the second dead zone controller is 1.0, and the actual angular frequency omega of the grid voltage is omegagRated angular frequency omega of power grid0Deviation Δ ω of (a)gBy means of an angular frequency voltage controller (angular frequency (deviation) voltage control coefficient of Kvb) The constant voltage charging control is introduced, the power of the constant voltage charging control of the electric automobile is reduced or increased by properly reducing or increasing the constant voltage charging voltage and reducing or increasing the charging current, so that the descending and descending speed or the ascending and ascending speed of the angular frequency (or frequency) of the power grid is reduced, and the frequency of the power grid is stabilized.
When the grid load fluctuation causes the actual angular frequency omega of the grid voltageg(corresponding to a frequency fg) Rated angular frequency omega of power grid0(corresponding to a frequency f0) Deviation Δ ω of (a)g(corresponding to a frequency deviation of Δ fg) Gain (amplification) of a second frequency deviation dead band controller, i.e. a second dead band controller, when the frequency deviation does not exceed a range set by the frequency dead band controller (e.g. +/-0.2 Hz or + -0.1 Hz of a frequency deviation limit specified by the national grid standard or the respective grid standard)Multiple) is 0, and the angular frequency voltage controller (angular frequency (deviation) voltage control coefficient is Kvb) And when the charging reference voltage value is not used, the power battery of the electric automobile is charged according to the set charging reference voltage value. At this time, other characteristics (such as damping, inertia and the like) of the electric vehicle charging system as Load Virtual Synchronous Machine (LVSM) control are not changed
The second frequency deviation dead zone controller is combined with the regulation (national standard) requirement of power grid frequency regulation, so that the flexibility of the electric vehicle power battery charging participating in the dynamic regulation and control of the power grid frequency is improved, the frequency of charging voltage regulation during the constant voltage charging of the electric vehicle power battery is reduced, and the service life of the electric vehicle power battery is prolonged.
Illustratively, with the constant current charging mode as the verification, the verification process is as follows:
setting: 220V of effective value of power grid phase voltage, 700V of LVSM direct current bus voltage and C of direct current bus capacitordc10000 muF, 2mH of PWM rectifier filter inductor, 20mH of DC/DC conversion module DC filter inductor, 400V of battery voltage, 125A of charging current and control coefficient K of angular frequency (deviation) current controlib＝15.92A·s/rad。
A set of LVSM control parameters (parameter 1) was selected as: j is 0.1kg m2、D＝12W·s2/rad2、Kp＝80W/V、KiThe effect of introducing (angular) frequency (offset) current (frequency-current) control on the dynamic process and steady state operation of the system was studied 300W/(V · s). To compare different effects, an alternative set of parameters (parameter 2) is: j is 0.5kg m2、D＝27W·s2/rad2、Kp＝60W/V、Ki＝100W/(V·s)。
When t is 0s, the local load is increased, and the grid frequency is reduced; when t is 2s, after the power grid frequency is sensed to be increased, the power grid active power instruction is correspondingly increased, so that the input power is matched with the output power, and the power grid frequency is recovered; when t is 4s, the local load is reduced, and the frequency of the power grid is increased; and when t is 6s, the power grid active power command is correspondingly reduced, so that the input power is matched with the output power. The dynamic response process of the grid frequency, LVSM dc bus voltage and charging current are shown in fig. 10, 11 and 12, respectively.
Comparison of FIG. 10 with or without fg-IbThe curve of the (angular) frequency (deviation) -current control (device) can be known, and f is introducedg-IbAfter control, the variation of the grid frequency is reduced. When the grid frequency drop caused by sudden load increase occurs, f is not introducedg-IbFrequency deviation Δ f during controlg0.12Hz, frequency (deviation) -frequency deviation delta f after current controlg0.08 Hz. According to the operation condition of the east China power system, 50 +/-0.1 Hz is a normal working frequency region, the power grid is maintained in the normal working region through the proposed control strategy, and the stability of the power grid frequency is guaranteed.
The corresponding three curves in fig. 11 indicate: not introducing fg-IbIn control, the sudden increase and decrease of the local load causes a drop in the dc bus voltage amplitude of about 30V; introduction of fg-IbAfter control, the sudden increase of the local load reduces the drop amount of the voltage amplitude of the direct current bus. Because the LVSM is dynamically de-loaded by the frequency-current control, the effect of the local load on the DC bus voltage is reduced.
The corresponding three curves in fig. 12 show that a sudden rise or fall in the grid frequency changes the charging current by about 9%, and the dynamic process has the same trend as the grid frequency change, without current overshoot.
Simulation results show that the adaptability of the power grid to large-scale electric automobile access is improved through grid-load interaction, the electric automobile load has certain demand side response adjustment capacity, actively participates in operation management of the power distribution network, has certain inertia and damping, and the influence of the high-power electric automobile load on the power grid is reduced.
It should be understood that, the sequence numbers of the steps in the foregoing embodiments do not imply an execution sequence, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present invention.
The above embodiments are only used to illustrate the technical solutions of the present application, and not to limit the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present application and are intended to be included within the scope of the present application.

Claims (10)

1. A power battery charging/discharging control system for adjusting the frequency of a power grid is characterized by comprising a constant current control module, a constant voltage control module, a signal acquisition module and a signal giving module;
the constant current control module comprises a constant current frequency adjusting unit, a first battery current control unit and a first signal generator which are sequentially connected; the constant current frequency adjusting unit and the first battery current control unit are also respectively connected with the signal acquisition module and the signal giving module;
the constant voltage control module comprises a constant voltage frequency adjusting unit, a battery voltage control unit, a second battery current control unit and a second signal generator which are sequentially connected; the constant voltage frequency adjusting unit and the battery voltage control unit are also respectively connected with the signal acquisition module and the signal giving module; the second current control unit is also connected with the signal acquisition module; and the first signal generator and the second signal generator are both connected with a DC/DC conversion module of a power battery charging and discharging circuit.
2. The power battery charge/discharge control system for grid frequency regulation according to claim 1, wherein the constant current frequency regulation unit comprises a first phase locked loop, a first subtractor, a first dead band controller, and an angular frequency current controller;
the first phase-locked loop, the first subtractor, the first dead zone controller, the angular frequency current controller and the first battery current control unit are connected in sequence; the first phase-locked loop is also connected with the signal acquisition module; the first subtracter is also connected with the signal giving module;
the first phase-locked loop takes the three-phase voltage of the power grid sent by the signal acquisition module as an input signal, and outputs a signal to the first subtracter; wherein, the output signal of the first phase-locked loop is the actual angular frequency of the power grid;
the first subtractor takes the output signal of the first phase-locked loop and the rated angular frequency of the power grid sent by the signal giving module as input signals, and the output signal is sent to the first dead zone controller; wherein, the output signal of the first subtracter is the angular frequency deviation of the power grid;
the first dead zone controller takes an output signal of the first subtracter as an input signal, and the output signal is sent to the angular frequency current controller;
the angular frequency current controller takes an output signal of the first dead zone controller as an input signal, and outputs the output signal to the first battery current control unit; the output signal of the angular frequency current controller is the output signal of the constant current frequency adjusting unit;
the first battery current control unit takes an actual battery current value sent by the signal acquisition module, a first reference battery current value sent by the signal giving module and an output signal sent by the angular frequency current controller as input signals, and the output signals are sent to the first signal generator;
the first signal generator generates a first PWM wave and a second PWM wave according to an output signal of the first battery current control unit, and transmits the first PWM wave and the second PWM wave to the DC/DC conversion module.
3. The power battery charge/discharge control system for grid frequency regulation according to claim 1, wherein the first battery current control unit comprises a first operator, a first current PI controller, and a first current limiter;
the constant current frequency adjusting unit, the first arithmetic unit, the first current PI controller, the first current amplitude limiter and the first signal generator are connected in sequence; the first arithmetic unit is also connected with the signal acquisition module and the signal giving module respectively;
the first arithmetic unit takes the actual battery current value sent by the signal acquisition module, the first reference battery current value sent by the signal setting module and the output signal of the constant current frequency adjusting unit as input signals, and the output signals are sent to the first current PI controller and are used for summing the difference value obtained by subtracting the actual battery current value from the first reference battery current value and the output signal of the constant current frequency adjusting unit to obtain the output signal of the first arithmetic unit;
the first current PI controller takes an output signal of the first arithmetic unit as an input signal, and outputs the signal to the first current limiter;
the first current amplitude limiter takes an output signal of the first current PI controller as an input signal, and an output signal is sent to the first signal generator; wherein an output signal of the first current limiter is an output signal of the first battery current control unit.
4. The power battery charge/discharge control system for grid frequency regulation according to claim 1, wherein the constant voltage frequency regulation unit comprises a second phase locked loop, a second subtractor, a second dead band controller, and an angular frequency voltage controller;
the second phase-locked loop, the second subtractor, the second dead zone controller, the angular frequency voltage controller and the battery voltage control unit are connected in sequence; the second phase-locked loop is also connected with the signal acquisition module; the second subtracter is also connected with the signal giving module;
the second phase-locked loop takes the three-phase voltage of the power grid sent by the signal acquisition module as an input signal, and outputs a signal to the second subtractor; the output signal of the second phase-locked loop is the actual angular frequency of the power grid;
the second subtracter takes an output signal of the second phase-locked loop and the rated angular frequency of the power grid sent by the signal setting module as input signals, and the output signal is sent to the second dead zone controller; the output signal of the second subtracter is the angular frequency deviation of the power grid;
the second dead zone controller takes an output signal of the second subtracter as an input signal, and the output signal is sent to the angular frequency voltage controller;
the angular frequency voltage controller takes the output signal of the second dead zone controller as an input signal, and the output signal is sent to the battery voltage control unit;
the battery voltage control unit takes a battery reference voltage value sent by the signal giving module, an actual battery voltage value sent by the signal acquisition module and an output signal of the angular frequency voltage controller as input signals, and outputs the input signals to the second battery current control unit; the output signal of the battery voltage control unit is a second reference battery current value;
the second battery current control unit takes the output signal of the battery voltage control unit and the actual battery current value sent by the signal acquisition module as input signals, and the output signals are sent to the second signal generator;
the second signal generator generates a third PWM wave and a fourth PWM wave according to the output signal of the first current limiter, and sends the third PWM wave and the fourth PWM wave to the DC/DC conversion module.
5. The power battery charge/discharge control system for grid frequency regulation according to claim 1, wherein the battery voltage control unit comprises a second operator, a voltage PI controller, and a second current limiter;
the constant voltage frequency adjusting unit, the second arithmetic unit, the voltage PI controller, the second current limiter and the second battery current control unit are connected in sequence; the second arithmetic unit is also connected with the signal acquisition module and the signal giving module respectively;
the second arithmetic unit takes the battery reference voltage value sent by the signal giving module, the actual battery voltage value sent by the signal acquisition module and the output signal of the constant voltage frequency adjusting unit as input signals, and the output signals are sent to the voltage PI controller and are used for summing the difference value obtained by subtracting the actual battery voltage value from the battery reference voltage value and the output signal of the constant voltage frequency adjusting unit to obtain the output signal of the second arithmetic unit;
the voltage PI controller takes an output signal of the second arithmetic unit as an input signal, and an output signal is sent to the second current limiter;
the second current limiter takes an output signal of the voltage PI controller as an input signal, and outputs the signal to the second battery current control unit; wherein, the output signal of the second current limiter is the output signal of the battery voltage control unit and is also the second reference battery current value.
6. The power battery charge/discharge control system for grid frequency regulation according to claim 1, wherein the second battery current control unit comprises a third subtractor, a second current PI controller, and a third current limiter;
the battery voltage control unit, the third subtractor, the second current PI controller, the third current limiter and the second signal generator are connected in sequence; the third subtracter is also connected with the signal acquisition module;
the third subtracter takes an output signal of the battery voltage control unit and an actual battery current value sent by the signal acquisition module as input signals, and the output signal is sent to the second current PI controller;
the second current PI controller takes an output signal of the third subtracter as an input signal, and an output signal is sent to the third current limiter;
the third current amplitude limiter takes an output signal of the second current PI controller as an input signal, and an output signal is sent to the second signal generator; wherein an output signal of the third current limiter is an output signal of the second battery current control unit.
7. The power battery charge/discharge control system for grid frequency regulation according to any one of claims 1 to 6, characterized in that the power battery charge/discharge control system for grid frequency regulation further comprises an LVSM control module based on an analog synchronous motor for controlling an AC/DC conversion module of a power battery charge/discharge circuit;
the LVSM control module comprises an active power control unit and a reactive power control unit;
the active power control unit takes an actual direct current bus voltage value sent by the signal acquisition module and a direct current bus reference voltage value sent by the signal given module as input signals.
8. The power battery charge/discharge control system for grid frequency regulation according to claim 7, wherein the calculation formula of the moment of inertia and the damping coefficient of the active power control unit is:
Figure FDA0002943835220000051
wherein J is the moment of inertia, D is the damping coefficient, ElIs the effective value of virtual internal potential, V, of each phase of the LVSM control modulesFor the effective value, X, of the network phase voltagesBeing the impedance of the filter inductor, omega0For rating the angular frequency, omega, of the gridpcFor open loop cut-off angular frequency, ζ, of active power control looppThe damping ratio of the active power control loop.
9. The power battery charge/discharge control system for grid frequency regulation according to claim 7, wherein the loop gain of the dc bus voltage loop of the active power control unit is:
Figure FDA0002943835220000052
where s is the Laplace operator, Tvdc(s) is the loop gain of the DC bus voltage loop, J is the moment of inertia, D is the damping coefficient, ElIs the effective value of virtual internal potential, V, of each phase of the LVSM control modulesFor the effective value, X, of the network phase voltagesBeing the impedance of the filter inductor, omega0For rating the angular frequency, K, of the gridpIs the proportional regulation coefficient, K, of a DC bus voltage PI regulator in an active power control unitiIs the integral regulation coefficient, G, of a DC bus voltage PI regulator in the active power control unitmIs the amplitude margin of the DC bus voltage, CdcIs the capacitance value of the DC bus, VdcAnd the voltage between the positive electrode and the negative electrode of the direct current bus.
10. A power battery charging/discharging control method for grid frequency regulation, which is applied to the power battery charging/discharging control system for grid frequency regulation according to any one of claims 1 to 9, and comprises the following steps:
if the absolute value of the difference value between the rated angular frequency of the power grid and the actual angular frequency of the power grid is larger than the preset difference value, the constant-current frequency adjusting unit and the constant-voltage frequency adjusting unit both output first gain signals; the first gain signal is used for introducing the constant-current frequency adjusting unit into constant-current charging/discharging control and introducing the constant-voltage frequency adjusting unit into constant-voltage charging/discharging control;
if the absolute value of the difference value between the rated angular frequency of the power grid and the actual angular frequency of the power grid is not larger than the preset difference value, the constant-current frequency adjusting unit and the constant-voltage frequency adjusting unit both output second gain signals; wherein the second gain signal is used to disable the constant current frequency adjusting unit and the constant voltage frequency adjusting unit during battery charging/discharging.
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Publication number Priority date Publication date Assignee Title
CN102739054A (en) * 2011-04-14 2012-10-17 Nxp股份有限公司 A controller for a switched mode power converter
CN106505602A (en) * 2016-11-01 2017-03-15 北京科诺伟业科技股份有限公司 A kind of control method of energy-storage system
CN107196318A (en) * 2017-04-17 2017-09-22 华北电力大学 A kind of electric automobile based on V2G technologies participates in power grid frequency modulation control method

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102739054A (en) * 2011-04-14 2012-10-17 Nxp股份有限公司 A controller for a switched mode power converter
CN106505602A (en) * 2016-11-01 2017-03-15 北京科诺伟业科技股份有限公司 A kind of control method of energy-storage system
CN107196318A (en) * 2017-04-17 2017-09-22 华北电力大学 A kind of electric automobile based on V2G technologies participates in power grid frequency modulation control method

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