阅读说明：本技术 基于蓄电池剩余电量的改进下垂控制方法及系统 (Improved droop control method and system based on residual electric quantity of storage battery ) 是由 王洪荣 孙强 施成章 王乐 刘志峰 于 2021-08-04 设计创作，主要内容包括：本发明提供了一种基于蓄电池剩余电量的改进下垂控制方法及系统,包括：步骤S1：检测变换器输出电压u-(dc1)和输出电流i-(dc1),并根据输出电压u-(dc1)和输出电流i-(dc1)得到变换器输出功率p-(dc1)；步骤S2：检测蓄电池剩余容量的值Soc-(1),根据变换器输出功率和下垂法计算公式,得到新的参考电压u-(dcref)；步骤S3：实际输出电压u-(dc1)与新的参考电压u-(dcref)进行比较,经过电压控制环得到电流的参考值；步骤S4：电流参考值与实际输出电流i-(dc1)进行比较,经过电流控制环得到变换器开关PWM驱动波形；步骤S5：通过PWM驱动波形控制变换器的电压,从而控制蓄电池输出功率。(The invention provides an improved droop control method and system based on the residual electric quantity of a storage battery, which comprises the following steps: step S1: detecting converter output voltage u dc1 And an output current i dc1 And according to the output voltage u dc1 And an output current i dc1 Obtaining the output power p of the converter dc1 (ii) a Step S2: detecting the value Soc of the remaining capacity of the battery 1 Obtaining a new reference voltage u according to a calculation formula of the output power of the converter and a droop method dcref (ii) a Step S3: actual output voltage u dc1 With a new reference voltage u dcref Comparing, and obtaining a reference value of the current through a voltage control loop; step S4: current reference value and actual output current i dc1 Comparing, and obtaining a PWM driving waveform of a converter switch through a current control loop; step S5: the voltage of the converter is controlled by the PWM driving waveform, so that the output power of the storage battery is controlled.)

1. An improved droop control method based on the residual capacity of a storage battery is characterized by comprising the following steps:

step S1: detecting converter output voltage u_dc1And an output current i_dc1And according to the output voltage u_dc1And an output current i_dc1Obtaining the output power p of the converter_dc1；

Step S2: detecting the value Soc of the remaining capacity of the battery₁Obtaining a new reference voltage u according to a calculation formula of the output power of the converter and a droop method_dcref；

Step S3: actual output voltage u_dc1With a new reference voltage u_dcrefComparing, and obtaining a reference value of the current through a voltage control loop;

step S4: current reference value and actual output current i_dc1Comparing, and obtaining a PWM driving waveform of a converter switch through a current control loop;

step S5: the voltage of the converter is controlled by the PWM driving waveform, so that the output power of the storage battery is controlled.

2. The method for improving the droop control based on the residual capacity of the storage battery according to claim 1, wherein the step S2 comprises:

wherein u is_dcrefIs a new reference voltage; m is₀Represents the initial sag factor; soc₁Representing a residual quantity value; p is a radical of₁Representing converter output power p_dc1Power through a low pass filter; n represents the number of batteries operating in parallel.

3. The method for improving the droop control based on the residual capacity of the storage battery according to claim 1, wherein the step S3 comprises: when the actual output voltage u is_dc1Greater than the new reference voltage u_dcrefReducing the output voltage of the current storage battery and slowing down the descending speed of the SOC state; when the actual output voltage u is_dc1Less than the new reference voltage u_dcrefThe output voltage of the battery is increased to accelerate the rate of decrease in the SOC state.

4. The method for improving the droop control based on the residual capacity of the storage battery according to claim 1, wherein the step S4 comprises: and performing difference operation on the actual output current and the current reference value, and controlling the output current of the storage battery according to the sign of the difference.

5. The method for improving the droop control based on the residual capacity of the storage battery according to claim 1, wherein the reference value of the current is as follows:

u_dc1-u_dcref＝R_di_dc (2)

wherein i_dcRepresents a current reference value; r_dRepresenting the resistance.

6. An improved droop control system based on the remaining capacity of a storage battery, comprising:

module M1: detecting converter output voltage u_dc1And an output current i_dc1And according to the output voltage u_dc1And an output current i_dc1Obtaining the output power p of the converter_dc1；

Module M2: detecting the value Soc of the remaining capacity of the battery₁Obtaining a new reference voltage u according to a calculation formula of the output power of the converter and a droop method_dcref；

Module M3: actual output voltage u_dc1With a new reference voltage u_dcrefComparing, and obtaining a reference value of the current through a voltage control loop;

module M4: current reference value and actual output current i_dc1Comparing, and obtaining a PWM driving waveform of a converter switch through a current control loop;

module M5: the voltage of the converter is controlled by the PWM driving waveform, so that the output power of the storage battery is controlled.

7. The improved droop control system based on battery residual capacity of claim 6, wherein the module M2 employs:

wherein u is_dcrefIs a new reference voltage; m is₀Represents the initial sag factor; soc₁Representing a residual quantity value; p is a radical of₁Representing converter output power p_dc1Power through a low pass filter; n represents the number of batteries operating in parallel.

8. The improved droop control system based on battery residual capacity of claim 6, wherein the module M3 employs: when the actual output voltage u is_dc1Greater than the new reference voltage u_dcrefReducing the output voltage of the current storage battery and slowing down the descending speed of the SOC state; when the actual output voltage u is_dc1Less than the new reference voltage u_dcrefThe output voltage of the battery is increased to accelerate the rate of decrease in the SOC state.

9. The improved droop control system based on battery residual capacity of claim 6, wherein the module M4 employs: and performing difference operation on the actual output current and the current reference value, and controlling the output current of the storage battery according to the sign of the difference.

10. The improved droop control system based on battery remaining capacity of claim 6, wherein the reference value of the current is selected from the group consisting of:

u_dc1-u_dcref＝R_di_dc (2)

wherein i_dcRepresents a current reference value; r_dRepresenting the resistance.

Technical Field

The invention relates to the technical field of industry, in particular to an improved droop control method and system based on the residual capacity of a storage battery, and more particularly to an improved droop control strategy based on the residual capacity of the storage battery.

Background

At present, droop control is widely applied to micro-grid operation, and the voltage control on a bus is achieved by utilizing the proportional relation between the output current of a converter and the impedance of a cable and the output impedance, so that the voltage control of the bus fluctuates within a certain range. In the actual operation process, the cable impedance cannot be ignored, and when the cable impedance is considered, the voltages of all the distributed power generation units are not completely the same, so that the shunt precision is reduced. Therefore, improvements in droop control are needed to ensure certain shunt accuracy and smaller voltage deviations.

Patent document CN104901394A (application number: 201510362466.0) discloses a quasi-PR droop control method for a light storage charging station based on SOC, which relates to the technical field of micro-grids and solves the technical problem of regulating and controlling an ac inverter. The method comprises the steps that a quasi-PR droop control formula is utilized to calculate the phase angle of an alternating current side of an alternating current inverter and the offset of voltage, and the offset is respectively added to the rated voltage and the rated phase angle of the alternating current side through a self-PI link to obtain three-phase voltage reference signals; converting the three-phase voltage reference signal into a component on a two-phase static coordinate system, subtracting the actual voltage of the corresponding component, and calculating by using a quasi-PR controller to obtain a current reference signal under the two-phase static coordinate; and subtracting the current reference signal under the two-phase static coordinate from the actual current of the corresponding component, and obtaining a reference signal of output voltage through a proportion P regulator, thereby realizing the regulation control of the alternating current inverter.

In the prior art, when a small droop coefficient is selected, the voltage deviation is small, but the corresponding shunt precision is poor. When a large droop coefficient is selected, the voltage deviation is large. The current droop control method needs improvement of the control method, so that balance between shunt precision and bus voltage deviation is achieved.

Disclosure of Invention

In view of the defects in the prior art, the present invention provides an improved droop control method and system based on the remaining battery capacity.

The invention provides an improved droop control method based on the residual capacity of a storage battery, which comprises the following steps:

step S1: detecting converter output voltage u_dc1And an output current i_dc1And according to the output voltage u_dc1And an output current i_dc1Obtaining the output power p of the converter_dc1；

Step S2: detecting the value Soc of the remaining capacity of the battery₁Obtaining a new reference voltage u according to a calculation formula of the output power of the converter and a droop method_dcref；

Step S3: actual output voltage u_dc1With a new reference voltage u_dcrefComparing, and obtaining a reference value of the current through a voltage control loop;

step S4: current reference value and actual output current i_dc1Comparing, and obtaining a PWM driving waveform of a converter switch through a current control loop;

step S5: the voltage of the converter is controlled by the PWM driving waveform, so that the output power of the storage battery is controlled.

Preferably, the step S2 adopts:

wherein u is_dcrefIs a new reference voltage; m is₀Represents the initial sag factor; soc₁Representing a residual quantity value; p is a radical of₁Representing converter output power p_dc1Power through a low pass filter; n represents the number of batteries operating in parallel.

Preferably, the step S3 adopts: when the actual output voltage u is_dc1Greater than the new reference voltage u_dcrefThen the current output of the battery is reducedVoltage, slowing the rate of decrease of the SOC state; when the actual output voltage u is_dc1Less than the new reference voltage u_dcrefThe output voltage of the battery is increased to accelerate the rate of decrease in the SOC state.

Preferably, the step S4 adopts: and performing difference operation on the actual output current and the current reference value, and controlling the output current of the storage battery according to the sign of the difference.

Preferably, the reference value of the current is:

u_dc1-u_dcref＝R_di_dc (2)

wherein i_dcRepresents a current reference value; r_dRepresenting the resistance.

According to the invention, the improved droop control system based on the residual capacity of the storage battery comprises:

module M1: detecting converter output voltage u_dc1And an output current i_dc1And according to the output voltage u_dc1And an output current i_dc1Obtaining the output power p of the converter_dc1；

Module M2: detecting the value Soc of the remaining capacity of the battery₁Obtaining a new reference voltage u according to a calculation formula of the output power of the converter and a droop method_dcref；

Module M3: actual output voltage u_dc1With a new reference voltage u_dcrefComparing, and obtaining a reference value of the current through a voltage control loop;

module M4: current reference value and actual output current i_dc1Comparing, and obtaining a PWM driving waveform of a converter switch through a current control loop;

module M5: the voltage of the converter is controlled by the PWM driving waveform, so that the output power of the storage battery is controlled.

Preferably, the module M2 employs:

wherein u is_dcrefAs a new referencePressing; m is₀Represents the initial sag factor; soc₁Representing a residual quantity value; p is a radical of₁Representing converter output power p_dc1Power through a low pass filter; n represents the number of batteries operating in parallel.

Preferably, the module M3 employs: when the actual output voltage u is_dc1Greater than the new reference voltage u_dcrefReducing the output voltage of the current storage battery and slowing down the descending speed of the SOC state; when the actual output voltage u is_dc1Less than the new reference voltage u_dcrefThe output voltage of the battery is increased to accelerate the rate of decrease in the SOC state.

Preferably, the module M4 employs: and performing difference operation on the actual output current and the current reference value, and controlling the output current of the storage battery according to the sign of the difference.

Preferably, the reference value of the current is:

u_dc1-u_dcref＝R_di_dc (2)

wherein i_dcRepresents a current reference value; r_dRepresenting the resistance.

Compared with the prior art, the invention has the following beneficial effects: in the adjustment of the droop control coefficient, the residual capacity of the storage battery is introduced, and the power balance is realized according to the relation between the residual capacity of the storage battery and the output power.

Drawings

Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:

fig. 1 is a block diagram of an improved droop control based on battery remaining capacity.

Fig. 2 is a specific control block diagram of a voltage loop and a current loop.

Fig. 3 is a droop control circuit based on the remaining capacity of the battery.

Fig. 4 is a diagram of the control circuit output driving waveform.

Fig. 5 is an expanded view of the driving waveform of the control circuit.

Fig. 6 is a curve of the remaining capacity of the battery with n-2.

Fig. 7 is a curve of the battery output power with n-2.

Fig. 8 is a curve of the remaining capacity of the battery with n-3.

Fig. 9 is a curve of the output power of the battery with n-3.

Fig. 10 is a curve of the remaining battery capacity, where n is 6.

Fig. 11 shows the output power curve of the battery with n-6.

Detailed Description

The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that it would be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit of the invention. All falling within the scope of the present invention.

Example 1

The invention provides an improved droop control method based on the residual capacity of a storage battery, which comprises the following steps:

step S1: detecting converter output voltage u_dc1And an output current i_dc1And according to the output voltage u_dc1And an output current i_dc1Obtaining the output power p of the converter_dc1；

Step S2: detecting the value Soc of the remaining capacity of the battery₁Obtaining a new reference voltage u according to a calculation formula of the output power of the converter and a droop method_dcref；

Step S3: actual output voltage u_dc1With a new reference voltage u_dcrefComparing, and obtaining a reference value of the current through a voltage control loop;

step S4: current reference value and actual output current i_dc1Comparing, and obtaining a PWM driving waveform of a converter switch through a current control loop;

step S5: the voltage of the converter is controlled by the PWM drive waveform, and the output power of the battery can be influenced by the drive waveform because the voltage has a fixed relationship with the current.

Specifically, the step S2 employs:

wherein u is_dcrefIs a new reference voltage; m is₀Represents the initial sag factor; soc₁Representing a residual quantity value; p is a radical of₁Representing converter output power p_dc1Power through a low pass filter; n represents the number of batteries operating in parallel.

Specifically, the step S3 employs: when the actual output voltage u is_dc1Greater than the new reference voltage u_dcrefReducing the output voltage of the current storage battery and slowing down the descending speed of the SOC state; when the actual output voltage u is_dc1Less than the new reference voltage u_dcrefThe output voltage of the battery is increased to accelerate the rate of decrease in the SOC state.

Specifically, the step S4 employs: and performing difference operation on the actual output current and the current reference value, and controlling the output current of the storage battery according to the sign of the difference.

Specifically, the reference value of the current is:

u_dc1-u_dcref＝R_di_dc (2)

wherein i_dcRepresents a current reference value; r_dRepresenting the resistance.

According to the invention, the improved droop control system based on the residual capacity of the storage battery comprises:

module M1: detecting converter output voltage u_dc1And an output current i_dc1And according to the output voltage u_dc1And an output current i_dc1Obtaining the output power p of the converter_dc1；

Module M2: detecting the value Soc of the remaining capacity of the battery₁Obtaining a new reference voltage u according to a calculation formula of the output power of the converter and a droop method_dcref；

Module M3: actual output voltage u_dc1With new reference voltagesu_dcrefComparing, and obtaining a reference value of the current through a voltage control loop;

module M4: current reference value and actual output current i_dc1Comparing, and obtaining a PWM driving waveform of a converter switch through a current control loop;

module M5: the voltage of the converter is controlled by the PWM drive waveform, and the output power of the battery can be influenced by the drive waveform because the voltage has a fixed relationship with the current.

Specifically, the module M2 employs:

wherein u is_dcrefIs a new reference voltage; m is₀Represents the initial sag factor; soc₁Representing a residual quantity value; p is a radical of₁Representing converter output power p_dc1Power through a low pass filter; n represents the number of batteries operating in parallel.

Specifically, the module M3 employs: when the actual output voltage u is_dc1Greater than the new reference voltage u_dcrefReducing the output voltage of the current storage battery and slowing down the descending speed of the SOC state; when the actual output voltage u is_dc1Less than the new reference voltage u_dcrefThe output voltage of the battery is increased to accelerate the rate of decrease in the SOC state.

Specifically, the module M4 employs: and performing difference operation on the actual output current and the current reference value, and controlling the output current of the storage battery according to the sign of the difference.

Specifically, the reference value of the current is:

u_dc1-u_dcref＝R_di_dc (2)

wherein i_dcRepresents a current reference value; r_dRepresenting the resistance.

Example 2

Example 2 is a preferred example of example 1

In the adjustment of the droop control coefficient, the residual capacity of the storage battery is introduced, and according to the relation between the residual capacity of the storage battery and the output power, the storage battery with larger initial residual capacity starts to output higher load power, and the storage battery with smaller initial residual capacity starts to output lower load power, so that the power balance is realized.

According to the invention, through the power of the converter and the residual capacity state of the storage battery, the storage battery with a higher charge state can output higher power, the capacity can be reduced more quickly, the corresponding residual capacity is introduced into the droop coefficient, and the droop coefficient is dynamically corrected, so that the balance among the storage battery packs with different residual capacities is realized, and further the power output among the storage batteries is within an allowable range.

According to the relation between the residual capacity and the output power of the storage battery, the storage battery with the larger initial residual capacity starts to output higher load power, and the storage battery with the smaller initial residual capacity starts to output lower load power, so that power balance is realized. Thus, a control block diagram like fig. 1 is derived:

(1) the converter output voltage and output current are detected. (2) And obtaining the output power according to the output voltage and the output current of the converter. (3) And detecting the value of the residual capacity of the storage battery, combining an output power and droop method calculation formula to obtain a control circuit based on the residual capacity of the storage battery, and sending a control signal by the control circuit based on the residual capacity of the storage battery according to the SOC state and the voltage and current of the storage battery. (4) The actual output voltage is compared with the new reference voltage, and the reference value of the current is obtained through the voltage control loop. (5) The current reference value is compared with the actual output current, and the PWM driving waveform of the converter switching tube is obtained through the current control loop, so that the control effect is achieved.

The control module detects the output voltage u of the converter first_dc1And an output current i_dc1The output power P of the converter is obtained through calculation_dc1Is output P via a low-pass filter₁. Detecting the value of the SoC of the battery, combined with the power P through the low-pass filter₁And a droop method calculation formula, and a control circuit based on the residual capacity of the storage battery is provided. The actual output voltage is compared with the new reference voltageAnd performing line comparison, and obtaining a current reference value through a voltage control loop. And comparing the current reference value with the actual output current, and obtaining the PWM driving waveform of the switching tube of the converter through current control and conversion. The specific control block diagram is shown in fig. 2:

and (3) building a system simulation model based on MATLAB/Simulink, and verifying a theoretical analysis result. The battery parameters are shown in table 1:

TABLE 1 Battery Module parameters

The droop control circuit based on the residual capacity of the storage battery is shown in fig. 3:

the driving signal is shown in fig. 4, and the waveform is developed as shown in fig. 5: as shown in fig. 4 and 5, the duty ratios of the driving waveforms of the two switching tubes of the converter are changed continuously, and the duty ratios are different at the same moment, so that the output current of the converter and the output power of the converter can be dynamically adjusted.

When the two storage batteries are operated in parallel, the residual electric quantity of the two storage batteries gradually tends to be the same according to an improved droop control strategy. When n is 2, the two battery SoC values and the two battery SoC difference values change as shown in fig. 6 and 7:

when n is 3, the values of the two batteries SoC and the difference between the two batteries SoC are changed as shown in fig. 8 and 9

The residual capacities of the two parallel storage batteries reach the balance at about 900s, which is similar to the time of the calculation structure of the formula. Initial output total power 1001W, single converter output is all around 500W after realizing the equilibrium, along with the difference of remaining capacity reduces to 0 from 0.1, the difference of output power also reduces to about the same from 174.5W.

When n is 6, the two battery SoC value changes and the two battery SoC difference value changes are as shown in fig. 10 and fig. 11:

the residual capacities of the two parallel storage batteries reach balance at about 200s, and the speed is obviously faster than the case of n-2 and n-3, which is consistent with the fact that the higher n is in a reasonable range, the faster the balance is realized. The initial output total power is 1000W, the difference value is 333W, the output power of the two converters is basically equal after 250s along with the gradual trend of the residual electric quantity of the storage battery, both the output power is about 501W, and the power balance is realized.

Those skilled in the art will appreciate that, in addition to implementing the systems, apparatus, and various modules thereof provided by the present invention in purely computer readable program code, the same procedures can be implemented entirely by logically programming method steps such that the systems, apparatus, and various modules thereof are provided in the form of logic gates, switches, application specific integrated circuits, programmable logic controllers, embedded microcontrollers and the like. Therefore, the system, the device and the modules thereof provided by the present invention can be considered as a hardware component, and the modules included in the system, the device and the modules thereof for implementing various programs can also be considered as structures in the hardware component; modules for performing various functions may also be considered to be both software programs for performing the methods and structures within hardware components.

The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The embodiments and features of the embodiments of the present application may be combined with each other arbitrarily without conflict.