CN109347153B - Single-phase power control method and system for hybrid unit cascaded H-bridge energy storage system - Google Patents

Abstract

The invention provides a hybrid unit cascade H-bridge energy storage system, which includes: a plurality of battery cascade units; the plurality of battery cascade units are connected in series and then connected to a power grid; the battery cascade units include capacitor cascade units, An energy storage battery module and a switch; the energy storage battery module is connected in series with the switch and then connected in parallel with the capacitor cascade unit; the switch is used for switching according to whether the energy storage battery module is faulty; when the energy storage battery module is normal , the switch is closed; when the energy storage battery module fails, the switch is disconnected; at least one energy storage battery module in the plurality of battery cascading power supplies is normal. The technical solution provided by the present invention can provide voltage support with the capacitor cascade units running reactively in the case of multi-battery unit failure in the cascaded H-bridge energy storage system, so that the voltage of the cascaded H-bridge energy storage system can still reach Grid connection requirements, continue to output the active power of the energy storage battery cascade units.

Description

A single-phase power control method and system for a hybrid unit cascaded H-bridge energy storage system

technical field

The invention relates to the field of converter control, in particular to a single-phase power control method and system for a hybrid unit cascaded H-bridge energy storage system.

Background technique

The increasing penetration rate of new energy power generation increases the instability of the power system. In the process of energy Internet promotion, as an important way to compensate for the fluctuating power of new energy power plants, the demand for large-scale energy storage systems is getting higher and higher. The cascaded H-bridge energy storage power conversion system can connect multiple low-voltage cascaded units in series and directly connect to the power grid. It has the characteristics of low loss, good output characteristics, and easy control. It can well solve the connection between medium and high-voltage large-capacity energy storage systems. the problem of connecting to the grid.

The prior art proves the advantages of cascaded H-bridge multilevel topology in active power control of energy storage systems, fault-tolerant operation, etc. The H-bridge energy storage system will have a better output waveform, higher power quality, and reduce the requirements for the system switching frequency.

In addition, a lot of research has been done on the operation control technology of cascaded H-bridge energy storage PCS under the failure of a few cascaded units. The current control and processing technologies for the failure of cascaded units are mostly based on pre-redundantly setting a part of the cascaded units, and after bypassing the faulty cascaded units, the research is carried out to ensure that the output phase voltage is symmetrical. In order to avoid the expansion of the fault range, it is first necessary to perform bypass removal processing on the fault cascade unit. The bypass mode can be divided into two modes: online bypass and shutdown bypass. There are three schemes for the setting of the online bypass mechanism: Traditional electromagnetic AC contactor, thyristor + rectifier bridge, bidirectional thyristor. There are two ways of bypassing the faulty unit: same-level bypassing and bypassing only the faulty unit. After bypassing the faulty cascaded units, the output voltage of the system is increased by adjusting the modulation ratio. Some scholars also pointed out that for the cascaded H-bridge energy storage system, as long as the line voltage is kept consistent with the power grid before and after the fault, the system can operate normally, and the zero-sequence voltage injection method and the neutral point offset method are proposed. To ensure the symmetrical relationship between the line voltages, from the simulation and experimental results, the above control method has a good control effect. However, the above fault operation control is all designed on the premise that the battery voltage can still meet the grid-connection requirements after the cascaded unit fails. will fail and cannot maintain the ability of the system to continue to operate stably.

SUMMARY OF THE INVENTION

In order to solve the above problems, the present invention proposes a single-phase power control method and system for a hybrid unit cascaded H-bridge energy storage system, which can control the active power and reactive power of the cascaded H-bridge energy storage system after the failure of multiple battery units. Control, to achieve precise control of active power, so that the energy of the remaining battery cells in the system can continue to be used.

The purpose of this invention is to adopt following technical scheme to realize:

A hybrid unit cascade H-bridge energy storage system, characterized in that it includes: a plurality of battery cascade units;

The plurality of battery cascade units are connected to the power grid after being connected in series;

The battery cascading unit includes a capacitor cascading unit, an energy storage battery module and a switch;

The energy storage battery module is connected in series with the switch and then connected in parallel with the capacitor cascade unit;

The switch is used for switching on and off according to whether the energy storage battery module is faulty; when the energy storage battery module is normal, the switch is closed; when the energy storage battery module is faulty, the switch is disconnected;

At least one energy storage battery module in the plurality of battery cascaded power sources is normal.

Preferably, the capacitor cascade unit includes: a single-phase H-bridge power conversion module and a capacitor;

The single-phase H-bridge power conversion module is connected in parallel with the capacitor.

Preferably, the battery cascading unit further includes a first reactor; the first reactor is connected in series with the switch.

Preferably, the number of battery cascading units in the system is the number of cascading units in the preset battery cascading units in the grid energy storage system in which the single-phase H-bridge power conversion module operates normally.

Preferably, the system further includes a second reactor; the second reactor is connected in series with the battery cascading unit.

A method for determining parameters of a hybrid unit cascaded H-bridge energy storage system, the method comprising:

Calculate the absolute value of the angle between the grid-connected current vector and the grid voltage vector according to the active power and reactive power of the pre-set hybrid unit cascaded H-bridge energy storage system;

Calculate the absolute value of the angle between the capacitor cascade unit voltage vector and the grid voltage vector according to the absolute value of the angle between the grid-connected current vector and the grid voltage vector;

According to the absolute value of the angle between the capacitor cascade unit voltage vector and the grid voltage vector, the angle between the battery cascade unit voltage vector and the grid voltage vector is calculated, and the operating point of the battery cascade unit voltage vector is determined.

Preferably, the absolute value of the included angle between the grid-connected current vector and the grid voltage is calculated as follows:

并网电流矢量与电网电压矢量之间的夹角；P：有功功率；Q：无功功率。In the formula,

Angle between grid-connected current vector and grid voltage vector; P: active power; Q: reactive power.

Preferably, there is a constraint relationship between the active power and the reactive power, as shown in the following formula:

In the formula, U _r1 : battery cascade unit voltage amplitude; U _s : grid voltage amplitude, S: apparent power; P: active power; Q: reactive power;

Among them, the voltage amplitude U _r1 of the battery cascade unit is calculated as follows:

的调制比；U_battery：剩余正常电池级联单元总电压。In the formula, M: the voltage vector of the given battery cascade unit

The modulation ratio of ; U _battery : the total voltage of the remaining normal battery cascade units.

Preferably, the absolute value of the angle between the capacitor cascade unit voltage vector and the grid voltage vector is calculated as follows:

In the formula: δ ₁ : the angle between the voltage vector of the capacitor cascade unit and the grid voltage vector.

Preferably, the angle between the battery cascade unit voltage vector and the grid voltage vector is calculated as follows:

In the formula, δ: the angle between the battery cascade unit voltage vector and the grid voltage vector.

Preferably, the absolute value of the angle between the battery cascade unit voltage vector and the grid voltage vector is calculated as follows:

In the formula, U _r1 : the voltage amplitude of the battery cascade unit; U _s : the grid voltage amplitude.

Preferably, the determination of the voltage vector operating point of the battery cascade unit is calculated as follows:

A parameter determination system of a hybrid unit cascaded H-bridge energy storage system, the system comprises: a first calculation module, a second calculation module and a determination module;

The first calculation module: used to calculate the absolute value of the angle between the grid-connected current vector and the grid voltage vector according to the active power and reactive power of the pre-set hybrid unit cascaded H-bridge energy storage system;

The second calculation module: used to calculate the absolute value of the angle between the capacitor cascade unit voltage vector and the grid voltage vector according to the absolute value of the angle between the grid-connected current vector and the grid voltage vector;

Determination module: It is used to calculate the angle between the voltage vector of the battery cascade unit and the grid voltage vector according to the absolute value of the angle between the voltage vector of the capacitor cascade unit and the grid voltage vector, and determine the operating point of the battery cascade unit voltage vector.

A single-phase power control method for a hybrid unit cascaded H-bridge energy storage system, the method comprising:

According to the battery cascading unit voltage operating point obtained by the parameter determination method of the hybrid unit cascading H-bridge energy storage system, the closed-loop control of the capacitor cascading unit voltage is performed to obtain the reference voltage of the capacitor cascading unit voltage;

The single-phase power is controlled according to the reference voltage of the capacitor cascade unit voltage.

Preferably, the operating point of the battery cascade unit voltage obtained according to the parameter determination method of the hybrid unit cascade H-bridge energy storage system; the closed-loop control of the capacitor cascade unit voltage, and obtaining the reference voltage of the capacitor cascade unit voltage includes:

The reference value of the DC side voltage of the capacitor cascade unit is poor compared with the DC side voltage of the capacitor cascade unit. After being adjusted by PI, the amplitude of the active current component is output;

The active power reference value is compared with the active power actually output by the battery cascade unit. After adjustment by PI, the amplitude of the reactive current component is output;

The sampled grid voltage is passed through the phase-locked loop to obtain the corresponding phase angle, and then the amplitude of the active current component is multiplied by the sine value of the phase angle, and the amplitude of the reactive current component is multiplied by the cosine value of the phase angle. The given value of the loop instantaneous current is compared with the feedback current of the system to obtain the error value, and the voltage deviation adjustment amount is obtained after P adjustment;

The grid voltage and the battery cascading unit voltage are compared to generate a reactive voltage component, which is then compared with the voltage deviation adjustment amount to obtain the reference voltage of the capacitor cascading unit.

Preferably, the controlling the single-phase power according to the reference voltage of the capacitor cascade unit voltage includes:

The reference voltage of the capacitor cascade unit voltage is output to the carrier phase-shifted sinusoidal pulse width modulation trigger pulse generator to generate a switch tube trigger pulse, and the single-phase power is controlled by the switch tube trigger pulse.

A hybrid unit cascaded H-bridge energy storage system single-phase power control system, the system includes: a calculation module and a control module;

Voltage calculation module: used to perform closed-loop control on the voltage of the capacitor cascade unit according to the operating point of the battery cascade unit voltage, so as to obtain the reference voltage of the capacitor cascade unit voltage;

Power control module: used to control the single-phase power according to the reference voltage of the capacitor cascade unit voltage.

Compared with the closest prior art, the technical scheme provided by the present invention has the following beneficial effects:

The technical scheme provided by the present invention can utilize the cascaded units in which the energy storage battery module is faulty and the power conversion module is normal in the case of failure of multiple battery cells in the cascaded H-bridge energy storage system, and the capacitor level operating with reactive power The cascading unit provides voltage support, so that the voltage of the cascaded H-bridge energy storage system can still meet the grid connection requirements, and the active power of the cascaded units of the energy storage battery can continue to be output, and the energy of the remaining cascaded battery units can continue to be used.

The technical scheme provided by the present invention can adopt the method of battery cascade unit voltage open-loop control and capacitor cascade unit voltage closed-loop control method after the failure of multiple battery units, to control the active power and reactive power of the cascaded H-bridge energy storage system. The power is controlled, so as to realize the precise control of the active power, so that the energy of the remaining battery cells in the system can be continuously utilized.

The invention can realize the power control of the single-phase system, has good applicability, solves the problem that the cascaded H-bridge energy storage system cannot be operated due to the failure of multiple battery units, and improves the utilization of the cascaded H-bridge energy storage system rate and increase economic efficiency.

Description of drawings

Fig. 1 is the topological structure schematic diagram of a kind of hybrid unit cascade H-bridge energy storage system of the present invention;

Fig. 2 is the schematic diagram of the topology structure change of the hybrid unit cascade H-bridge energy storage system of the present invention;

3 is a schematic diagram of a method for determining parameters of a hybrid unit cascaded H-bridge energy storage system according to the present invention;

4 is a schematic diagram of a single-phase power control method for a hybrid unit cascaded H-bridge energy storage system according to the present invention;

5 is a schematic diagram of a parameter determination system of a hybrid unit cascaded H-bridge energy storage system according to the present invention;

6 is a schematic diagram of a hybrid unit cascaded H-bridge energy storage single-phase power control system according to the present invention;

Fig. 7 is the topological structure schematic diagram of the 35kV single-phase cascade H-bridge energy storage system of the present invention;

Fig. 8 is the schematic diagram of each electrical vector relationship of the present invention;

FIG. 9 is a schematic diagram of the closed-loop voltage control of the capacitor cascade unit according to the present invention;

10 is a single-phase power control simulation model of the hybrid unit cascade H-bridge energy storage system of the present invention;

Figure 11 is the power output of the P=500kW, Q=-1.25Mvar hybrid unit cascaded H-bridge energy storage system of the present invention;

Figure 12 is the power output of the P=500kW, Q=-1.25Mvar hybrid unit cascaded H-bridge energy storage system of the present invention;

Fig. 13 shows that the active power of the hybrid unit cascade H-bridge energy storage system of the present invention is adjusted from 0.5MW to 1MW.

Detailed ways

In order to better understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, and Not all examples.

Embodiment 1.

The energy storage converter (Power Control System--PCS) can control the charging and discharging process of the battery, perform AC-DC conversion, and can directly supply power to the AC load when there is no power grid. The PCS consists of a DC/AC bidirectional converter, a control unit, and the like. The PCS controller receives the background control command through communication, and controls the converter to charge or discharge the battery according to the sign and size of the power command, so as to adjust the active power and reactive power of the grid. The PCS controller communicates with the BMS through the CAN interface to obtain the status information of the battery pack, which can realize the protective charging and discharging of the battery and ensure the safe operation of the battery.

The energy storage converter (PCS) can control the charging and discharging process of the battery, perform AC-DC conversion, and can directly supply power to the AC load when there is no power grid. The PCS consists of a DC/AC bidirectional converter, a control unit, and the like. The PCS controller receives the background control command through communication, and controls the converter to charge or discharge the battery according to the sign and size of the power command, so as to adjust the active power and reactive power of the grid. The PCS controller communicates with the BMS through the CAN interface to obtain the status information of the battery pack, which can realize the protective charging and discharging of the battery and ensure the safe operation of the battery.

A hybrid unit cascade H-bridge energy storage system, as shown in Figure 1, includes: a plurality of battery cascade units;

The plurality of battery cascade units are connected to the power grid after being connected in series;

The battery cascading unit includes a capacitor cascading unit, an energy storage battery module and a switch;

The energy storage battery module is connected in series with the switch and then connected in parallel with the capacitor cascade unit;

The switch is used for switching on and off according to whether the energy storage battery module is faulty; when the energy storage battery module is normal, the switch is closed; when the energy storage battery module is faulty, the switch is disconnected;

At least one energy storage battery module in the plurality of battery cascaded power sources is normal.

Specifically, the capacitor cascade unit includes: a single-phase H-bridge power conversion module and a capacitor;

The single-phase H-bridge power conversion module is connected in parallel with the capacitor.

Specifically, the battery cascading unit further includes a first reactor; the first reactor is connected in series with the switch.

Specifically, the number of battery cascading units in the system is the number of cascading units in the preset battery cascading units in the power grid energy storage system in which the single-phase H-bridge power conversion module operates normally.

Specifically, the system further includes a second reactor; the second reactor is connected in series with the battery cascading unit.

When the battery cascade unit is working normally, the switch is closed. After the energy storage battery module in the battery cascading unit fails, the switch is turned off, and the single-phase H-bridge power conversion module can be connected to the grid as a capacitor cascading unit under the condition of normal operation. The topology change of the energy storage system is shown in Figure 2. In the case of the failure of the energy storage battery module, the switch of the battery cascading unit M _i is turned off, and it is connected to the power grid as a capacitor cascading unit to form a hybrid cascading unit H-bridge storage. energy system.

Since the fault condition of the single-phase battery cascade unit preset in the energy storage system is uncertain, the series connection form of the battery cascade unit and the capacitor cascade unit in the hybrid unit cascade H-bridge energy storage system needs to be based on the battery cascade Unit failure conditions are determined.

Embodiment two,

A method for determining parameters of a hybrid unit cascaded H-bridge energy storage system, as shown in FIG. 3 , the method includes:

Step 1: Calculate the absolute value of the angle between the grid-connected current vector and the grid voltage vector according to the active power and reactive power of the pre-set hybrid unit cascaded H-bridge energy storage system;

Step 2: According to the absolute value of the angle between the grid-connected current vector and the grid voltage vector, calculate the absolute value of the angle between the capacitor cascade unit voltage vector and the grid voltage vector;

Step 3: According to the absolute value of the angle between the capacitor cascade unit voltage vector and the grid voltage vector, calculate the angle between the battery cascade unit voltage vector and the grid voltage vector, and determine the battery cascade unit voltage vector operating point.

Step 1: Calculate the absolute value of the angle between the grid-connected current vector and the grid voltage vector according to the active power and reactive power of the pre-set hybrid unit cascaded H-bridge energy storage system.

Specifically, the absolute value of the angle between the grid-connected current vector and the grid voltage is calculated as follows:

并网电流矢量与电网电压矢量之间的夹角；P：有功功率；Q：无功功率。In the formula,

Angle between grid-connected current vector and grid voltage vector; P: active power; Q: reactive power.

Specifically, there is a constraint relationship between the active power and the reactive power, as shown in the following formula:

In the formula, U _r1 : battery cascade unit voltage amplitude; U _s : grid voltage amplitude, S: apparent power; P: active power; Q: reactive power;

Among them, the voltage amplitude U _r1 of the battery cascade unit is calculated as follows:

电池级联单元电压矢量；M：给定电池级联单元电压矢量

的调制比；U_battery：剩余正常电池级联单元总电压。In the formula,

Battery cascade unit voltage vector; M: given battery cascade unit voltage vector

The modulation ratio of ; U _battery : the total voltage of the remaining normal battery cascade units.

Step 2: Calculate the absolute value of the included angle between the capacitor cascade unit voltage vector and the grid voltage vector according to the absolute value of the included angle between the grid-connected current vector and the grid voltage vector.

Specifically, the absolute value of the angle between the capacitor cascade unit voltage vector and the grid voltage vector is calculated as follows:

In the formula: δ ₁ : the angle between the voltage vector of the capacitor cascade unit and the grid voltage vector.

Step 3: According to the absolute value of the angle between the capacitor cascade unit voltage vector and the grid voltage vector, calculate the angle between the battery cascade unit voltage vector and the grid voltage vector, and determine the battery cascade unit voltage vector operating point.

Specifically, the angle between the battery cascade unit voltage vector and the grid voltage vector is calculated as follows:

In the formula, δ: the angle between the battery cascade unit voltage vector and the grid voltage vector.

Specifically, the absolute value of the angle between the battery cascade unit voltage vector and the grid voltage vector is calculated as follows:

In the formula, U _r1 : the voltage amplitude of the battery cascade unit; U _s : the grid voltage amplitude.

Specifically, the determination of the voltage vector operating point of the battery cascade unit is calculated as follows:

Embodiment three,

A single-phase power control method for a hybrid unit cascaded H-bridge energy storage system, as shown in FIG. 4 , the method includes:

Step 4: according to the battery cascade unit voltage operating point obtained by the parameter determination method of the hybrid unit cascade H-bridge energy storage system, the closed-loop control of the capacitor cascade unit voltage is performed to obtain the reference voltage of the capacitor cascade unit voltage;

Step 5: control the single-phase power according to the reference voltage of the capacitor cascade unit voltage;

Step 4: According to the battery cascading unit voltage operating point obtained by the parameter determination method of the hybrid unit cascading H-bridge energy storage system, the closed-loop control of the capacitor cascading unit voltage is performed to obtain a reference voltage of the capacitor cascading unit voltage, such as: As shown in Figure 9, including:

The reference value of the DC side voltage of the capacitor cascade unit is poor compared with the DC side voltage of the capacitor cascade unit. After being adjusted by PI, the amplitude of the active current component is output;

The active power reference value is compared with the active power actually output by the energy storage battery cascade unit. After adjustment by PI, the amplitude of the reactive current component is output;

The sampled grid voltage is passed through the phase-locked loop to obtain the corresponding phase angle, and then the amplitude of the active current component is multiplied by the sine value of the phase angle, and the amplitude of the reactive current component is multiplied by the cosine value of the phase angle. The given value of the loop instantaneous current is compared with the feedback current of the system to obtain the error value, and the voltage deviation adjustment amount is obtained after P adjustment;

The reactive voltage component is generated after the grid voltage is different from the voltage of the battery cascade unit, and then the reference voltage of the capacitor cascade unit is obtained after the difference is compared with the voltage deviation adjustment amount.

Step 5: Controlling the single-phase power according to the reference voltage of the capacitor cascade unit voltage includes:

The reference voltage of the capacitor cascade unit voltage is output to the carrier phase-shifted sinusoidal pulse width modulation trigger pulse generator to generate a switch tube trigger pulse, and the single-phase power is controlled by the switch tube trigger pulse.

P adjustment is proportional adjustment, which is used to enlarge or reduce the error value. The adjustment precision of P adjustment is low, but the system responds quickly and there is no oscillation.

Embodiment four,

A parameter determination system of a hybrid unit cascaded H-bridge energy storage system, as shown in FIG. 5 , includes: a first calculation module, a second calculation module and a determination module;

The first calculation module: calculate the absolute value of the angle between the grid-connected current vector and the grid voltage vector according to the active power and reactive power of the pre-set hybrid unit cascaded H-bridge energy storage system;

The second calculation module: used to calculate the absolute value of the angle between the capacitor cascade unit voltage vector and the grid voltage vector according to the absolute value of the angle between the grid-connected current vector and the grid voltage vector;

Determination module: It is used to calculate the angle between the voltage vector of the battery cascade unit and the grid voltage vector according to the absolute value of the angle between the voltage vector of the capacitor cascade unit and the grid voltage vector, and determine the operating point of the battery cascade unit voltage vector.

Specifically, in the first calculation module, the absolute value of the angle between the grid-connected current vector and the grid voltage is calculated as follows:

并网电流矢量与电网电压矢量之间的夹角；P：有功功率；Q：无功功率。In the formula,

Angle between grid-connected current vector and grid voltage vector; P: active power; Q: reactive power.

Specifically, in the second calculation module, the absolute value of the angle between the capacitor cascade unit voltage vector and the grid voltage vector is calculated as follows:

并网电流矢量与电网电压矢量之间的夹角。In the formula: δ ₁ : the angle between the voltage vector of the capacitor cascade unit and the grid voltage vector;

The angle between the grid-connected current vector and the grid voltage vector.

Specifically, the angle between the battery cascade unit voltage vector and the grid voltage vector is calculated as follows:

In the formula, δ: the angle between the battery cascade unit voltage vector and the grid voltage vector; P: active power; Q: reactive power.

Specifically, the determination of the voltage vector operating point of the battery cascade unit is calculated as follows:

电池级联单元电压矢量；δ：电池级联单元电压矢量与电网电压矢量之间的夹角。In the formula,

The battery cascade unit voltage vector; δ: the angle between the battery cascade unit voltage vector and the grid voltage vector.

Embodiment five,

A single-phase power control system of a hybrid unit cascaded H-bridge energy storage system, as shown in FIG. 6 , the system includes: a voltage calculation module and a power control module;

Voltage calculation module: used for obtaining the operating point of the voltage of the battery cascade unit according to the parameter determination method of the hybrid unit cascade H-bridge energy storage system; performing closed-loop control on the voltage of the capacitor cascade unit to obtain a reference for the voltage of the capacitor cascade unit Voltage;

Power control module: used to control the single-phase power according to the reference voltage of the capacitor cascade unit voltage.

Specifically, according to the operating point of the voltage of the battery cascade unit, the voltage calculation module performs closed-loop control on the voltage of the capacitor cascade unit to obtain the reference voltage of the capacitor cascade unit voltage, as shown in FIG. 9 , including:

The reference value of the DC side voltage of the capacitor cascade unit is poor compared with the DC side voltage of the capacitor cascade unit. After being adjusted by PI, the amplitude of the active current component is output;

The active power reference value is compared with the active power actually output by the energy storage battery cascade unit. After adjustment by PI, the amplitude of the reactive current component is output;

The sampled grid voltage is passed through the phase-locked loop to obtain the corresponding phase angle, and then the amplitude of the active current component is multiplied by the sine value of the phase angle, and the amplitude of the reactive current component is multiplied by the cosine value of the phase angle. The given value of the loop instantaneous current is compared with the feedback current of the system to obtain the error value, and the voltage deviation adjustment amount is obtained after P adjustment;

The reactive voltage component is generated after the grid voltage is different from the voltage of the battery cascade unit, and then the reference voltage of the capacitor cascade unit is obtained after the difference is compared with the voltage deviation adjustment amount.

Specifically, controlling the single-phase power according to the reference voltage of the capacitor cascade unit voltage in the power control module includes:

The reference voltage of the capacitor cascade unit voltage is output to the carrier phase-shifted sinusoidal pulse width modulation trigger pulse generator to generate a switch tube trigger pulse, and the single-phase power is controlled by the switch tube trigger pulse.

Embodiment six,

A 35kV single-phase cascaded H-bridge energy storage system, the topology is shown in Figure 7. The capacitor cascade unit model is composed of a single-phase H-bridge power conversion module connected in parallel with a 160mF capacitor, and the battery cascade unit model is composed of a single-phase H-bridge power conversion module, a capacitor and a DC voltage source connected in parallel.

The hybrid unit cascaded H-bridge energy storage system cannot transmit pure active power to the grid alone. While transmitting active power, a certain amount of reactive power needs to be compensated for support, and the nature of the reactive power compensated by the capacitor cascade unit is different from that of the hybrid unit. The overall reactive power compensation characteristics of the cascaded H-bridge energy storage system are consistent, otherwise the system cannot operate normally. There are four operating modes of the hybrid unit cascaded H-bridge energy storage system: system charging, compensating capacitive reactive power; system charging, compensating inductive reactive power; system discharging, compensating capacitive reactive power; system discharging, supplementing inductive reactive power. The electrical vector relationship of the hybrid unit cascaded H-bridge energy storage system is shown in Figure 8, and the symbolic relationship between the electrical quantities in different operating modes is shown in the following table.

Table 1 The symbolic relationship between the electrical quantities in different operating modes

直流侧电容为160mF。以系统运行在感性无功工况为例，由系统设置可求得电池级联单元电压可以确定指令无功功率Q和有功功率之间的关系：Q＜-2.22P。当系统进行有功充电时，设置系统指令有功功率为P＝500kW，在Q取值范围内可设置无功功率指令值为500×(-2.5)＝-1250kvar，此时δ＝-42.835°。Set the ratio of the capacitor cascade unit voltage to the capacitor cascade unit voltage: U _r1 :U _r2 =1:2, set U _r1 =11745V, U _r2 =11745×2=23490V, the single-phase grid voltage amplitude is

The DC side capacitance is 160mF. Taking the system running in the inductive reactive power condition as an example, the voltage of the battery cascade unit can be obtained from the system settings, and the relationship between the command reactive power Q and the active power can be determined: Q<-2.22P. When the system is actively charging, set the system command active power to P=500kW, and within the range of Q, the reactive power command value can be set to 500×(-2.5)=-1250kvar, at this time δ=-42.835°.

Through the system simulation model, as shown in Figure 10, the power output situation is simulated.

As shown in Figure 11, it can be seen from the simulation waveform that the system output active power and reactive power basically realize the tracking of the command power. It can be seen that the reactive power is in an inductive state (set the inductance to be negative), and the system command charging power P =500kW, command reactive power Q=-1.25Mvar, which satisfies the initially set Q=-2.5P relationship, but the fluctuation of reactive power is relatively larger, which verifies the correctness of the power control method.

When the delta angle is not changed, the commanded charging power of the system is changed to P=1MW. According to the initially set relationship of Q=-2.5P, the commanded reactive power should be Q=-2.5Mvar. The actual situation of the simulated power output is shown in Figure 12. The commanded charging power is P=1MW, and the commanded reactive power Q=-2.3Mvar. The active power has been accurately tracked, and the reactive power has a slight deviation.

As shown in Figure 13, when the active power of the system is increased from 500kW to 1MW, it can be seen that the dynamic adjustment process of the system is very short, the output power does not fluctuate greatly, and the tracking accuracy still maintains a good level.

The above facts show that the method for determining the single-phase power parameters of the hybrid unit cascaded H-bridge energy storage system, the system and the single-phase power control method provided in this embodiment can control the active power and reactive power of the cascaded H-bridge energy storage system. , to achieve precise control of active power and improve the utilization rate of the cascaded H-bridge energy storage system.

As will be appreciated by those skilled in the art, the embodiments of the present application may be provided as a method, a system, or a computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the present application. It will be understood that each flow and/or block in the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to the processor of a general purpose computer, special purpose computer, embedded processor or other programmable data processing device to produce a machine such that the instructions executed by the processor of the computer or other programmable data processing device produce Means for implementing the functions specified in a flow or flow of a flowchart and/or a block or blocks of a block diagram.

These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory result in an article of manufacture comprising instruction means, the instructions The apparatus implements the functions specified in the flow or flow of the flowcharts and/or the block or blocks of the block diagrams.

These computer program instructions can also be loaded on a computer or other programmable data processing device to cause a series of operational steps to be performed on the computer or other programmable device to produce a computer-implemented process such that The instructions provide steps for implementing the functions specified in the flow or blocks of the flowcharts and/or the block or blocks of the block diagrams.

The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art can still modify or equivalently replace the specific embodiments of the present invention. , any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention are all within the protection scope of the claims of the present invention for which the application is pending.

Claims (11)

1. A parameter determination method for a hybrid unit cascaded H-bridge energy storage system is characterized by comprising the following steps:

calculating an included angle absolute value of a grid-connected current vector and a grid voltage vector according to active power and reactive power of a preset hybrid unit cascade H-bridge energy storage system;

calculating the absolute value of an included angle between a voltage vector of the capacitor cascade unit and a voltage vector of the power grid according to the absolute value of the included angle between the grid-connected current vector and the voltage vector of the power grid;

calculating an included angle between a voltage vector of the battery cascade unit and a voltage vector of a power grid according to an absolute value of the included angle between the voltage vector of the capacitor cascade unit and the voltage vector of the power grid, and determining a voltage vector operating point of the battery cascade unit;

the absolute value of the included angle between the grid-connected current vector and the grid voltage is calculated according to the following formula:

in the formula (I), the compound is shown in the specification,

an included angle between the grid-connected current vector and the grid voltage vector; p: active power; q: reactive power;

there is a constraint relationship between the active power and the reactive power, as shown in the following equation:

in the formula of U _r1 : a battery cascade cell voltage amplitude; u shape _s : grid voltage amplitude, S: apparent power; p: active powerPower; q: reactive power;

wherein, the voltage amplitude U of the battery cascade unit _r1 The calculation is performed as follows:

in the formula, M: given battery cascade cell voltage vector

A modulation ratio of (d); u shape _battery : the total voltage of the rest normal battery cascade unit;

the absolute value of an included angle between the voltage vector of the capacitor cascade unit and the voltage vector of the power grid is calculated according to the following formula:

in the formula: delta. For the preparation of a coating ₁ : the included angle between the voltage vector of the capacitor cascade unit and the voltage vector of the power grid;

the included angle between the voltage vector of the battery cascade unit and the voltage vector of the power grid is calculated according to the following formula:

in the formula, δ: the included angle between the voltage vector of the battery cascade unit and the voltage vector of the power grid;

the absolute value of an included angle between the voltage vector of the battery cascade unit and the voltage vector of the power grid is calculated according to the following formula:

in the formula of U _r1 : a battery cascade cell voltage amplitude; u shape _s : electric network voltage amplitudeA value;

the determination of the voltage vector operating point of the battery cascade unit is calculated according to the following formula:

2. a parameter determination system of a hybrid unit cascaded H-bridge energy storage system, comprising: the device comprises a first calculation module, a second calculation module and a determination module;

a first calculation module: the device comprises a power grid voltage vector calculation unit, a power grid load calculation unit and a power grid load calculation unit, wherein the power grid voltage vector calculation unit is used for calculating the absolute value of an included angle between a grid-connected current vector and the grid voltage vector according to active power and reactive power of a preset mixed unit cascade H-bridge energy storage system;

a second calculation module: the device comprises a capacitor cascade unit, a grid voltage vector, a grid current vector, a grid voltage vector and a grid voltage vector, wherein the grid current vector is connected with the grid voltage vector through a grid connection current line;

a determination module: the device comprises a capacitor cascade unit, a grid voltage vector, a battery cascade unit voltage vector operating point and a control unit, wherein the capacitor cascade unit voltage vector is used for calculating an included angle between the battery cascade unit voltage vector and the grid voltage vector according to an absolute value of the included angle between the capacitor cascade unit voltage vector and the grid voltage vector, and the battery cascade unit voltage vector operating point is determined;

the absolute value of an included angle between the grid-connected current vector and the grid voltage is calculated according to the following formula:

in the formula (I), the compound is shown in the specification,

an included angle between the grid-connected current vector and the grid voltage vector; p: active power; q: reactive power;

there is a constraint relationship between the active power and the reactive power, as shown in the following equation:

in the formula of U _r1 : the voltage amplitude of the battery cascade unit; u shape _s : grid voltage amplitude, S: apparent power; p: active power; q: reactive power;

wherein, the voltage amplitude U of the battery cascade unit _r1 The calculation is performed as follows:

in the formula, M: given battery cascade cell voltage vector

The modulation ratio of (c); u shape _battery : the total voltage of the residual normal battery cascade unit;

the absolute value of an included angle between the voltage vector of the capacitor cascade unit and the voltage vector of the power grid is calculated according to the following formula:

in the formula: delta. For the preparation of a coating ₁ : the included angle between the voltage vector of the capacitor cascade unit and the voltage vector of the power grid;

the included angle between the voltage vector of the battery cascade unit and the voltage vector of the power grid is calculated according to the following formula:

in the formula, δ: the included angle between the voltage vector of the battery cascade unit and the voltage vector of the power grid;

the absolute value of an included angle between the voltage vector of the battery cascade unit and the voltage vector of the power grid is calculated according to the following formula:

in the formula of U _r1 : a battery cascade cell voltage amplitude; u shape _s : the amplitude of the grid voltage;

the determined voltage vector operating point of the battery cascade unit is calculated according to the following formula:

3. a single-phase power control method of a hybrid cell cascaded H-bridge energy storage system, the method comprising:

the battery cascading unit voltage vector operating point obtained by the parameter determining method according to claim 1 performs closed-loop control on the voltage of the capacitor cascading unit to obtain a reference voltage of the capacitor cascading unit;

and controlling the single-phase power according to the reference voltage of the capacitor cascade unit.

4. The method of claim 3, wherein the step of performing closed-loop control on the voltage of the capacitor cascade unit according to the operating point of the voltage of the battery cascade unit to obtain the reference voltage of the capacitor cascade unit comprises:

comparing the direct-current side voltage reference value of the capacitor cascade unit with the direct-current side voltage of the capacitor cascade unit to make a difference, and outputting an active current component amplitude value after PI regulation;

comparing the active power reference value with the active power actually output by the battery cascade unit to make a difference, and outputting a reactive current component amplitude value after PI regulation;

sampling the voltage of a power grid, obtaining a corresponding phase angle through a phase-locked loop, multiplying the active current component amplitude by the phase angle sine value, multiplying the reactive current component amplitude by the phase angle cosine value, comparing an inner ring instantaneous current set value obtained by synthesizing two currents with a system feedback current to obtain an error value, and obtaining a voltage deviation regulating variable through P regulation;

and generating reactive voltage components after the difference between the power grid voltage and the battery cascade unit voltage, and comparing the reactive voltage components with the voltage deviation regulating quantity to obtain the reference voltage of the capacitor cascade unit.

5. The method of claim 3, wherein the controlling single phase power according to the reference voltage of the capacitor cascade cell voltage comprises:

and outputting the reference voltage of the capacitor cascade unit to a carrier phase-shifting sine pulse width modulation trigger pulse generator to generate a switching tube trigger pulse, and controlling the single-phase power by the switching tube trigger pulse.

6. A hybrid unit cascaded H-bridge energy storage system single phase power control system, the system comprising: the device comprises a calculation module and a control module;

a voltage calculation module: the closed-loop control circuit is used for carrying out closed-loop control on the voltage of the capacitor cascade unit according to the operating point of the voltage of the battery cascade unit to obtain the reference voltage of the capacitor cascade unit;

a power control module: the single-phase power is controlled according to the reference voltage of the capacitor cascade unit;

the absolute value of an included angle between a grid-connected current vector and the grid voltage is calculated according to the following formula:

in the formula (I), the compound is shown in the specification,

an included angle between the grid-connected current vector and the grid voltage vector; p: active power; q: reactive power;

there is a constraint relationship between the active power and the reactive power, as shown in the following equation:

in the formula of U _r1 : a battery cascade cell voltage amplitude; u shape _s : grid voltage amplitude, S: apparent power; p: active power; q: reactive power;

wherein, the voltage amplitude U of the battery cascade unit _r1 Calculated as follows:

in the formula, M: given battery cascade cell voltage vector

A modulation ratio of (d); u shape _battery : the total voltage of the residual normal battery cascade unit;

the absolute value of an included angle between the voltage vector of the capacitor cascade unit and the voltage vector of the power grid is calculated according to the following formula:

in the formula: delta ₁ : the included angle between the voltage vector of the capacitor cascade unit and the voltage vector of the power grid;

the included angle between the voltage vector of the battery cascade unit and the voltage vector of the power grid is calculated according to the following formula:

in the formula, δ: the included angle between the voltage vector of the battery cascade unit and the voltage vector of the power grid;

the absolute value of an included angle between the voltage vector of the battery cascade unit and the voltage vector of the power grid is calculated according to the following formula:

in the formula of U _r1 : the voltage amplitude of the battery cascade unit; u shape _s : the amplitude of the grid voltage;

determining the voltage vector operating point of the battery cascade unit and calculating according to the following formula:

7. a hybrid cell cascaded H-bridge energy storage system for use in a method for parameter determination of a hybrid cell cascaded H-bridge energy storage system according to claim 1, comprising: a plurality of battery cascade units;

the plurality of battery cascade units are connected in series and then are connected into a power grid;

the battery cascade unit comprises a capacitor cascade unit, an energy storage battery module and a switch;

the energy storage battery module is connected with the switch in series and then connected with the capacitor cascade unit in parallel;

the switch is used for switching on and off according to whether the energy storage battery module is in fault; when the energy storage battery module is normal, the switch is closed; when the energy storage battery module is in fault, the switch is switched off;

at least one energy storage battery module in the plurality of battery cascade units is normal.

8. The system of claim 7, wherein the capacitance cascade unit comprises: a single-phase H-bridge power conversion module and a capacitor;

the single-phase H-bridge power conversion module is connected with the capacitor in parallel.

9. The system of claim 7, wherein the battery cascade unit further comprises a first reactor; the first reactor is connected in series with the switch.

10. The system of claim 8, wherein the number of the battery cascade units in the system is the number of cascade units of a single-phase H-bridge power conversion module in the preset battery cascade units in the grid energy storage system, which are normally operated.

11. The system of claim 7, further comprising a second reactor; the second reactor is connected in series with the battery cascade unit.

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