CN109347153B - Single-phase power control method and system for hybrid unit cascaded H-bridge energy storage system - Google Patents
Single-phase power control method and system for hybrid unit cascaded H-bridge energy storage system Download PDFInfo
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- CN109347153B CN109347153B CN201811112481.XA CN201811112481A CN109347153B CN 109347153 B CN109347153 B CN 109347153B CN 201811112481 A CN201811112481 A CN 201811112481A CN 109347153 B CN109347153 B CN 109347153B
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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
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
- H02J3/48—Controlling the sharing of the in-phase component
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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
- H02J3/28—Arrangements for balancing of the load in a network by storage of energy
- H02J3/32—Arrangements for balancing of the load in a network by storage of energy using batteries with converting means
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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
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
- H02J3/50—Controlling the sharing of the out-of-phase component
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Abstract
The invention provides a hybrid unit cascade H bridge energy storage system, which comprises: 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 power supplies is normal. According to the technical scheme provided by the invention, under the condition that a plurality of battery units in the cascade H-bridge energy storage system have faults, the capacitor cascade unit which runs in a reactive mode is used for providing voltage support, so that the voltage of the cascade H-bridge energy storage system can still meet the grid-connected requirement, and the active power of the energy storage battery cascade unit is continuously output.
Description
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 cascade H-bridge energy storage system.
Background
The new energy power generation with the continuously improved permeability increases the unstable factors of the power system, and the demand of a large-scale energy storage system is higher and higher as an important way for compensating the fluctuating power of a new energy power station in the energy internet propulsion process. The cascade H-bridge energy storage power conversion system can directly access a plurality of low-voltage cascade units into a power grid after being connected in series, has the characteristics of small loss, good output characteristic, convenience in control and the like, and can well solve the problem that a medium-high voltage high-capacity energy storage system is accessed into the power grid.
The prior art proves the advantages of the cascaded H-bridge multilevel topological structure in the aspects of active power control, fault-tolerant operation and the like of the energy storage system, and points out that compared with other switching signal modulation technologies, carrier phase-shifting pulse width modulation applied to the cascaded H-bridge energy storage system has better output waveform and higher electric energy quality, and reduces the requirement on the switching frequency of the system.
In addition, the operation control technology of the cascade H-bridge energy storage PCS under the fault of a few cascade units has been studied. The current control processing technology for the cascade unit faults is mostly based on the research that a part of cascade units are arranged on the basis of redundancy in advance, and after the fault cascade units are bypassed, the aim of ensuring the symmetry of output phase voltages is fulfilled. In order to avoid the expansion of the fault range, firstly, the bypass removal processing needs to be carried out on the fault cascade unit, the bypass mode can be divided into an online bypass mode and a shutdown bypass mode, and three schemes exist aiming at the setting of an online bypass mechanism: the traditional electromagnetic alternating current contactor, a thyristor + a rectifier bridge and a bidirectional thyristor. The mode of bypassing the fault unit also comprises a same-level bypass mode and a bypass fault unit, and the output voltage of the system is improved by adopting a mode of adjusting the modulation ratio after the bypass fault cascade unit. The inventor also points out that aiming at the cascade H bridge energy storage system, the system can normally operate as long as the line voltage is kept consistent with the power grid before and after the fault, a zero sequence voltage injection method and a neutral point offset method are provided, the symmetrical relation between the line voltages is ensured by adjusting the phase of the phase voltage, and the control method has good control effect from the aspects of simulation and experimental results. However, the above fault operation control is designed on the premise that after the cascade unit fails, the battery voltage still can meet the grid-connected requirement, and when the battery unit fails too much, the fault control method fails to maintain the capability of the system to continue to operate stably.
Disclosure of Invention
In order to solve the problems, the invention provides a single-phase power control method and a single-phase power control system for a hybrid unit cascaded H bridge energy storage system, which can control the active power and the reactive power of the cascaded H bridge energy storage system after a plurality of battery units are in fault, realize the accurate control of the active power and enable the energy of the rest battery units of the system to be continuously utilized.
The purpose of the invention is realized by adopting the following technical scheme:
a hybrid unit cascaded H-bridge energy storage system, 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 power supplies is normal.
Preferably, the capacitance cascade unit includes: 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.
Preferably, the battery cascade unit further includes a first reactor; the first reactor is connected in series with the switch.
Preferably, the number of the battery cascade units in the system is the number of the cascade units, which are preset in the power grid energy storage system and are used for normally operating the single-phase H-bridge power conversion module, in the battery cascade units.
Preferably, the system further comprises a second reactor; the second reactor is connected in series with the battery cascade unit.
A parameter determination method for a hybrid unit cascade H-bridge energy storage system comprises 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 an included angle absolute value between a voltage vector of the capacitor cascade unit and a voltage vector of the power grid according to the included angle absolute value between the grid-connected current vector and the voltage vector of the power grid;
and calculating the included angle between the voltage vector of the battery cascade unit and the voltage vector of the power grid according to the 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 the voltage vector operating point of the battery cascade unit.
Preferably, 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: and (4) 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 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
A modulation ratio of (d); u shape battery : the total voltage of the normal battery cascade unit is remained.
Preferably, an 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 : and the included angle between the voltage vector of the capacitor cascade unit and the voltage vector of the power grid.
Preferably, 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, δ: and the included angle between the voltage vector of the battery cascade unit and the voltage vector of the power grid.
Preferably, the absolute value of 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 of U r1 : the voltage amplitude of the battery cascade unit; u shape s : the grid voltage amplitude.
Preferably, the determination of the voltage vector operating point of the battery cascade unit is calculated according to the following formula:
a parameter determination system of a hybrid unit cascaded H-bridge energy storage system comprises: 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 method is used for calculating the included angle between the voltage vector of the battery cascade unit and the voltage vector of the power grid according to the 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 the voltage vector operating point of the battery cascade unit.
A single-phase power control method of a hybrid unit cascaded H-bridge energy storage system, the method comprising:
performing closed-loop control on the voltage of the capacitor cascade unit 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 to obtain the reference voltage of the capacitor cascade unit;
and controlling the single-phase power according to the reference voltage of the capacitor cascade unit.
Preferably, the battery cascade unit voltage operating point obtained by the method is determined according to the parameters of the hybrid unit cascade H-bridge energy storage system; the step of performing closed-loop control on the voltage of the capacitor cascade unit to obtain the reference voltage of the capacitor cascade unit comprises the following steps:
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 obtain 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 amplitude of an active current component by the sine value of the phase angle, multiplying the amplitude of a reactive current component by the cosine value of the phase angle, synthesizing two currents to obtain an inner ring instantaneous current given value, comparing the inner ring instantaneous current given value 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, comparing the reactive voltage components with the voltage deviation regulating quantity, and obtaining the reference voltage of the capacitor cascade unit.
Preferably, the controlling of the single-phase power according to the reference voltage of the capacitor cascade unit includes:
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.
A hybrid unit cascaded H-bridge energy storage system single phase power control system, the system comprising: 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: and the single-phase power control circuit is used for controlling the single-phase power according to the reference voltage of the capacitor cascade unit.
Compared with the closest prior art, the technical scheme provided by the invention has the following beneficial effects:
according to the technical scheme provided by the invention, under the condition that multiple battery units in the cascaded H-bridge energy storage system have faults, the cascaded units with the faults of the energy storage battery modules and the normal power conversion modules are utilized, the capacitor cascaded units which run in a reactive mode provide voltage support, so that the voltage of the cascaded H-bridge energy storage system still can meet the grid-connected requirement, the active power of the energy storage battery cascaded units is continuously output, and the energy of the residual cascaded battery units is continuously utilized.
According to the technical scheme provided by the invention, after a plurality of battery units have faults, the active power and the reactive power of the cascade H-bridge energy storage system can be controlled by adopting a method of battery cascade unit voltage open-loop control and capacitor cascade unit voltage closed-loop control, so that the accurate control of the active power is realized, and the energy of the rest battery units of the system can be continuously utilized.
The invention can realize the power control of the single-phase system, has better applicability, solves the problem that the cascaded H bridge energy storage system cannot operate due to the failure of a plurality of battery units, improves the utilization rate of the cascaded H bridge energy storage system and increases the economic benefit.
Drawings
FIG. 1 is a schematic diagram of a topology of a hybrid unit cascaded H-bridge energy storage system according to the present invention;
FIG. 2 is a schematic diagram showing a change of a topology structure of the hybrid unit cascaded H-bridge energy storage system of the invention;
FIG. 3 is a schematic diagram of a parameter determination method for a hybrid unit cascaded H-bridge energy storage system according to the present invention;
FIG. 4 is a schematic diagram of a single-phase power control method of a hybrid unit cascaded H-bridge energy storage system according to the present invention;
FIG. 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;
FIG. 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 a schematic diagram of a topological structure of the 35kV single-phase cascade H-bridge energy storage system of the invention;
FIG. 8 is a schematic diagram of the electrical vector relationships of the present invention;
FIG. 9 is a schematic diagram of the voltage closed loop control of the capacitor cascade unit according to the present invention;
FIG. 10 is a single-phase power control simulation model of the hybrid unit cascaded H-bridge energy storage system of the present invention;
FIG. 11 is a power output of a P =500kW, Q = -1.25Mvar hybrid unit cascaded H-bridge energy storage system of the present invention;
FIG. 12 is a power output of a 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 is adjusted from 0.5MW to 1MW.
Detailed Description
For better understanding of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments.
The first embodiment,
The energy storage converter (Power Control System-PCS) can Control the charging and discharging process of the storage battery, carry out AC/DC conversion and directly supply Power to an AC load under the condition of no Power grid. The PCS is composed of a DC/AC bidirectional converter, a control unit and the like. The PCS controller receives a background control instruction through communication, and controls the converter to charge or discharge the battery according to the symbol and the size of the power instruction, so that the active power and the reactive power of the power grid are adjusted. The PCS controller is communicated with the BMS through the CAN interface to acquire the state information of the battery pack, so that the protective charging and discharging of the battery CAN be realized, and the running safety of the battery is ensured.
The energy storage converter (PCS) can control the charging and discharging processes of the storage battery, carry out alternating current and direct current conversion, and can directly supply power for alternating current loads under the condition of no power grid. The PCS is composed of a DC/AC bidirectional converter, a control unit and the like. The PCS controller receives a background control instruction through communication, and controls the converter to charge or discharge the battery according to the symbol and the size of the power instruction, so that the active power and the reactive power of the power grid are adjusted. The PCS controller is communicated with the BMS through the CAN interface to acquire the state information of the battery pack, so that the protective charging and discharging of the battery CAN be realized, and the running safety of the battery is ensured.
A hybrid unit cascaded H-bridge energy storage system, as shown in fig. 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 power supplies is normal.
Specifically, the capacitance cascade unit includes: 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.
Specifically, the battery cascade unit further includes a first reactor; the first reactor is connected in series with the switch.
Specifically, the number of the battery cascade units in the system is the number of the cascade units, which are preset in the power grid energy storage system and are used for normally operating the single-phase H-bridge power conversion module, in the battery cascade units.
Specifically, the system further comprises a second reactor; the second reactor is connected in series with the battery cascade unit.
When the battery cascade unit works normally, the switch is in a closed state. And after the energy storage battery module in the battery cascade unit fails, the switch is switched off, and the single-phase H-bridge power conversion module can be used as a capacitor cascade unit to be connected into a power grid under the condition of normal operation. The topological structure of the energy storage system is changed as shown in figure 2, and the battery cascade unit M i And under the condition of the fault of the energy storage battery module, the switch is disconnected and is used as a capacitor cascade unit to be connected into a power grid, so that a hybrid cascade unit H-bridge energy storage system is formed.
Because the fault condition of the single-phase battery cascade unit preset in the energy storage system is uncertain, the serial 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 determined based on the fault condition of the battery cascade unit.
Example II,
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: calculating an absolute value of an included angle between 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;
and 2, step: calculating an included angle absolute value between a voltage vector of the capacitor cascade unit and a voltage vector of the power grid according to the included angle absolute value between the grid-connected current vector and the voltage vector of the power grid;
and 3, step 3: and calculating the included angle between the voltage vector of the battery cascade unit and the voltage vector of the power grid according to the 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 the voltage vector operating point of the battery cascade unit.
Step 1: and calculating the absolute value of an included angle between a grid-connected current vector and a grid voltage vector according to the active power and the reactive power of the preset hybrid unit cascade H-bridge energy storage system.
Specifically, 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.
Specifically, 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 Calculated as follows:
in the formula (I), the compound is shown in the specification,
a battery cascade cell voltage vector; m: given battery cascade cell voltage vector
A modulation ratio of (d); u shape battery : and the total voltage of the normal battery cascade unit is remained.
Step 2: and calculating the absolute value of the included angle between the voltage vector of the capacitor cascade unit and the 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.
Specifically, 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 : and the included angle between the voltage vector of the capacitor cascade unit and the voltage vector of the power grid.
And 3, step 3: and calculating the included angle between the voltage vector of the battery cascade unit and the voltage vector of the power grid according to the 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 the voltage vector operating point of the battery cascade unit.
Specifically, an included angle between a voltage vector of the battery cascade unit and a voltage vector of a power grid is calculated according to the following formula:
in the formula, δ: and the included angle between the voltage vector of the battery cascade unit and the voltage vector of the power grid.
Specifically, 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 grid voltage amplitude.
Specifically, the determination of the voltage vector operating point of the battery cascade unit is calculated according to the following formula:
example III,
A single-phase power control method for a hybrid unit cascaded H-bridge energy storage system, as shown in fig. 4, the method includes:
and 4, step 4: performing closed-loop control on the voltage of the capacitor cascade unit 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 to obtain the reference voltage of the capacitor cascade unit;
and 5: controlling the single-phase power according to the reference voltage of the capacitor cascade unit;
and 4, 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, performing closed-loop control on the voltage of the capacitor cascade unit to obtain the reference voltage of the capacitor cascade unit, as shown in fig. 9, the method includes:
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 obtain 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 energy storage 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.
And 5: controlling the single-phase power according to the reference voltage of the capacitor cascade unit 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.
The P adjustment is a proportional adjustment and is used for amplifying or reducing the error value, the adjustment precision of the P adjustment is low, but the system response is fast, and oscillation does not occur.
Examples IV,
A parameter determination system for a hybrid unit cascaded H-bridge energy storage system, as shown in fig. 5, includes: the device comprises a first calculation module, a second calculation module and a determination module;
a first calculation module: 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;
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 capacitor cascade unit is used for carrying out grid connection on a grid voltage vector;
a determination module: the method is used for calculating the included angle between the voltage vector of the battery cascade unit and the voltage vector of the power grid according to the 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 the voltage vector operating point of the battery cascade unit.
Specifically, in the first calculation module, an 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.
Specifically, in the second calculation module, an 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;
and the included angle between the grid-connected current vector and the grid voltage vector.
Specifically, 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, δ: the included angle between the voltage vector of the battery cascade unit and the voltage vector of the power grid; p: active power; q: reactive power.
Specifically, the determination of the voltage vector operating point of the battery cascade unit is calculated according to the following formula:
in the formula (I), the compound is shown in the specification,
a battery cascade cell voltage vector; δ: and the included angle between the voltage vector of the battery cascade unit and the voltage vector of the power grid.
Example V,
A hybrid unit cascaded H-bridge energy storage system single-phase power control system, as shown in fig. 6, the system comprising: the device comprises a voltage calculation module and a power control module;
a voltage calculation module: the operation point of the voltage of the battery cascade unit is obtained according to the parameter determination method of the hybrid unit cascade H-bridge energy storage system; carrying out closed-loop control on the voltage of the capacitor cascade unit to obtain a reference voltage of the capacitor cascade unit;
a power control module: and the single-phase power control circuit is used for controlling the single-phase power according to the reference voltage of the capacitor cascade unit.
Specifically, the voltage calculation module performs 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, as shown in fig. 9, and includes:
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 energy storage battery cascade unit to obtain a difference, and outputting a reactive current component amplitude value after PI (proportion integration) adjustment;
sampling the voltage of a power grid, obtaining a corresponding phase angle through a phase-locked loop, multiplying the amplitude of an active current component by the sine value of the phase angle, multiplying the amplitude of a reactive current component by the cosine value of the phase angle, synthesizing two currents to obtain an inner ring instantaneous current given value, comparing the inner ring instantaneous current given value 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.
Specifically, the controlling the single-phase power according to the reference voltage of the capacitor cascade unit in the power control module includes:
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.
Examples six,
A35 kV single-phase cascade H bridge energy storage system is shown in the figure 7 in a topological structure. The inside of the capacitor cascade unit model is formed by connecting a single-phase H-bridge power conversion module and a 160mF capacitor in parallel, and the inside of the battery cascade unit model is formed by connecting the single-phase H-bridge power conversion module, the capacitor and a direct-current voltage source in parallel.
The hybrid unit cascaded H-bridge energy storage system cannot singly transmit pure active power to a power grid, certain reactive power needs to be compensated for supporting while the active power is transmitted, the property of the reactive power compensated by the capacitor cascaded unit is consistent with the overall reactive power compensation property of the hybrid unit cascaded H-bridge energy storage system, and otherwise the system cannot normally operate. There are four operating modes of the hybrid unit cascaded H-bridge energy storage system: charging a system and compensating capacitive reactive power; charging the system and compensating inductive reactive power; discharging the system and compensating capacitive reactive power; and discharging the system to supplement inductive reactive power. The electrical vector relationship of the hybrid unit cascaded H-bridge energy storage system is shown in FIG. 8, and the symbolic relationship among the electrical quantities in different operation modes is shown in the following table.
TABLE 1 symbolic relationship between electrical quantities in different operation modes
Setting the voltage ratio of the capacitor cascade unit to the voltage of the capacitor cascade unit: u shape r1 :U r2 1, set U r1 ＝11745V，U r2 =11745 × 2=23490v, single-phase grid voltage amplitude is
The dc side capacitance was 160mF. Taking the system running in the inductive reactive working condition as an example, the system setting can be used for solvingThe battery cascade unit voltage can determine the relationship between the command reactive power Q and the active power: q < -2.22P. When the system is in active charging, the system instruction active power is set to be P =500kW, and the reactive power instruction value can be set to be 500 x (-2.5) = -1250kvar in the Q value range, wherein delta = -42.835 degrees.
The power output situation is simulated through a system simulation model, as shown in fig. 10.
As shown in fig. 11, it can be seen from the simulation waveforms that the system outputs active power and reactive power to substantially track the commanded power, and it can be seen that the reactive power is in an inductive state (if the inductance is negative), the commanded charging power P =500kW of the system, and the commanded reactive power Q = -1.25Mvar satisfy the relationship of Q = -2.5P set preliminarily, but the fluctuation of the reactive power is relatively large, thereby verifying the correctness of the power control method.
When the delta angle is not changed, the system instruction charging power is changed to be P =1MW, according to the preliminarily set Q = -2.5P relation, the reactive power Q = -2.5Mvar should be instructed, the actual situation of the simulation power output is shown in FIG. 12, the instruction charging power is P =1MW, the instruction reactive power Q = -2.3Mvar, the active power is accurately tracked, and the reactive power slightly deviates.
As shown in fig. 13, when the active power of the system operation 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 fact shows that the method and the system for determining the single-phase power parameter of the hybrid unit cascaded H-bridge energy storage system and the single-phase power control method provided by the embodiment can control the active power and the reactive power of the cascaded H-bridge energy storage system, realize accurate control of the active power, and improve the utilization rate of the cascaded H-bridge energy storage system.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or 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, and the like) 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 application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can make modifications and equivalents to the embodiments of the present invention without departing from the spirit and scope of the present invention, and such modifications and equivalents are within the scope of the claims of the present invention as hereinafter claimed.
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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