CN117713332A - Energy storage type power supply device for transformer temperature rise test - Google Patents
Energy storage type power supply device for transformer temperature rise test Download PDFInfo
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- CN117713332A CN117713332A CN202311575293.1A CN202311575293A CN117713332A CN 117713332 A CN117713332 A CN 117713332A CN 202311575293 A CN202311575293 A CN 202311575293A CN 117713332 A CN117713332 A CN 117713332A
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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
- H02J9/00—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting
- H02J9/04—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source
- H02J9/06—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source with automatic change-over, e.g. UPS systems
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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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Abstract
本发明属于电气设备领域，公开了一种用于互感器温升试验的储能型试验电源装置，包括三电平AC/DC、DC/AC、双向DC/DC与储能系统；所述AC/DC通过并网开关与电网连接，AC/DC通过DC/AC与VFI负载连接；AC/DC与并网开关之间用于接入VFD负载；所述储能系统通过双向DC/DC接入AC/DC与DC/AC之间；所述储能系统的最大放电功率不小于VFI负载和VFD负载的额定功率之和；还包括DC‑DC控制器与AC/DC控制器。本发明能够向VFI和VFD的关键负载提供应急电力，降低了成本并提高了蓄电池利用率，最大限度地减少了需求管理与应急供电模式切换带来的暂态过程。
The invention belongs to the field of electrical equipment and discloses an energy storage type test power supply device for temperature rise test of transformer, including three-level AC/DC, DC/AC, bidirectional DC/DC and energy storage system; the AC /DC is connected to the grid through the grid-connected switch, AC/DC is connected to the VFI load through DC/AC; the connection between AC/DC and the grid-connected switch is used to connect the VFD load; the energy storage system is connected through bidirectional DC/DC Between AC/DC and DC/AC; the maximum discharge power of the energy storage system is not less than the sum of the rated power of the VFI load and the VFD load; it also includes a DC‑DC controller and an AC/DC controller. The invention can provide emergency power to key loads of VFI and VFD, reduces costs, improves battery utilization, and minimizes transient processes caused by demand management and emergency power supply mode switching.
Description
Technical Field
The invention belongs to the field of electrical equipment, and particularly relates to an energy storage type test power supply device for a transformer temperature rise test.
Background
Energy Storage Systems (ESS) have attracted attention as a method of avoiding a large-scale power outage caused by sudden increases in power consumption in summer and winter. ESS can be used to address power quality issues by providing auxiliary services to the grid such as peak shaving, load shifting, etc. Meanwhile, uninterruptible Power Supply (UPS) systems have been widely used in data centers, hospitals, and the like to provide reliable power for critical loads such as communication systems, network servers, medical equipment, and the like.
Conventional arrangements proposed by the prior art include an ESS for demand management and an online UPS for emergency power, wherein the stored energy of the ESS battery is used for demand management, but the stored energy of the UPS battery is used only in case of grid failure. In addition, when the grid fails, the AC-DC rectifier of the online UPS stops operating and the DC-AC inverter provides emergency power only to the Voltage Frequency Independent (VFI) load. Therefore, how to provide an energy storage type test power supply device capable of providing emergency power for critical loads such as VFI, voltage frequency related (VFD) and the like is of great significance for ensuring safe and stable operation of a power system.
Disclosure of Invention
The invention aims to solve the problems in the prior art and provide an energy storage type test power supply device for a transformer temperature rise test.
The invention is realized by the following technical scheme: an energy storage type power supply device comprises three levels of AC/DC, DC/AC, bidirectional DC/DC and an energy storage system;
the AC/DC is connected with a power grid through a grid-connected switch, and is connected with a VFI load through a DC/AC; the AC/DC and the grid-connected switch are used for being connected with a VFD load;
the energy storage system is connected between the AC/DC and the DC/AC through a bidirectional DC/DC; the maximum discharge power of the energy storage system is not less than the sum of rated powers of the VFI load and the VFD load;
the system also comprises a DC-DC controller and an AC/DC controller; the DC-DC controller is used for controlling the bidirectional DC-DC switching working mode according to the state of the power grid and the charge and discharge power of the energy storage system, and adopts a demand management mode when the power grid is normal and adopts an emergency power supply mode when the power grid fails;
the AC/DC controller is used for controlling the three-level AC/DC switching working mode according to the state of the power grid, the power grid adopts a demand management mode when in normal state, and the power grid adopts an emergency power supply mode when in fault state.
Further, the demand management mode includes the following:
mode D1: charging when the power consumption is low, and accumulating energy into the energy storage system;
mode D2: the discharge power of the energy storage system is smaller than the required VFI load power, and the VFI load power is provided by the power grid and the energy storage system;
mode D3: the discharging power of the energy storage system is larger than the required VFI load power, and the VFD load power is provided by the power grid and the energy storage system;
mode D4: the discharging power of the energy storage system is larger than the sum of the VFD load power and the VFI load power, and the discharging power of the energy storage system flows from the energy storage system to the power grid.
Further, the emergency power supply mode includes the following:
e1 mode: when the SOC of the energy storage system is larger than the SOC threshold value, the energy storage system discharges through the DC-DC to provide emergency power for the VFI load and the VFD load;
e2 mode: when the SOC of the energy storage system drops to the SOC threshold, the energy storage system provides emergency power only to the VFI load while stopping providing emergency power to the VFD load.
Further, the SOC threshold is a battery SOC for providing emergency power to the rated VFI load and is estimated through EMS demand prediction.
Further, the DC-DC controller includes the following:
two reference DC link voltage controllers PI 1 And PI (proportional integral) 3 The power grid control circuit is used for adjusting the direct current link voltage when the power grid fails; reference DC link voltage controller PI 1 And PI (proportional integral) 3 Output is respectively carried out through a Limiter Limiter1 and a Limiter Limiter 3;
battery voltage controller PI 2 The constant voltage charging circuit is used for performing constant voltage charging after the voltage of the energy storage system reaches the final discharging voltage; battery voltage controller PI 2 Outputting through Limiter Limiter 2;
current controller PI 4 The energy storage system is used for controlling the energy storage system to charge or discharge;
limiter Limited 1 outputs to Limiter Limited 2, limiter Limited 2 outputs to Limiter Limited 3, and Limiter Limited 3 outputs to current controller PI 4 。
Further, reference is made to the DC link voltage controller PI 1 And PI (proportional integral) 3 A kind of electronic deviceAnd->Respectively determined as follows
In the method, in the process of the invention,like the nominal DC link voltage regulated by a three level AC-DC converter, Δv is the allowable range of DC link voltage ripple caused by disturbances, only if the DC link voltage drops to +.>Below or rise to +.>In the above case, the control target is switched from the battery current to the dc link voltage.
Further, a bi-directional DC-DC converterConstant current charging of the battery until the battery is fully charged, when V b PI when the final discharge voltage of the battery is reached 2 Is activated and begins to regulate V b To a constant voltage->To V (V) b Adjust to->Charging current->The method comprises the following steps:
in the method, in the process of the invention,is the limit value of Limiter limit 3, < >>Is->And V is equal to b The difference passes through the battery voltage controller PI 2 The obtained value>Is the battery reference voltage of the energy storage system, V b Is the battery voltage of the energy storage system.
Further, when the power grid fails in the battery charging process, the voltage of the direct current link drops to activate PI 3 Switching the control target from the battery current or the battery voltage to the direct current link voltage by switching from the demand management mode to the emergency power supply mode;
when the power grid fails in the discharging process of the battery, the voltage of the direct current link is increased to activate PI 1 The demand management mode is changed to the emergency power supply mode, and the control target is switched from the battery current or the battery voltage to the direct-current link voltage.
Further, the AC/DC controller comprises a direct current link voltage control module, a power grid side current control module and a capacitor voltage control module; the input end of the power grid side current control module is connected with the direct current link voltage control module, and the output end of the power grid side current control module is connected with the capacitor voltage control module through the mode control switch.
Further, the three-level AC-DC converter operates in an emergency power supply mode, and the capacitor reference voltage on the grid side is determined as:
in the method, in the process of the invention,respectively represent d component of capacitor reference voltage, q component of capacitor reference voltage, grid voltage V g The d component of (2).
Compared with the prior art, the invention has the beneficial effects that:
the invention provides an energy storage type test power supply device for a transformer temperature rise test based on the existing ESS and UPS researches, and the invention has the following advantages: 1) emergency power can be provided to the critical loads of the VFI and VFD, 2) cost is reduced and battery utilization is improved, 3) transient processes caused by demand management and emergency power mode switching are minimized.
Drawings
FIG. 1 is a circuit topology of an energy storage type test power supply device;
FIG. 2 is a control schematic diagram in demand management mode;
FIG. 3 is a control schematic diagram in emergency power mode;
FIG. 4 is a power flow diagram of different demand management modes;
FIG. 5 is a power flow diagram for different emergency power modes;
FIG. 6 is a control block diagram of an autonomous seamless mode conversion algorithm for a bi-directional DC-DC converter;
fig. 7 is a control block diagram of an autonomous seamless mode conversion algorithm of a three-level AC-DC converter.
Detailed Description
The invention is described in further detail below with reference to the attached drawing figures:
one) establishing circuit topology, operating mode and control strategy
Referring to fig. 1, an energy storage type power supply apparatus employing a T-type three-level topology to reduce the size of a filter and achieve high power conversion efficiency has two types of critical loads, one is a Voltage Frequency Independent (VFI) load connected to the output of a DC-AC inverter and the other is a Voltage Frequency Dependent (VFD) load connected to the main grid side.
The power supply device is used for the temperature rise test of the transformer, namely the application occasion of the power supply device is particularly used for providing a test power supply for the temperature rise test of the transformer.
The system consists of a 250kw hybrid Energy Storage System (ESS) with a demand management function and a 250kw online Uninterruptible Power Supply (UPS) with an emergency power supply function, wherein the rated power of a VFD load and a VFI load is respectively 250kw, the storage capacity of a storage battery is 500kwh, namely the sum of the storage battery capacities of a conventional ESS and a UPS, and therefore, the rated power of an AC-DC converter and a DC-AC inverter is 250kw.
The invention integrates ESS+UPS into a storage battery with the capacity of 500 kwh.
Under normal conditions of the power grid, the system operates in a demand management mode, in which the battery is charged or discharged, depending on the power demand and the state of charge (SOC) of the battery.
In a battery charging mode, the power grid can supply power to the VFI load through the AC-DC converter and the DC-AC inverter, and can charge the battery through the AC-DC converter and the DC-DC converter, so that the sum of the power of the VFI load and the power of the battery charging is limited to 250Kw in the battery charging mode.
In the battery discharging mode, the battery is discharged through the DC-DC converter, and not only is the power supplied to the VFI load through the DC-AC inverter, but also the power is supplied to the VFD load and the power grid through the AC-DC converter, so that the sum of the load power of the frequency converter (the load power of the VFD) and the injection power to the power grid is limited to 250kw, and the rated power of the DC-DC converter is 250kw. In summary, the maximum discharge power of the battery is 500kw, i.e., the sum of the rated powers of the VFI and the VFD load.
The control targets for the different modes of operation of the respective inverters are shown in fig. 2 to 3. The control target of the provided energy storage type test power supply device; (a) Demand management mode, (b) emergency power supply mode
When the AC input voltage is within a preset tolerance, the proposed system operates in a demand management mode, as shown in fig. 2 below, in which the AC-DC converter regulates the DC link voltage, while the DC-AC inverter provides a well-regulated three-phase voltage to the VFI load, and the DC-DC converter charges or discharges according to a reference battery current determined by an Energy Management System (EMS). The energy management system determines that the reference battery current belongs to the prior art and is not described in detail herein.
The direct current link refers to a line from the AC-DC converter to the DC-AC inverter and a line from the AC-DC converter to the DC-DC inverter.
When the grid fails, the system operates in an emergency power mode, as shown in fig. 3, in which the Magnetic Contactor (MC) disconnects the AC-DC converter from the grid, the AC-DC converter changes its control target from the DC link voltage to the VFD load voltage, and the DC-DC converter's control target also changes from the battery current to the DC link voltage. In order to obtain good dynamic performance, transients during modal changes should be minimized.
The DC-DC converter converts the output voltage of the storage battery into a direct-current link reference voltage and supplies the direct-current link reference voltage to the AC-DC converter and the DC-AC inverter, respectively. The precondition for stabilizing the system including the VFD load is that the dc link voltage is stabilized and the VFD load voltage is stabilized.
The demand management mode is based on the power grid state and the charge and discharge power P of the storage battery b Can be further divided into four modes D1, D2, D3, D4, as shown in fig. 4. Mode D1 represents a battery charging mode, and when power consumption is low, typically during the night, the system will accumulate energy in the battery. In D2, D3, and D4 modes, the DC-DC converter performs battery discharge for demand management, mode D2 representing that since the battery discharge power is less than the required VFI load power, the VFI load power is provided by the grid and the battery; in the D3 mode, since the battery discharge power is greater than the required VFI load power, the VFD load power is provided by the grid and the battery; in the D4 mode, the battery discharge power is greater than the sum of the VFD load power and the VFI load power, so that the battery discharge power flows from the battery to the power grid.
The emergency power supply mode is based on the power grid state and the charging and discharging power P of the storage battery b Can be further divided into two modes E1, E2, as shown in fig. 5. When the power grid fails, the MC disconnects the system from the power grid, the system enters an E1 mode, the DC-DC converter discharges the storage battery, and an emergency power supply is provided for the VFI load and the VFD load; when the SOC of the storage battery drops to the SOC 1 At this time, the system enters mode E2, where SOC 1 Defined as a battery SOC that supplies emergency power to the rated VFI load for 30 minutes during mode E1, at which time the system only provides emergency power to the VFI load while stopping providing emergency power to the VFD load.
SOC 2 The battery SOC, defined as the rated VFI load providing emergency power, and the demand forecast estimated by the EMS demand forecast is based on load distribution data accumulated during system operation, and the amounts of electricity for the VFI and VFD loads before grid failure. EMS estimation SOC 2 Belongs to the prior art and is not described in detail herein.
Grid power P g From the power P of the accumulator b Load power P L VFD load power P VFD VFI load power P VFI The sum is determined as follows
P g ＝P b +P L +P VFD +P VFI (1)
t 1 The power grid fails at the moment, the system is switched from the D3 mode to the E1 mode, and the discharge power of the storage battery is
P b ＝-(P VFD +P VFI ) (2)
When the SOC of the storage battery is reduced to the SOC 1 When the system stops supplying power to the VFD load, the emergency power supply is only continuously supplied to the VFI load under the condition that the system has no demand prediction. On the other hand, since the system is operated based on the EMS demand predicted data, the battery SOC drops to SOC 2 (non-SOC) 1 ) When the system stops supplying power to the VFD load, only to the VFI load. Thus, by demand prediction, the system is able to extend the length of time that emergency power is provided to the VFD load, thereby more efficiently using the battery power. The invention adopts SOC 2 Replacement SOC 1 The VFD load supply time is prolonged.
The energy storage type test power supply device based on the power demand mode and the storage battery SOC utilizes the power demand prediction system to predict the power demand to obtain the power demand mode, the EMS also schedules the charging and discharging of the storage battery according to the power demand mode to manage the storage battery SOC, and the standby energy stored in the storage battery represents the sum of the standby power supply capacity for supplying power to the VFI load and the standby power supply capacity for supplying power to the VFD load in the operation time of the standby storage battery determined by a user.
The device charges the storage battery in a light load period of low electric charge (D1 mode), discharges the storage battery in a heavy load period of high electric charge to perform demand management (D2/D3/D4 mode), wherein basically half of energy stored in the system is used for demand management, and the rest of energy (reserved energy for UPS) is used for emergency power supply. The demand prediction of the energy storage system can change the quantity of energy storage reserves, and when a power grid fails, the system enters an E1 mode or an E2 mode according to the SOC of the storage battery; in the event of a grid fault 1, the battery SOC is sufficiently high, the proposed system operating in E1 mode; on the other hand, in case of grid fault 2, the battery SOC is low and the proposed system operates in mode E2.
The power grid fault 1 is the power grid fault when the SOC of the storage battery is high enough, and the power grid fault 2 is the power grid fault when the SOC of the storage battery is low.
Two), autonomous seamless mode conversion algorithm of bidirectional DC-DC converter
The proposed energy storage type test power supply device should provide emergency power for the VFD load and the VFI load when the power grid fails, in order to provide emergency power for the VFD load, an AC-DC converter is required to switch a control target from a DC link voltage to a VFD load voltage, a DC-DC converter is required to switch a control target from a battery current to a DC link voltage, and switching of the control target may cause large transients on the VFD load and the DC link, so that both the AC-DC converter and the DC-DC converter need a fast smooth mode conversion algorithm.
The control block diagram of the bidirectional DC-DC converter autonomous seamless mode switching algorithm is shown in fig. 6, and the algorithm is based on a variable limiter technology and a communication mode DC-bus signaling taking a direct current bus as a communication link and consists of three parts: two voltage controllers PI 1 And PI (proportional integral) 3 The power grid control circuit is used for adjusting the direct current link voltage when the power grid fails; battery voltage controller PI 2 For performing constant voltage charge after the battery voltage reaches the final discharge voltage; current controller PI 4 For charging or discharging the battery.
Each voltage controller is in a saturated state or an activated state according to the state of the power grid, and when the saturated state controller is activated, a controller winding caused by accumulated errors of an integrator may occur, so that in the mode conversion process, in order to prevent the controller from stopping, a reverse stopping technology is adopted.
Reference DC link voltage controller PI 1 And PI (proportional integral) 3 A kind of electronic deviceAnd->Respectively determined as follows
Is +.>Is +.>
Wherein,like the nominal DC-link voltage regulated by the AC-DC converter, Δv is the allowable range of DC-link voltage fluctuations caused by disturbances, only if the DC-link voltage drops to +.>Below or rise to due to wave motionIn the above case, the DC-DC converter should switch the control target from the battery current to the DC link voltage, and the design of DeltaV should consider the worst-case ripple margin, i.e. & lt & gt>5% of (C).
Reference voltage of batterySet to the final discharge voltage of the battery, +.>Battery reference current from EMS in Constant Current (CC) mode (D1 mode) or demand management mode (D2, D3, D4 mode), DC link voltage V when grid is normal dc Regulated by an AC-DC converter to +.>This results in a controller PI 1 Saturation is negative, the output of the limiter1 is zero, and the controller PI 3 Saturation is positive, so that limiter3 outputs +.>Suppose that the battery voltage has not yet reached +.>Controller PI 2 Also saturated to a positive value, resulting in limiter2 outputting +.>Thus battery current reference->Becomes as follows
Is the limit value of limiter3, < >>The battery reference current from the EMS is set in the constant current mode (D1 mode) or the demand management mode (D2, D3, D4 mode).
Between the three limiters, the output of the former is related to or equal to the limit value of the latter.
For limiter1 only, when the input is negative, the output of the limiter is 0; the output of the limiters 2, 3 is not related to the lower limit value.
The activation condition of the controller is adjusted by setting the allowable range Δv of the dc link voltage fluctuation caused by the disturbance.
The output of the limiter1 is defined as [0, upper limit ] according to the input, and the outputs of the limiters 2, 3 are defined as [ lower limit, upper limit ], (lower limit, upper limit) according to the input.
Thus, bi-directional DC-DC converterConstant current charging of the battery until the battery is fully charged, when V b PI when the final discharge voltage of the battery is reached 2 Is activated and begins to regulate V b To a constant voltage->To V (V) b Adjust to->Charging current->Is that
Is->And V is equal to b The difference is through PI 2 The obtained values are shown in FIG. 6.
When the power grid fails during the battery charging process, the DC link voltage starts to drop, the demand management mode is changed into the emergency power supply mode (the battery is changed into the discharging mode), the bidirectional DC-DC converter should switch the control target from the battery current or the battery voltage to the DC link voltage and start to regulate the DC link voltage instead of the AC-DC converter, and the reduction of the DC link voltage activates the PI 3 Its output of(Representing discharge current) becomes +.>To regulate the DC link voltage, whereIs a current reference for regulating the DC link voltage, V dc From PI 3 Is adjusted to
By adjusting the discharge current to adjust the dc link voltage, the final dc link voltage is controlled to a given reference voltage.
On the other hand, when the grid fails during the discharge of the battery, the grid is broken down due to V dc Start to increase, PI 1 Is activated, PI 1 Output of (2)Becomes regulation V dc To->Current reference of->By->Determine->Limit value is->And (5) limiting. The DC-DC converter may thus autonomously switch from the battery current control mode to the DC-link voltage control mode by changing the DC-link voltage.
Autonomous seamless mode conversion algorithm of three-level and three-level AC-DC converter
The control block diagram of the autonomous seamless mode switching algorithm of the three-level AC-DC converter is shown in fig. 7, and the autonomous seamless mode switching algorithm consists of a direct-current link voltage controller, a power grid side current controller and a capacitor voltage controller, and in a demand management mode, a mode control switch Q 1 And Q 2 Connected to "D", the AC-DC converter regulates the DC link voltage by controlling the grid-side current, note v cf The PI controller of the control block is used to control the grid side current.
The DC link voltage controller, the grid side current controller and the capacitor voltage controller correspond to v in FIG. 7 respectively dc Control module, i Lg Control module, v cf Control module
When the power grid fails, the mode control switch Q 1 And Q 2 Connected to "E", the AC-DC converter entering emergency power mode, v cf The PI controller of the control block is still activated, although the control target switches from dc link voltage to capacitor voltage, resulting in negligible transients for the VFD load (capacitor voltage cannot transient so the transient voltage for the VFD load does not transient).
Emergency power supply moduleUnder v only cf The control block works, and the other two controllers exit from operation.
In demand management mode, grid side inductor voltage v Lg Grid voltage V g Capacitive voltage referenceGrid-side inductor current reference->The relationship of (2) can be expressed as
From equation (9), the capacitance voltage required for regulating the grid-side current can be calculated by d-q transformation
In the method, in the process of the invention,for peak voltage of the network, ">For the grid voltage V g Is equal to zero after phase synchronization; formula (10) i as shown above Lg The three-level ac-dc converter controls the grid-side current by controlling the capacitor voltage based on (10), as shown in the control block. The capacitor voltage refers to the capacitor C in FIG. 1 f Which belongs to the grid side capacitance.
When the power grid fails, the three-level AC-DC converter works in an emergency power supply mode, and the reference voltage of the capacitor is determined to be
Respectively represent d component of capacitor reference voltage, q component of capacitor reference voltage, grid voltage V g The d component of (2).
In emergency power mode, the three-level AC-DC converter regulates the capacitor voltage to the same level as the grid voltage (in equation 11) Thereby enabling emergency power supply to the inverter load, please note +>There is a small variation (10% of nominal) and v cf The control parameters of the controller are not changed when the mode changes (the parameters of the PI controller are not changed because the set control parameters have certain applicability), so the proposed control can provide stable voltage for the VFD load in the clearing time, and seamless mode conversion is realized.
The foregoing technical solutions are merely specific embodiments of the present invention, and various modifications and variations can be easily made by those skilled in the art based on the principles disclosed in the present invention, and are not limited to the technical solutions described in the foregoing specific embodiments of the present invention, therefore, the foregoing description is only preferred and not in any limiting sense.
Claims (10)
1. The energy storage type power supply device is characterized by comprising three levels of AC/DC, DC/AC, bidirectional DC/DC and an energy storage system;
the AC/DC is connected with a power grid through a grid-connected switch, and is connected with a VFI load through a DC/AC; the AC/DC and the grid-connected switch are used for being connected with a VFD load;
the energy storage system is connected between the AC/DC and the DC/AC through a bidirectional DC/DC; the maximum discharge power of the energy storage system is not less than the sum of rated powers of the VFI load and the VFD load;
the system also comprises a DC-DC controller and an AC/DC controller; the DC-DC controller is used for controlling the bidirectional DC-DC switching working mode according to the state of the power grid and the charge and discharge power of the energy storage system, and adopts a demand management mode when the power grid is normal and adopts an emergency power supply mode when the power grid fails;
the AC/DC controller is used for controlling the three-level AC/DC switching working mode according to the state of the power grid, the power grid adopts a demand management mode when in normal state, and the power grid adopts an emergency power supply mode when in fault state.
2. The energy storage type power supply device according to claim 1, wherein the demand management mode includes:
mode D1: charging when the power consumption is low, and accumulating energy into the energy storage system;
mode D2: the discharge power of the energy storage system is smaller than the required VFI load power, and the VFI load power is provided by the power grid and the energy storage system;
mode D3: the discharging power of the energy storage system is larger than the required VFI load power, and the VFD load power is provided by the power grid and the energy storage system;
mode D4: the discharging power of the energy storage system is larger than the sum of the VFD load power and the VFI load power, and the discharging power of the energy storage system flows from the energy storage system to the power grid.
3. The energy storage power supply device of claim 1, wherein the emergency power supply mode includes the following:
e1 mode: when the SOC of the energy storage system is larger than the SOC threshold value, the energy storage system discharges through the DC-DC to provide emergency power for the VFI load and the VFD load;
e2 mode: when the SOC of the energy storage system drops to the SOC threshold, the energy storage system provides emergency power only to the VFI load while stopping providing emergency power to the VFD load.
4. The energy storage type power supply device according to claim 3, wherein the SOC threshold value is a battery SOC for supplying emergency power to a rated VFI load, and is estimated by demand prediction of EMS.
5. The energy storage type power supply device according to claim 1, wherein the DC-DC controller includes:
two reference DC link voltage controllers PI 1 And PI (proportional integral) 3 The power grid control circuit is used for adjusting the direct current link voltage when the power grid fails; reference DC link voltage controller PI 1 And PI (proportional integral) 3 Output is respectively carried out through a Limiter Limiter1 and a Limiter Limiter 3;
battery voltage controller PI 2 The constant voltage charging circuit is used for performing constant voltage charging after the voltage of the energy storage system reaches the final discharging voltage; battery voltage controller PI 2 Outputting through Limiter Limiter 2;
current controller PI 4 The energy storage system is used for controlling the energy storage system to charge or discharge;
limiter Limited 1 outputs to Limiter Limited 2, limiter Limited 2 outputs to Limiter Limited 3, and Limiter Limited 3 outputs to current controller PI 4 。
6. The energy storage type power supply device according to claim 5, wherein the reference dc link voltage controller PI 1 And PI (proportional integral) 3 A kind of electronic deviceAnd->Respectively determined as follows
In the method, in the process of the invention,like the nominal DC link voltage regulated by a three level AC-DC converter, Δv is the allowable range of DC link voltage ripple caused by disturbances, only if the DC link voltage drops to +.>Below or rise to +.>In the above case, the control target is switched from the battery current to the dc link voltage.
7. The energy storage type power supply device according to claim 5, wherein the bidirectional DC-DC converter comprisesConstant current charging of the battery until the battery is fully charged, when V b PI when the final discharge voltage of the battery is reached 2 Is activated and begins to regulate V b To a constant voltage->To V (V) b Adjust to->Charging current->The method comprises the following steps:
in the method, in the process of the invention,is the limit value of Limiter limit 3, < >>Is->And V is equal to b The difference passes through the battery voltage controller PI 2 The obtained value>Is the battery reference voltage of the energy storage system, V b Is the battery voltage of the energy storage system.
8. The energy storage power supply device of claim 5, wherein the dc link voltage drop activates PI when the grid fails during battery charging 3 Switching the control target from the battery current or the battery voltage to the direct current link voltage by switching from the demand management mode to the emergency power supply mode;
when the power grid fails in the discharging process of the battery, the voltage of the direct current link is increased to activate PI 1 The demand management mode is changed to the emergency power supply mode, and the control target is switched from the battery current or the battery voltage to the direct-current link voltage.
9. The energy storage type power supply device according to claim 1, wherein the AC/DC controller includes a direct current link voltage control module, a grid-side current control module, and a capacitor voltage control module; the input end of the power grid side current control module is connected with the direct current link voltage control module, and the output end of the power grid side current control module is connected with the capacitor voltage control module through the mode control switch.
10. The energy storage type power supply device according to claim 1, wherein when the power grid fails, the three-level AC-DC converter operates in an emergency power supply mode, and the capacitor reference voltage on the power grid side is determined as:
in the method, in the process of the invention,respectively represent d component of capacitor reference voltage, q component of capacitor reference voltage, grid voltage V g The d component of (2).
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| CN202311575293.1A CN117713332A (en) | 2023-11-23 | 2023-11-23 | Energy storage type power supply device for transformer temperature rise test |
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| CN202311575293.1A CN117713332A (en) | 2023-11-23 | 2023-11-23 | Energy storage type power supply device for transformer temperature rise test |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN118693985A (en) * | 2024-08-28 | 2024-09-24 | 福建时代星云科技有限公司 | A high-efficiency discharge energy storage system and discharge method thereof |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN118693985A (en) * | 2024-08-28 | 2024-09-24 | 福建时代星云科技有限公司 | A high-efficiency discharge energy storage system and discharge method thereof |
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