CN115001047A - Energy router and transformer parallel system and control method thereof - Google Patents

Energy router and transformer parallel system and control method thereof Download PDF

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Publication number
CN115001047A
CN115001047A CN202210928807.6A CN202210928807A CN115001047A CN 115001047 A CN115001047 A CN 115001047A CN 202210928807 A CN202210928807 A CN 202210928807A CN 115001047 A CN115001047 A CN 115001047A
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China
Prior art keywords
loss
transformer
energy router
current
load
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Chinese (zh)
Inventor
桑子夏
方仍存
雷何
颜炯
郑旭
黄家祺
侯婷婷
汪颖翔
杨东俊
王琪鑫
徐秋实
余轶
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Economic and Technological Research Institute of State Grid Hubei Electric Power Co Ltd
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Economic and Technological Research Institute of State Grid Hubei Electric Power Co Ltd
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Priority to CN202210928807.6A priority Critical patent/CN115001047A/en
Publication of CN115001047A publication Critical patent/CN115001047A/en
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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
    • 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
    • H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
    • H02J3/1821—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators
    • 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
    • H02J3/26—Arrangements for eliminating or reducing asymmetry in polyphase networks
    • 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
    • H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
    • H02J2203/20—Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

A parallel system of an energy router and a transformer and a control method thereof are disclosed, the system comprises a power supply, the energy router, the transformer and a load and control analysis module, wherein the power supply is connected with the load through a common bus after sequentially passing through the energy router and a first change-over switch; during control, whether the system needs to enter a reactive compensation mode or not is judged through the power factor, whether the system is in a three-phase load unbalance mode or not is judged through the three-phase current unbalance degree, the loss when the energy router is connected and the loss when the transformer is connected are calculated, then the loss when the energy router is connected and the loss when the transformer is connected are compared, and the energy router or the transformer is selected to be connected to supply power for the load through the comparison result. The invention can effectively reduce the line loss.

Description

Energy router and transformer parallel system and control method thereof
Technical Field
The invention relates to the technical field of electricity, in particular to an energy router and transformer parallel system and a control method thereof, which are mainly suitable for reducing line loss.
Background
International standards require that the efficiency of dry distribution transformers is greater than 97%, and the efficiency of most oil-immersed transformers is close to 99.5%. The energy router consists of power electronic converters, and the prior research shows that the maximum efficiency of each stage of power electronic converter is only 97-98%, the efficiency of a multi-stage rectifier, a full bridge and an inverter EPT which are most widely applied in the United states is only 91.185%, and the loss of the energy router model in the future renewable power transmission and management network of North Care State university in the United states is only 94% at most after an inverter structure is omitted on the output side. Therefore, compared with the traditional transformer, the energy router has high operation loss and low efficiency, which becomes a great obstacle for the application of the energy router to the power distribution network. However, compared to conventional transformers, the energy router may provide many additional functions in addition to the basic functions of voltage transformation, electrical isolation and power transfer, such as: the automatic voltage regulation, the power factor correction and the direct current link plus energy storage unit can improve the power supply reliability, the power flow control, the fault current limitation and the compensation of three-phase unbalanced current.
The load of the power distribution network in rural and remote areas is dispersed, the power distribution distance is usually long, and a low power factor phenomenon and single-phase load are widely existed in the rural power distribution network along with the entrance of a large number of high-power electrical equipment into a family; because loads in the distribution network of the industrial and mining enterprises are mostly irregular single-phase loads or single-phase and three-phase loads, such as single-phase motors, lighting loads and the like, the problem also exists in the distribution network of the industrial and mining enterprises which is far away from a distribution center and needs to transmit electric energy in a long distance; in addition, low power factor and unbalanced current phenomena are also abundant in some single-phase traction electric transportation or railway systems.
By combining the above analysis, in general situations, the transmission efficiency of the energy router is lower than that of the traditional transformer, and higher power loss exists; however, in some specific operating conditions, if the additional functions of the energy router are considered, the energy router is applied to the power distribution network to reduce the overall power loss of the energy router compared with the traditional transformer. Therefore, how to select an energy router and a conventional transformer to reduce loss under different working conditions becomes an urgent problem to be solved.
Disclosure of Invention
The invention aims to overcome the defects and problems of high line loss in the prior art, and provides an energy router and transformer parallel system with low line loss and a control method thereof.
In order to achieve the above purpose, the technical solution of the invention is as follows: a control method of an energy router and transformer parallel system comprises the following steps:
s1, connecting a power supply to a load through an energy router, a first change-over switch and a common bus, and connecting the power supply to the load through a transformer, a second change-over switch and the common bus; meanwhile, a second change-over switch is closed, and a power supply supplies power to the load through a transformer;
s2, calculating the loss of the energy router during access and the loss of the transformer during access;
and S3, comparing the loss of the energy router during access with the loss of the transformer during access, and selecting the accessed energy router or the transformer to supply power to the load according to the comparison result.
In step S2, the loss of the energy router during access is calculated from the loss of the energy router itself and the line loss saved by the power supply of the energy router; the self loss of the energy router comprises conduction loss and switching loss of power electronic switching devices of an alternating current-direct current module and a direct current-alternating current module, conduction loss and switching loss of the power electronic switching devices of the direct current-direct current module, and magnetic core loss and winding loss of the intermediate frequency transformer;
and calculating the loss of the transformer when the transformer is accessed through the loss of the transformer.
The power electronic switching devices of the alternating current-direct current module and the direct current-alternating current module of the energy router comprise an IGBT and a diode;
the turn-on loss of the IGBT is:
Figure DEST_PATH_IMAGE002
in the formula (I), the compound is shown in the specification,
Figure DEST_PATH_IMAGE004
the holding voltage of the IGBT is provided,
Figure DEST_PATH_IMAGE006
in order to obtain the load factor,
Figure DEST_PATH_IMAGE008
for the magnitude of the phase current,
Figure DEST_PATH_IMAGE010
is the forward on-resistance of the IGBT,
Figure DEST_PATH_IMAGE012
in order to adjust the degree of modulation,
Figure DEST_PATH_IMAGE014
is the collector current of the IGBT;
the conduction loss of the diode is:
Figure DEST_PATH_IMAGE016
in the formula (I), the compound is shown in the specification,
Figure DEST_PATH_IMAGE018
is the no-load voltage of the freewheeling diode,
Figure DEST_PATH_IMAGE020
is the on-state resistance of the freewheeling diode;
the switching losses of the IGBT are:
Figure DEST_PATH_IMAGE022
in the formula (I), the compound is shown in the specification,
Figure DEST_PATH_IMAGE024
is the switching frequency of the IGBT or IGBTs,
Figure DEST_PATH_IMAGE026
is the phase voltage amplitude;
Figure DEST_PATH_IMAGE028
、
Figure DEST_PATH_IMAGE030
、
Figure DEST_PATH_IMAGE032
is a characteristic constant of the IGBT;
Figure DEST_PATH_IMAGE034
rated voltage of IGBT;
the switching losses of the diodes are:
Figure DEST_PATH_IMAGE036
in the formula (I), the compound is shown in the specification,
Figure DEST_PATH_IMAGE038
is the switching frequency of the diode or diodes,
Figure DEST_PATH_IMAGE040
、
Figure DEST_PATH_IMAGE042
is the characteristic constant of the diode;
the conduction losses of the IGBT and the diode of the direct current-direct current module of the energy router are respectively as follows:
Figure DEST_PATH_IMAGE044
Figure DEST_PATH_IMAGE046
in the formula (I), the compound is shown in the specification,
Figure DEST_PATH_IMAGE048
the average current flowing through the IGBT for the rated power,
Figure DEST_PATH_IMAGE050
is the collector-emitter saturation voltage of the IGBT module,
Figure DEST_PATH_IMAGE052
is the conduction voltage drop of the diode,
Figure DEST_PATH_IMAGE054
the average current flowing through the diode is the rated power;
the switching losses of the IGBT and the diode of the dc-dc module of the energy router are respectively:
Figure DEST_PATH_IMAGE056
Figure DEST_PATH_IMAGE058
the core loss is:
Figure DEST_PATH_IMAGE060
in the formula (I), the compound is shown in the specification,
Figure DEST_PATH_IMAGE062
in order for the core to lose power density,
Figure DEST_PATH_IMAGE064
is the effective volume of the magnetic core of the intermediate frequency transformer,
Figure DEST_PATH_IMAGE066
the frequency of the square wave signal in the intermediate frequency transformer,
Figure DEST_PATH_IMAGE068
is the density of the magnetic flux in the magnetic core,
Figure DEST_PATH_IMAGE070
is the magnetic flux form factor;
Figure DEST_PATH_IMAGE072
、
Figure DEST_PATH_IMAGE074
、
Figure DEST_PATH_IMAGE076
are all coefficients, which are related to the magnetic core material of the intermediate frequency transformer;
the winding loss is:
Figure DEST_PATH_IMAGE078
in the formula (I), the compound is shown in the specification,
Figure DEST_PATH_IMAGE080
is the direct-current resistance of the winding,
Figure DEST_PATH_IMAGE082
is a direct current component in the winding current,
Figure DEST_PATH_IMAGE084
is composed of
Figure DEST_PATH_IMAGE086
The effective value of the sub-harmonic current,
Figure DEST_PATH_IMAGE088
is composed of
Figure 371044DEST_PATH_IMAGE086
The AC/DC resistance ratio of the winding under subharmonic excitation;
the energy router's own losses are:
Figure DEST_PATH_IMAGE090
。
in step S2, in the reactive compensation mode, the line loss saved by using the power supplied by the energy router is:
Figure DEST_PATH_IMAGE092
in the formula (I), the compound is shown in the specification,
Figure DEST_PATH_IMAGE094
for the energy router power to be the power,
Figure DEST_PATH_IMAGE096
in order to distribute the network voltage,
Figure DEST_PATH_IMAGE098
is the resistance of the distribution line and,
Figure DEST_PATH_IMAGE100
the power factor of the transformer and the load as a whole.
In step S2, the relationship between the phase current and the sequence current is:
Figure DEST_PATH_IMAGE102
in the formula (I), the compound is shown in the specification,
Figure DEST_PATH_IMAGE104
in order to be the positive-sequence current component,
Figure DEST_PATH_IMAGE106
is a negative-sequence current component of the current,
Figure DEST_PATH_IMAGE108
is a zero sequence current component;
Figure DEST_PATH_IMAGE110
in order to be a phase-shift operator,
Figure DEST_PATH_IMAGE112
；
Figure DEST_PATH_IMAGE114
、
Figure DEST_PATH_IMAGE116
、
Figure DEST_PATH_IMAGE118
unbalanced three-phase current;
degree of current imbalance
Figure DEST_PATH_IMAGE120
Comprises the following steps:
Figure DEST_PATH_IMAGE122
in the formula (I), the compound is shown in the specification,
Figure DEST_PATH_IMAGE124
is the three-phase average current;
current on neutral line
Figure DEST_PATH_IMAGE126
Comprises the following steps:
Figure DEST_PATH_IMAGE128
extra power loss consumed on the neutral line
Figure DEST_PATH_IMAGE130
Comprises the following steps:
Figure DEST_PATH_IMAGE132
in the formula (I), the compound is shown in the specification,
Figure DEST_PATH_IMAGE134
in order to be a neutral line resistance, the resistance,
Figure DEST_PATH_IMAGE136
is the root mean square of the positive sequence component of the current,
Figure DEST_PATH_IMAGE138
root mean square of the negative sequence component of the current;
additional power loss on three-phase current imbalance phase line
Figure DEST_PATH_IMAGE140
Comprises the following steps:
Figure DEST_PATH_IMAGE142
in the formula (I), the compound is shown in the specification,
Figure DEST_PATH_IMAGE144
is a phase line resistor;
under the unbalanced three-phase load mode, the line loss that the adoption energy router power supply was practiced thrift is:
Figure DEST_PATH_IMAGE146
。
in step S2, the loss of the transformer itself is:
Figure DEST_PATH_IMAGE148
in the formula (I), the compound is shown in the specification,
Figure DEST_PATH_IMAGE150
in order to be a load loss, the load,
Figure DEST_PATH_IMAGE152
is the reactive power of the transformer and is,
Figure DEST_PATH_IMAGE154
for the transformer losses measured during nominal voltage operation,
Figure DEST_PATH_IMAGE156
in order to be rated for the load loss,
Figure DEST_PATH_IMAGE158
is the load factor when the transformer is in operation,
Figure DEST_PATH_IMAGE160
is the capacity of the transformer and is,
Figure DEST_PATH_IMAGE162
is the percentage of the load current of the transformer,
Figure DEST_PATH_IMAGE164
is the impedance voltage percentage of the transformer.
In step S3, a difference between the loss at the time of the access of the energy router and the loss at the time of the access of the transformer is calculated
Figure DEST_PATH_IMAGE166
：
Figure DEST_PATH_IMAGE168
When in use
Figure DEST_PATH_IMAGE170
When the energy router is not used, the first change-over switch is closed, and the energy router is selected to supply power to the load;
when the temperature is higher than the set temperature
Figure DEST_PATH_IMAGE172
And when the load is in a normal state, the second selector switch is switched on, and the load is supplied with power through the transformer.
The system comprises a power supply, an energy router, a transformer, a load and a control analysis module, wherein the power supply is connected with the load through a common bus after sequentially passing through the energy router and a first change-over switch, the power supply is connected with the load through the common bus after sequentially passing through the transformer and a second change-over switch, the control analysis module is connected with the energy router, the transformer, the first change-over switch and the second change-over switch, the control analysis module is used for judging whether the system needs to enter a reactive compensation mode through a power factor, judging whether the system is in a three-phase load unbalance mode through three-phase current unbalance, calculating loss when the energy router is connected and loss when the transformer is connected, and controlling the first change-over switch through comparing the loss when the energy router is connected with the loss when the transformer is connected, And the second change-over switch is turned on and off.
Compared with the prior art, the invention has the beneficial effects that:
in the energy router and transformer parallel system and the control method thereof, loss when the energy router is connected and loss when the transformer is connected are compared based on reactive compensation and three-phase load unbalance characteristics, and the energy router or the transformer is selected to be connected to supply power for the load according to the comparison result, so that the line loss is effectively reduced. Therefore, the invention reduces the line loss.
Drawings
Fig. 1 is a schematic structural diagram of a parallel system of an energy router and a transformer according to the present invention.
Fig. 2 is a flowchart of a control method of the parallel system of the energy router and the transformer according to the invention.
In the figure: the device comprises a power supply 1, an energy router 2, a transformer 3, a load 4, a first selector switch 5, a second selector switch 6 and a common bus 7.
Detailed Description
The present invention will be described in further detail with reference to the following description and embodiments in conjunction with the accompanying drawings.
Referring to fig. 1, a control method of an energy router and transformer parallel system includes the following steps:
s1, connecting the power supply 1 to the load 4 through the energy router 2, the first change-over switch 5 and the common bus 7, and connecting the power supply 1 to the load 4 through the transformer 3, the second change-over switch 6 and the common bus 7; meanwhile, the second change-over switch 6 is closed, and the power supply 1 supplies power to the load 4 through the transformer 3;
s2, calculating the loss of the energy router 2 during access and the loss of the transformer 3 during access;
and S3, comparing the loss when the energy router 2 is accessed with the loss when the transformer 3 is accessed, and selecting the accessed energy router 2 or the transformer 3 to supply power to the load 4 according to the comparison result.
In step S2, the loss of the energy router 2 during access is calculated from the loss of the energy router 2 itself and the line loss saved by the power supply of the energy router 2; the self loss of the energy router 2 comprises conduction loss and switching loss of power electronic switching devices of an alternating current-direct current module and a direct current-alternating current module, conduction loss and switching loss of the power electronic switching devices of the direct current-direct current module, and magnetic core loss and winding loss of an intermediate frequency transformer;
the loss of the transformer 3 during access is calculated from the loss of the transformer 3 itself.
The power electronic switching devices of the AC-DC module and the DC-AC module of the energy router 2 comprise an IGBT and a diode;
the turn-on loss of the IGBT is:
Figure 829795DEST_PATH_IMAGE002
in the formula (I), the compound is shown in the specification,
Figure 343953DEST_PATH_IMAGE004
the holding voltage for the IGBT is set,
Figure 270321DEST_PATH_IMAGE006
in order to be the load factor,
Figure 881431DEST_PATH_IMAGE008
for the magnitude of the phase current,
Figure 438314DEST_PATH_IMAGE010
is the forward on-resistance of the IGBT,
Figure 502085DEST_PATH_IMAGE012
in order to adjust the degree of modulation,
Figure 232144DEST_PATH_IMAGE014
is the collector current of the IGBT;
the conduction loss of the diode is:
Figure 635443DEST_PATH_IMAGE016
in the formula (I), the compound is shown in the specification,
Figure 425545DEST_PATH_IMAGE018
is the no-load voltage of the freewheeling diode,
Figure 914295DEST_PATH_IMAGE020
is the on-state resistance of the freewheeling diode;
the switching losses of the IGBT are:
Figure 182465DEST_PATH_IMAGE022
in the formula (I), the compound is shown in the specification,
Figure 237009DEST_PATH_IMAGE024
is the switching frequency of the IGBT or IGBTs,
Figure 463591DEST_PATH_IMAGE026
is the phase voltage amplitude;
Figure 439637DEST_PATH_IMAGE028
、
Figure DEST_PATH_IMAGE173
、
Figure 42657DEST_PATH_IMAGE032
is a characteristic constant of the IGBT;
Figure 420549DEST_PATH_IMAGE034
rated voltage of IGBT;
the switching losses of the diodes are:
Figure 552453DEST_PATH_IMAGE036
in the formula (I), the compound is shown in the specification,
Figure 15795DEST_PATH_IMAGE038
is the switching frequency of the diode or diodes,
Figure 628698DEST_PATH_IMAGE040
、
Figure 923413DEST_PATH_IMAGE042
is the characteristic constant of the diode;
the conduction losses of the IGBT and the diode of the dc-dc module of the energy router 2 are respectively:
Figure 429480DEST_PATH_IMAGE044
Figure 911277DEST_PATH_IMAGE046
in the formula (I), the compound is shown in the specification,
Figure 590520DEST_PATH_IMAGE048
the average current flowing through the IGBT for the rated power,
Figure 677425DEST_PATH_IMAGE050
is the collector-emitter saturation voltage of the IGBT module,
Figure 416711DEST_PATH_IMAGE052
is the conduction voltage drop of the diode,
Figure 385804DEST_PATH_IMAGE054
the average current flowing through the diode is the rated power;
the switching losses of the IGBT and diode of the dc-dc module of the energy router 2 are:
Figure 540842DEST_PATH_IMAGE056
Figure 544570DEST_PATH_IMAGE058
the core loss is:
Figure DEST_PATH_IMAGE174
in the formula (I), the compound is shown in the specification,
Figure 189178DEST_PATH_IMAGE062
in order for the core to lose power density,
Figure 911146DEST_PATH_IMAGE064
is the effective volume of the magnetic core of the intermediate frequency transformer,
Figure 869875DEST_PATH_IMAGE066
is composed ofThe frequency of the square wave signal in the frequency transformer,
Figure 728110DEST_PATH_IMAGE068
is the density of the magnetic flux in the magnetic core,
Figure 543619DEST_PATH_IMAGE070
is the magnetic flux form factor;
Figure DEST_PATH_IMAGE175
、
Figure 487304DEST_PATH_IMAGE074
、
Figure 46461DEST_PATH_IMAGE076
are all coefficients, which are related to the magnetic core material of the intermediate frequency transformer;
the winding loss is:
Figure 962465DEST_PATH_IMAGE078
in the formula (I), the compound is shown in the specification,
Figure 948875DEST_PATH_IMAGE080
is the direct-current resistance of the winding,
Figure DEST_PATH_IMAGE176
is a direct current component in the winding current,
Figure 379857DEST_PATH_IMAGE084
is composed of
Figure 680388DEST_PATH_IMAGE086
The effective value of the sub-harmonic current,
Figure 513215DEST_PATH_IMAGE088
is composed of
Figure 685175DEST_PATH_IMAGE086
The alternating current-direct current resistance ratio of the winding under the sub-harmonic excitation;
the self-loss of the energy router 2 is:
Figure DEST_PATH_IMAGE177
。
in step S2, in the reactive compensation mode, the line loss saved by the power supply of the energy router 2 is:
Figure 337873DEST_PATH_IMAGE092
in the formula (I), the compound is shown in the specification,
Figure 504412DEST_PATH_IMAGE094
for the power of the energy router 2,
Figure 129429DEST_PATH_IMAGE096
in order to distribute the network voltage,
Figure 723221DEST_PATH_IMAGE098
is the resistance of the power distribution line,
Figure 66478DEST_PATH_IMAGE100
the power factor of the transformer 3 and the load 4 as a whole.
In step S2, the relationship between the phase current and the sequence current is:
Figure 771129DEST_PATH_IMAGE102
in the formula (I), the compound is shown in the specification,
Figure 578548DEST_PATH_IMAGE104
in order to be the positive-sequence current component,
Figure 280924DEST_PATH_IMAGE106
is a negative-sequence current component of the current,
Figure 173794DEST_PATH_IMAGE108
is a zero sequence current component;
Figure 416557DEST_PATH_IMAGE110
in order to be a phase-shift operator,
Figure 547324DEST_PATH_IMAGE112
；
Figure 482919DEST_PATH_IMAGE114
、
Figure 597505DEST_PATH_IMAGE116
、
Figure 581642DEST_PATH_IMAGE118
unbalanced three-phase current;
degree of current imbalance
Figure DEST_PATH_IMAGE178
Comprises the following steps:
Figure DEST_PATH_IMAGE179
in the formula (I), the compound is shown in the specification,
Figure 629232DEST_PATH_IMAGE124
is the three-phase average current;
current on neutral line
Figure 735728DEST_PATH_IMAGE126
Comprises the following steps:
Figure 540873DEST_PATH_IMAGE128
extra power loss consumed on the neutral line
Figure 391018DEST_PATH_IMAGE130
Comprises the following steps:
Figure 761956DEST_PATH_IMAGE132
in the formula (I), the compound is shown in the specification,
Figure 977037DEST_PATH_IMAGE134
in order to be a neutral line resistance, the resistance,
Figure DEST_PATH_IMAGE180
is the root mean square of the positive sequence component of the current,
Figure 803566DEST_PATH_IMAGE138
root mean square of the negative sequence component of the current;
additional power loss on phase line when three-phase current is unbalanced
Figure 191822DEST_PATH_IMAGE140
Comprises the following steps:
Figure 682846DEST_PATH_IMAGE142
in the formula (I), the compound is shown in the specification,
Figure 68828DEST_PATH_IMAGE144
a phase line resistor;
under the unbalanced three-phase load mode, the line loss that adopts energy router 2 power supply to practice thrift is:
Figure DEST_PATH_IMAGE181
。
in step S2, the loss of the transformer 3 itself is:
Figure DEST_PATH_IMAGE182
in the formula (I), the compound is shown in the specification,
Figure 176462DEST_PATH_IMAGE150
in order to be a load loss, the load,
Figure 368408DEST_PATH_IMAGE152
is the reactive power of the transformer 3 and,
Figure 448360DEST_PATH_IMAGE154
for the losses of the transformer 3 measured during nominal voltage operation,
Figure 270822DEST_PATH_IMAGE156
in order to be rated for the load loss,
Figure 334593DEST_PATH_IMAGE158
for the load factor at which the transformer 3 operates,
Figure 267914DEST_PATH_IMAGE160
in order to be the capacity of the transformer 3,
Figure DEST_PATH_IMAGE183
is the percentage of the load current of the transformer 3,
Figure 999110DEST_PATH_IMAGE164
is the impedance voltage percentage of the transformer 3.
In step S3, the difference between the loss at the time of access of the energy router 2 and the loss at the time of access of the transformer 3 is calculated
Figure 992474DEST_PATH_IMAGE166
：
Figure 543541DEST_PATH_IMAGE168
When in use
Figure 811711DEST_PATH_IMAGE170
When the energy router is started, the first change-over switch 5 is closed, and the energy router 2 is selected to supply power to the load 4;
when the temperature is higher than the set temperature
Figure 69517DEST_PATH_IMAGE172
And when the power supply is started, the second selector switch 6 is closed, and the power supply for the load 4 is selected through the transformer 3.
An energy router and transformer parallel system comprises a power supply 1, an energy router 2, a transformer 3, a load 4 and a control analysis module, wherein the power supply 1 sequentially passes through the energy router 2 and a first change-over switch 5 and then is connected with the load 4 through a common bus 7, the power supply 1 sequentially passes through the transformer 3 and a second change-over switch 6 and then is connected with the load 4 through the common bus 7, the control analysis module is connected with the energy router 2, the transformer 3, the first change-over switch 5 and the second change-over switch 6, and the control analysis module is used for judging whether the system needs to enter a reactive compensation mode through a power factor, judging whether the system is in a three-phase load unbalance mode through three-phase current unbalance, calculating loss when the energy router 2 is connected and loss when the transformer 3 is connected, and controlling the first change-over switch 5 through comparing the loss when the energy router 2 is connected with the loss when the transformer 3 is connected, And the second switch 6 is turned on and off.
The principle of the invention is illustrated as follows:
firstly, the input end of the energy router consists of a voltage source converter, and the voltage source converter can independently adjust the power factor in the power distribution network to ensure that the power distribution network keeps operating at the whole power factor, so that the voltage drop on the power distribution line can be compensated, and the active power transmission loss of the power distribution network is reduced; secondly, when unbalanced load operation produces three-phase unbalanced current in the distribution network, the energy router can make the three-phase current of distribution network keep balance by injecting negative sequence compensating current into the distribution network or adopting the topology design that can adapt to three-phase unbalanced current, thereby reduces the extra loss on distribution network phase line and neutral line brought by unbalanced current.
The parallel system has three working modes, namely a three-phase load balancing mode, a reactive compensation mode and a three-phase load unbalance mode. Three-phase load balancing mode: the three-phase load is basically symmetrical, reactive compensation is not needed, the energy router basically runs in a no-load mode at the moment, and the load is supplied with power by a traditional transformer. And a reactive compensation mode: the load is an inductive load, the energy router supplies power and completes a reactive compensation function, and the traditional transformer is in no-load; in the mode, the load is a large inductive load, and because the voltage and the current of the load are asynchronous, if a traditional transformer is adopted, the phase difference between the voltage and the current of the distribution network is large, and the line loss on the power transmission line is large; therefore, the energy router is adopted to supply power to the load, reactive power absorbed by the load can be completely compensated by the energy router, and therefore, the terminal voltage and the current phase of the power distribution network can be completely synchronized, and the line loss of the power distribution network can be greatly reduced in the case. Three-phase load unbalance mode: the load is three-phase asymmetric, the energy router supplies power and completes three-phase current asymmetric compensation, and three-phase symmetric operation is realized; remote rural areas, industrial plants and mining power supply enterprise power distribution networks or electric railway power distribution systems, wherein a large number of single-phase loads are continuously operated, and an energy router can compensate three-phase unbalanced loads in the power distribution networks to adjust the loads to realize three-phase symmetrical operation, so that extra loss on a power distribution line is reduced.
The corresponding current three-phase unbalance degree and the additional loss caused by the three-phase unbalance degree are corresponding no matter how the three-phase unbalance current changes; therefore, no matter what the respective values of the three-phase currents are, the loss reduced by introducing the power distribution network into the energy router under different three-phase imbalances can be analyzed by using the current imbalance as a uniform variable.
Example (b):
referring to fig. 1, a control method of an energy router and transformer parallel system includes the following steps:
s1, connecting the power supply 1 to the load 4 through the energy router 2, the first change-over switch 5 and the common bus 7, and connecting the power supply 1 to the load 4 through the transformer 3, the second change-over switch 6 and the common bus 7; meanwhile, the second change-over switch 6 is closed, and the power supply 1 supplies power to the load 4 through the transformer 3;
s2, calculating the loss of the energy router 2 during access and the loss of the transformer 3 during access;
calculating the loss of the energy router 2 when the energy router 2 is accessed through the self loss of the energy router 2 and the line loss saved by adopting the power supply of the energy router 2; the self loss of the energy router 2 comprises conduction loss and switching loss of power electronic switching devices of an alternating current-direct current module and a direct current-alternating current module, conduction loss and switching loss of the power electronic switching devices of the direct current-direct current module, and magnetic core loss and winding loss of an intermediate frequency transformer;
the power electronic switching devices of the AC-DC module and the DC-AC module of the energy router 2 comprise an IGBT and a diode;
the turn-on loss of the IGBT is:
Figure 30520DEST_PATH_IMAGE002
in the formula (I), the compound is shown in the specification,
Figure 803304DEST_PATH_IMAGE004
the holding voltage of the IGBT is provided,
Figure 78427DEST_PATH_IMAGE006
the loading rate is 0-100%,
Figure 518636DEST_PATH_IMAGE008
for the magnitude of the phase current,
Figure DEST_PATH_IMAGE184
is the forward on-resistance of the IGBT,
Figure DEST_PATH_IMAGE185
the degree of modulation is 0 to 100%,
Figure 919049DEST_PATH_IMAGE014
is the collector current of the IGBT;
the conduction loss of the diode is:
Figure 179129DEST_PATH_IMAGE016
in the formula (I), the compound is shown in the specification,
Figure 992364DEST_PATH_IMAGE018
is the no-load voltage of the freewheeling diode,
Figure 287079DEST_PATH_IMAGE020
to continueAn on-resistance of the flow diode;
the switching losses of the IGBT are:
Figure 527568DEST_PATH_IMAGE022
in the formula (I), the compound is shown in the specification,
Figure 540523DEST_PATH_IMAGE024
is the switching frequency of the IGBT,
Figure 954187DEST_PATH_IMAGE026
is the phase voltage amplitude;
Figure 41092DEST_PATH_IMAGE028
、
Figure 780378DEST_PATH_IMAGE030
、
Figure 749471DEST_PATH_IMAGE032
the characteristic constant of the IGBT can be obtained by fitting a switching loss and collector current characteristic curve and an IGBT switching recovery loss characteristic curve provided by IGBT manufacturers;
Figure 904508DEST_PATH_IMAGE034
rated voltage of IGBT;
the switching losses of the diodes are:
Figure 173816DEST_PATH_IMAGE036
in the formula (I), the compound is shown in the specification,
Figure 756107DEST_PATH_IMAGE038
is the switching frequency of the diode or diodes,
Figure 478075DEST_PATH_IMAGE040
、
Figure 233541DEST_PATH_IMAGE042
the characteristic constant of the diode can be obtained by fitting a switching loss and collector current characteristic curve and a diode switching recovery loss characteristic curve provided by a diode manufacturer;
the conduction losses of the IGBT and the diode of the dc-dc module of the energy router 2 are respectively:
Figure DEST_PATH_IMAGE186
Figure 91776DEST_PATH_IMAGE046
in the formula (I), the compound is shown in the specification,
Figure 110548DEST_PATH_IMAGE048
the average current flowing through the IGBT for the rated power,
Figure 54233DEST_PATH_IMAGE050
is the collector-emitter saturation voltage of the IGBT module,
Figure 613390DEST_PATH_IMAGE052
is the conduction voltage drop of the diode,
Figure 529394DEST_PATH_IMAGE054
the average current flowing through the diode for rated power;
the switching losses of the IGBT and diode of the dc-dc module of the energy router 2 are:
Figure 781383DEST_PATH_IMAGE056
Figure 415627DEST_PATH_IMAGE058
the core loss is expressed as the modified Steinmetz equation:
Figure 512896DEST_PATH_IMAGE174
in the formula (I), the compound is shown in the specification,
Figure 345723DEST_PATH_IMAGE062
in order for the core to lose power density,
Figure 706297DEST_PATH_IMAGE064
is the effective volume of the magnetic core of the intermediate frequency transformer,
Figure 627504DEST_PATH_IMAGE066
the frequency of the square wave signal in the intermediate frequency transformer,
Figure 528464DEST_PATH_IMAGE068
is the density of the magnetic flux in the magnetic core,
Figure 419060DEST_PATH_IMAGE070
is the magnetic flux form factor;
Figure 12852DEST_PATH_IMAGE175
、
Figure 356109DEST_PATH_IMAGE074
、
Figure 60760DEST_PATH_IMAGE076
both Steinmetz coefficients, which are related to the core material of the intermediate frequency transformer;
the winding loss is:
Figure DEST_PATH_IMAGE187
in the formula (I), the compound is shown in the specification,
Figure 602599DEST_PATH_IMAGE080
is the direct-current resistance of the winding,
Figure 367293DEST_PATH_IMAGE176
is a direct current component in the winding current,
Figure 994583DEST_PATH_IMAGE084
is composed of
Figure 175029DEST_PATH_IMAGE086
The effective value of the sub-harmonic current,
Figure 102534DEST_PATH_IMAGE088
is composed of
Figure 975812DEST_PATH_IMAGE086
The AC/DC resistance ratio of the winding under subharmonic excitation;
the self-loss of the energy router 2 is:
Figure 90398DEST_PATH_IMAGE177
in the reactive compensation mode, the line loss saved by adopting the power supply of the energy router 2 is as follows:
Figure 136852DEST_PATH_IMAGE092
in the formula (I), the compound is shown in the specification,
Figure 856546DEST_PATH_IMAGE094
is the power of the energy router 2 and,
Figure 963042DEST_PATH_IMAGE096
in order to distribute the network voltage,
Figure 564925DEST_PATH_IMAGE098
is the resistance of the distribution line and,
Figure 352752DEST_PATH_IMAGE100
the power factor of the transformer 3 and the load 4 as a whole;
suppose that the unbalanced three-phase currents of the distribution network are respectively
Figure 989270DEST_PATH_IMAGE114
、
Figure 204351DEST_PATH_IMAGE116
And
Figure 27950DEST_PATH_IMAGE118
which can be converted into positive sequence current components respectively according to a symmetrical component method
Figure 681786DEST_PATH_IMAGE104
Negative sequence current component
Figure 110493DEST_PATH_IMAGE106
And zero sequence current component
Figure 558792DEST_PATH_IMAGE108
The relationship between phase current and sequence current is:
Figure 338529DEST_PATH_IMAGE102
in the formula (I), the compound is shown in the specification,
Figure 256108DEST_PATH_IMAGE104
is a component of the positive-sequence current,
Figure 601638DEST_PATH_IMAGE106
is a negative-sequence current component of the current,
Figure 424101DEST_PATH_IMAGE108
is a zero sequence current component;
Figure 753451DEST_PATH_IMAGE110
in order to be a phase-shift operator,
Figure 483510DEST_PATH_IMAGE112
；
Figure 886809DEST_PATH_IMAGE114
、
Figure 676911DEST_PATH_IMAGE116
、
Figure 962398DEST_PATH_IMAGE118
unbalanced three-phase current;
degree of current imbalance
Figure 699410DEST_PATH_IMAGE178
Comprises the following steps:
Figure 753954DEST_PATH_IMAGE179
in the formula (I), the compound is shown in the specification,
Figure 714957DEST_PATH_IMAGE124
is the three-phase average current;
current on neutral line
Figure 691003DEST_PATH_IMAGE126
Comprises the following steps:
Figure 28443DEST_PATH_IMAGE128
additional power loss consumed on the neutral line
Figure 140756DEST_PATH_IMAGE130
Comprises the following steps:
Figure 272660DEST_PATH_IMAGE132
in the formula (I), the compound is shown in the specification,
Figure 532740DEST_PATH_IMAGE134
in order to be a neutral line resistance, the resistance,
Figure 611554DEST_PATH_IMAGE136
is the root mean square of the positive sequence component of the current,
Figure 640690DEST_PATH_IMAGE138
root mean square of the negative sequence component of the current;
additional power loss on phase line when three-phase current is unbalanced
Figure DEST_PATH_IMAGE188
Comprises the following steps:
Figure 677916DEST_PATH_IMAGE142
in the formula (I), the compound is shown in the specification,
Figure 690872DEST_PATH_IMAGE144
a phase line resistor;
under the unbalanced three-phase load mode, the line loss that adopts energy router 2 power supply to practice thrift is:
Figure 307798DEST_PATH_IMAGE181
calculating the loss of the transformer 3 when the transformer 3 is accessed through the loss of the transformer 3;
the self-losses of the transformer 3 are:
Figure 725528DEST_PATH_IMAGE182
in the formula (I), the compound is shown in the specification,
Figure 199235DEST_PATH_IMAGE150
in order to be a load loss, the load,
Figure 168328DEST_PATH_IMAGE152
is the reactive power of the transformer 3 and,
Figure 588945DEST_PATH_IMAGE154
for the losses of the transformer 3 measured during nominal voltage operation,
Figure 592673DEST_PATH_IMAGE156
in order to be rated for the load loss,
Figure 440544DEST_PATH_IMAGE158
for the load factor at which the transformer 3 operates,
Figure 162512DEST_PATH_IMAGE160
in order to be the capacity of the transformer 3,
Figure 917978DEST_PATH_IMAGE183
is the percentage of the load current of the transformer 3,
Figure 979475DEST_PATH_IMAGE164
is the impedance voltage percentage of the transformer 3;
s3, comparing the loss of the energy router 2 during access with the loss of the transformer 3 during access, and selecting the access energy router 2 or the transformer 3 to supply power for the load 4 according to the comparison result;
calculating the difference between the loss of the energy router 2 and the loss of the transformer 3
Figure 60564DEST_PATH_IMAGE166
：
Figure 738670DEST_PATH_IMAGE168
When in use
Figure 501089DEST_PATH_IMAGE170
When the energy router is started, the first change-over switch 5 is closed, and the energy router 2 is selected to supply power to the load 4;
when the temperature is higher than the set temperature
Figure 479410DEST_PATH_IMAGE172
And when the power supply is started, the second selector switch 6 is closed, and the power supply for the load 4 is selected through the transformer 3.
Referring to fig. 2, an energy router and transformer parallel system comprises a power supply 1, an energy router 2, a transformer 3, a load 4 and a control analysis module, wherein the power supply 1 sequentially passes through the energy router 2 and a first change-over switch 5 and then is connected with the load 4 through a common bus 7, the power supply 1 sequentially passes through the transformer 3 and a second change-over switch 6 and then is connected with the load 4 through the common bus 7, the control analysis module is connected with the energy router 2, the transformer 3, the first change-over switch 5 and the second change-over switch 6, the control analysis module (acquiring electric energy characteristic information such as voltage, current, phase and frequency) is used for judging whether the system needs to enter a reactive compensation mode through a power factor, judging whether the system is in a three-phase load unbalance mode through a three-phase current unbalance degree, and calculating loss when the energy router 2 is connected and loss when the transformer 3 is connected, and the on and off of the first change-over switch 5 and the second change-over switch 6 are controlled by comparing the loss when the energy router 2 is accessed with the loss when the transformer 3 is accessed.

Claims (8)

1. A control method of an energy router and transformer parallel system is characterized by comprising the following steps:
s1, connecting the power supply (1) to a load (4) through the energy router (2), the first selector switch (5) and the common bus (7), and connecting the power supply (1) to the load (4) through the transformer (3), the second selector switch (6) and the common bus (7); meanwhile, the second switch (6) is closed, and the power supply (1) supplies power to the load (4) through the transformer (3);
s2, calculating the loss of the energy router (2) during access and the loss of the transformer (3) during access;
and S3, comparing the loss when the energy router (2) is accessed with the loss when the transformer (3) is accessed, and selecting to access the energy router (2) or the transformer (3) to supply power for the load (4) according to the comparison result.
2. The method for controlling the energy router and transformer parallel system according to claim 1, wherein:
in step S2, the loss of the energy router (2) during access is calculated according to the loss of the energy router (2) and the line loss saved by adopting the power supply of the energy router (2); the self loss of the energy router (2) comprises conduction loss and switching loss of power electronic switching devices of an alternating current-direct current module and a direct current-alternating current module, conduction loss and switching loss of the power electronic switching devices of the direct current-direct current module, and magnetic core loss and winding loss of an intermediate frequency transformer;
the loss of the transformer (3) during access is calculated through the loss of the transformer (3).
3. The method for controlling the energy router and transformer parallel system according to claim 2, wherein:
the power electronic switching devices of the alternating current-direct current module and the direct current-alternating current module of the energy router (2) comprise an IGBT and a diode;
the turn-on loss of the IGBT is:
Figure DEST_PATH_IMAGE001
in the formula (I), the compound is shown in the specification,
Figure 59017DEST_PATH_IMAGE002
the holding voltage of the IGBT is provided,
Figure DEST_PATH_IMAGE003
in order to obtain the load factor,
Figure 304054DEST_PATH_IMAGE004
for the magnitude of the phase current,
Figure DEST_PATH_IMAGE005
is the forward on-resistance of the IGBT,
Figure 552633DEST_PATH_IMAGE006
in order to modulate the degree of the modulation,
Figure DEST_PATH_IMAGE007
is the collector current of the IGBT;
the conduction loss of the diode is:
Figure 275738DEST_PATH_IMAGE008
in the formula (I), the compound is shown in the specification,
Figure DEST_PATH_IMAGE009
is the no-load voltage of the freewheeling diode,
Figure 683586DEST_PATH_IMAGE010
is the on-state resistance of the freewheeling diode;
the switching losses of the IGBT are:
Figure DEST_PATH_IMAGE011
in the formula (I), the compound is shown in the specification,
Figure 709310DEST_PATH_IMAGE012
is the switching frequency of the IGBT,
Figure DEST_PATH_IMAGE013
is the phase voltage amplitude;
Figure 569819DEST_PATH_IMAGE014
、
Figure DEST_PATH_IMAGE015
、
Figure 96615DEST_PATH_IMAGE016
is a characteristic constant of the IGBT;
Figure DEST_PATH_IMAGE017
rated voltage of IGBT;
the switching losses of the diodes are:
Figure 968756DEST_PATH_IMAGE018
in the formula (I), the compound is shown in the specification,
Figure DEST_PATH_IMAGE019
is the switching frequency of the diode or diodes,
Figure 555596DEST_PATH_IMAGE020
、
Figure DEST_PATH_IMAGE021
is the characteristic constant of the diode;
the conduction losses of the IGBT and the diode of the direct current-direct current module of the energy router (2) are respectively as follows:
Figure 637821DEST_PATH_IMAGE022
Figure DEST_PATH_IMAGE023
in the formula (I), the compound is shown in the specification,
Figure 843674DEST_PATH_IMAGE024
the average current flowing through the IGBT for the rated power,
Figure DEST_PATH_IMAGE025
is the collector-emitter saturation voltage of the IGBT module,
Figure 709604DEST_PATH_IMAGE026
is the conduction voltage drop of the diode,
Figure DEST_PATH_IMAGE027
the average current flowing through the diode is the rated power;
the switching losses of the IGBT and the diode of the direct current-direct current module of the energy router (2) are respectively as follows:
Figure 608290DEST_PATH_IMAGE028
Figure DEST_PATH_IMAGE029
the core loss is:
Figure 443391DEST_PATH_IMAGE030
in the formula (I), the compound is shown in the specification,
Figure DEST_PATH_IMAGE031
in order for the core to lose power density,
Figure 46411DEST_PATH_IMAGE032
is the effective volume of the magnetic core of the intermediate frequency transformer,
Figure DEST_PATH_IMAGE033
the frequency of the square wave signal in the intermediate frequency transformer,
Figure 158723DEST_PATH_IMAGE034
is the density of the magnetic flux in the magnetic core,
Figure DEST_PATH_IMAGE035
is the magnetic flux form factor;
Figure 821786DEST_PATH_IMAGE036
、
Figure DEST_PATH_IMAGE037
、
Figure 19549DEST_PATH_IMAGE038
are all coefficients, which are related to the magnetic core material of the intermediate frequency transformer;
the winding loss is:
Figure DEST_PATH_IMAGE039
in the formula (I), the compound is shown in the specification,
Figure 426259DEST_PATH_IMAGE040
is the direct-current resistance of the winding,
Figure DEST_PATH_IMAGE041
is a direct current component in the winding current,
Figure 517712DEST_PATH_IMAGE042
is composed of
Figure DEST_PATH_IMAGE043
The effective value of the sub-harmonic current,
Figure 492621DEST_PATH_IMAGE044
is composed of
Figure 36735DEST_PATH_IMAGE043
The AC/DC resistance ratio of the winding under subharmonic excitation;
the self loss of the energy router (2) is as follows:
Figure DEST_PATH_IMAGE045
。
4. the method for controlling the energy router and transformer parallel system according to claim 3, wherein:
in step S2, in the reactive compensation mode, the line loss saved by the power supply of the energy router (2) is:
Figure 388082DEST_PATH_IMAGE046
in the formula (I), the compound is shown in the specification,
Figure DEST_PATH_IMAGE047
is the power of the energy router (2),
Figure 68462DEST_PATH_IMAGE048
in order to distribute the network voltage,
Figure DEST_PATH_IMAGE049
is the resistance of the distribution line and,
Figure 341836DEST_PATH_IMAGE050
the power factor of the whole of the transformer (3) and the load (4).
5. The method for controlling the energy router and transformer parallel system according to claim 3, wherein:
in step S2, the relationship between the phase current and the sequence current is:
Figure DEST_PATH_IMAGE051
in the formula (I), the compound is shown in the specification,
Figure 248612DEST_PATH_IMAGE052
in order to be the positive-sequence current component,
Figure DEST_PATH_IMAGE053
is a negative-sequence current component of the current,
Figure 262705DEST_PATH_IMAGE054
is a zero sequence current component;
Figure DEST_PATH_IMAGE055
in order to be a phase-shift operator,
Figure 63170DEST_PATH_IMAGE056
；
Figure DEST_PATH_IMAGE057
、
Figure 645461DEST_PATH_IMAGE058
、
Figure DEST_PATH_IMAGE059
unbalanced three-phase current;
degree of current imbalance
Figure 898588DEST_PATH_IMAGE060
Comprises the following steps:
Figure DEST_PATH_IMAGE061
in the formula (I), the compound is shown in the specification,
Figure 591738DEST_PATH_IMAGE062
is the three-phase average current;
current on neutral line
Figure DEST_PATH_IMAGE063
Comprises the following steps:
Figure 981131DEST_PATH_IMAGE064
extra power loss consumed on the neutral line
Figure DEST_PATH_IMAGE065
Comprises the following steps:
Figure 858957DEST_PATH_IMAGE066
in the formula (I), the compound is shown in the specification,
Figure DEST_PATH_IMAGE067
in order to be a neutral line resistance, the resistance,
Figure 474746DEST_PATH_IMAGE068
is the root mean square of the positive sequence component of the current,
Figure DEST_PATH_IMAGE069
root mean square of the negative sequence component of the current;
additional power loss on phase line when three-phase current is unbalanced
Figure 96220DEST_PATH_IMAGE070
Comprises the following steps:
Figure DEST_PATH_IMAGE071
in the formula (I), the compound is shown in the specification,
Figure 605699DEST_PATH_IMAGE072
a phase line resistor;
under the three-phase load unbalanced mode, the line loss saved by adopting the power supply of the energy router (2) is as follows:
Figure DEST_PATH_IMAGE073
。
6. the method for controlling the energy router and transformer parallel system according to claim 4 or 5, wherein:
in step S2, the loss of the transformer (3) itself is:
Figure 264213DEST_PATH_IMAGE074
in the formula (I), the compound is shown in the specification,
Figure DEST_PATH_IMAGE075
in order to be a load loss, the load,
Figure 494862DEST_PATH_IMAGE076
is the reactive power of the transformer (3),
Figure DEST_PATH_IMAGE077
for the losses of the transformer (3) measured during nominal voltage operation,
Figure 529814DEST_PATH_IMAGE078
in order to be rated for the load loss,
Figure DEST_PATH_IMAGE079
is the load factor when the transformer (3) is running,
Figure 159379DEST_PATH_IMAGE080
is the capacity of the transformer (3),
Figure DEST_PATH_IMAGE081
is the percentage of the load current of the transformer (3),
Figure 113428DEST_PATH_IMAGE082
is the impedance voltage percentage of the transformer (3).
7. The method for controlling the energy router and transformer parallel system according to claim 6, wherein:
in step S3, the difference between the loss at the time of access of the energy router (2) and the loss at the time of access of the transformer (3) is calculated
Figure DEST_PATH_IMAGE083
：
Figure 703810DEST_PATH_IMAGE084
When in use
Figure DEST_PATH_IMAGE085
When the energy router is started, the first switch (5) is closed, and the energy router (2) is selected to supply power to the load (4);
when in use
Figure 401507DEST_PATH_IMAGE086
And when the load is in use, the second switch (6) is closed, and the power supply for the load (4) is selected through the transformer (3).
8. An energy router and transformer parallel system applied to the control method of any one of claims 1-7, wherein: the system comprises a power supply (1), an energy router (2), a transformer (3), a load (4) and a control analysis module, wherein the power supply (1) sequentially passes through the energy router (2) and a first change-over switch (5) and then is connected with the load (4) through a common bus (7), the power supply (1) sequentially passes through the transformer (3) and a second change-over switch (6) and then is connected with the load (4) through the common bus (7), the control analysis module is connected with the energy router (2), the transformer (3), the first change-over switch (5) and the second change-over switch (6), and the control analysis module is used for judging whether the system needs to enter a reactive compensation mode through a power factor, judging whether the system is in a three-phase load unbalance mode through a three-phase current unbalance degree and calculating loss when the energy router (2) is connected and loss when the transformer (3) is connected, and the on and off of the first change-over switch (5) and the second change-over switch (6) are controlled by comparing the loss when the energy router (2) is connected with the loss when the transformer (3) is connected.
CN202210928807.6A 2022-08-03 2022-08-03 Energy router and transformer parallel system and control method thereof Pending CN115001047A (en)

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Application publication date: 20220902