CN110854882B - Device and method for controlling demand of double-power supply system - Google Patents
Device and method for controlling demand of double-power supply system Download PDFInfo
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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
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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
- H02J3/04—Circuit arrangements for ac mains or ac distribution networks for connecting networks of the same frequency but supplied from different sources
- H02J3/06—Controlling transfer of power between connected networks; Controlling sharing of load between connected networks
Abstract
The invention discloses a device and a method for demand control of a double-circuit power supply system, wherein a power tide regulator consisting of an isolation transformer, a series-side inverter and a parallel-side inverter is connected in parallel on a spare power automatic switching bus-bar switch between two power supply buses of the double-circuit power supply system, and when the sum of two real-time demands in the double-circuit power supply exceeds a total demand limit value, the energy of one power supply bus is transferred to the other power supply bus by the power tide regulator, so that the sum of the total demands of the system, namely the demand of a user metering point is reduced, the basic electric charge is reduced, and the electric energy demand of a load can be ensured to be met. The invention can solve various problems faced by other demand controllers in the current market, such as reducing the demand by reducing the load power, influencing the load stability and the like, reducing the control difficulty and the equipment maintenance amount, prolonging the service life of the equipment and having good economic benefit.
Description
Technical Field
The invention relates to the field of power supply and distribution, in particular to a device and a method for controlling demand of a double-circuit power supply system.
Background
The electricity charge is one of the main costs of industrial enterprises, particularly large industrial users, the reasonable and orderly power load management can enhance the economy of the power consumption of the enterprises, maintain the economic operation of the power supply and distribution network of the enterprises, improve the economic benefits of the enterprises and be beneficial to the implementation of the comprehensive resource planning of the enterprises. At present, for users with the capacity of a power receiving transformer not less than 315kVA in large-scale industrial enterprise users in China, according to the current electricity price system, the users need to execute industrial electricity prices and execute two electricity making prices, and the charging of basic electricity charges can be measured by adopting the installed capacity of the transformer or according to the maximum demand.
The electric charge comprises basic electric charge, electric power charge and power rate adjustment charge, wherein the basic electric charge is declared monthly and is charged according to unit kVA/month based on a metering mode of maximum demand; the international maximum demand is the average power of 15 minutes, and the maximum value (MD) of the average power of 15 minutes in the month is taken as the basis for calculating the basic electricity fee.
In addition, the national code "design code of power supply and distribution system" GB 50052-95 states that the primary load should be supplied by two power sources, and when one power source fails, the other power source should not be damaged at the same time. When two-way power supply is used, two-way power supply can be used for one or more than one, and can also work simultaneously, and each can be used for supplying a part of load. When the power supply load of the double-circuit power supply is calculated, the operation load (primary load and secondary load) of each circuit is considered according to 100 percent (different from the double power supply is 70 percent), and a spare power automatic switching bus-coupler switch is arranged between the two circuits for automatic switching. Therefore, for large-power-consumption places, the two-way power supply is adopted for supplying power, and the basic power cost is calculated according to the maximum demand, and the total maximum demand of the system is equal to the sum of the independent maximum demands of each loop.
Generally, large-scale industrial enterprise power consumers have impact on the operation of a power grid due to complex equipment, high power consumption and severe load fluctuation, mainly show that voltage flicker is caused, negative sequence current and harmonic are generated, even the stability of the power grid is damaged, and meanwhile, basic electricity charges of the consumers are wasted. Therefore, such enterprises need to monitor the power consumption of the whole enterprise, reasonably arrange the operation modes of all the processes, particularly effectively control the processes of the impact load, select to avoid the simultaneous starting or operation of high-power equipment as much as possible, or reasonably adjust the power of the equipment, properly reduce the power of certain equipment which does not affect the production when the loads are overlapped, reduce the peak load of the enterprise, and achieve the purposes of stabilizing the loads and reducing the basic electric charge expenditure.
The traditional mode is that the demand of an enterprise is controlled by a power demand control system, and the reasonable allocation of the power consumption of the enterprise is completed by means of power reduction, power delay, power removal and the like, so that the influence of impact current on power equipment is reduced, the power consumption quality of the enterprise is improved, and the power consumption cost of the enterprise is reduced. At present, at home and abroad, the power demand control system is widely applied to the energy conservation and power saving aspects of enterprises, and the economic benefits of energy conservation and cost reduction are obvious.
The traditional power demand control method mainly comprises the following steps: and after the power data of the system is acquired and comprehensively analyzed, the maximum demand is predicted, and the load is adjusted. This method often has the following problems in implementing demand control: the method of interrupting power supply to the load or reducing the power of the load often seriously affects the normal operation of production, causes great inconvenience to the execution and scheduling of production plan, and causes that the demand control technology is difficult to popularize generally.
Moreover, the method is not really 'peak shifting and valley filling', only 'peak clipping' is realized, and the required 'valley point' is not really utilized; in addition, the demand is reduced by controlling the load and reducing the load power, which may cause unstable product quality, and finally cause material waste and increase production cost.
Therefore, a more efficient and convenient demand control technology is needed, and under the premise of not affecting normal production of users, peak shifting and valley filling are realized in the true sense, so that the demand of electric power on the load side can be met, the load operation is stable, the total demand of a power supply system can be reduced, and the power utilization cost is finally reduced.
Disclosure of Invention
In order to solve the problems, the invention provides a device for controlling demand of a two-way power supply system, which is connected in parallel to a spare power automatic switching bus-tie switch between two buses of the two-way power supply system, is a power tide current regulator, comprises a series coupling transformer, a series side inverter, a parallel side inverter, an inlet wire switch, an outlet wire switch and a spare power automatic switching switch, and is used for controlling the sum of the maximum demand of the two-way power supply system, reducing the demand of a user metering point and further reducing basic electric charge.
Preferably, the secondary side of the series coupling transformer is connected in parallel to two ends of the automatic bus tie switch, one end of the secondary side is connected with one path of power supply bus of the double-path power supply system, and the other end of the secondary side is connected with the other path of power supply bus; the primary side of the series coupling transformer is connected with the series side inverter, and the series side inverter can adjust the amplitude and the phase of output voltage and bidirectionally adjust active power between two paths of power supply systems; the parallel side inverter of one path of power supply system arranged at one end of the spare power automatic switching bus-coupled switch is connected with the power supply bus of the path in parallel, and is used for stabilizing the direct current bus voltage of the series side inverter and the parallel side inverter and controlling the flow of reactive power between the buses of the two paths of power supply systems; the series-side inverter and the parallel-side inverter are connected by a common direct-current bus.
Preferably, the series-side inverter and the parallel-side inverter are composed of a three-phase full-bridge power circuit capable of realizing bidirectional power flow, and the topology of the three-phase full-bridge power circuit is two levels or cascade multi-level.
Preferably, an energy storage device is added to a common direct current bus of the series side inverter and the parallel side inverter, and the flexibility of demand control of the two-way power supply system is further realized through charging and discharging of the energy storage device.
Preferably, the output voltage of the series coupling transformer is dynamically regulated, so that the amplitude variation range is 0-maximum and the phase angle variation range is 0-360 degrees, thereby realizing the bidirectional regulation of the transmission power between the two power supply systems in a fixed range, finally realizing the control of the sum of the maximum demands of the two power supply systems and controlling the sum of the demands of the two power supply systems to be at a target value; wherein the control of the dc bus voltage and the system reactive power is achieved by a parallel side inverter of the device.
In order to solve the above problems, the present invention provides a method for controlling the above apparatus, which is characterized in that the amplitude and phase of the voltage at two ends of the series coupling transformer are dynamically adjusted to realize the adjustment of the output power of the two power supply systems within a fixed range, and the requirement of the sum of the demand of the two power supply systems is realized, and the method specifically includes the following steps:
the power and the demand of the two power supplies of the two-way power supply system are monitored for a long time, the maximum demand value and the demand curve of each way are obtained, and the optimal limit value of the sum of the demands of the two power supply systems is determined.
The method comprises the steps of detecting incoming line voltage and current of each system on two sides of a bus-tie spare power automatic switching switch, calculating power of two power supply systems, superposing demand values obtained by real-time calculation of two power supplies according to the requirement of overall control of system demand, carrying out closed-loop control on a difference value between the sum of the real-time demand and a total demand limiting target value to obtain secondary side voltage variation of a series coupling transformer to be regulated, obtaining a series compensation voltage value to be compensated according to the relation between the voltage variation and the series compensation voltage, and finally obtaining the required series compensation voltage through voltage and current closed-loop control of a series side inverter.
Preferably, the series-side inverter solves the problem of voltage and phase adjustment through closed-loop control, and specifically includes the following steps:
(1) acquiring a voltage phase of a power supply bus end at a series side through a phase-locked loop (PLL);
(2) collecting voltage and current on a power supply bus at the inverter end of the series side, calculating real-time active and reactive power, comparing the real-time active and reactive power with a given active/reactive limit value, calculating amplitude and phase angle on the basis of considering voltage and current amplitude limits and the like by an offset amplifier and a voltage limiter to obtain UpqThe controller is a PI controller;
(3) the control quantity of the closed loop output directly controls the gate drive of the power device to realize the final control requirement.
Preferably, the parallel side inverter solves the reactive power control problem and the direct current end voltage stabilization problem through closed-loop control, and specifically includes the following steps:
(1) acquiring a voltage phase of a power supply bus end at a parallel side through a phase-locked loop (PLL);
(2) collecting voltage and current of a power supply bus at the inverter end of the parallel side, calculating a power factor, performing closed-loop control by giving the power factor as 1, and adjusting reactive power component in real time; or extracting the output current positive sequence component of the power supply bus at the end, detecting the difference between the feedback reactive current positive sequence component and the reactive current given value, and respectively performing closed-loop control on dq axes, wherein the controller is a PI controller;
(3) detecting the difference between the fed-back direct current bus voltage and a given value, and realizing the stable control of the direct current bus voltage through voltage and current closed-loop control, wherein the controller is a PI controller according to the requirement;
(4) in order to improve the stability and the dynamic response performance of the inverter, a current loop is added, a voltage instruction from the current loop is modulated by SVPWM to obtain a corresponding PWM signal, and the corresponding IGBT module is driven by isolation amplification.
Compared with the prior art, the invention has the following advantages:
(1) the invention provides a device and a method for controlling demand of a double-power supply system, which can avoid upgrading and reconstructing two paths of distribution transformers, not only can not cause waste of old equipment, but also can effectively reduce the total power demand.
(2) According to the invention, the real 'peak shifting and valley filling' is realized by carrying out power monitoring, demand forecasting and real-time power control on the two power supply buses of the two-way power supply system, namely, the demand 'peak' value on one power supply is transferred to the demand 'valley' value on the other power supply, so that the sum of the maximum demand of each power supply system and the demand of the system is reduced, the total power demand of the load is ensured to be unchanged, and the running stability of each load is ensured.
(3) The demand regulation is carried out by adopting the power electronic device, and the quick switching device is selected, so that the system has high response speed and high control precision, avoids frequent action on a mechanical structure in the traditional demand control mode, reduces mechanical abrasion and prolongs the service life of each load device.
(4) The invention is directly installed at two ends of the spare power automatic switching bus coupler switch of two paths of power supply buses, has simple connection mode, can be quickly cut off when in fault, does not influence the work of the original system, and is safe and reliable.
Drawings
FIG. 1 is a block diagram of an embodiment of an apparatus for demand control for a dual power supply system of the present invention;
FIG. 2 is a schematic diagram of the apparatus of the present invention for demand control of a dual power supply system;
FIG. 3 shows a simplified control diagram and vector diagram of the apparatus of the present invention for demand control of a dual power supply system;
FIG. 4 illustrates the active and reactive power operating ranges for a dual power system demand control implemented by the apparatus of the present invention;
FIG. 5 illustrates a block diagram of a strategy for implementing demand control for a dual power supply system in accordance with the present invention;
fig. 6 shows a vector control strategy block diagram for implementing demand control of a dual power supply system according to the present invention.
Detailed Description
Fig. 1 is a block diagram of an embodiment of an apparatus for demand control of a dual-power supply system, where the apparatus includes a series coupling transformer, a series-side inverter, and a parallel-side inverter, a secondary side of the series coupling transformer is connected in parallel to two ends of a backup power automatic switching bus-tie switch, one end of the series coupling transformer is connected to one of power supply buses of the dual-power supply system, and the other end of the series coupling transformer is connected to the other power supply bus; the series side inverter is connected to the primary side of the series coupling transformer, and the parallel side inverter is connected with a power supply bus at one end of the automatic bus transfer device coupler switch in parallel. The series side inverter and the parallel side inverter are composed of three-phase full-bridge power circuits capable of realizing bidirectional power flow, and the topology of the three-phase full-bridge power circuits is two levels or cascade multilevel.
As shown in fig. 1, two incoming lines of the two-way power supply system each have a demand metering point, and through the metering points, it can be measured that the respective demands of the two-way power supply system are respectively the maximum value of the real-time demands, i.e. | PA|maxAnd | PB|max. Without the demand control means shown in the figure, the total demand of the two-way mains supply system would be equal to | PA|maxAnd | PB|maxAnd (4) summing.
After the device of the invention is added, the maximum demand limiting value P is set0The instantaneous total demand of the two power supply systems can be controlled not to exceed the limit value P in real time0And the total demand of the two-way power supply systemThe metering mode is the maximum value of the sum of the real-time demands of the two paths of systems, namely | PA+PB|max＝P0. Therefore, when the maximum demand is limited by the value P0＜|PA|max+|PB|maxThe total demand of the system can be effectively reduced.
Fig. 2 shows a schematic diagram of the apparatus of the present invention for two-way mains power supply system demand control. The device is arranged at two ends of a bus tie switch of the automatic bus transfer equipment in parallel, and the voltages of the low-voltage sides of two paths of distribution transformers of a two-path power supply are respectively USAnd UrThe equivalent reactance on the two power supply buses of the two-way power supply is X respectively1And X2(including distribution transformer equivalent reactance as well as line equivalent reactance). The AC end voltage of the inverter at the series side is connected in series between two paths of power supply buses through a series coupling transformer and is connected in parallel with the spare power automatic switching bus-coupled switch, and the AC end voltage of the inverter at the parallel side is connected in parallel with one end of the spare power automatic switching bus-coupled switch. The two inverters are both DC/AC bidirectional converters, the two inverters are connected through a common direct current bus, and an energy storage device consisting of a super capacitor or an energy storage battery is added at a direct current end. The power electronic conversion system consisting of the series coupling transformer, the series side inverter, the parallel side inverter and the control system thereof can comprehensively regulate and control the fundamental voltage, the active power and the reactive power of two load ends of the two-way power supply system.
Series compensation voltage U for controlling output of series side inverterpqThe amplitude and the phase of the voltage of the corresponding power supply bus can be regulated and controlled, the active current and the reactive current flowing in the power transmission line are changed in a fixed range, the active power and the reactive power transmitted by the power transmission line can be regulated and controlled, and the power (demand) of the double-circuit power supply can also be regulated and controlled.
Fig. 3 shows a simplified control diagram and vector diagram of the apparatus of the present invention for demand control of a dual power supply system. Terminal voltage U of parallel side inverter side power supply bussLeading the voltage U of the power supply bus at the side of the inverter at the series siderThe power angle is delta, and when a series compensation voltage U is introduced between two power supply busespqThen, in FIG. 3The output end voltage of the demand controller is U2，U2＝Us+Upq. U in vector diagrampqLeading UsIs ρ.
USEnd transmission power P and UrEnd-supplied reactive power-jQrThe sum of the following components:
"x" denotes a complex conjugate number,
when U is turnedpqWhen the value is equal to 0, then
When U is turnedpqWhen not equal to 0, the total active power and reactive power are as follows:
wherein the content of the first and second substances,
will relation formula Us、Ur、UpqSubstitution into
Obtaining:
in the formula:
at any transmission angle delta, the controllable ranges of active power and reactive power are respectively as follows:
from the above formula, it can be seen that in this working state, the controllable range of the power transmitted by the system is widened, and fig. 4 shows the active power and reactive power operating ranges of the device of the present invention for realizing the demand regulation of the two-way power supply system. It can be seen from fig. 4 that U is equal to pi/2- δ when ρ ═ pi/2- δpqThe active power P of the line has the maximum action quantity
Therefore, the device can better meet the requirement of the two power transmission systems on power change during demand control.
From the above analysis, it can be concluded that U is regulatedpqThe change of the power supply voltage can realize the regulation of the output active power of the power supply voltage within the required range, and completely meets the technical requirement of demand control of a double-circuit power supply system.
Therefore, the regulation of the output active power of the power supply at the inverter side at the parallel side can be realized by controlling the output voltage of the inverter at the series side, namely the series compensation voltage of the series coupling transformer, and the requirement of the demand control of a double-circuit power supply system is also realized; the parallel side inverter mainly realizes the stable control of the common direct current bus and the control of the reactive power of the parallel side.
Fig. 5 shows a control strategy block diagram for implementing demand control of a dual power supply system according to the present invention. As shown in fig. 5, the difference between the given power (limited demand value) and the actual power (obtained by real-time terminal voltage and current collection) is adjusted by PID to obtain the changed power Δ p, so as to obtain the series compensation voltage U having a linear relationship with Δ ppqThe series compensation voltage given value adopts closed-loop control after considering voltage limitation or frequency range limitation, and the closed-loop control output value is the control output of the inverter on the series side.
Both the series-side inverter and the parallel-side inverter can adopt a vector control strategy, and as shown in fig. 6, the main functional modules include: the device comprises a PLL phase-locked loop for detecting the voltage phase of a series side power supply bus, a PI controller, a coordinate transformation module (abc/dq transformation and dq/abc transformation), a comparator and the like. By means of vector control it is possible to keep the respective given quantities (including dc voltage, grid side power, grid side voltage d-axis q-axis component, load side current d-axis q-axis component) at the set values.
The closed-loop control of the series side inverter solves the problem of active power transmission of the system, and the injection voltage vector U connected in series in the linepqThe amplitude and the phase angle of the phase angle are controlled, and the control method comprises the following steps:
(1) obtaining a grid phase theta by a phase locked loop PLLs；
(2) Collecting the voltage and current of the power supply bus at the side of the inverter at the series side, and calculating the real-time active powerThe reactive power is compared with a given active/reactive limit value, the obtained difference value passes through a deviation amplifier and a voltage limiter, and amplitude and phase angle calculation is carried out on the basis of considering voltage, current and other amplitude limits to obtain UpqThe amplitude and phase angle of the voltage, the controller can be a PI controller according to the requirement;
(3) the control quantity of the closed loop output directly controls the gate drive of the power device to realize the final control requirement.
The parallel side inverter closed-loop control solves the reactive power control problem and the direct current short voltage stability problem, and is realized by the following steps:
(1) obtaining the voltage phase theta of the power supply bus at the side of the inverter at the parallel side through a phase-locked loop PLLs；
(2) The method comprises the steps of collecting voltage and current of a power supply bus at the side of an inverter at the parallel side, calculating a power factor, and performing closed-loop control by giving the power factor as 1 to realize real-time adjustment of reactive power components. Or extracting the output current positive sequence component of the power supply bus at the inverter side of the parallel side, detecting the difference between the feedback reactive current positive sequence component and the given value of the reactive current, and respectively carrying out closed-loop control on the dq axis. The controller may be a PI controller, as desired;
(3) and the difference between the fed back direct current bus voltage and a given value is detected, and the stable control of the direct current bus voltage can be realized through voltage and current closed-loop control. The controller may be a PI controller, as desired;
(4) in order to improve the stability and the dynamic response performance of the converter, a current loop is added, a voltage instruction from the current loop is modulated by SVPWM to obtain a corresponding PWM signal, and the corresponding IGBT module is driven by isolation amplification.
The foregoing is a more detailed description of the invention in connection with specific preferred embodiments thereof, and it is not intended to limit the practice of the invention to those embodiments, and in particular, to provide consistent results in other ways of adjusting the structure of the apparatus. For those skilled in the art to which the invention pertains, several equivalent substitutions or obvious modifications, which are equivalent in performance or use, should be considered to fall within the scope of the present invention without departing from the spirit of the invention.
Claims (4)
1. A device for demand control of a two-way power supply system is connected in parallel to a spare power automatic switching bus-bar switch between two buses of the two-way power supply system, is a power tide current regulator, comprises a series coupling transformer, a series side inverter, a parallel side inverter, an incoming line switch, an outgoing line switch and a spare power automatic switching switch, and is used for controlling the sum of the maximum demands of the two-way power supply system and reducing the demands of a user metering point, thereby reducing basic electric charge;
the secondary side of the series coupling transformer is connected in parallel at two ends of the spare power automatic switching bus coupler switch, one end of the series coupling transformer is connected with one path of power supply bus of the two-path power supply system, and the other end of the series coupling transformer is connected with the other path of power supply bus; the primary side of the series coupling transformer is connected with the series side inverter, and the series side inverter can adjust the amplitude and the phase of output voltage and bidirectionally adjust active power between two paths of power supply systems; the parallel side inverter of one path of power supply system arranged at one end of the spare power automatic switching bus-coupled switch is connected with the power supply bus of the path in parallel, and is used for stabilizing the direct current bus voltage of the series side inverter and the parallel side inverter and controlling the flow of reactive power between the buses of the two paths of power supply systems; the series side inverter and the parallel side inverter are connected through a common direct current bus;
the method comprises the following steps of dynamically adjusting the amplitude and the phase of the voltage at two ends of a series coupling transformer to adjust the output power transmitted between two power supply systems within a fixed range, and meeting the requirement of adjusting the sum of the demands of the two power supply systems, and specifically comprises the following steps:
monitoring the respective power and demand of two paths of power supplies of a two-path power supply system for a long time to obtain the maximum demand value and demand curve of each path, and determining the optimal limit value of the sum of the demands of the two paths of power supply systems;
detecting the incoming line voltage and current of each system at two sides of the bus-tie automatic bus-tie switch, calculating the power of two power supply systems, superposing demand values obtained by real-time calculation of two power supplies according to the requirement of overall control of system demand, carrying out closed-loop control on the difference between the sum of the real-time demand and a total demand limiting target value to obtain the secondary side voltage variation of the series coupling transformer to be regulated, obtaining the series compensation voltage value to be compensated according to the relation between the voltage variation and the series compensation voltage, and finally obtaining the required series compensation voltage through the voltage and current closed-loop control of the series side inverter; the output voltage of the series coupling transformer is dynamically regulated, so that the amplitude variation range is 0-maximum, the phase angle variation range is 0-360 degrees, the bidirectional regulation of the transmission power between the two power supply systems in a fixed range is realized, the control of the sum of the maximum demands of the two power supply systems is finally realized, and the sum of the demands of the two power supply systems is controlled at a target value.
2. The apparatus of claim 1, wherein the series-side inverter and the parallel-side inverter are composed of a three-phase full-bridge power circuit capable of realizing bidirectional power flow, and the topology is two-level or cascade multi-level; the parallel-side inverter of the device can realize the control of direct-current bus voltage and system reactive power.
3. The apparatus of claim 1, wherein in order to further enhance the flexibility and implementation capability of demand control, an energy storage device is added to the common dc bus of the series-side inverter and the parallel-side inverter, and the flexibility of demand control of the dual-power supply system is further implemented by charging and discharging the energy storage device.
4. The apparatus of claim 1, wherein the demand control is a series-side inverter that solves the voltage and phase regulation problem by closed-loop control, comprising the steps of:
(1) acquiring a voltage phase of a power supply bus end at a series side through a phase-locked loop (PLL);
(2) collecting voltage and current on power supply bus at inverter end on series side, and calculatingReal-time active and reactive power are compared with a given active/reactive limit value, the obtained difference value is calculated by a deviation amplifier through a voltage limiter according to the amplitude and phase angle on the basis of considering voltage and current amplitude limiting to obtainU pq A magnitude and a phase angle of the voltage, wherein the controller is a PI controller;
(3) the control quantity of the closed loop output directly controls the gate drive of the power device to realize the final control requirement.
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Denomination of invention: Device and method for demand control of dual power supply system Effective date of registration: 20221024 Granted publication date: 20210820 Pledgee: Bank of Nanjing Jiangbei District branch of Limited by Share Ltd. Pledgor: NANJING HEXI ELECTRIC CO.,LTD. Registration number: Y2022320000642 |
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