CN210838950U - Device for active demand power flow transfer between double-circuit power supply systems - Google Patents
Device for active demand power flow transfer between double-circuit power supply systems Download PDFInfo
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- CN210838950U CN210838950U CN201922146436.2U CN201922146436U CN210838950U CN 210838950 U CN210838950 U CN 210838950U CN 201922146436 U CN201922146436 U CN 201922146436U CN 210838950 U CN210838950 U CN 210838950U
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Abstract
The utility model discloses a device that is used for active demand trend to shift between double-circuit power supply system, connect in parallel one by isolation transformer on the bus gang switch of throwing oneself with fully oneself with between two way power supply bus of double-circuit power supply, the power tide regulator that series connection side dc-to-ac converter and parallelly connected side dc-to-ac converter constitute, when two way real-time demand in the double-circuit power supply sum surpassed total demand limit value, through this power tide regulator, with wherein during the energy transfer of a certain power supply bus all the way shifts another way power supply bus, thereby both reduced the total demand sum of system, the demand of user metering point, thereby reduce basic charges of electricity, the electric energy demand that can guarantee load again obtains satisfying. The utility model discloses can solve the various problems that other demand controllers faced in the existing market, for example, need reduce the demand through reducing load power, make load stability receive influence etc.. The control difficulty and the equipment maintenance amount are reduced, the service life of the equipment is prolonged, and the economic benefit is good.
Description
Technical Field
The utility model relates to a supply and distribution field, concretely relates to a device that is used for active demand trend to shift between 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 above problems, the present invention provides a device for transferring active demand power flow between two-way power supply systems, which is connected in parallel to a bus-tie switch of a backup power automatic switch between two-way buses of two-way power supply, and is a power flow regulator, comprising a series coupling transformer, a series side inverter, a parallel side inverter and a switch circuit;
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, the other end of the series coupling transformer is connected with the other path of power supply bus, and the primary side of the series coupling transformer is connected with the series side inverter.
Preferably, the series inverter can regulate the amplitude and the phase of output voltage and bidirectionally regulate active power between the two-way power supply systems; the parallel side inverter of one path of power supply system arranged at one end of the 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 series side inverter and the parallel side inverter are composed of three-phase full-bridge power circuits capable of realizing power bidirectional flow, and the topology of the three-phase full-bridge power circuits is two levels or cascade multilevel;
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, the transmission power between the two power supply systems is bidirectionally regulated within a certain range, 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.
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 active demand power flow transfer between the two-way power supply systems is further realized through charging and discharging of the energy storage device.
Preferably, the active power of the energy storage device is transferred to one power supply system of the bus tie switch through the series-side inverter, or the active power of the energy storage device is transferred to the other power supply bus connected with the parallel-side inverter through the parallel-side inverter.
The utility model has the advantages of as follows:
(1) the utility model provides a device and method for double-circuit power supply system demand control can avoid upgrading the transformation to two way distribution transformer, not only can not cause the waste of old equipment, can effectively reduce total electric power demand moreover.
(2) The utility model discloses a two way power supply generating lines to double-circuit power supply system carry out power monitoring, demand prediction, real-time power control, realize real "peak shifting and fill up the millet", on the demand "peak" value that is about to on the power of the same kind shifts the demand "millet" value of another way power, when having reduced the sum of every way power supply system maximum demand and system demand, guaranteed that the total power demand of load is unchangeable, ensured the stability of each way load operation.
(3) The utility model discloses a power electronics device carries out the demand and adjusts, chooses for use fast switch device, and system response is fast, and control accuracy is high, has avoided in the traditional demand control mode to mechanical structure's frequent action, has reduced mechanical wear, has increased each load equipment's life.
(4) The utility model discloses direct mount is at two way power supply generating line's the female switch both ends of joining in marriage of switching fully oneself with, and connected mode is simple, can amputate fast and can not influence the work of former system, safe and reliable during the trouble.
Drawings
Fig. 1 shows a block diagram of an embodiment of a device for demand control of a two-way power supply system according to the present invention;
FIG. 2 is a schematic diagram of the device 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 device of the present invention for controlling the demand of the two-way power supply system;
fig. 4 shows the utility model discloses active power and reactive power operating range when device realization double-circuit electrical power generating system demand control.
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 utility model is added, the limiting value P of the maximum demand is set0The instantaneous total demand of the two power supply systems can be controlled not to exceed the limit value P in real time0At the moment, the total demand metering mode of the two-way power supply system is the maximum value of the sum of the real-time demands of the two-way system, 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 device of the present invention for demand control of a dual power supply system. As shown in fig. 2, will the utility model discloses a device is parallelly connected to be installed at the both ends of being equipped with the automatic switching bus tie switch, and two way distribution transformer low pressure side voltage of double-circuit power supply is U respectivelySAnd 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 can be 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 to a certain extent, active current and reactive current flowing in the power transmission line are changed within a certain range, active power and reactive power transmitted by the power transmission line can be regulated and controlled, and power (demand) of a double-circuit power supply can also be regulated and controlled.
Fig. 3 shows a simplified control diagram and vector diagram of the device of the present invention when it performs demand control of a dual power supply system. Parallel inverter side supplyElectric bus terminal voltage UsLeading the voltage U of the power supply bus at the side of the series inverterrThe power angle is delta, and when a series compensation voltage U is introduced between two power supply busespqThe output voltage of the demand controller is U in FIG. 32，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:
it can be seen from the above formula that under this kind of operating condition, the controllable range of power of system transmission is widened, and fig. 4 shows the utility model discloses the device realizes the active power and the reactive power operating range of double-circuit power supply system demand regulation. 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
The output voltage of the series coupling transformer is dynamically adjusted to make the amplitude change range of the output voltage be 0The maximum value is about, the phase angle change range is 0-360 degrees, thereby realizing the bidirectional adjustment of the transmission power between the two power supply systems within a certain 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 at a target value. 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 side of the parallel inverter can be realized by controlling the output voltage of the inverter at the side of the series, 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.
The above description is further detailed in connection with specific preferred embodiments of the present invention, and it is not to be understood that the embodiments of the present invention are limited to these descriptions, and in particular, other embodiments based on the structure of the device of the present invention are essentially consistent with the present invention. To the ordinary skilled person in the technical field of the present invention, without departing from the present invention, make a plurality of equivalent substitutes or obvious variants, and the performance or the usage is the same, should all regard as belonging to the protection scope of the present invention.
Claims (4)
1. A device for transferring active demand power flow between two-way power supply systems is characterized in that the device is connected in parallel to a spare power automatic switching bus-coupled switch between two buses of two-way power supply, and the device is a power flow regulator and comprises a series coupling transformer, a series side inverter, a parallel side inverter and a switch circuit;
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, the other end of the series coupling transformer is connected with the other path of power supply bus, and the primary side of the series coupling transformer is connected with the series side inverter.
2. The apparatus of claim 1, wherein the series inverter is operable to regulate the magnitude and phase of the output voltage and to regulate the active power between the two-way power supply systems in both directions; the parallel side inverter of one path of power supply system arranged at one end of the 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 series side inverter and the parallel side inverter are composed of three-phase full-bridge power circuits capable of realizing power bidirectional flow, and the topology of the three-phase full-bridge power circuits is two levels or cascade multilevel;
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, the transmission power between the two power supply systems is bidirectionally regulated within a certain range, 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.
3. The device according to claim 1 or 2, characterized in that an energy storage device is added on a common direct current bus of the series-side inverter and the parallel-side inverter, and the flexibility of the active demand power flow transfer between the two-way power supply systems is further realized through the charging and discharging of the energy storage device.
4. The apparatus of claim 3, wherein the active power of the energy storage device is transferred to one power supply system of the buscouple switch through the series-side inverter or to another power supply bus connected to the parallel-side inverter through the parallel-side inverter.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113991670A (en) * | 2021-11-29 | 2022-01-28 | 南京赫曦电气有限公司 | Alternating-current flexible loop closing control device for power grid and control method thereof |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113991670A (en) * | 2021-11-29 | 2022-01-28 | 南京赫曦电气有限公司 | Alternating-current flexible loop closing control device for power grid and control method thereof |
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Denomination of utility model: A device for active power demand and power flow transfer between two power supply systems Effective date of registration: 20221024 Granted publication date: 20200623 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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Granted publication date: 20200623 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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