Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F30/00—Fixed transformers not covered by group H01F19/00
  • H01F30/06—Fixed transformers not covered by group H01F19/00 characterised by the structure
  • H01F30/12—Two-phase, three-phase or polyphase transformers
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F27/00—Details of transformers or inductances, in general
  • H01F27/42—Circuits specially adapted for the purpose of modifying, or compensating for, electric characteristics of transformers, reactors, or choke coils
  • H01F27/422—Circuits specially adapted for the purpose of modifying, or compensating for, electric characteristics of transformers, reactors, or choke coils for instrument transformers
  • H01F27/425—Circuits specially adapted for the purpose of modifying, or compensating for, electric characteristics of transformers, reactors, or choke coils for instrument transformers for voltage 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
  • H02J3/26—Arrangements for eliminating or reducing asymmetry in polyphase networks
• • 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
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
  • Y02E40/50—Arrangements for eliminating or reducing asymmetry in polyphase networks

Definitions

• the present invention relates to a current balancer and a power distribution system, and more particularly to a current balancer that averages a three-phase voltage imbalance and a three-phase four-wire low-voltage power distribution system using the current balancer.
• a three-phase four-wire low-voltage distribution system has been used as a method of supplying three-phase AC power using four electric wires and cables.
• the three-phase four-wire low-voltage power distribution system is widely used in Japan, but when compared with other power distribution systems, the number of wires and cables can be reduced. It is widely used in other countries including developing countries due to the advantages such as sharing of electric transformers.
• Voltage imbalance at the load point has various adverse effects on the operation and life of the electrical equipment connected to the load point.
• a three-phase induction motor rotating copper loss occurs, the mechanical output of the induction machine decreases, and further problems such as a decrease in power factor and an increase in temperature occur.
• the electric power used in the electric motor increases and wasteful electric power is consumed.
• extreme voltage drop at the load point described above In order to cope with this, there is an example in which a higher voltage is supplied to the entire three phases.
• the applicant of the present invention has proposed a balancer transformer integrated with a step-down transformer function as described in Patent Document 1 and Patent Document 2. It was.
• the current balancer is known not only as a three-phase four-wire low-voltage distribution system but also as a means of correcting voltage imbalance in a multi-phase AC power source.
• FIG. 11 is a diagram for explaining a current balancer in a three-phase four-wire low-voltage distribution system.
• the three-phase four-wire power distribution transformer 30 has U, V, W phases and is connected with loads 32a, 32b, 32c respectively! If the loads 32a, 32b, and 32c have an unbalanced force, there will be a difference in the current that flows from the self-voltage transformer 30 to the load of each phase. At this time, a voltage drop occurs due to the wiring transformer 30 and the wiring resistance to each load, and the voltage of each phase differs. As a result, the current I due to the unbalance that does not flow when each phase is balanced is included in the N phase of the joint return.
• FIG. 12 is a diagram showing a configuration of a balancer transformer disclosed in Patent Document 1.
• This balancer transformer has a configuration of a distribution transformer composed of a series coil section 20 and a shunt coil section 23, and combines the function of a current balancer and the function of a step-down transformer for adjusting output voltage. .
• the series coil section 20 includes first straight IJ coins 21a, 21b, 21c and second straight IJ coins 22a, 22b, 22c, which have the same number of turns and reverse winding directions.
• the seal portion 23 is also provided with first shunt coils 24a, 24b, 24c and second shunt coils 25a, 25b, 25c that have the same number of turns and reverse winding directions.
• the function as a current balancer is improved by connecting coils sequentially to adjacent phases, passing a current through each phase of the three phases, and canceling the magnetic flux by a reverse current.
• FIG. 13 is a diagram showing a connection configuration of the balancer transformer of Patent Document 1.
• the balancer transformer having the configuration of Patent Document 1 described above has the following problems.
• the tap portion needs to be adjusted in the series coil portion.
• a step-down transformer since the number of turns of the series coil section is small, it is difficult to produce a tap that can finely adjust the output voltage with a large amount of voltage change around several coils. Accordingly, it is difficult to finely adjust the voltage in each phase.
• the function of the step-down transformer since the function of the step-down transformer is incorporated, the overall configuration of the current balancer becomes large and the entire device becomes large and heavy. For this reason, there were problems such as restrictions on the installation location and difficulty in handling during installation work.
• the present invention has been made in view of such a problem, and an object of the present invention is to reduce a distribution loss by providing a current balancer having a further improved current balance performance compared to the conventional art. This improves the quality of the power supply system and makes the current balancer smaller and easier to handle.
• the current balancer function required for the power supply system can be selected more flexibly.
• the voltage adjustment unit is not required and voltage adjustment is possible using the existing distribution transformer, which simplifies the overall power supply system and reduces costs. It becomes possible.
• Patent Document 1 Japanese Patent Laid-Open No. 11 32437
• Patent Document 2 Utility Model Registration No. 3047691
• the present invention is characterized in that the invention according to claim 1 is connected to each phase voltage in a power distribution system that supplies three phase voltages to and from a neutral point.
• a current balancer that reduces the unbalance of each phase voltage by flowing a balancer current, and a coil through which a first phase balancer current flows and a coil through which a second phase balancer current flows are
• a balancer current is closely wound on the first phase iron core so as to generate magnetic fluxes in opposite directions in the first phase iron core to form a first phase coil pair, and One end of the coil through which the balancer current of the first phase flows is connected to one end of one coil of the third phase coil pair that is in close contact with the iron core of the third phase, and the first phase The balancer current flows through the first phase and
• One of the coils through which the second phase balancer current flows Is connected to one end of one coil of a second phase coil pair that is in close contact with the second phase iron core, and the second phase balancer current is connected to the first phase and The first phase coil pair, the first phase coil pair, the first phase coil core, and the second phase iron core.
• the second phase coil pair and the third phase coil pair form a first coil pair group, and each coil constituting each of the coil pairs has a same number of turns.
• the other end of the one coil of the second phase coil pair in the first coil pair group is connected cyclically and symmetrically, and the other end of the first phase forming the next coil pair group It is further connected to one coil of the coil pair, and is interposed between the first phase end and the neutral point end.
• the coils are connected in series so that the first phase balancer current flows alternately between the first phase and the second phase across the plurality of divided coil pair groups,
• the coil pairs constituting the plurality of coil pair groups are connected cyclically and symmetrically
• the invention described in claim 2 is a three-phase four-wire low-voltage distribution system using output power from the R-phase, S-phase, and T-phase, wherein the R-phase is in parallel with the load of each phase.
• the present invention it is possible to provide a current balancer with a further improved current balance as compared with the prior art, reducing distribution loss and improving the quality of the power feeding system. Improve.
• the current balancer can be made smaller and easier to handle.
• the current balancer function required for the power supply system can be selected more flexibly.
• the voltage adjustment unit for each phase can be eliminated by improving the current balance performance. By enabling the voltage adjustment using the existing distribution transformer, the entire power supply system can be simplified and the cost can be reduced.
• FIG. 1 is a diagram showing coil connection of a current balancer of the present invention.
• FIG. 2 is a diagram showing a more physical configuration of the current balancer of the present invention.
• FIG. 3 is a coil connection diagram according to another expression of the current balancer of the present invention.
• FIG. 4 is a diagram for explaining magnetic flux in a coil pair.
• Fig. 5 is a diagram for explaining the magnetic flux in the coil pair wound in lap.
• FIG. 6A is a coil connection diagram between the U-phase end and the neutral point end of the current balancer of the present invention.
• FIG. 6B is a diagram illustrating a voltage distribution applied to each coil between the U-phase end and the neutral point end.
• FIG. 7A is a diagram showing a correction effect of phase voltage imbalance by the current balancer of the present invention.
• FIG. 7B is a diagram showing a measurement system that obtains effect comparison data of a current balancer.
• FIG. 8 is a diagram showing a three-phase four-wire low-voltage distribution system including a current balancer of the present invention.
• FIG. 9 is a diagram showing another three-phase four-wire low-voltage distribution system including the current balancer of the present invention.
• FIG. 10 is a diagram showing another modified application example of the current balancer of the present invention.
• FIG. 11 is a diagram for explaining the operating principle of a current balancer.
• FIG. 12 is a diagram showing a configuration of a conventional balancer transformer.
• FIG. 13 is a diagram showing a configuration of a prior art balancer transformer.
• FIG. 1 is a diagram showing the connection of each coil in the current balancer of the present invention. This corresponds to FIG. 2, which is a configuration diagram showing a more physical image of the current balancer, which will be described later. By referring to both figures in contrast, it is easier to understand the configuration of the current balancer of the present invention.
• the current balancer of the present invention shown in Fig. 1 is most suitable for a three-phase four-wire low-voltage distribution system. Each coil belongs to one of U phase 14, V phase 15 and W phase 16 corresponding to each leg (iron core) of the current balancer.
• the U-phase end 17, V-phase end 18 and W-phase end 19 that are connected to each phase voltage of the three-phase four-wire low-voltage distribution system are connected via a plurality of coils connected in series. Connected to neutral wire end N20.
• the neutral point end 20 is connected to the neutral line of a three-phase four-wire low voltage distribution system.
• the balancer current of each phase flows between the U-phase end 17, the V-phase end 18, the W-phase end 19 and the neutral point end 20.
• each coil of the coil pair is based on the direction flowing from the neutral wire end N20 to the U-phase end 17, the V-phase end 18, and the W-phase end 19 for convenience of explanation.
• the coil la and the coil lb arranged in the U phase 14 will be described as starting points.
• the coil la and the coil lb of the first group 101 are wound around the iron core of the U phase 14 as a coil pair.
• Coil lc and coil Id, and coil le and coil If are also wound as a coil pair on the V-phase 15 and W-phase 16 iron cores, respectively.
• coil 2a and coil 2b, coil 2c and coil 2d, coil 2e and coil 2f, coil 3a and coil 3b, coil 3c and coil 3d, and coil 3e and coil 3f are also wound in layers.
• Each coil The pairs are divided into a first group 101, a second group 102, and a third group 103.
• One end 1 of the coil la is connected to the neutral point end N20, and the other end 2 is connected to one end 4 of the coil If of the coil le and the coil If constituting the coil pair in the W phase 16.
• the other end 3 of the coil If is connected to one end 5 of the coil 2 a in the U phase 14 of the second group 102.
• the balancer current flowing through the coil la from the neutral point N20 passes through the coil If of the U phase 14 through the coil If of the W phase 16 and then returns to the U phase 14 and flows through the coil 2a.
• the balancer current flows in the coil la and the coil If so that the magnetic fluxes in the opposite directions to each other are generated in the leg direction of the current balancer. As each terminal is connected, it has attracted much attention.
• a similar connection method is repeated in the coil 2a and coil 2f of the second group 102 and the coil 3a and coil 3f of the third group 103. Therefore, from the neutral point end N20 to the W phase end 19, a balancer current flows alternately between two different phases in the order of the U phase, the W phase, the U phase, the W phase, the U phase, and the W phase.
• the coil la of the U phase 14 of the first group 101 is finally connected to the W phase end 19 via one end 11 of the coil 3f of the W phase 16 of the third group 103.
• one end 4 of coil lb wound with coil la is connected to the other end 2 of V-phase 15 coil lc with one end 1 connected to neutral point end N20. .
• the other end 3 of the coil lb is connected to one end 5 of the coil 2 c in the V phase 15 of the second group 102.
• the balancer current flowing from the neutral point end 20 through the coil lc passes through the coil lb from the V-phase 15 through the coil lb from the U-phase 14 and then returns to the V-phase 15 again and flows through the coil 2c. .
• each of the coil pairs is such that the balancer current flows in the coils lc and lb so as to generate magnetic fluxes in opposite directions with respect to the leg direction of the current balancer.
• the terminal is connected, and it has attracted much attention.
• a similar connection method is repeated in the coil 2b and coil 2c of the second group 102 and the coil 3b and coil 3c of the third group 103. Therefore, from the neutral point end 20 to the U phase end 17, the balancer current alternately flows between the two different phases in this order: V phase, U phase, V phase, U phase, V phase, U phase. Become.
• V phase 15 coil lc is Finally, it is connected to the U-phase end 17 via one end 11 of the coil 3b of the U-phase 14 of the third group.
• the balancer current is also generated so that magnetic fluxes in the opposite directions are generated in the same iron core in each coil of the coiled pair of coils. It can be seen that the connection relationship is flowing.
• a balancer current flows in each of coil la and coil lb so that magnetic fluxes in opposite directions are generated in the U-phase 14 iron core. The same applies to the coils lc and Id and the coils le and If.
• FIG. 2 is a connection diagram more specifically showing the physical connection form of each coil of the current balancer of the present invention.
• the coil la and the coil lb are overlapped to form one coil pair.
• U phase 14, V phase 15 and W phase 16 correspond to the core legs of each phase around which each coil pair is wound.
• the shape of the iron core is any tripod-shaped core that constitutes a three-phase transformer that shares the return path of the magnetic flux of each phase, as long as the balance effect of the magnetic flux described later can be produced. But it doesn't matter.
• each coil pair of each group 101, 102, 103 of each coil pair is arranged side by side along the axis of the iron core of one phase.
• Structure It is not limited to success. That is, the first group of coil pairs is first wound around the iron core of each phase, and then the second group 102 coil pair and the third group 103 coil pair are arranged in this order.
• a structure in which layers are sequentially stacked on top of each other may be used.
• FIG. 3 is a coil connection diagram showing the configuration of the current balancer of the present invention.
• the terminal numbers of each coil are the same as the terminal numbers in Figs. It can be seen that the coils are connected cyclically and symmetrically for the U phase, V phase, and W phase.
• FIG. 4 is a diagram illustrating the magnetic flux in each coil pair of the current balancer of the present invention.
• the coils la and lb of the U-phase coil pair of the first group are schematically shown.
• the coil pair of the present invention is overlaid, so it is not arranged in the positional relationship as shown in FIG. 4.
• each coil la and coil lb are wound so that currents I and I flow in opposite directions. Therefore, in each coil
• FIG. 5 is a diagram for explaining that the magnetic flux is canceled in one leg by the coil winding.
• the coil pair in the current balancer of the present invention is wound with two coil wires in close contact in parallel as shown in FIG. Magnetic flux ⁇ , ⁇ generated by each coil
• the current balancer of the present invention has one feature in that a pair of coils wound in a lap manner is used.
• a splitting method which is another feature of the current balancer of the present invention, will be described.
• FIG. 6 is a diagram for explaining the effect of the split winding method according to the present invention.
• FIG. 6A shows only the coil connected between the U-phase end and the neutral point end N in FIG. 1 for easy understanding. From Fig. 6A, as explained in Fig. 1, U phase and V phase It can be seen that the coils are alternately connected to each other. With this connection method, the current flowing through the u-phase end and the neutral point end N flows equally between the two phases. The current flows in an alternating manner across each phase, so that the current acts in a balanced manner.
• FIG. 6B is a diagram for explaining a voltage distribution applied to each coil in FIG. 6A.
• a U-phase all-phase voltage E is applied between the U-phase end and the neutral point end N.
• the phase voltage E is equally divided into the respective coils.
• the voltage of EZ6 is applied to this. Therefore, the maximum withstand voltage that must be taken into consideration for a coil pair that is closely stacked is EZ6.
• the coil of the current balancer of the present invention is divided into a plurality of groups of coil pairs between each phase end and the neutral point end.
• the coil pair can be sufficiently insulated by an insulating material for each group. Furthermore, within a group of one coil pair, it is connected via two different phase coil pairs. When the balancer current flows through the current path having a configuration in which the coils are connected in multiple stages in series, it is possible to divide the phase applied voltage and to prevent the insulation withstand voltage from being lowered at the overlapping coil pair.
• the coil pairs are divided into three groups from the first group to the third group, and the configuration is divided into three. ! /
• the present invention is not limited to this, and may be divided into two or four.
• FIG. 7A is a diagram showing data comparing the effects of correcting the unbalance between the current balancer of the present invention and the current balancer of the prior art.
• a variable test load is connected to each of the R phase, S phase, and T phase to form an unbalanced load and there is no current balancer (No 1, 4), or when a conventional current balancer is present
• a comparison was made between (No 2, 5) and (No 3, 6) when there is a current balancer of the configuration of the present invention.
• the conventional current balancer was compared and evaluated only for the current balancer function part, except for the step-down function in the configuration of FIG.
• FIG. 7B is a diagram showing a configuration of a measurement system that acquires the above-described comparison data.
• the interphase voltage and phase current on the power supply side were measured on the distribution transformer 70 side of the simulated wiring resistance 71a, 71b, 71c, 71d.
• An unbalanced load is formed by the variable test loads 75a, 75b and 75c.
• Variable test loads 75a, 75b, and 75c are connected in parallel via a circuit breaker (MCCB).
• a flow balancer 72 is connected.
• the N-phase current that flows to the power supply side via the common return is 16.7A (Nol) force when there is no current balancer by installing the current balancer of the present invention. It can be seen that it is dramatically reduced to 0.6A (No2).
• the variation width of the interphase voltage on the load side is greatly reduced to 1Z3 from 54V (Nol) without a current balancer to 17V (No3). It can be seen that the variation range is within 10% of the output voltage. It can be seen that the installation of the current balancer of the present invention eliminates the extremely low voltage among the interphase voltages, and has the effect of increasing the interphase voltage as a whole.
• the conventional balancer transformer compares only the current balancer function part with the current balancer of the present invention. Therefore, it can be said that the above-described effects are the effects of the overlapped coil pair, the connection across the phases in the group of coil pairs, and the split winding method using a plurality of coil pair groups.
• FIG. 8 is a diagram showing an embodiment of a three-phase four-wire low-voltage power distribution system using the current balancer of the present invention.
• Each phase voltage supplied from distribution transformer 50 is connected to distribution board 51 by each phase wiring and neutral wire.
• the wiring to the distribution board 51 has wiring resistances r, r, r, r.
• the output from the distribution board 51 is connected to the voltage regulator 53.
• Each voltage regulator 53 Each phase has a voltage adjustment tap, and the output tap of each phase is connected to one end of loads 55a, 55b, and 55c.
• the neutral wire end of the voltage regulator 53 and the other end of each load 55a, 55b, 55c are connected to the neutral wire end of the distribution board 51.
• the current balancer 52 of the present invention is connected in parallel to each phase in the vicinity of the output side of the distribution board 51.
• the unbalanced current generated by the unbalanced loads 55a, 55b and 55c is absorbed in the current balancer 52, and the joint return current I can be significantly reduced at the point B. Therefore, even if the wiring from the distribution transformer 50 to the distribution board 51 is long, the distribution loss due to the wiring resistance of the joint return can be greatly reduced.
• the voltage regulator 53 is generally used to adjust the phase voltage so as to obtain a power saving effect by reducing the power consumption in the device as much as possible while ensuring the stable operation of the load device.
• the voltage regulator 53 can be omitted by using the current balancer of the present invention. Since the phase voltage at the load point is made uniform by the current balancer of the present invention, the need for voltage adjustment for each individual phase is reduced. In such a case, the distribution transformer 50 and the distribution board 51 can be adjusted to a voltage satisfying a desired power saving effect by collectively adjusting the three-phase voltages.
• Table 1 shows an example of a tap configuration of a general distribution transformer.
• the voltage can be adjusted from + 5% to -5% at the maximum.
• a voltage of about 10% can be adjusted at once. Therefore, even if the step-down function of the conventional balancer transformer is not included, voltage regulation using the distribution transformer that is the existing equipment is also possible by suppressing the voltage variation between each phase with the current balancer of the present invention. It becomes.
• Table 2 shows a comparative calculation example of the device capacity of the conventional balancer transformer and the current balancer of the present invention. Shown in Table 2 shows an example of calculating the phase capacities for a conventional balancer transformer. Since the conventional balancer transformer is inserted in series in the distribution system path, the total equipment capacity is the sum of the capacity of each phase, and 168.3 KVA is required.
• the current balancer of the present invention requires a device capacity of 1Z10 or less. In the current balancer of the present invention inserted in parallel with the load of each phase, the capacity and capacity of the equipment can be reduced, so that the overall size and weight of the equipment can be greatly reduced.
• the current balancer can be easily repaired and replaced, and the maintainability of the equipment is improved.
• the voltage regulator 53 can be omitted from the three-phase four-wire low-voltage distribution system by further improving the current averaging performance as compared with the prior art balancer transformer. The cost of the entire power distribution system can be reduced. Further, by omitting the voltage regulator 53, the degree of freedom increases in the installation location of other electrical equipment, and the ease of installation 'construction can be improved.
• the phase advance capacitor 54 is used as necessary for adjusting the power factor of the load.
• FIG. 9 is a diagram showing another embodiment of a three-phase four-wire low-voltage power distribution system using the current balancer of the present invention.
• This is an application example where loads with a long distribution distance from distribution transformer 60 are distributed.
• Distribution transformer 60 to wiring resistance 61a, 61b, 61c, 61d it
• the load 65a is connected through the R line, S line, T line, and shore line.
• R, S, T, and H lines with wiring resistance 63a, 63b, 63c, and 63d are extended from load 65a and connected to second load 65b.
• the current balancers 62a and 62b of the present invention are connected in parallel near the load 65a and near the second load 65b, respectively.
• the current flowing through the common return line in each distribution section can be reduced and the distribution loss can be reduced.
• the effect of improving the quality of the power supply by reducing the power distribution loss due to the extended distance of the power distribution part by four wires is significant.
• FIG. 10 is a diagram showing a configuration for further stabilizing the current balancer of the present invention.
• the current balancer of the present invention can further include a stabilizing coil.
• the configuration shown in Fig. 10 is obtained by adding additional current to the coils 4a, 4b, and 4c that are ⁇ -connected to the current balancer shown in Fig. 1. By adding a few ⁇ connected coils, the performance of the current balancer is stabilized.
• the ⁇ winding coil forms a closed circuit and is not connected to either the excitation power source or the load of the current balancer. Stabilizes neutral point potential and reduces zero layer impedance. It has the effect of increasing the N-phase current absorption effect.
• the present invention it is possible to provide a current balancer with a further improved current balance than before, reducing distribution loss and improving the quality of the power feeding system. .
• the current balancer can be made smaller, easier to handle and easier.
• voltage adjustment can be made unnecessary by using existing distribution transformers to enable voltage adjustment. This simplifies the entire power supply system and reduces costs. Only the current balancer function required for the power supply system can be selected flexibly.
• the present invention it is possible to provide a current balancer in which the current balance is further improved as compared with the prior art. It can be used for a power supply system in which power distribution loss is reduced.

Landscapes

• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Supply And Distribution Of Alternating Current (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (1)

Family

ID=39135589

Family Applications (1)

Country Status (3)

Families Citing this family (4)

Citations (3)

• 2006
  • 2006-08-30 JP JP2006234355A patent/JP5026029B2/ja not_active Expired - Fee Related
  • 2006-10-27 WO PCT/JP2006/321518 patent/WO2008026297A1/ja active Application Filing
  • 2006-10-27 CN CN2006800557428A patent/CN101507078B/zh not_active Expired - Fee Related

Patent Citations (3)

Also Published As

Similar Documents

Legal Events