CN103001191B - Bus differential protection method and system for flexible direct-current closed-loop intelligent power distribution network - Google Patents
Bus differential protection method and system for flexible direct-current closed-loop intelligent power distribution network Download PDFInfo
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- CN103001191B CN103001191B CN201210425664.3A CN201210425664A CN103001191B CN 103001191 B CN103001191 B CN 103001191B CN 201210425664 A CN201210425664 A CN 201210425664A CN 103001191 B CN103001191 B CN 103001191B
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Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/02—Details
- H02H3/06—Details with automatic reconnection
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
- H02H7/261—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured involving signal transmission between at least two stations
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
- H02H7/268—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured for dc systems
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/02—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess current
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- Engineering & Computer Science (AREA)
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Abstract
The invention provides a busbar differential protection system and a busbar differential protection method for a flexible direct-current closed-loop intelligent power distribution network, wherein the system comprises: n direct current buses and N direct current transmission lines; each direct current bus is connected with the direct current transmission line at intervals to form a flexible direct current closed-loop intelligent power distribution network; the method comprises the following steps that a region where one direct current bus of N direct current buses is located is a main node converter station, and regions where the other direct current buses are located are sub-node converter stations; each direct current bus is connected with an alternating current system rectifying station; one end of the alternating current system rectifying station is connected with the direct current bus through the direct current transformer and the direct current switch, and the other end of the alternating current system rectifying station is connected with an alternating current system; each direct current bus is also connected with a user inverter station and a PT; the bus differential protection system of the flexible direct current closed-loop intelligent power distribution network further comprises: and the bus differential protection device is arranged on the main node converter station. The invention can provide support for voltage stabilization, improve voltage quality, and can timely remove faults when the direct current bus fails, thereby ensuring normal power supply.
Description
Technical field
The present invention relates to technical field of electric power, particularly relate to a kind of bus differential protection method and system of flexible direct-current closed-loop intelligent distribution network.
Background technology
Along with the development of power electronic device and control technology, there is novel semiconductor device-igbt (Insulated Gate Bipolar Transistor, IGBT) in the application of low-voltage system, make IGBT as voltage source converter (the Voltage-Sourced Converter of switching device, VSC), be used widely on industrial drives device subsequently, again after the voltage of IGBT device subsequently and capacity are repeatedly upgraded, the voltage source converter adopting igbt to form is applied in direct current transmission and distribution net become a reality.
In the application of direct current transmission and distribution net, converter adopts IGBT valve and two level (or many level) three-phase mechanism, and use pulse modulation technology (Pulse Width Modulation, PWM) control IGBT valve cut-off situation, make the DC distribution net system be made up of it be different from conventional direct current transmission and distribution in many aspects after possessing above-mentioned functions, the multi-class problem presented in conventional direct current transmission and distribution can be overcome.This novel direct current transmission and distribution technology, referred to as " flexible direct current (High Voltage Direct Current Flexible, HVDC-Flexible) ".Current flexible direct current power transmission system all based on point-to-point, as shown in Figure 1.
Flexible direct current (HVDC-Flexible) is from customary DC power transmission and distribution technical development, advantage is the advantage of its customary DC power transmission and distribution, such as: flexible direct current electric line will lack a wire compared to exchanging transmission and distribution network circuit in operation at present, make its line cost low, loss is little, has saved a large amount of corridor of electric line; Flexible direct current distribution network system is in order to realize less failure rate, and the general cable that adopts is as distribution network system passage, and the transmission capacity of cable is large, loss is little, life cycle is long, fed distance is unrestricted; Flexible direct current distribution network system adopts cable as power transmission and distribution passage, and generally use directly buried technology in underground, engineering cost is low, the duration is short, also reduces the impact on environment; In addition, flexible direct current distribution network system is stable strong; Flexible direct current distribution network system can realize the interconnected of asynchronous system; The active power that flexible direct current distribution network system is carried and reactive power can independently control fast; Flexible direct current distribution network system is built by separate periods, favorable expandability preferably; Fast recovery of power supply and black starting-up after accident; Can to passive mains supply etc.
But the flexible direct current power transmission system put into operation at present is mostly double ended system, only can realizes point-to-point direct current power and pass on.When backcross more streaming system feed-in time need to take direct current interconnected, need many DC power transmission line; In addition, have multi-user, during many renewable energy resources (as wind energy, solar energy etc.) feed-in, the point of interface of this flexible direct current power transmission system can not satisfy the demands.
In addition, work as DC bus, containing the PT(Potential transformer on DC bus, voltage transformer) etc. equipment when breaking down, cannot find fault point in time, the power supply reliability of the distribution network system causing this flexible direct current reduces by greatly.
Summary of the invention
In order to the point of interface solving the flexible direct current distribution network system put into operation at present can not meet power demands; and when DC bus (containing equipment such as the PT on DC bus) breaks down; the technical problem that power supply reliability that fault point causes reduces greatly cannot be found in time; the invention provides a kind of bus differential protection method and system of flexible direct-current closed-loop intelligent distribution network; it can provide support for voltage stabilization; improve quality of voltage; and when DC bus breaks down; can fix a breakdown in time, ensure normal power supply.
The bus differential protection system of a kind of flexible direct-current closed-loop intelligent distribution network provided by the invention, comprising:
N bar DC bus and N bar DC power transmission line; Every bar DC bus and DC power transmission line interval are connected, composition flexible direct-current closed-loop intelligent distribution network; N be more than or equal to 3 natural number;
Wherein, the region at a DC bus place in described N bar DC bus is host node current conversion station, and the region at all the other DC bus places is child node current conversion station;
Described every bar DC bus is connected with at least one for the electric energy of AC system is rectified into direct current energy, imports the AC system converting plant of described closed-loop shaped intelligent distribution network; Described AC system converting plant one end is connected with described DC bus with DC switch by direct current instrument transformer, and the other end connects an AC system;
Described every bar DC bus is also connected with M and direct current energy is reverse into alternating current to supply user's Inverter Station of user's use, each described user's Inverter Station is all connected with described DC bus with DC switch by direct current instrument transformer; M be more than or equal to 1 natural number;
Described every bar DC bus is also connected with the PT that the DC bus high-voltage variable collected is changed into secondary voltage by least one;
The bus differential protection system of described flexible direct-current closed-loop intelligent distribution network also comprises: be arranged on the bus differential protection device on described host node current conversion station;
Direct current instrument transformer on described host node current conversion station and child node current conversion station gathers electric current and the voltage signal of the DC bus at its place, and is pooled to described bus differential protection device;
Described bus differential protection device is according to from the electric current of described host node current conversion station and each child node current conversion station and voltage signal; judge whether to there is unsymmetrical current; in this way; then judge that described flexible direct-current closed-loop intelligent distribution network exists fault; as no, then judge that flexible direct-current closed-loop intelligent distribution network normally works.
Wherein, DC power transmission line described in every bar is provided with K platform and fault point is carried out the DC switch of isolating for the tripping operation when described DC power transmission line has fault; K be more than or equal to 2 natural number.
Wherein, described bus differential protection device comprises:
The electric current gathered for the direct current instrument transformer gathered by optical-fibre channel on described host node current conversion station and the host node current/voltage collecting unit of voltage signal;
The child node current/voltage collecting unit of the electric current that multiple direct current instrument transformer on each child node current conversion station described in being gathered by optical-fibre channel is gathered and voltage signal;
Be connected with described host node current/voltage collecting unit, for the host node current/voltage converting unit converting digital quantity to electric current and voltage signal to gathered;
Multiple and described child node current/voltage collecting unit is connected, for the child node current/voltage converting unit converting digital quantity to electric current and voltage signal to gathered;
Be connected, for carrying out the protective device read group total comparing unit that read group total compares to its converted digital quantity with described host node current/voltage converting unit and each child node current/voltage converting unit;
Be connected with described protective device read group total comparing unit; for judging whether described flexible direct-current closed-loop intelligent distribution network exists unsymmetrical current according to the result of calculation of protective device read group total comparing unit, and carry out the command executing unit of Fault Isolation process when judging that described flexible direct-current closed-loop intelligent distribution network exists unsymmetrical current.
Wherein, described command executing unit is connected with described host node current conversion station and child node current conversion station by optical-fibre channel.
Wherein, in the AC system converting plant that Mei Zu DC bus district connects, at least one AC system converting plant is as the voltage regulating station for controlling direct voltage.
Accordingly, present invention also offers a kind of bus differential protection method of the bus differential protection system based on above-mentioned flexible direct-current closed-loop intelligent distribution network, the bus differential protection system of described flexible direct-current closed-loop intelligent distribution network, comprising:
N bar DC bus and N bar DC power transmission line; Every bar DC bus and DC power transmission line interval are connected, composition flexible direct-current closed-loop intelligent distribution network; N be more than or equal to 3 natural number;
Wherein, the region at a DC bus place in described N bar DC bus is host node current conversion station, and the region at all the other DC bus places is child node current conversion station;
Described every bar DC bus is connected with at least one for the electric energy of described AC system is rectified into direct current energy, imports the AC system converting plant of described closed-loop shaped intelligent distribution network; Described AC system converting plant one end is connected with described DC bus with DC switch by direct current instrument transformer, and the other end connects an AC system;
Described every bar DC bus is also connected with M and direct current energy is reverse into alternating current to supply user's Inverter Station of user's use, described each user's Inverter Station is all connected with described DC bus with DC switch by direct current instrument transformer; M be more than or equal to 1 natural number;
Described every bar DC bus is also connected with the PT that the DC bus high-voltage variable collected is changed into secondary voltage by least one;
The bus differential protection system of described flexible direct-current closed-loop intelligent distribution network also comprises: be arranged on the bus differential protection device on described host node current conversion station;
The bus differential protection method of the bus differential protection system of described flexible direct-current closed-loop intelligent distribution network, comprising:
Direct current instrument transformer on described host node current conversion station and child node current conversion station gathers electric current and the voltage signal of the DC bus at its place, and is pooled to described bus differential protection device;
Described bus differential protection device, according to from the electric current of described host node current conversion station and each child node current conversion station and voltage signal, judges whether to there is unsymmetrical current;
As there is unsymmetrical current, then bus differential protection device judges that described flexible direct-current closed-loop intelligent distribution network exists fault;
If there is not unsymmetrical current, then bus differential protection device judges that flexible direct-current closed-loop intelligent distribution network normally works.
Wherein, described bus differential protection device according to from the electric current of described host node current conversion station and each child node current conversion station and voltage signal, judges whether to there is unsymmetrical current, comprising:
The host node current/voltage collecting unit of described bus differential protection device gathers electric current and the voltage signal of the direct current instrument transformer collection on described host node current conversion station by optical-fibre channel;
Multiple child node current/voltage collecting units of described bus differential protection device gather electric current and the voltage signal of the direct current instrument transformer collection on each child node current conversion station described by optical-fibre channel;
The host node current/voltage converting unit of described bus differential protection device by described host node current/voltage collecting unit its gather convert digital quantity to electric current and voltage signal;
The child node current/voltage converting unit of described bus differential protection device converts the collection of child node current/voltage converting unit to digital quantity to electric current and voltage signal;
The read group total comparing unit of described bus differential protection device carries out read group total to described host node current/voltage converting unit and the converted digital quantity of child node current/voltage converting unit and compares;
According to the result of calculation of described protective device read group total comparing unit, the command executing unit of described bus differential protection device judges whether described flexible direct-current closed-loop intelligent distribution network exists unsymmetrical current, and carry out Fault Isolation process when judging that described flexible direct-current closed-loop intelligent distribution network exists unsymmetrical current.
Implement the present invention, there is following beneficial effect:
The bus differential protection method and system of a kind of flexible direct-current closed-loop intelligent distribution network provided by the invention, it is designed by closed-loop shaped, the technical problem that the point of interface solving point-to-point flexible direct current power distribution network existence in prior art can not satisfy the demands; And using the region at the DC bus place of in this flexible direct-current closed-loop intelligent distribution network as host node current conversion station; all the other are as child node current conversion station; host node current conversion station is provided with bus differential protection device; carry out breakdown judge according to the electric current on the host node current conversion station collected and child node current conversion station and voltage, effectively and efficiently can carry out failture evacuation.
Accompanying drawing explanation
In order to be illustrated more clearly in the embodiment of the present invention or technical scheme of the prior art, be briefly described to the accompanying drawing used required in embodiment or description of the prior art below, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to these accompanying drawings.
Fig. 1 is the schematic diagram of the point-to-point flexible direct current power transmission system of prior art;
Fig. 2 is the structural representation of flexible direct-current closed-loop intelligent distribution network provided by the invention;
Fig. 3 is the structural representation in the DC bus district of flexible direct-current closed-loop intelligent distribution network provided by the invention;
Fig. 4 is the structural representation of the bus differential protection system embodiment one of flexible direct-current closed-loop intelligent distribution network provided by the invention;
Fig. 6 is the structural representation of the bus differential protection system embodiment two of flexible direct-current closed-loop intelligent distribution network provided by the invention;
Fig. 7 is the structural representation of the bus differential protection embodiment of the method one of flexible direct-current closed-loop intelligent distribution network provided by the invention;
Fig. 8 is the structural representation of the bus differential protection embodiment of the method two of flexible direct-current closed-loop intelligent distribution network provided by the invention.
Embodiment
In order to the point of interface solving the flexible direct current distribution network system put into operation at present can not meet power demands; and when DC bus (containing equipment such as the PT on DC bus) breaks down; the technical problem that power supply reliability that fault point causes reduces greatly cannot be found in time; the invention provides a kind of bus differential protection method and system of flexible direct-current closed-loop intelligent distribution network; it can provide support for voltage stabilization; improve quality of voltage; and when DC bus breaks down; can fix a breakdown in time, ensure normal power supply.
The bus differential protection system of a kind of flexible direct-current closed-loop intelligent distribution network provided by the invention, comprising:
N bar DC bus and N bar DC power transmission line; Every bar DC bus and DC power transmission line interval are connected, composition flexible direct-current closed-loop intelligent distribution network; N be more than or equal to 3 natural number;
Wherein, the region at a DC bus place in described N bar DC bus is host node current conversion station, and the region at all the other DC bus places is child node current conversion station;
Described every bar DC bus is connected with at least one for the electric energy of described AC system is rectified into direct current energy, imports the AC system converting plant of described closed-loop shaped intelligent distribution network; Described AC system converting plant one end is connected with described DC bus with DC switch by direct current instrument transformer, and the other end connects an AC system;
Wherein, in the AC system converting plant that described Mei Zu DC bus district connects, at least one AC system converting plant is as the voltage regulating station for controlling direct voltage.
Described every bar DC bus is also connected with M and direct current energy is reverse into alternating current to supply user's Inverter Station of user's use, described each user's Inverter Station is all connected with described DC bus with DC switch by direct current instrument transformer; M be more than or equal to 1 natural number;
Described every bar DC bus is also connected with the PT that the DC bus high-voltage variable collected is changed into secondary voltage by least one;
The bus differential protection system of described flexible direct-current closed-loop intelligent distribution network also comprises: be arranged on the bus differential protection device on described host node current conversion station;
Direct current instrument transformer on described host node current conversion station and child node current conversion station gathers electric current and the voltage signal of the DC bus at its place, and is pooled to described bus differential protection device;
Described bus differential protection device is according to from the electric current of described host node current conversion station and each child node current conversion station and voltage signal; judge whether to there is unsymmetrical current; in this way; then judge that described flexible direct-current closed-loop intelligent distribution network exists fault; as no, then judge that flexible direct-current closed-loop intelligent distribution network normally works.
Wherein, described every bar DC power transmission line is provided with K platform and fault point is carried out the DC switch of isolating for the tripping operation when described DC power transmission line has fault; K be more than or equal to 2 natural number.
Wherein, described bus differential protection device comprises:
The electric current gathered for the direct current instrument transformer gathered by optical-fibre channel on described host node current conversion station and the host node current/voltage collecting unit of voltage signal;
The child node current/voltage collecting unit of the electric current that multiple direct current instrument transformer on each child node current conversion station described in being gathered by optical-fibre channel is gathered and voltage signal;
Be connected with described host node current/voltage collecting unit, for the host node current/voltage converting unit converting digital quantity to electric current and voltage signal to gathered;
Multiple and described child node current/voltage collecting unit is connected, for the child node current/voltage converting unit converting digital quantity to electric current and voltage signal to gathered;
Be connected, for carrying out the protective device read group total comparing unit that read group total compares to its converted digital quantity with described host node current/voltage converting unit and each child node current/voltage converting unit;
Be connected with described protective device read group total comparing unit; for judging whether described flexible direct-current closed-loop intelligent distribution network exists unsymmetrical current according to the result of calculation of protective device read group total comparing unit, and carry out the command executing unit of Fault Isolation process when judging that described flexible direct-current closed-loop intelligent distribution network exists unsymmetrical current.
Wherein, described command executing unit is connected with described host node current conversion station and child node current conversion station by optical-fibre channel.
Implement the present invention, there is following beneficial effect:
The bus differential protection system of a kind of flexible direct-current closed-loop intelligent distribution network provided by the invention, it is designed by closed-loop shaped, the technical problem that the point of interface solving point-to-point flexible direct current power distribution network existence in prior art can not satisfy the demands; And using the region at the DC bus place of in this flexible direct-current closed-loop intelligent distribution network as host node current conversion station; all the other are as child node current conversion station; host node current conversion station is provided with bus differential protection device; carry out breakdown judge according to the electric current on the host node current conversion station collected and child node current conversion station and voltage, effectively and efficiently can carry out failture evacuation.
Below citing is described in detail the concrete structure of the bus differential protection system of a kind of flexible direct-current closed-loop intelligent distribution network provided by the invention.
First referring to Fig. 2, is the structural representation of a kind of flexible direct-current closed-loop intelligent distribution network provided by the invention, and this embodiment is be not yet the schematic diagram of this power distribution network configuration bus differential protection device.
A kind of flexible direct-current closed-loop intelligent distribution network shown in Fig. 2, it is that the closed-loop shaped intelligent distribution network being formed " handing in hand " with 3 DC buss and 3 DC power transmission line is described.
Concrete, the closed-loop shaped intelligent distribution network system based on flexible direct current shown in Fig. 2 comprises:
Article 3, DC bus, respectively: DC bus 1, DC bus 2, DC bus 3; Article 3, DC power transmission line is DC power transmission line 1, DC power transmission line 2, DC power transmission line 3 respectively;
This closed-loop shaped intelligent distribution network system also at least comprises: 6 DC switchs (QF1, QF2, QF3, QF4, QF5, QF6), certainly looks concrete condition, and the DC switch that every bar DC power transmission line is arranged can be more than two; At least comprise 3 AC system converting plants (or voltage regulating station), be respectively AC system converting plant (or voltage regulating station) 1, AC system converting plant (or voltage regulating station) 2, AC system converting plant (or voltage regulating station) 3;
In addition, each DC bus there is M platform user Inverter Station, concrete: DC bus 1 to have user Inverter Station 1-1 ... 1-m; DC bus 2 there is user Inverter Station 2-1 ... 2-n; DC bus 3 there is user Inverter Station 3-1 ... 3-m;
In this closed-loop shaped intelligent distribution network system, the effect of all parts is as follows:
The effect of DC bus 1, DC bus 2, DC bus 3 forms the closed-loop shaped intelligent distribution network of " handing in hand " mainly through DC power transmission line, connect each AC system converting plant (or voltage regulating station) simultaneously, play the effect collecting electric energy.
Each bar DC bus 1, DC bus 2, DC bus 3 link together by the effect of DC power transmission line 1, DC power transmission line 2, DC power transmission line 3, realize power delivery and electric energy uniform distribution.
DC switch (QF1, QF2, QF3, QF4, QF5, QF6) effect that DC power transmission line is arranged mainly is tripped when each bar DC power transmission line (1,2,3) has fault and is isolated fault point.
As d1 point failure in DC power transmission line in Fig. 21, the DC switch (QF1, QF2) of the protection act tripping both sides of this DC power transmission line 1, can realize Fault Isolation.
The alternating current supply that direct current energy is reverse into required for user by inversion transformation technique mainly uses by each user's Inverter Station effect that DC bus is arranged.
AC system converting plant (or voltage regulating station) Main Function is that the electric energy of AC system is rectified into direct current energy by commutation technique, imports the closed-loop shaped intelligent distribution network system of flexible direct current, realizes power distribution; Have at least 1 AC system converting plant to serve as voltage regulating station at the closed-loop shaped intelligent distribution network system of flexible direct current, effect mainly controls direct voltage, plays balance sysmte direct voltage function.
The Main Function of AC system 1, AC system 2, AC system 3 provides electric energy.
It should be noted that, the number of DC bus and DC power transmission line can also be other quantity such as 4,5,6,7; The quantity of AC system converting plant (voltage regulating station), AC system and user's inverter on every bar DC bus also can be arranged flexibly; DC switch quantity in every bar DC power transmission line also can be arranged to different numerical value.
Its main feature of flexible direct-current closed-loop intelligent distribution network system converter station shown in Fig. 2 utilizes DC bus as gathering and the link of transmission of electric energy, point of interface demand when can solve multi-user, many renewable energy resources (as wind energy, solar energy etc.) feed-in, also has and strengthens many-sided advantages such as improving power supply reliability.
Further; in order to avoid when DC bus (containing equipment such as the PT on DC bus) breaks down; the technical problem that power supply reliability that fault point causes reduces greatly cannot be found in time; the invention provides a kind of bus differential protection system of flexible direct-current closed-loop intelligent distribution network; it can provide support for voltage stabilization; improve quality of voltage; and when DC bus breaks down (the DC bus district 1 such as shown in Fig. 2 break down a d2); can fix a breakdown in time, ensure normal power supply.
See Fig. 3, it is the structural representation in the DC bus district of the bus differential protection system of flexible direct-current closed-loop intelligent distribution network provided by the invention.
As shown in Figure 3; first the bus differential protection system of the flexible direct-current closed-loop intelligent distribution network that the present embodiment one provides is configured the DC bus district of flexible direct-current closed-loop intelligent distribution network as shown in Figure 2; be described for the DC bus district 1 at the DC bus 1 of in Fig. 2 place, as follows:
This DC bus is provided with more than at least 1 AC system converting plant; And at least 1 above user side Inverter Station (as there being N platform in Fig. 3), be also provided with DC switch 1, DC switch 2 and DC switch N; And direct current instrument transformer 1, direct current mutual inductance 2 and direct current instrument transformer N; Separately, this DC bus is also provided with 1 PT.
This DC bus and the effect of above element that it is arranged as follows:
DC bus effect forms the closed-loop shaped intelligent distribution network of " handing in hand " mainly through DC power transmission line, connects each AC system converting plant (or voltage regulating station) simultaneously, plays and collect electric energy;
The effect of DC switch 1-N is mainly tripped when there being fault and buffer action is carried out in fault point;
PT is mainly transformed into collecting DC bus high voltage the secondary voltage protected and need as requested;
Direct current instrument transformer 1, direct current instrument transformer 2 and direct current instrument transformer N Main Function are that the electric current gathering each branch road is transformed into the secondary current protected and need as requested; Wherein, these direct current instrument transformers are optic current transformer, and the signal of collection passes through Optical Fiber Transmission in the mode of light.
It should be noted that, in Fig. 3, DC bus schematic diagram and involved element thereof belong to closed-loop shaped intelligent distribution network system wherein 1 current conversion station interior.
In Fig. 3, DC bus schematic diagram is the bus on closed-loop shaped intelligent distribution network system 1 node, and arranging of the DC bus on other nodes is identical, does not repeat them here.
For flexible direct-current closed-loop intelligent distribution network system provided by the invention, large node can be understood as, and in Fig. 3, DC bus can be understood as a child node.Flexible direct-current closed-loop intelligent distribution network in the present invention shown in Fig. 2 can be understood as large poor protection, for judging whether closed-loop shaped intelligent distribution network system exists fault; And the DC bus shown in Fig. 3 can be understood as little difference protection, for judging the concrete fault bus of closed-loop shaped intelligent distribution network system.Provided by the invention based on flexible direct-current closed-loop intelligent distribution network system bus differential protection system by large poor protection and little poor protection structure.
Each bus that the closed-loop shaped intelligent distribution network bus differential protection system of the flexible direct current that the present invention proposes relates to is dispersed in different local characteristics, therefore 1 current conversion station in flexible direct-current closed-loop intelligent distribution network can be selected to be host node current conversion station, as selected the DC bus 1 of the closed-loop shaped intelligent distribution network of the flexible direct current shown in Fig. 2 as host node current conversion station, a bus differential protection device is installed thereon, flexible direct-current closed-loop intelligent distribution network bus differential protection system provided by the invention can be formed, specifically as shown in Figure 4, each section of DC bus in certain Fig. 4 is provided with direct current instrument transformer and DC switch etc. all as shown in Figure 3, for the purpose of directly perceived, be not shown specifically in Fig. 4, those of ordinary skill in the art are to be understood that, the DC bus district at its each DC bus section place is arranged all as shown in Figure 3.
Concrete, bus differential protection device concrete structure as shown in Figure 5:
Bus differential protection device in the present embodiment comprises:
The electric current gathered for the direct current instrument transformer gathered by optical-fibre channel on described host node current conversion station and the host node current/voltage collecting unit of voltage signal;
The child node current/voltage collecting unit of the electric current that multiple direct current instrument transformer on each child node current conversion station described in being gathered by optical-fibre channel is gathered and voltage signal;
Be connected with described host node current/voltage collecting unit, for the host node current/voltage converting unit converting digital quantity to electric current and voltage signal to gathered;
Multiple and described child node current/voltage collecting unit is connected, for the child node current/voltage converting unit converting digital quantity to electric current and voltage signal to gathered;
Be connected, for carrying out the protective device read group total comparing unit that read group total compares to its converted digital quantity with described host node current/voltage converting unit and each child node current/voltage converting unit;
Be connected with described protective device read group total comparing unit; for judging whether described flexible direct-current closed-loop intelligent distribution network exists unsymmetrical current according to the result of calculation of protective device read group total comparing unit, and carry out the command executing unit of Fault Isolation process when judging that described flexible direct-current closed-loop intelligent distribution network exists unsymmetrical current.
Wherein, described command executing unit is connected with described host node current conversion station and child node current conversion station by optical-fibre channel.
In addition, bus differential protection device can also comprise: information print-out unit, human-computer dialogue unit etc., and its effect is as follows respectively:
Information print-out unit is used for printing protection act etc.
Human-computer dialogue unit is used for checking fixed value modification and state.
Fig. 6 is the structural representation of the bus differential protection system embodiment two of a kind of flexible direct-current closed-loop intelligent distribution network provided by the invention.
The bus differential protection system of the flexible direct-current closed-loop intelligent distribution network in above-described embodiment is only a single closed-loop shaped intelligent distribution network system; can according to urban development need be extended to many closed-loop shaped and be connected to each other intelligent distribution network system (ring, two rings ... N ring); wherein; connected by DC contact circuit between the closed-loop shaped intelligent distribution network of each ring, to strengthen the ability of conveying electricity.Specifically as shown in Figure 6; wherein; in order to for simplicity; not shown for the bus differential protection device that the configuration in DC bus district and each ring connect; those of ordinary skill in the art are to be understood that; wherein each ring is all connected with bus differential protection device, and its DC bus district is arranged all as shown in Figure 3 as in.
Accordingly, present invention also offers a kind of bus differential protection method of the bus differential protection system based on above-mentioned flexible direct-current closed-loop intelligent distribution network.
As shown in Figure 7, the bus differential protection method of the bus differential protection system of flexible direct-current closed-loop intelligent distribution network provided by the invention, comprising:
Step 100, the direct current instrument transformer on host node current conversion station and child node current conversion station gathers electric current and the voltage signal of the DC bus at its place, and is pooled to described bus differential protection device;
Step 101, bus differential protection device, according to from the electric current of described host node current conversion station and each child node current conversion station and voltage signal, judges whether to there is unsymmetrical current;
Step 102, as there is unsymmetrical current, then bus differential protection device judges that described flexible direct-current closed-loop intelligent distribution network exists fault;
Step 103, if there is not unsymmetrical current, then bus differential protection device judges that flexible direct-current closed-loop intelligent distribution network normally works.
As shown in Figure 8, bus differential protection device according to from the electric current of described host node current conversion station and each child node current conversion station and voltage signal, judges whether the step that there is unsymmetrical current, comprising:
Step 200, the host node current/voltage collecting unit of bus differential protection device gathers electric current and the voltage signal of the direct current instrument transformer collection on described host node current conversion station by optical-fibre channel;
Step 201, multiple child node current/voltage collecting units of bus differential protection device gather electric current and the voltage signal of the direct current instrument transformer collection on each child node current conversion station described by optical-fibre channel;
Step 202, the host node current/voltage converting unit of bus differential protection device by described host node current/voltage collecting unit its gather convert digital quantity to electric current and voltage signal;
Step 203, the child node current/voltage converting unit of bus differential protection device converts the collection of child node current/voltage converting unit to digital quantity to electric current and voltage signal;
Step 204, the read group total comparing unit of bus differential protection device carries out read group total to described host node current/voltage converting unit and the converted digital quantity of child node current/voltage converting unit and compares;
Step 205; according to the result of calculation of described protective device read group total comparing unit, the command executing unit of bus differential protection device judges whether described flexible direct-current closed-loop intelligent distribution network exists unsymmetrical current, and carry out Fault Isolation process when judging that described flexible direct-current closed-loop intelligent distribution network exists unsymmetrical current.
The embody rule of the bus differential protection method of the bus differential protection system of flexible direct-current closed-loop intelligent distribution network provided by the invention is as follows:
The each child node current conversion station of flexible direct-current closed-loop intelligent distribution network gathers the magnitude of current by direct current instrument transformer.Host node current conversion station gathers the magnitude of current by DC current transformer simultaneously.
Each for closed-loop shaped intelligent distribution network system minor node current conversion station is pooled to by the DC current transformer collection magnitude of current bus differential protection device that host node current conversion station connects carry out calculating and comparing.
If broken down in closed-loop shaped intelligent distribution network, the large poor protection of the bus differential protection device that host node current conversion station connects senses unsymmetrical current, and is sudden change, and namely all fault currents flow into toward fault point, and current break increases, and voltage reduces.The load that whole closed-loop shaped intelligent distribution network system flows to outflow if broken down outside closed-loop shaped intelligent distribution network is equal.
The little difference protection of corresponding each child node current conversion station is had in the bus differential protection device that host node current conversion station connects; sense unsymmetrical current equally; and be sudden change (current break increases, and voltage reduces), can calculate thus and compare the DC bus child node broken down.As shown in Figure 2, DC bus 1 fault calculates current conversion station 1 node at main website bus differential protection device difference stream etc.
Trip signal is passed on the child node broken down, is carried out tripping Fault Isolation after waiting for the little poor protection calculation of corresponding each child node current conversion station by the bus differential protection device that host node current conversion station connects.
Implement the present invention, there is following beneficial effect:
The first, flexible direct-current closed-loop intelligent distribution network bus differential protection system and method for the present invention, can solve in flexible DC power transmission, adopt at present point-to-point direct current power to pass on weak problem.
The second, flexible direct-current closed-loop intelligent distribution network bus differential protection system and method for the present invention, can solve and exchange for point voltage problem of poor quality at present.Concrete, the present invention adopts the closed-loop shaped intelligent distribution network system of flexible direct current to have at least 1 AC system converting plant to serve as voltage regulating station, and effect mainly controls direct voltage, plays balance sysmte direct voltage function, improves quality of voltage.
3rd, flexible direct-current closed-loop intelligent distribution network bus differential protection system and method for the present invention, can solve the technical problem of the nervous situation in passway for transmitting electricity corridor.Concrete, the present invention adopts the closed-loop shaped intelligent distribution network system of flexible direct current, be mainly used in the city of relatively concentrating, direct current cables transmission of electricity is adopted in DC power transmission line, only need two passways for transmitting electricity, save a passway for transmitting electricity (just can reduce by 3 passways for transmitting electricity if any three transmission lines), in addition also not by the restriction in transmission of electricity corridor, be convenient to dilatation.In addition, do not need any converting plant and Inverter Station are installed at the DC power transmission line two ends of the closed-loop shaped intelligent distribution network system based on flexible direct current provided by the invention, cost-saving.
4th; flexible direct-current closed-loop intelligent distribution network bus differential protection system and method for the present invention; its using the region at the DC bus place of in this flexible direct-current closed-loop intelligent distribution network as host node current conversion station; all the other are as child node current conversion station; host node current conversion station is provided with bus differential protection device; carry out breakdown judge according to the electric current on the host node current conversion station collected and child node current conversion station and voltage, effectively and efficiently can carry out failture evacuation.
Above content is in conjunction with concrete preferred implementation further description made for the present invention, can not assert that specific embodiment of the invention is confined to these explanations.For general technical staff of the technical field of the invention, without departing from the inventive concept of the premise, some simple deduction or replace can also be made, all should be considered as belonging to protection scope of the present invention.
Claims (3)
1. a bus differential protection system for flexible direct-current closed-loop intelligent distribution network, is characterized in that, comprising:
N bar DC bus and N bar DC power transmission line; Every bar DC bus and DC power transmission line interval are connected, composition flexible direct-current closed-loop intelligent distribution network; N be more than or equal to 3 natural number;
Wherein, the region at a DC bus place in described N bar DC bus is host node current conversion station, and the region at all the other DC bus places is child node current conversion station;
Described every bar DC bus is connected with at least one for the electric energy of AC system is rectified into direct current energy, imports the AC system converting plant of described closed-loop shaped intelligent distribution network; Described AC system converting plant one end is connected with described DC bus with DC switch by direct current instrument transformer, and the other end connects an AC system;
Described every bar DC bus is also connected with M and direct current energy is reverse into alternating current to supply user's Inverter Station of user's use, each described user's Inverter Station is all connected with described DC bus with DC switch by direct current instrument transformer; M be more than or equal to 1 natural number;
Described every bar DC bus is also connected with the voltage transformer pt that the DC bus high-voltage variable collected is changed into secondary voltage by least one;
The bus differential protection system of described flexible direct-current closed-loop intelligent distribution network also comprises: be arranged on the bus differential protection device on described host node current conversion station;
Direct current instrument transformer on described host node current conversion station and child node current conversion station gathers electric current and the voltage signal of the DC bus at its place, and is pooled to described bus differential protection device;
Described bus differential protection device is according to from the electric current of described host node current conversion station and each child node current conversion station and voltage signal, judge whether to there is unsymmetrical current, in this way, then judge that described flexible direct-current closed-loop intelligent distribution network exists fault, as no, then judge that flexible direct-current closed-loop intelligent distribution network normally works;
Wherein, DC power transmission line described in every bar is provided with K platform and fault point is carried out the DC switch of isolating for the tripping operation when described DC power transmission line has fault; K be more than or equal to 2 natural number;
wherein, described bus differential protection device comprises:
The electric current gathered for the direct current instrument transformer gathered by optical-fibre channel on described host node current conversion station and the host node current/voltage collecting unit of voltage signal;
The child node current/voltage collecting unit of the electric current that multiple direct current instrument transformer on each child node current conversion station described in being gathered by optical-fibre channel is gathered and voltage signal;
Be connected with described host node current/voltage collecting unit, for the host node current/voltage converting unit converting digital quantity to electric current and voltage signal to gathered;
Multiple and described child node current/voltage collecting unit is connected, for the child node current/voltage converting unit converting digital quantity to electric current and voltage signal to gathered;
Be connected, for carrying out the protective device read group total comparing unit that read group total compares to its converted digital quantity with described host node current/voltage converting unit and each child node current/voltage converting unit;
Be connected with described protective device read group total comparing unit, for judging whether described flexible direct-current closed-loop intelligent distribution network exists unsymmetrical current according to the result of calculation of protective device read group total comparing unit, and carry out the command executing unit of Fault Isolation process when judging that described flexible direct-current closed-loop intelligent distribution network exists unsymmetrical current;
wherein, described command executing unit is connected with described host node current conversion station and child node current conversion station by optical-fibre channel;
wherein, in the AC system converting plant that Mei Zu DC bus district connects, at least one AC system converting plant is as the voltage regulating station for controlling direct voltage.
2. based on a bus differential protection method for the bus differential protection system of flexible direct-current closed-loop intelligent distribution network described in claim 1, it is characterized in that, the bus differential protection system of described flexible direct-current closed-loop intelligent distribution network, comprising:
N bar DC bus and N bar DC power transmission line; Every bar DC bus and DC power transmission line interval are connected, composition flexible direct-current closed-loop intelligent distribution network; N be more than or equal to 3 natural number;
Wherein, the region at a DC bus place in described N bar DC bus is this host node current conversion station, and the region at all the other DC bus places is child node current conversion station;
Described every bar DC bus is connected with at least one for the electric energy of described AC system is rectified into direct current energy, imports the AC system converting plant of described closed-loop shaped intelligent distribution network; Described AC system converting plant one end is connected with described DC bus with DC switch by direct current instrument transformer, and the other end connects an AC system;
Described every bar DC bus is also connected with M and direct current energy is reverse into alternating current to supply user's Inverter Station of user's use, each described user's Inverter Station is all connected with described DC bus with DC switch by direct current instrument transformer; M be more than or equal to 1 natural number;
Described every bar DC bus is also connected with the PT that the DC bus high-voltage variable collected is changed into secondary voltage by least one;
The bus differential protection system of described flexible direct-current closed-loop intelligent distribution network also comprises: be arranged on the bus differential protection device on described host node current conversion station;
The bus differential protection method of the bus differential protection system of described flexible direct-current closed-loop intelligent distribution network, comprising:
Direct current instrument transformer on described host node current conversion station and child node current conversion station gathers electric current and the voltage signal of the DC bus at its place, and is pooled to described bus differential protection device;
Described bus differential protection device, according to from the electric current of described host node current conversion station and each child node current conversion station and voltage signal, judges whether to there is unsymmetrical current;
As there is unsymmetrical current, then bus differential protection device judges that described flexible direct-current closed-loop intelligent distribution network exists fault;
If there is not unsymmetrical current, then bus differential protection device judges that flexible direct-current closed-loop intelligent distribution network normally works.
3. the bus differential protection method of the bus differential protection system of flexible direct-current closed-loop intelligent distribution network as claimed in claim 2; it is characterized in that; described bus differential protection device is according to from the electric current of described host node current conversion station and each child node current conversion station and voltage signal; judge whether to there is unsymmetrical current, comprising:
The host node current/voltage collecting unit of described bus differential protection device gathers electric current and the voltage signal of the direct current instrument transformer collection on described host node current conversion station by optical-fibre channel;
Multiple child node current/voltage collecting units of described bus differential protection device gather electric current and the voltage signal of the direct current instrument transformer collection on each child node current conversion station described by optical-fibre channel;
The host node current/voltage converting unit of described bus differential protection device by described host node current/voltage collecting unit its gather convert digital quantity to electric current and voltage signal;
The child node current/voltage converting unit of described bus differential protection device converts the collection of child node current/voltage converting unit to digital quantity to electric current and voltage signal;
The read group total comparing unit of described bus differential protection device carries out read group total to described host node current/voltage converting unit and the converted digital quantity of child node current/voltage converting unit and compares;
According to the result of calculation of described protective device read group total comparing unit, the command executing unit of described bus differential protection device judges whether described flexible direct-current closed-loop intelligent distribution network exists unsymmetrical current, and carry out Fault Isolation process when judging that described flexible direct-current closed-loop intelligent distribution network exists unsymmetrical current.
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