CN103730883B - For the guard method of radial pattern direct-flow distribution system DC line short trouble - Google Patents
For the guard method of radial pattern direct-flow distribution system DC line short trouble Download PDFInfo
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Abstract
The invention provides a kind of guard method for radial pattern direct-flow distribution system DC line short trouble, said method comprising the steps of: malfunction monitoring point is set; Starting element action; Determine DC line short trouble, and disconnect dc circuit breaker. Guard method for radial pattern direct-flow distribution system DC line short trouble provided by the invention; this guard method principle is simple; when this line fault, rapidity is good; ensure in situation that subordinate's DC distribution circuit or AC distribution line fault are the most serious simultaneously; protect not malfunction, for the safe and reliable operation of direct-flow distribution system provides technical support.
Description
Technical field
The present invention relates to a kind of guard method, specifically relate to a kind of for radial pattern direct-flow distribution system DC line short troubleGuard method.
Background technology
DC distribution technology based on pulsewidth modulation is as a kind of novel distribution technique, have that the quality of power supply is high, transmission capacity large,Reliability is high, topological structure is simple, good economy performance and the advantage such as electric energy loss is low, especially adapts to the access of distributed power source multiple spot,Can the make greater efforts to promote development of direct current household electrical appliances and " direct current ecological residence ", meets the inherent requirement of intelligent grid development. Therefore, domesticOuter numerous scholar turns one's attention to the research of direct-flow distribution system. At present, to the research of direct-flow distribution system be still in theory analysis,Modeling and simulating and experimental study stage.
For ensureing the safe and reliable operation of direct-flow distribution system in power system, complete relay protection system is indispensable. ButCurrent research seldom relates to protection philosophy and the configuration of direct-flow distribution system, and existing protection research is also mainly to lay particular emphasis on macroscopic viewUpper exploration is based on dc circuit breaker and between the performance difference based on dc circuit breaker protection, multizone protection, do not coordinate and direct current is joinedElectric system protection requires standard etc., in direct-flow distribution system the research of equipment protection principle less, especially at DC distribution circuitThe exploration of protection philosophy aspect. DC line protection that at present can reference mainly concentrate on DC traction, naval vessel DC distribution andThe aspects such as D.C. high voltage transmission; But, because DC distribution and the above-mentioned straight-flow system of power system are widely different, reference is notObviously.
Summary of the invention
In order to overcome above-mentioned the deficiencies in the prior art, the invention provides a kind of for the short circuit of radial pattern direct-flow distribution system DC lineThe guard method of fault, this guard method principle is simple, and when this line fault, rapidity is good, ensures subordinate's DC distribution line simultaneouslyIn the most serious situation of road or AC distribution line fault, protect not malfunction, for the safe and reliable operation of direct-flow distribution system providesTechnical support.
In order to realize foregoing invention object, the present invention takes following technical scheme:
The invention provides the guard method for radial pattern direct-flow distribution system DC line short trouble, described method comprises followingStep:
Step 1: malfunction monitoring point is set;
Step 2: starting element action;
Step 3: determine DC line short trouble, and disconnect dc circuit breaker.
In described step 1, in direct current transmission and distribution system, DC line fault monitoring point is arranged on distribution current conversion station DC side and goes outMouth place, the DC voltage u in Real-time Collection exit and DC current i.
In described step 2, according to the distribution current conversion station DC side exit malfunction monitoring point DC voltage u gathering, calculate in real timeGo out instantaneous DC voltage rate of descent du/dt, if the continuous DC voltage that exceedes protection startup for three times of the du/dt calculating declinesRate setting valve du/dt_set, start fault distinguishing program, and record now DC current sampled value I0, enter step 3; OtherwiseProtection fault distinguishing program does not start.
Described step 3 comprises the following steps:
Step 3-1: establishing k is DC line overload magnification, if starting element action moment DC current sampled value I0Be greater than k doublyDC line maximum load current ImaxTime, meet I0＞kImax, be judged to be DC line short trouble, send immediately jumpingLock instruction, disconnects dc circuit breaker; Otherwise execution step 3-2;
Step 3-2: by DC current sampled value I0As a reference value, calculate in real time current increment Δ I, start after-current in protectionIncrement protection is differentiated time setting value Δ T_setIn time, if Δ I=i-I0＞ΔI_set, wherein Δ I_setFor rate of current rise protection actionCurrent increment setting valve, be judged to be DC line short trouble, disconnect dc circuit breaker;
Step 3-3: if I0＞kImaxWith start Δ T in protection_setΔ I > Δ I in time_setAll be false, show DC lineOn there is not short trouble, return to the self-inspection of step 2 starting element.
Described radial pattern direct-flow distribution system is rectified into medium voltage DC by distribution current conversion station by High Level AC Voltage, through direct currentCable distributes power to user area; In the customer substation of user area, medium voltage DC is reverse into low-voltage AC, step-down becomes low-pressure directStream electricity, to AC load and DC load power supply, the middle pressure dc bus that connects direct current cables also can be directly to DC load respectivelyPower. Meanwhile, distributed power source and energy storage device directly can be connected on dc bus; Described distribution current conversion station comprises and fallingPressure transformer and voltage-source type rectifier.
Compared with prior art, beneficial effect of the present invention is:
1. can fast and reliable action send trip command when DC line fault, and AC system breaks down and exchanges with downstreamSide, the reliably locking of DC side fault, ensured reliability, quick-action, selective and sensitivity that protection is moved;
2. when the fault of DC line exit, protection can be with without deferred action tripping operation, the DC line end fault that is short-circuited, alsoCan in 10ms, trip by starting protection, therefore there is good quick-action;
3. this guard method principle is simple, and when this line fault, rapidity is good, ensures that subordinate's DC distribution circuit or interchange join simultaneouslyIn the most serious situation of line fault, protect not malfunction, for the safe and reliable operation of direct-flow distribution system provides technical support.
Brief description of the drawings
Fig. 1 is radial pattern direct-flow distribution system test model topology diagram;
Fig. 2 is voltage-source type rectifier topology structure figure in distribution current conversion station;
Fig. 3 is voltage-source type rectifier control strategy sketch in distribution current conversion station;
Fig. 4 does not consider in relay protection action situation, DC line short trouble transient DC voltage, DC current emulation rippleShape figure;
Fig. 5 do not consider in relay protection action situation, and DC line short trouble transient DC voltage, DC current waveform showIntention;
Fig. 6 is the guard method flow chart for radial pattern direct-flow distribution system DC line short trouble.
Detailed description of the invention
Below in conjunction with accompanying drawing, the present invention is described in further detail.
EmbodimentGuard method for radial pattern direct-flow distribution system DC line short trouble provided by the invention is applied in to the institute as Fig. 2Show on direct-flow distribution system simulation model, carry out case verification.
In instance model, when steady-state operation, DC line voltage is 20kV, and DC current is 0.5kA. For this model,Arrange protection operating criterion in each parameter tuning value as follows.
du/dt_set=600V/ms，Imax=1kA，k=2，ΔI_set=0.5kA，ΔT_set=2ms
In PSCAD model, transient fault is set, the data of DC voltage, DC current before and after fault are input to MatlabIn the failure criterion that programming realizes, draw to draw a conclusion:
(1) straightening Flow Line tail end direct short-circuit fault in, protection criterion can be sent dc circuit breaker trip signal in 10ms,And earth fault can not make protection action;
(2) in low-voltage alternating-current circuit head end in the time there is single-phase direct ground connection, line to line fault, the direct earth fault of three-phase, and protection allBe failure to actuate;
(3), when low-voltage direct circuit head end generation direct short-circuit fault, protection meeting is moved after 700ms, thereby can lead to completelyIn crossing, straightening Flow Line and low-voltage direct cooperation of line protection are eliminated protection nonaction;
(4) in, when straightening Flow Line generation high resistant short trouble, protection there will be misaction.
By PSCAD and Matlab simulating, verifying, confirm the feasibility of DC line protection method.
Finally should be noted that: above embodiment is only in order to illustrate that technical scheme of the present invention is not intended to limit, although referenceAbove-described embodiment has been described in detail the present invention, and those of ordinary skill in the field are to be understood that: still can be to thisInvention detailed description of the invention modify or be equal to replacement, and do not depart from spirit and scope of the invention any amendment or etc.With replacing, it all should be encompassed in the middle of claim scope of the present invention.
Claims (1)
1. for the guard method of radial pattern direct-flow distribution system DC line short trouble, it is characterized in that: described method comprisesFollowing steps:
Step 1: malfunction monitoring point is set;
Step 2: starting element action;
Step 3: determine DC line short trouble, and disconnect dc circuit breaker;
In described step 1, in direct current transmission and distribution system, DC line fault monitoring point is arranged on distribution current conversion station DC side and goes outMouth place, the DC voltage u in Real-time Collection exit and DC current i;
In described step 2, according to the distribution current conversion station DC side exit malfunction monitoring point DC voltage u gathering, calculate in real timeGo out instantaneous DC voltage rate of descent du/dt, if the continuous DC voltage that exceedes protection startup for three times of the du/dt calculating declinesRate setting valve du/dt_set, start fault distinguishing program, and record now DC current sampled value I0, enter step 3; OtherwiseProtection fault distinguishing program does not start;
Described step 3 comprises the following steps:
Step 3-1: establishing k is DC line overload magnification, if starting element action moment DC current sampled value I0Be greater than k doublyDC line maximum load current ImaxTime, meet I0＞kImax, be judged to be DC line short trouble, send immediately jumpingLock instruction, disconnects dc circuit breaker; Otherwise execution step 3-2;
Step 3-2: by DC current sampled value I0As a reference value, calculate in real time current increment Δ I, start after-current in protectionIncrement protection is differentiated time setting value Δ T_setIn time, if Δ I=i-I0＞ΔI_set, wherein Δ I_setFor rate of current rise protection actionCurrent increment setting valve, be judged to be DC line short trouble, disconnect dc circuit breaker;
Step 3-3: if I0＞kImaxWith start Δ T in protection_setΔ I > Δ I in time_setAll be false, show DC lineOn there is not short trouble, return to the self-inspection of step 2 starting element;
Described radial pattern direct-flow distribution system is rectified into medium voltage DC by distribution current conversion station by High Level AC Voltage, through direct currentCable distributes power to user area; In the customer substation of user area, medium voltage DC is reverse into low-voltage AC, step-down becomes low-pressure directStream electricity, to AC load and DC load power supply, the middle pressure dc bus that connects direct current cables also can be directly to DC load respectivelyPower; Meanwhile, distributed power source and energy storage device directly can be connected on dc bus; Described distribution current conversion station comprises and fallingPressure transformer and voltage-source type rectifier.
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Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104009452B (en) * | 2014-05-29 | 2016-10-12 | 天津大学 | A kind of protection scheme for direct-flow distribution system short trouble |
| CN104300518B (en) * | 2014-10-13 | 2017-02-15 | 天津大学 | Quick direct current system protection scheme based on voltage source type current converter |
| CN105449647B (en) * | 2015-11-16 | 2018-03-02 | 三峡大学 | A kind of class radar guard method of power distribution network |
| CN106684841B (en) * | 2017-02-03 | 2018-12-07 | 许继电气股份有限公司 | Flexible direct current network system direct-current short circuit fault protecting method and device |
| CN107478950A (en) * | 2017-07-28 | 2017-12-15 | 许继集团有限公司 | A kind of discrimination method of the bipolar short trouble of DC line |
| CN110120657B (en) | 2018-02-06 | 2022-04-08 | 西门子公司 | Unit power grid protection device, large power grid and method for controlling unit power grid protection device |
| CN108493980A (en) * | 2018-03-28 | 2018-09-04 | 许继电气股份有限公司 | A kind of flexible direct current network re-active power control method for coordinating and system |
| CN108683160B (en) * | 2018-04-28 | 2020-01-14 | 西安理工大学 | Transient energy protection method for fault current of direct-current transmission line |
| CN109687419B (en) * | 2019-02-18 | 2020-05-08 | 福州大学 | Medium-voltage direct-current distribution network fault current limiting method based on capacitance protection |
| CN112713576B (en) * | 2020-12-21 | 2024-10-11 | 西安理工大学 | Short-circuit protection method for radial direct current micro-grid |
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| CN202068184U (en) * | 2010-12-09 | 2011-12-07 | 国家电网公司 | Cascade converter station and cascade multi-terminal HVDC system |
| CN102856881A (en) * | 2012-09-05 | 2013-01-02 | 华北电力大学 | Full-bridge MMC (multi-media card)-HVDC (high-voltage direct current) fault classification detection and protection method |
| CN103004048A (en) * | 2010-06-14 | 2013-03-27 | Abb研究有限公司 | Fault protection of HVDC transmission lines |
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| CN101702506A (en) * | 2009-10-30 | 2010-05-05 | 中国船舶重工集团公司第七一九研究所 | Method and device for rapidly detecting short-circuit fault of power system |
| CN103004048A (en) * | 2010-06-14 | 2013-03-27 | Abb研究有限公司 | Fault protection of HVDC transmission lines |
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