CN101872964B - Wide area measurement system based back-up protection method of multi-terminal high-voltage power transmission area - Google Patents

Abstract

The invention discloses a wide area measurement system based back-up protection method of a multi-terminal high-voltage power transmission area, belonging to the technical field of relay protection of electric power systems. In the method, the wide area measurement system based back-up protection of the multi-terminal high-voltage power transmission area and the synchronous real-time measurement on the voltage and current phasors of nodes provided with phasor measuring units are realized through adding centralized decision-making servers by utilizing the wide area measurement system of the multi-terminal high-voltage power transmission area, and a master station and a wide area back-up protecting server carrying out computation and analysis to accurately fix specific fault phases and fault line and issue control commands to execution substations of all lines in the area. The invention can make a decision within at most 200 milliseconds and sends the decision to every execution substation through adding the centralized decision making server and a remote control execution system, thereby realizing the wide area information based back-up protection of the multi-terminal high-voltage power transmission areas and avoiding the fault of power failure in a large area due to protection misoperation after the fault occurs.

Description

Back-up protection method of multi-terminal high-voltage power transmission area based on WAMS

Technical field

The invention belongs to the Relay Protection Technology in Power System field, specifically relate to a kind of back-up protection method of the multi-terminal high-voltage power transmission area based on WAMS.

Background technology

After electrical network broke down, the route protection in the electric power system was used for realizing to the automatic of faulty line and fast excision and isolated fault, to guarantee normal operation personal and device security and fault-free part.The main protection of circuit is according to the on the spot information of circuit, and at once tripping circuit breaker on the spot excises on the spot circuit, isolated fault when fault.The backup protection of circuit is used in the situation that power line main protection is malfunctioning or line-breaker is malfunctioning, and the circuit breaker of tripping this locality or All other routes is realized the isolation of line fault.Yet, along with electric network composition is increasingly sophisticated, operational mode is day by day flexible, make a strategic decision and traditional backup protection of judging exists many defectives based on local information: 1. the backup protection matching relationship is complicated, operate time is long, might be discontented with the desired critical clearing time of pedal system stability when serious, and then become the potential safety hazard of large electrical network; 2. backup protection configuration is large with the difficulty of adjusting, and variation that can not the tracking system operational mode, even mismatch or under-sensitive situation might occur protecting; 3. when changes of operating modes, for guaranteeing the selectivity of backup protection far away, the definite value amount of calculation is huge, in supergrid even might can't cooperate; Often configure multiple backup protection on each element, so that protection structure is complicated, cost increases.Therefore, under the complex electric network environment, the problem that the close examination backup protection exists, studying new backup protection principle and configuration scheme is the important content that ensures power grid security.

Ultra-high-tension power transmission line is the main artery of the normal operation of electrical network, both undertaken the task of transmitting great power, be again the tie of each large grid network operation, its operational reliability affects the power supply reliability of whole electrical network, is again maximum place of breaking down in the electric power system simultaneously.If the backup protection mistake is excised normal high-tension line; to cause on this circuit a large amount of power to shift; and then easily cause on the All other routes backup protection because of protected circuit overload malfunction, thereby the accelerating system collapse causes the generation of the long-time power outage of large tracts of land.It is exactly because the northern Akron of Ohio, USA is backlogged protection excision Quick Extended to 4 interconnections between the Cleveland because of overload that the U.S. on August 14th, 2003 strengthens power outage.On July 1st, 2006,500kV Song Shan to Zhengzhou two back transmission lines hinder for some reason rear protection malfunction and in succession excise, and directly cause in Yu Xi, the Henan many 220kV circuits because overload is backlogged the protection excision, cause the west, Henan to have a power failure on a large scale.Therefore, research trunk high-voltage power transmission area wide area backup protection principle has important practice significance.

Along with the appearance of wide area synchronized phasor measurement technology and the raising of computer process ability, so that concentrate to obtain the synchronous electric tolerance of regional power grid multiple spot, and carry out the collective analysis decision-making and become possibility.The present invention will utilize the WAMS of multi-terminal high-voltage power transmission area, by increasing the realization of centralized decision-making server and distant place control executive system based on the backup protection of the multi-terminal high-voltage power transmission area of Wide-area Measurement Information.Avoid causing because protect misoperation after the fault fault of large-area power-cuts.

Summary of the invention

The object of the present invention is to provide a kind of back-up protection method of multi-terminal high-voltage power transmission area based on WAMS; utilize the WAMS of multi-terminal high-voltage power transmission area, by increasing the realization of centralized decision-making server and distant place control executive system based on the multi-terminal high-voltage power transmission area backup protection of Wide-area Measurement Information.

The objective of the invention is to be achieved through the following technical solutions:

At first utilize the existing WAMS of multi-terminal high-voltage power transmission area to realize that all are equipped with the voltage of phasor measurement unit node, the synchronous real-time measurement of electric current phasor to this zone; computational analysis through WAMS main website and wide area backup protection server; accurately determine concrete fault phase and faulty line, and issue the execution substation that control command arrives each circuit in this zone.Concrete steps are as follows:

(1) formulates the phasor measurement unit allocation plan, voltage, the electric current phasor at each phasor measurement unit real-time measurement mounting points place, calculate amplitude and the phase place of voltage, electric current according to voltage, the electric current phasor of real-time measurement, and the quantity of states such as amplitude, phase calculation result and circuit breaker position, disconnecting link position and the markers in the corresponding moment by delivering to the phasor data concentrator of main website on the communication network;

(2) the wide area backup protection server obtains the data of delivering to main website phasor data concentrator on above-mentioned (1) and carries out computational analysis, whether adopt the wide area current differential protection to detect in the protection zone breaks down, if discovery is broken down in the protection zone, then determine the separate and transition resistance situation of concrete fault, and accurately determine faulty line according to the faulty line system of selection; After definite faulty line and fault were separate, the main website at once execution substation on the faulty line sent trip signal;

(3) utilize the inherent delay of communication system and main station judging decision system, realize the main protection of circuit tradition, the backup protection of circuit tradition and time coordination based on the multi-terminal high-voltage power transmission area backup protection of WAMS.

The principal character of the wide area line backup protection system that the present invention proposes is as follows:

(1) to be one be similar T shape transmission line by external port configuration phasor measurement unit, the inner transmission line that does not configure phasor measurement unit and contain a plurality of branch roads to described multi-terminal high-voltage power transmission area, or the Grid that comprises many transmission lines that is surrounded by configuration phasor measurement unit node, bus nodes does not configure phasor measurement unit in this district.

(2) the phasor measurement unit allocation plan of multi-terminal high-voltage power transmission area refers to that inner each transformer station of multi-terminal high-voltage power transmission area does not configure phasor measurement unit in each transformer station's configuration phasor measurement unit of multi-terminal high-voltage power transmission area outermost.

(3) data communication system: communication network adopts the electric power data Ethernet also can adopt special line, the synchronized phasor the data Transmission Control Protocol transmission of Real-time Collection, and the control command that main website wide area backup protection server issues adopts the udp protocol transmission.Measurement data is no more than 150ms to the delay of main website, and control command is issued to carries out the substation, postpones to be no more than 50ms.

(4) wide area backup protection function: comprise that the protection zone internal fault detects and fault branch is selected, implementation method is as follows:

A) voltage, the electric current phasor at each phasor measurement unit mounting points place of collecting according to main website in real time of wide area backup protection policy server; adopt the wide area current differential protection to detect in the protection zone and whether break down, in finding the protection zone, break down and then determine the separate and transition resistance situation of concrete fault.

B) the wide area current differential protection in the above-mentioned steps (a) comprises the protection of wide area full current differential and the protection of wide area fault component based differential protection, the two replenishes the internal fault Detection task that is used for bearing multi-terminal high-voltage power transmission area mutually, wherein, the protection of wide area full current differential refers to that the wide area backup protection server directly carries out Phase-Sequence Transformation to the real-time measurement data of sending on each phasor measurement unit, the center of choosing multi-terminal high-voltage power transmission area is reference point, based on distributed parameter model, each order component of first and last end by multi-terminal high-voltage power transmission area is calculated each order differential current and each the order stalling current that obtains the reference point place to reference point respectively, then syntheticly obtain each corresponding differential current and stalling current, utilize at last ratio-restrained characteristic to consist of the full current differential protection; Wide area fault component current differential protection refers to that the wide area backup protection server is just calculating each phasor measurement unit mounting points place; negative; residual voltage fault component and just; negative; the zero-sequence current fault component; the center of choosing multi-terminal high-voltage power transmission area is reference point; based on distributed parameter model; each order fault component of first and last end by multi-terminal high-voltage power transmission area is calculated each order fault component based differential protection electric current and each the order fault component braking electric current that obtains the reference point place to reference point respectively; then syntheticly obtain each corresponding fault component based differential protection electric current and fault component braking electric current, utilize at last ratio-restrained characteristic to consist of the fault component current differential protection.

C) in detecting the protection zone, break down; then accurately determine faulty line according to the faulty line system of selection; then main website is to the execution substation sending action order of faulty line; the execution substation of other regular links sends the locking order in the protection zone; wherein; the faulty line system of selection refers to based on distributed parameter model, is calculated to reference edge respectively by each proper order component and obtains the solution χ that faulty line is selected equation _IR(I=1 ..., N), if χ _IR(I=1 ..., satisfy χ between N) _1R＜χ _2R＜...＜χ _KR＜χ _K+1R=...=χ _NR, then _PK+ 1 _PKLine fault; If χ _IR(I=1 ..., satisfy χ between N) _1R＜χ _2R＜... χ _K-1R＜χ _K+1R=...=χ _NR＜χ _KR, K then _PKLine fault; Wherein R is reference edge, and N is the node sum of multi-terminal high-voltage zone outermost.

D) faulty line in the above-mentioned steps (c) selects equation to refer to that its expression formula is based on the synchronous fault distance-finding method of the double line terminal of distributed parameter model

Wherein

χ _IRCalculate the solution of the faulty line selection equation that obtains to reference edge R for rectified the order component by I,

Positive sequence voltage, electric current for reference edge R;

Be P ₁Node is to the distance of reference edge R;

For rectifying the order component to P by I ₁Node is calculated the P that obtains ₁Node voltage, P ₁Node outlet electric current; Z _C1, γ ₁Be transmission line positive sequence wave impedance and propagation constant.

The computational analysis time of above-mentioned realization backup protection in main website backup protection policy server is superelevation 200ms not.

(5) carry out the substation: carry out the core of substation by consisting of with the logic tripping controller; its input is that (open is 0 for the folding condition of circuit breaker; be combined into 1) and the trip signal that comes from the wide area backup protection main website (normally be 0; tripping operation is 1); only have when the folding condition of circuit breaker is 1 entirely with the trip signal input that comes from the wide area backup protection main website; be output as 1 with the logic tripping controller, just the corresponding line-breaker of tripping.

The present invention is based on WAMS and realize the multi-terminal high-voltage power transmission area backup protection, can in 200 milliseconds, make a policy at most and send to and respectively carry out the substation.The method of segmentation ladder time delay is taked in the traditional circuit backup protection in order to realize selectivity, one-level ladder time delay just needs 500 milliseconds usually, and multistage time delay may be up to the several seconds.Therefore, responsiveness of the present invention is slower than power line main protection, faster than the traditional circuit backup protection based on this locality amount decision-making.Thereby, can keep under traditional trunk high-voltage power transmission area power line main protection and the traditional circuit reserve prerequisite, between the two, increase together new defence line, i.e. back-up protection method of multi-terminal high-voltage power transmission area based on WAMS proposed by the invention.

Description of drawings

Fig. 1 is based on the backup protection overall plan schematic diagram of WAMS multi-terminal high-voltage power transmission area among the present invention;

Fig. 2 is main website and execution substation structural representation among the present invention;

Fig. 3 analyzes schematic diagram based on WAMS multi-terminal high-voltage power transmission area backup protection function calculating among the present invention;

Fig. 4 a is P among the present invention _K+1P _KMulti-terminal high-voltage power transmission area schematic diagram during line fault;

Fig. 4 b is KP among the present invention _KMulti-terminal high-voltage power transmission area schematic diagram during line fault;

Fig. 4 c is P among the present invention _HP _H-1Multi-terminal high-voltage power transmission area schematic diagram during line fault;

Fig. 4 d is HP among the present invention _HMulti-terminal high-voltage power transmission area schematic diagram during line fault;

Fig. 5 is P among the present invention _K+1P _KP during line fault _K+1P _KThe positive sequence order net figure of circuit;

Fig. 6 is P _K+1P _KBranch road, KP _Kχ during branch trouble _IR(I=1,2,3 ..., the relation that satisfies between N);

Fig. 7 is 5 end high voltage power transmission single phase model schematic diagrames.

Embodiment

The present invention is further detailed explanation below in conjunction with accompanying drawing and example.

General layout Plan of the present invention as shown in Figure 1.It is similar T shape transmission line by external port configuration phasor measurement unit, the inner transmission line that does not configure phasor measurement unit and contain a plurality of branch roads that multi-terminal high-voltage power transmission area shown in Figure 1 can be one, or the Grid that comprises many transmission lines that is surrounded by configuration phasor measurement unit node, bus nodes does not configure phasor measurement unit in this district.

The detailed structure of main website of the present invention and execution substation as shown in Figure 2.At multi-terminal high-voltage power transmission area the wide area backup protection main website is set, usually can utilizes the communication network of existing WAMS and the Data Centralized Processing unit of main website.Each transformer station of outermost in the protected area arranges phasor measurement unit, and each transformer station does not arrange phasor measurement unit in the protected area, and each bar circuit arranges the execution substation in the protected area.Communicate by the electric power data network of electric power system or the special data channel of bandwidth between main website and the substation.Suggestion is adopted the Transmission Control Protocol transmission to metric data, and control command is adopted the udp protocol transmission, to guarantee the rapidity of command execution.

The specific implementation process of multi-terminal high-voltage power transmission wide area backup protection is as follows:

(1) each phasor measurement unit is carried out phasor calculation one time every 10ms, calculate amplitude and the phase place of voltage, electric current according to the record wave number of voltage, electric current, and the quantity of states such as amplitude and phase calculation result and circuit breaker position, disconnecting link position and the markers in the corresponding moment by delivering to the phasor data concentrator of main website on the network.

(2) the phasor data concentrator of main website is realized the reception of phasor data, and realizes data storage, inquires about, calls and safeguard by real-time data base and historical data base.Whether the wide area backup protection server of WAMS main website obtains the profile data of protected area from real-time data base take 10ms as the cycle, adopt the wide area current differential protection to detect in the protection zone and break down.If wide area current differential protection action illustrate to have fault in the protected area, and accurately determine concrete fault separate with the transition resistance size cases.After finding and determining to break down in the protected district, adopt the fault system of selection accurately to determine concrete faulty line.Then, main website sends trip signal to the control device of the execution substation of faulty line at once.Among the present invention the computational analysis of main website backup protection policy server as shown in Figure 3, the specific implementation process is as follows:

One, internal fault detects

Satisfy during protection zone outer peripheral end node serial number

And each node serial number is 1 ..., N.By the N terminal voltage

N holds electric current

Calculate P _N-1Node voltage

With the outlet electric current

Calculate according to formula (1). $\left\{\begin{array}{c}{\stackrel{\&CenterDot;}{U}}_{P_{N-1}}={\stackrel{\&CenterDot;}{U}}_{N,P_{N-1}}={\stackrel{\&CenterDot;}{U}}_N\cosh {\mathrm{\&gamma;}}_1{l}_{{N,P}_{N-1}}-{\stackrel{\&CenterDot;}{I}}_{\mathrm{<figure-callout\; id="1"\; label="N\; Z\; c"\; filenames="HSA00000168474400011.png,HSA00000168474400022.png"\; state="\{\{state\}\}">N</figure-callout>}}{Z}_c{1}_{}\sinh {\mathrm{\&gamma;}}_1{l}_{{N,P}_{N-1}}\\ {\stackrel{\&CenterDot;}{I}}_{{N,P}_{N-1}}={\stackrel{\&CenterDot;}{I}}_N\cosh {\mathrm{\&gamma;}}_1{l}_{N,P_{N-1}}-{\stackrel{\&CenterDot;}{U}}_N\sinh {\mathrm{\&gamma;}}_1{l}_{N,P_{N-1}}/Z_{c1}\\ {\stackrel{\&CenterDot;}{I}}_{N-1,P_{N-1}}={\stackrel{\&CenterDot;}{I}}_{N-1}\cosh {\mathrm{\&gamma;}}_1{l}_{N-1,P_{N-1}}-{\stackrel{\&CenterDot;}{U}}_{N-1}\sinh {\mathrm{\&gamma;}}_1{l}_{N-1,P_{N-1}}/Z_{c1}\\ {\stackrel{\&CenterDot;}{I}}_{P_{N-1}}^{\&prime;}={\stackrel{\&CenterDot;}{I}}_{N,P_{N-1}}+{\stackrel{\&CenterDot;}{I}}_{N-1,P_{N-1}}={\stackrel{\&CenterDot;}{I}}_{P_{N-1}}\end{array}\right.---\left(1\right)$

By P _N-1Node voltage

P _N-1Node outlet electric current

Calculate P _N-2Node voltage

And P _N-2Node outlet electric current

Calculate according to formula (2).

$\left\{\begin{array}{c}{\stackrel{\&CenterDot;}{U}}_{P_{N-2}}={\stackrel{\&CenterDot;}{U}}_{P_{N-1},P_{N-2}}={\stackrel{\&CenterDot;}{U}}_{P_{N-1}}\cosh {\mathrm{\&gamma;}}_1{l}_{P_{N-1},P_{N-2}}-\\ {\stackrel{\&CenterDot;}{I}}_{P_{N-1}}^{\&prime;}{\mathrm{<figure-callout\; id="1"\; label="Z\; c"\; filenames="HSA00000168474400011.png,HSA00000168474400022.png"\; state="\{\{state\}\}">Z</figure-callout>}}_c\sin {\mathrm{\&gamma;}}_1{l}_{P_{N-1},P_{N-2}}\\ {\stackrel{\&CenterDot;}{I}}_{P_{N-1},P_{N-2}}={\stackrel{\&CenterDot;}{I}}_{P_{N-1}}^{\&prime;}\cosh {\mathrm{\&gamma;}}_1{l}_{P_{N-1},P_{N-2}}-\frac{{\stackrel{\&CenterDot;}{U}}_{P_{N-1}}}{{\mathrm{<figure-callout\; id="1"\; label="Z\; c"\; filenames="HSA00000168474400011.png,HSA00000168474400022.png"\; state="\{\{state\}\}">Z</figure-callout>}}_c}\sinh {\mathrm{\&gamma;}}_1{l}_{P_{N-1},P_{N-2}}\\ {\stackrel{\&CenterDot;}{I}}_{N-2,P_{N-2}}={\stackrel{\&CenterDot;}{I}}_{N-2}\cosh {\mathrm{\&gamma;}}_1{l}_{{N-2,P}_{N-2}}-\frac{{\stackrel{\&CenterDot;}{U}}_{N-2}}{{\mathrm{<figure-callout\; id="1"\; label="Z\; c"\; filenames="HSA00000168474400011.png,HSA00000168474400022.png"\; state="\{\{state\}\}">Z</figure-callout>}}_c}\sinh {\mathrm{\&gamma;}}_1{l}_{N-2,P_{N-2}}\\ {\stackrel{\&CenterDot;}{I}}_{P_{N-2}}^{\&prime;}={\stackrel{\&CenterDot;}{I}}_{P_{N-1},P_{N-2}}+{\stackrel{\&CenterDot;}{I}}_{N-2P_{N-2}}={\stackrel{\&CenterDot;}{I}}_{P_{N-2}}\end{array}\right.---\left(2\right)$

The like, extrapolate P _K+1Node voltage P _K+1Node outlet electric current And satisfy ${\stackrel{\&CenterDot;}{U}}_{P_{K+1}}={\stackrel{\&CenterDot;}{U}}_{P_{K+2},P_{K+1}},$ ${\stackrel{\&CenterDot;}{I}}_{P_{K+1}}^{\&prime;}={\stackrel{\&CenterDot;}{I}}_{P_{K+1}}.$

Wherein, l _{PK+1, PK}Expression circuit P _K+1P _KBetween distance; The r point is reference point; l _{K, PK}Expression circuit KP _KBetween distance.

1) P _K+1P _KBranch trouble

Fig. 4 a is P among the present invention _K+1P _KMulti-terminal high-voltage power transmission area schematic diagram during line fault.Fig. 5 is P _K+1P _KP during line fault _K+1P _KThe positive sequence order net figure of circuit.By P _K+1Node voltage

The outlet electric current

Calculate P _KNode voltage

With the outlet electric current

Calculate according to formula (3).

$\left\{\begin{array}{c}{\stackrel{\&CenterDot;}{U}}_{P_{K+1},P_K}={\stackrel{\&CenterDot;}{U}}_{P_K}+{\stackrel{\&CenterDot;}{I}}_{\mathrm{<figure-callout\; id="1"\; label="f\; Z\; c"\; filenames="HSA00000168474400011.png,HSA00000168474400022.png"\; state="\{\{state\}\}">f</figure-callout>}}{Z}_c{1}_{}\sinh {\mathrm{\&gamma;}}_1(l_f-l_{P_{K+1},P_K})\\ {\stackrel{\&CenterDot;}{I}}_{P_K}^{\&prime;}={\stackrel{\&CenterDot;}{I}}_{P_{K+1},P_K}+{\stackrel{\&CenterDot;}{I}}_{K,P_K}={\stackrel{\&CenterDot;}{I}}_{P_K}+{\stackrel{\&CenterDot;}{I}}_f\cosh {\mathrm{\&gamma;}}_1(l_f-l_{P_{K+1},P_K})\end{array}\right.---\left(3\right)$

Wherein,

l _fFault point f is apart from P in expression _K+1The distance of node.

The rest may be inferred, satisfies at reference point r place:

$\left\{\begin{array}{c}{\stackrel{\&CenterDot;}{I}}_{P_{\mathrm{\&tau;}},r}^{\&prime;}={\stackrel{\&CenterDot;}{I}}_{P_T,r}+{\stackrel{\&CenterDot;}{I}}_f\cosh \left[{\mathrm{\&gamma;}}_1(l_f-l_{P_{K+1},P_K}-l_{P_K,P_{K-1}}-...-l_{P_{\mathrm{\&tau;}+1},P_T}-l_{P_{\mathrm{\&tau;}},r})\right]\\ {\stackrel{\&CenterDot;}{U}}_{P_{\mathrm{\&tau;}},r}={\stackrel{\&CenterDot;}{U}}_r+{\stackrel{\&CenterDot;}{I}}_{\mathrm{<figure-callout\; id="1"\; label="f\; Z\; c"\; filenames="HSA00000168474400011.png,HSA00000168474400022.png"\; state="\{\{state\}\}">f</figure-callout>}}{Z}_c{1}_{}\sinh \left[{\mathrm{\&gamma;}}_1(l_f-l_{P_{K+1},P_K}-l_{P_K,P_{K-1}}-...-l_{P_{T+1},P_T}-l_{P_T,r})\right]\end{array}\right.---\left(4\right)$

Wherein,

Be P _TThe actual current that node-flow is ordered to r,

The virtual voltage of ordering for r.

In like manner, calculate to reference point r place and can get by R end electric weight

Again owing to satisfying at reference point r place

So this moment, (the r point is a Gauss point on the physical significance) consisted of the wide area current differential protection based on Kirchhoff's current law (KCL) at reference point r place, its braking amount and differential amount are respectively

$I_{\mathrm{Dr}}=|{\stackrel{\&CenterDot;}{I}}_{P_T,r}^{\&prime;}+{\stackrel{\&CenterDot;}{I}}_{P_{T-1},r}^{\&prime;}|=\left|({\stackrel{\&CenterDot;}{I}}_{\mathrm{<figure-callout\; id="1"\; label="f"\; filenames="HSA00000168474400011.png,HSA00000168474400022.png"\; state="\{\{state\}\}">f</figure-callout>}1}+{\stackrel{\&CenterDot;}{I}}_{f2})\cosh \right[{\mathrm{\&gamma;}}_1(l_f-l_{P_{K+1},P_K}-l_{P_K,P_{K-1}}-...$

$-l_{P_{T+1},P_T}-l_{P_T,r}\left)\right]+{\stackrel{\&CenterDot;}{I}}_{f0}\cosh \left[{\mathrm{\&gamma;}}_0(l_f-l_{P_{K+1},P_K}-l_{P_K,P_{K-1}}-...-l_{P_{T+1},P_T}-l_{P_T,r})\right]|$

$I_{\mathrm{Br}}=|{\stackrel{\&CenterDot;}{I}}_{P_T,r}^{\&prime;}-{\stackrel{\&CenterDot;}{I}}_{P_{T-1},r}^{\&prime;}|=\left|({\stackrel{\&CenterDot;}{I}}_{\mathrm{<figure-callout\; id="1"\; label="f"\; filenames="HSA00000168474400011.png,HSA00000168474400022.png"\; state="\{\{state\}\}">f</figure-callout>}1}+{\stackrel{\&CenterDot;}{I}}_{f2})\cosh \right[{\mathrm{\&gamma;}}_1(l_f-l_{P_{K+1},P_K}-l_{P_K,P_{K-1}}-...$

$-l_{P_{T+1},P_T}-l_{P_T,r}\left)\right]+{\stackrel{\&CenterDot;}{I}}_{f0}\cosh \left[{\mathrm{\&gamma;}}_0(l_f-l_{P_{K+1},P_K}-l_{P_K,P_{K-1}}-...-l_{P_{T+1},P_T}-l_{P_T,r})\right]-2{\stackrel{\&CenterDot;}{I}}_{r,\mathrm{load}}|$

If normal in the protection zone, at this moment

Wherein

The load current component of ordering for the r that flows through.

2) KP _KBranch trouble

Fig. 4 b is KP _KMulti-terminal high-voltage power transmission area schematic diagram during line fault.By deriving as can be known in the above-mentioned formula (1), at P _KNodes satisfies

Wherein

Be P _K+1P _KOn the branch road by P _K+1Point flow to P _KThe actual current of point.

So calculate ${\stackrel{\&CenterDot;}{I}}_{P_K}^{\&prime;}={\stackrel{\&CenterDot;}{I}}_{K,P_K}+{\stackrel{\&CenterDot;}{I}}_{P_{K+1},P_K}={\stackrel{\&CenterDot;}{I}}_{P_K}+{\stackrel{\&CenterDot;}{I}}_f\cosh {\mathrm{\&gamma;}}_1(l_f-l_{K,P_K})$

By P _KNodes voltage

Node outlet electric current

Continuation is calculated to reference point r place, can be got

$\left\{\begin{array}{c}{\stackrel{\&CenterDot;}{I}}_{P_{\mathrm{\&tau;}},r}^{\&prime;}={\stackrel{\&CenterDot;}{I}}_{P_T,r}+{\stackrel{\&CenterDot;}{I}}_f\cosh \left[{\mathrm{\&gamma;}}_1(l_{P_K,P_{K-1}}+l_{P_{K-1},P_{K-2}}+...+l_{P_{\mathrm{\&tau;}+1},P_T}+l_{P_{\mathrm{\&tau;}},r})\right]\cosh \left[{\mathrm{\&gamma;}}_1(l_f-l_{K,P_K})\right]\\ {\stackrel{\&CenterDot;}{U}}_{P_{\mathrm{\&tau;}},r}={\stackrel{\&CenterDot;}{U}}_r+{\stackrel{\&CenterDot;}{I}}_{\mathrm{<figure-callout\; id="1"\; label="f\; Z\; c"\; filenames="HSA00000168474400011.png,HSA00000168474400022.png"\; state="\{\{state\}\}">f</figure-callout>}}{Z}_c{1}_{}\sinh \left[{\mathrm{\&gamma;}}_1(l_{P_K,P_{K-1}}+l_{P_{K-1},P_{K-2}}+...+l_{P_{T+1},P_T}+l_{P_T,r})\right]\cosh \left[{\mathrm{\&gamma;}}_1(l_f-l_{K,P_K})\right]\end{array}\right.---\left(5\right)$

In like manner, calculate to reference point r place and can get by R end electric weight

So, consisting of the wide area current differential protection at reference point r place based on Kirchhoff's current law (KCL), its braking amount and differential amount are respectively

$I_{\mathrm{Dr}}=|{\stackrel{\&CenterDot;}{I}}_{P_T,r}^{\&prime;}+{\stackrel{\&CenterDot;}{I}}_{P_{T-1},r}^{\&prime;}|=\left|({\stackrel{\&CenterDot;}{I}}_{\mathrm{<figure-callout\; id="1"\; label="f"\; filenames="HSA00000168474400011.png,HSA00000168474400022.png"\; state="\{\{state\}\}">f</figure-callout>}1}+{\stackrel{\&CenterDot;}{I}}_{f2})\cosh \right[{\mathrm{\&gamma;}}_1(l_{P_K,P_{K-1}}+l_{P_{K-1},P_{K-2}}+...+l_{P_{T+1},P_T}+l_{P_T,r})\left]\cosh \right[{\mathrm{\&gamma;}}_1(l_f-l_{K,P_K})]+$

${\stackrel{\&CenterDot;}{I}}_{f0}\cosh \left[{\mathrm{\&gamma;}}_0(l_{P_K,P_{K-1}}-l_{P_{K-1},P_{K-2}}+...+l_{P_{T+1},P_T}+l_{P_T,r})\right]\cosh \left[{\mathrm{\&gamma;}}_0(l_f-l_{K,P_K})\right]|$

$I_{\mathrm{Br}}=|{\stackrel{\&CenterDot;}{I}}_{P_T,r}^{\&prime;}-{\stackrel{\&CenterDot;}{I}}_{P_{T-1},r}^{\&prime;}|=\left|({\stackrel{\&CenterDot;}{I}}_{\mathrm{<figure-callout\; id="1"\; label="f"\; filenames="HSA00000168474400011.png,HSA00000168474400022.png"\; state="\{\{state\}\}">f</figure-callout>}1}+{\stackrel{\&CenterDot;}{I}}_{f2})\cosh \right[{\mathrm{\&gamma;}}_1(l_{P_K,P_{K-1}}+l_{P_{K-1},P_{K-2}}+...+l_{P_{T+1},P_T}+l_{P_T,r})\left]\cosh \right[{\mathrm{\&gamma;}}_1(l_f-l_{K,P_K})]+{\stackrel{\&CenterDot;}{I}}_{f0}\cosh [{\mathrm{\&gamma;}}_0(l_{P_K,P_{K-1}}$

$+l_{P_{K-1},P_{K-2}}+...+l_{P_{T+1},P_T}+l_{P_T,r}\left)\right]\cosh \left[{\mathrm{\&gamma;}}_0(l_f-l_{K,P_K})\right]-2{\stackrel{\&CenterDot;}{I}}_{r,\mathrm{load}}|$

Wherein, l _fExpression fault point f is apart from the distance of K end node.

3) P _HP _H-1Branch trouble

Fig. 4 c is P _HP _H-1Multi-terminal high-voltage power transmission area schematic diagram during line fault.Can get P by above-mentioned formula (4) _HP _H-1During branch trouble, calculated to reference point r place by R end electric weight, have formula (6) relation.

$\left\{\begin{array}{c}{\stackrel{\&CenterDot;}{I}}_{P_{T-1},r}^{\&prime;}={\stackrel{\&CenterDot;}{I}}_{P_{T-1},r}+{\stackrel{\&CenterDot;}{I}}_f\cosh \left[{\mathrm{\&gamma;}}_1(l_f-l_{P_H,P_{H-1}}-l_{P_{H+1},P_H}-...-l_{P_{T-1},P_{T-2}}-l_{P_{T-1},r})\right]\\ {\stackrel{\&CenterDot;}{U}}_{P_{T-1},r}={\stackrel{\&CenterDot;}{U}}_r+{\stackrel{\&CenterDot;}{I}}_{\mathrm{<figure-callout\; id="1"\; label="f\; Z\; c"\; filenames="HSA00000168474400011.png,HSA00000168474400022.png"\; state="\{\{state\}\}">f</figure-callout>}}{Z}_c{1}_{}\sinh \left[{\mathrm{\&gamma;}}_1(l_f-l_{P_H,P_{H-1}}-l_{P_{H+1},P_H}-...-l_{P_{T-1},P_{T-2}}-l_{P_{T-1},r})\right]\end{array}\right.---\left(6\right)$

Wherein, l _fFault point f is apart from P in expression _H-1The distance of node.

In like manner, calculate to reference point r place and can get by N end electric weight

So, consisting of the wide area current differential protection at reference point r place based on Kirchhoff's current law (KCL), its braking amount and differential amount are respectively:

$I_{\mathrm{Dr}}=|{\stackrel{\&CenterDot;}{I}}_{P_T,r}^{\&prime;}+{\stackrel{\&CenterDot;}{I}}_{P_{T-1},r}^{\&prime;}|=\left|({\stackrel{\&CenterDot;}{I}}_{\mathrm{<figure-callout\; id="1"\; label="f"\; filenames="HSA00000168474400011.png,HSA00000168474400022.png"\; state="\{\{state\}\}">f</figure-callout>}1}+{\stackrel{\&CenterDot;}{I}}_{f2})\cosh \right[{\mathrm{\&gamma;}}_1(l_f-l_{P_H,P_{H-1}}-l_{P_{H+1},P_H}-...-l_{P_{T-1},P_{T-2}}-l_{P_{T-1},r})\left]\cosh \right[{\mathrm{\&gamma;}}_1(l_f-l_{P_H,P_{H-1}}-$

$l_{P_{H+1},P_H}-...-l_{P_{T-1},P_{T-2}}-l_{P_{T-1},r}\left)\right]|$

$I_{\mathrm{Br}}=|{\stackrel{\&CenterDot;}{I}}_{P_T,r}^{\&prime;}-{\stackrel{\&CenterDot;}{I}}_{P_{T-1},r}^{\&prime;}|=\left|({\stackrel{\&CenterDot;}{I}}_{\mathrm{<figure-callout\; id="1"\; label="f"\; filenames="HSA00000168474400011.png,HSA00000168474400022.png"\; state="\{\{state\}\}">f</figure-callout>}1}+{\stackrel{\&CenterDot;}{I}}_{f2})\cosh \right[{\mathrm{\&gamma;}}_1(l_f-l_{P_H,P_{H-1}}-l_{P_{H+1},P_H}-...-l_{P_{T-1},P_{T-2}}-l_{P_{T-1},r})]+{\stackrel{\&CenterDot;}{I}}_{f0}\cosh [{\mathrm{\&gamma;}}_0(l_f-l_{P_H,P_{H-1}}-$

$l_{P_{H+1},P_H}-...-l_{P_{T-1},P_{T-2}}-l_{P_{T-1},r}\left)\right]-2{\stackrel{\&CenterDot;}{I}}_{r,\mathrm{load}}|$

4) HP _HBranch trouble

Fig. 4 d is HP _HMulti-terminal high-voltage power transmission area schematic diagram during line fault.Can get HP by above-mentioned formula (5) _HDuring branch trouble, calculated to reference point r place by R end electric weight, have formula (7) relation.

$\left\{\begin{array}{c}{\stackrel{\&CenterDot;}{I}}_{P_{T-1},r}^{\&prime;}={\stackrel{\&CenterDot;}{I}}_{P_{T-1},r}+{\stackrel{\&CenterDot;}{I}}_f\cosh \left[{\mathrm{\&gamma;}}_1(l_{P_{H+1},P_H}+l_{P_{H+2},P_{H+1}}+...+l_{P_{T-1},P_{T-2}}+l_{P_{T-1},r})\right]\cosh \left[{\mathrm{\&gamma;}}_1(l_f-l_{H,P_H})\right]\\ {\stackrel{\&CenterDot;}{U}}_{P_{T-1},r}={\stackrel{\&CenterDot;}{U}}_r+{\stackrel{\&CenterDot;}{I}}_{\mathrm{<figure-callout\; id="1"\; label="f\; Z\; c"\; filenames="HSA00000168474400011.png,HSA00000168474400022.png"\; state="\{\{state\}\}">f</figure-callout>}}{Z}_c{1}_{}\sinh \left[{\mathrm{\&gamma;}}_1(l_{P_{H+1},P_H}+l_{P_{H+2},P_{H+1}}+...+l_{P_{T-1},P_{T-2}}+l_{P_{T-1},r})\right]\cosh \left[{\mathrm{\&gamma;}}_1(l_f-l_{H,P_H})\right]\end{array}\right.---\left(7\right)$

In like manner, calculate to reference point r place and can get by N end electric weight

So, consisting of the wide area current differential protection at reference point r place based on Kirchhoff's current law (KCL), its braking amount and differential amount are respectively

$I_{\mathrm{Dr}}=|{\stackrel{\&CenterDot;}{I}}_{P_T,r}^{\&prime;}+{\stackrel{\&CenterDot;}{I}}_{P_{T-1},r}^{\&prime;}|=\left|({\stackrel{\&CenterDot;}{I}}_{\mathrm{<figure-callout\; id="1"\; label="f"\; filenames="HSA00000168474400011.png,HSA00000168474400022.png"\; state="\{\{state\}\}">f</figure-callout>}1}+{\stackrel{\&CenterDot;}{I}}_{f2})\cosh \right[{\mathrm{\&gamma;}}_1(l_{P_{H+1},P_H}+l_{P_{H+2},P_{H+1}}+...$

$+l_{P_{T-1},P_{T-2}}+l_{P_{T-1},r}\left)\right]\cosh \left[{\mathrm{\&gamma;}}_1(l_f-l_{H,P_H})\right]+{\stackrel{\&CenterDot;}{I}}_{f0}\cosh [{\mathrm{\&gamma;}}_0(l_{P_{H+1},P_H}+l_{P_{H+2},P_{H+1}}+...$

$+l_{P_{T-1},P_{T-2}}+l_{P_{T-1},r}\left)\right]\cosh \left[{\mathrm{\&gamma;}}_0(l_f-l_{H,P_H})\right]|$

$I_{\mathrm{Br}}=|{\stackrel{\&CenterDot;}{I}}_{P_T,r}^{\&prime;}-{\stackrel{\&CenterDot;}{I}}_{P_{T-1},r}^{\&prime;}|=\left|({\stackrel{\&CenterDot;}{I}}_{\mathrm{<figure-callout\; id="1"\; label="f"\; filenames="HSA00000168474400011.png,HSA00000168474400022.png"\; state="\{\{state\}\}">f</figure-callout>}1}+{\stackrel{\&CenterDot;}{I}}_{f2})\cosh \right[{\mathrm{\&gamma;}}_1(l_{P_{H+1},P_H}+l_{P_{H+2},P_{H+1}}+...$

$+l_{P_{T-1},P_{T-2}}+l_{P_{T-1},r}\left)\right]\cosh \left[{\mathrm{\&gamma;}}_1(l_f-l_{H,P_H})\right]+{\stackrel{\&CenterDot;}{I}}_{f0}\cosh [{\mathrm{\&gamma;}}_0(l_{P_{H+1},P_H}$

$+l_{P_{H+2},P_{H+1}}+...+l_{P_{T-1},P_{T-2}}+l_{P_{T-1},r}\left)\right]\cosh \left[{\mathrm{\&gamma;}}_0(l_f-l_{H,P_H})\right]-2{\stackrel{\&CenterDot;}{I}}_{r,\mathrm{load}}|$

Wherein, l _fExpression fault point f is apart from the distance of H end node.

N in the above-mentioned analysis, T, T-1, I, I-1, K+1, K, K-1, H, H-1 represent the numbering of multi-terminal high-voltage power transmission area external port node; P _K+1, P _K, P _K-1, P _I, P _I-1, P _T, P _T-1, P _H, P _H-1The numbering of expression multi-terminal high-voltage power transmission area internal node.

Above-mentioned when having analyzed different line fault, by N end and R end differential amount and the braking amount situation to r point reckoning gained.So, separate in r point adoption rate braking characteristic failure judgement.When high resistance earthing fault occurs, can adopt zero-sequence current component to consist of Zero sequence current differential protection.

During high resistance earthing fault, because of load current impact, above-mentioned wide area full current differential protection may correct operation, by zero-sequence component differential protection action tripping three-phase.Though can excise fault like this, tripping normal phase, caused unnecessary protection action behavior to occur.Zero sequence current differential protection must withdraw from when open-phase operation, if this moment, high resistance earthing fault occured again, protection will tripping occur and can't excise in time fault.By above-mentioned derivation as can be known, when utilizing each order fault component to substitute corresponding each the order total current component of preamble, above-mentioned derivation is still set up.Therefore; the present invention considers to introduce fault component and on above-mentioned derivation basis; a kind of wide area fault component current differential protection is proposed; namely utilize fault component to substitute above-mentioned corresponding total current component, namely utilize the fault component positive sequence component to replace positive sequence component, fault component negative sequence component to replace negative sequence component, fault component zero-sequence component to replace zero-sequence component.Wide area fault component current differential protection criterion is identical with wide area full current differential protection criterion, and all adoption rate braking characteristic Judging fault is separate.

This wide area fault component current differential protection of characteristics that hinders for some reason component itself was applicable to after the fault in two weeks; behind the fault 40ms with out of service; bear the protection task by the protection of wide area full current differential; therefore, the protection of wide area fault component current differential protection proposed by the invention and wide area full current differential replenishes the internal fault detection that is used for bearing multi-terminal high-voltage power transmission area mutually.

Two, faulty line system of selection

1) P _K+1P _KBranch trouble

When by I (end of I 〉=K+1) to reference edge R calculate ask the fault point apart from reference edge R apart from χ _IRThe time, reference point r is selected in P _TDuring Nodes, get final product to get formula (8) by formula (4).

$\left\{\begin{array}{c}{\stackrel{\&CenterDot;}{U}}_{P_T,P_{T-1}}={\stackrel{\&CenterDot;}{U}}_{P_{T-1}}+{\stackrel{\&CenterDot;}{I}}_{\mathrm{<figure-callout\; id="1"\; label="f\; Z\; c"\; filenames="HSA00000168474400011.png,HSA00000168474400022.png"\; state="\{\{state\}\}">f</figure-callout>}}{Z}_c{1}_{}\sinh \left[{\mathrm{\&gamma;}}_1(l_f-l_{P_{K+1},P_K}-l_{P_K,P_{K+1}}-...-l_{P_T,P_{T-1}})\right]\\ {\stackrel{\&CenterDot;}{I}}_{P_{T-1}}^{\&prime;}={\stackrel{\&CenterDot;}{I}}_{P_{T-1}}+{\stackrel{\&CenterDot;}{I}}_f\cosh \left[{\mathrm{\&gamma;}}_1(l_f-l_{P_{K+1},P_K}-l_{P_K,P_{K-1}}-...-l_{P_T,P_{T-1}})\right]\end{array}\right.---\left(8\right)$

Wherein, T=K+1, K ..., 2; l _fFault point f is apart from P in expression _K+1The distance of node.So the structure faulty line selects equation suc as formula (9).

${\stackrel{\&CenterDot;}{U}}_R\cosh \left({\mathrm{\&gamma;}}_1{\mathrm{\&chi;}}_{\mathrm{IR}}\right)-{\stackrel{\&CenterDot;}{I}}_{\mathrm{<figure-callout\; id="1"\; label="R\; Z\; c"\; filenames="HSA00000168474400011.png,HSA00000168474400022.png"\; state="\{\{state\}\}">R</figure-callout>}}{Z}_c{1}_{}\sinh \left({\mathrm{\&gamma;}}_1{\mathrm{\&chi;}}_{\mathrm{IR}}\right)={\stackrel{\&CenterDot;}{U}}_{{\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="HSA00000168474400031.png,HSA00000168474400032.png"\; state="\{\{state\}\}">P</figure-callout>}}_2,{\mathrm{<figure-callout\; id="1"\; label="P"\; filenames="HSA00000168474400011.png,HSA00000168474400022.png"\; state="\{\{state\}\}">P</figure-callout>}}_1}\cosh \left[{\mathrm{\&gamma;}}_1({\mathrm{<figure-callout\; id="1"\; label="l\; P"\; filenames="HSA00000168474400011.png,HSA00000168474400022.png"\; state="\{\{state\}\}">l</figure-callout>}}_{P_{}}-{\mathrm{\&chi;}}_{\mathrm{IR}})\right]-{\stackrel{\&CenterDot;}{I}}_{{\mathrm{<figure-callout\; id="1"\; label="P"\; filenames="HSA00000168474400011.png,HSA00000168474400022.png"\; state="\{\{state\}\}">P</figure-callout>}}_1}^{\&prime;}\sinh \left[{\mathrm{\&gamma;}}_1({\mathrm{<figure-callout\; id="1"\; label="l\; P"\; filenames="HSA00000168474400011.png,HSA00000168474400022.png"\; state="\{\{state\}\}">l</figure-callout>}}_{P_{}}-{\mathrm{\&chi;}}_{\mathrm{IR}})\right]---\left(9\right)$

Can be got by formula (8) and formula (9) ${\mathrm{\&chi;}}_{\mathrm{IR}}=l_{P_{K+1},P_K}+l_{P_K,P_{K-1}}+...+{\mathrm{<figure-callout\; id="2"\; label="l\; P"\; filenames="HSA00000168474400031.png,HSA00000168474400032.png"\; state="\{\{state\}\}">l</figure-callout>}}_{P_{}}+{\mathrm{<figure-callout\; id="1"\; label="l\; P"\; filenames="HSA00000168474400011.png,HSA00000168474400022.png"\; state="\{\{state\}\}">l</figure-callout>}}_{P_{}}-l_f,I\&GreaterEqual;K+1---\left(10\right)$

In the practical application by

Try to achieve χ _IRWherein

$B=\frac{1}{2}\exp (-{\mathrm{\&gamma;}}_1{\mathrm{<figure-callout\; id="1"\; label="l\; P"\; filenames="HSA00000168474400011.png,HSA00000168474400022.png"\; state="\{\{state\}\}">l</figure-callout>}}_{P_{}})[{\stackrel{\&CenterDot;}{U}}_{{\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="HSA00000168474400031.png,HSA00000168474400032.png"\; state="\{\{state\}\}">P</figure-callout>}}_2,{\mathrm{<figure-callout\; id="1"\; label="P"\; filenames="HSA00000168474400011.png,HSA00000168474400022.png"\; state="\{\{state\}\}">P</figure-callout>}}_1}+Z_{c1}{\stackrel{\&CenterDot;}{I}}_{{\mathrm{<figure-callout\; id="1"\; label="P"\; filenames="HSA00000168474400011.png,HSA00000168474400022.png"\; state="\{\{state\}\}">P</figure-callout>}}_1}^{\&prime;}]-\frac{1}{2}[{\stackrel{\&CenterDot;}{U}}_R-Z_{c1}{\stackrel{\&CenterDot;}{I}}_R].$

When by I (end of I≤K) to the R end calculate ask fault point f apart from reference edge R apart from χ _IRThe time, by P ₁Node voltage

The outlet electric current

Calculate P _I-1Node voltage With the outlet electric current

Shown in (11).

$\left\{\begin{array}{c}{\stackrel{\&CenterDot;}{U}}_{P_1,P_{I-1}}={\stackrel{\&CenterDot;}{U}}_{P_I}\cosh {\mathrm{\&gamma;}}_1{l}_{P_I,P_{I-1}}-{\stackrel{\&CenterDot;}{I}}_{P_I}^{\&prime;}{Z}_{c1}\sinh {\mathrm{\&gamma;}}_1{l}_{P_I,P_{I-1}}\\ ={\stackrel{\&CenterDot;}{U}}_{P_{I-1}}-{\stackrel{\&CenterDot;}{I}}_f{Z}_{c1}\sinh {\mathrm{\&gamma;}}_1{l}_{P_I,P_{I-1}}\cosh [{\mathrm{\&gamma;}}_1(l_f-l_{P_{K+1},P_K}-l_{P_K,P_{K-1}}\\ -...-l_{P_{I+1},P_I\left)\right]}\\ {\stackrel{\&CenterDot;}{I}}_{P_I,P_{I-1}}={\stackrel{\&CenterDot;}{I}}_{P_I}^{\&prime;}\cosh {\mathrm{\&gamma;}}_1{l}_{P_I,P_{I-1}}-\frac{{\stackrel{\&CenterDot;}{U}}_{P_I}}{Z_{c1}}\sinh {\mathrm{\&gamma;}}_1{l}_{P_I,P_{I-1}}\\ {\stackrel{\&CenterDot;}{I}}_{I-1,P_{I-1}}={\stackrel{\&CenterDot;}{I}}_{I-1}\cosh {\mathrm{\&gamma;}}_1{l}_{I-1,P_{I-1}}-\frac{{\stackrel{\&CenterDot;}{U}}_{I-1}}{Z_{c1}}\sinh {\mathrm{\&gamma;}}_1{l}_{I-1},P_{I-1}\\ {\stackrel{\&CenterDot;}{I}}_{P_{I-1}}^{\&prime;}={\stackrel{\&CenterDot;}{I}}_{P_I,P_{I-1}}+{\stackrel{\&CenterDot;}{I}}_{I-1,P_{I-1}}={\stackrel{\&CenterDot;}{I}}_{P_1}+\\ {\stackrel{\&CenterDot;}{I}}_f\cosh {\mathrm{\&gamma;}}_1{l}_{P_1,P_{I-1}}\cosh \left[{\mathrm{\&gamma;}}_1(l_f-l_{P_{K+1},P_K}-l_{P_K,P_{K-1}}-...-l_{P_{I+1},P_I})\right]\end{array}\right.---\left(11\right)$

By formula (11) successively recursion, continue to P _T(T＜I≤K) node is calculated, at this moment P _TThere are formula (12) relation in node voltage and outlet electric current.

$\left\{\begin{array}{c}{\stackrel{\&CenterDot;}{U}}_{P_T,P_{T-1}}={\stackrel{\&CenterDot;}{U}}_{P_{T-1}}-{\stackrel{\&CenterDot;}{I}}_{\mathrm{<figure-callout\; id="1"\; label="f\; Z\; c"\; filenames="HSA00000168474400011.png,HSA00000168474400022.png"\; state="\{\{state\}\}">f</figure-callout>}}{Z}_c{1}_{}\sinh \left[{\mathrm{\&gamma;}}_1(l_{P_I,P_{I-1}}+l_{P_{I-1},P_{I-2}}+...+l_{P_T,P_{T-1}})\right]\cosh \left[{\mathrm{\&gamma;}}_1(l_f-l_{P_{K+1},P_K}-l_{P_K,P_{K-1}}-...-l_{P_{I+1},P_I})\right]\\ {\stackrel{\&CenterDot;}{I}}_{P_{T-1}}^{\&prime;}={\stackrel{\&CenterDot;}{I}}_{P_{T-1}}+{\stackrel{\&CenterDot;}{I}}_f\cosh \left[{\mathrm{\&gamma;}}_1(l_{P_I,P_{I-1}}+l_{P_{I-1},P_{I-2}}+...+l_{P_T,P_{T-1}})\right]\cosh \left[{\mathrm{\&gamma;}}_1(l_f-l_{P_{K+1},P_K}-l_{P_K,P_{K-1}}-...-l_{P_{I+1},P_I})\right]\end{array}\right.---\left(12\right)$

Wherein, T=I, I-1 ..., 2; l _fFault point f is apart from P in expression _K+1The distance of node.

Can be got by formula (12) and formula (9) ${\mathrm{\&chi;}}_{\mathrm{IR}}=l_{P_I,P_{I-1}}+l_{P_{I-1},P_{I-2}}...+{\mathrm{<figure-callout\; id="2"\; label="l\; P"\; filenames="HSA00000168474400031.png,HSA00000168474400032.png"\; state="\{\{state\}\}">l</figure-callout>}}_{P_{}}+{\mathrm{<figure-callout\; id="1"\; label="l\; P"\; filenames="HSA00000168474400011.png,HSA00000168474400022.png"\; state="\{\{state\}\}">l</figure-callout>}}_{P_{}},I\&le;K---\left(13\right)$

To sum up formula (10) and formula (13) can get circuit P _K+1P _KDuring fault, concerned to existing between the solution of reference edge R reckoning gained faulty line selection equation by each end electric weight:

χ _1R＜χ _2R＜...＜χ _KR＜χ _K+1R＝...＝χ _NR (14)

2) KP _KBranch trouble

When by I (end of I 〉=K+1) to reference edge R calculate ask the fault point apart from reference edge R apart from χ _IRThe time, the r point is elected P as in the formula (5) _TCan get during point

$\left\{\begin{array}{c}{\stackrel{\&CenterDot;}{U}}_{P_T,P_{T-1}}^{\&prime;}={\stackrel{\&CenterDot;}{U}}_{P_{T-1}}-{\stackrel{\&CenterDot;}{I}}_{\mathrm{<figure-callout\; id="1"\; label="f\; Z\; c"\; filenames="HSA00000168474400011.png,HSA00000168474400022.png"\; state="\{\{state\}\}">f</figure-callout>}}{Z}_c{1}_{}\sinh \left[{\mathrm{\&gamma;}}_1(l_{P_K,P_{K-1}}+l_{P_{K-1},P_{K-2}}+...+l_{P_T,P_{T-1}})\right]\cosh \left[{\mathrm{\&gamma;}}_1(l_f-l_{K,P_K})\right]\\ {\stackrel{\&CenterDot;}{I}}_{P_{T-1}}^{\&prime;}={\stackrel{\&CenterDot;}{I}}_{P_{T-1}}+{\stackrel{\&CenterDot;}{I}}_f\cosh \left[{\mathrm{\&gamma;}}_1(l_{P_K,P_{K-1}}+l_{P_{K-1},P_{K-2}}+...+l_{P_T,P_{T-1}})\right]\cos \left[{\mathrm{\&gamma;}}_1(l_f-l_{K,P_K})\right]\end{array}\right.---\left(15\right)$

Wherein, T=K, K-1 ..., 2; l _fExpression fault point f is apart from the distance of K end node.

Can be got by formula (15) and formula (9)

${\mathrm{\&chi;}}_{\mathrm{IR}}=l_{P_K,P_{K-1}}+l_{P_{K-1},P_{K-2}}+...+{\mathrm{<figure-callout\; id="2"\; label="l\; P"\; filenames="HSA00000168474400031.png,HSA00000168474400032.png"\; state="\{\{state\}\}">l</figure-callout>}}_{P_{}}+{\mathrm{<figure-callout\; id="1"\; label="l\; P"\; filenames="HSA00000168474400011.png,HSA00000168474400022.png"\; state="\{\{state\}\}">l</figure-callout>}}_{P_{}},I\&GreaterEqual;K+1---\left(16\right)$

When by K end to reference edge R calculate ask the fault point apart from reference edge R apart from χ _KRThe time, can get P by formula (4) _TNode voltage and outlet electric current are suc as formula shown in (17).

$\left\{\begin{array}{c}{\stackrel{\&CenterDot;}{U}}_{P_T,P_{T-1}}={\stackrel{\&CenterDot;}{U}}_{P_{T-1}}-{\stackrel{\&CenterDot;}{I}}_{\mathrm{<figure-callout\; id="1"\; label="f\; Z\; c"\; filenames="HSA00000168474400011.png,HSA00000168474400022.png"\; state="\{\{state\}\}">f</figure-callout>}}{Z}_c{1}_{}\sinh \left[{\mathrm{\&gamma;}}_1(l_{K,P_K}+l_{P_K,P_{K-1}}+l_{P_{K-1},P_{K-2}}+...+l_{P_T,P_{T-1}}-l_f)\right]\\ {\stackrel{\&CenterDot;}{I}}_{P_{T-1}}^{\&prime;}={\stackrel{\&CenterDot;}{I}}_{P_{T-1}}+{\stackrel{\&CenterDot;}{I}}_f\cosh \left[{\mathrm{\&gamma;}}_1(l_{K,P_K}+l_{P_K,P_{K-1}}+l_{P_{K-1},P_{K-2}}+...+l_{P_T,P_{T-1}}-l_f)\right]\end{array}\right.---\left(17\right)$

Wherein, T=K, K-1 ..., 2; l _fExpression fault point f is apart from the distance of K end node.

Can be got by formula (17) and formula (9) ${\mathrm{\&chi;}}_{\mathrm{KR}}=l_{K,P_K}+l_{P_K,P_{K-1}}+...+{\mathrm{<figure-callout\; id="2"\; label="l\; P"\; filenames="HSA00000168474400031.png,HSA00000168474400032.png"\; state="\{\{state\}\}">l</figure-callout>}}_{P_{}}+{\mathrm{<figure-callout\; id="1"\; label="l\; P"\; filenames="HSA00000168474400011.png,HSA00000168474400022.png"\; state="\{\{state\}\}">l</figure-callout>}}_{P_{}}-l_f---\left(18\right)$

When by I (end of I＜K) to the R end calculate ask fault point f apart from reference edge R apart from χ _IRThe time, P _TNode voltage and outlet electric current are $\left\{\begin{array}{c}{\stackrel{\&CenterDot;}{U}}_{P_T,P_{T-1}}={\stackrel{\&CenterDot;}{U}}_{P_{T-1}}-{\stackrel{\&CenterDot;}{I}}_f{Z}_{c1}\sinh [{\mathrm{\&gamma;}}_1(l_{P_I,P_{I-1}}+l_{P_{I-1},P_{I-2}}+...\\ +l_{P_T,P_{T-1}}\left)\right]\cosh {\mathrm{\&gamma;}}_1(l_f-l_{K,P_k})\cosh {\mathrm{\&gamma;}}_1(l_{P_k,P_{k-1}}-l_{P_{k-1},P_{k-2}}-...-l_{P_{I+1},P_I})\\ {\stackrel{\&CenterDot;}{I}}_{P_{T-1}}^{\&prime;}={\stackrel{\&CenterDot;}{I}}_{P_{T-1}}+{\stackrel{\&CenterDot;}{I}}_f\cosh [{\mathrm{\&gamma;}}_1(l_{P_I,P_{I-1}}+l_{P_{I-1},P_{I-2}}+...\\ +l_{P_T,P_{T-1}}\left)\right]\cosh {\mathrm{\&gamma;}}_1(l_f-l_{K,P_k})\cosh {\mathrm{\&gamma;}}_1(l_{P_k,P_{k-1}}-l_{P_{k-1},P_{k-2}}-...-l_{P_{I+1},P_I})\end{array}\right.---\left(19\right)$

Wherein, T=I, I-1,, 2; l _fFault point f is apart from P in expression _K+1The distance of node.

Can be got by formula (19) and formula (9) ${\mathrm{\&chi;}}_{\mathrm{IR}}=l_{P_I,P_{I-1}}+l_{P_{I-1},P_{I-2}}...+{\mathrm{<figure-callout\; id="2"\; label="l\; P"\; filenames="HSA00000168474400031.png,HSA00000168474400032.png"\; state="\{\{state\}\}">l</figure-callout>}}_{P_{}}+l_{P_I,R},I<K---\left(20\right)$

N in the above-mentioned analysis, T, T-1, I, I-1, K+1, K, K-1, H, H-1 represent the numbering of multi-terminal high-voltage power transmission area external port node; P _K+1, P _K, P _K-1, P ₁, P _1-1, P _T, P _T-1, P _H, P _H-1The numbering of expression multi-terminal high-voltage power transmission area internal node.

To sum up formula (16), formula (18) and formula (20) can get circuit KP _KDuring fault, concerned to existing between the solution of reference edge R reckoning gained faulty line selection equation by each end electric weight:

χ _1R＜χ _2R＜...χ _K-1R＜χ _K+1R＝...＝χ _NR＜χ _KR (21)

Fig. 6 has provided P _K+1P _KBranch road, KP _Kχ during branch trouble _IR(I=1,2,3 ..., the relation that satisfies between N).Concerned as can be known by Fig. 6 and Shi (14), formula (21), by analyzing χ _IR(I=1,2,3 ..., the relation between N) can accurately be determined concrete faulty line.

Three, result of calculation and analysis

Fig. 7 is the single-phase simulation model schematic diagrames of 5 end high voltage power transmissions, utilizes the PSCAD simulation software to build this model.When in the 5 end high voltage power transmisson systems dissimilar fault occuring, the Calculation results of main website of the present invention policy server is shown in Table 1.

Can be found out by table 1 result; when dissimilar fault occurs in different circuits in the protection zone; the present invention can accurately determine the transition resistance situation in the protection zone, concrete fault is separate and faulty line, has good reliability, selectivity, quick-action and sensitivity.

(3) carry out the substation structure as shown in Figure 2.Carrying out control device place, substation; the core of its tripping operation final controlling element is by consisting of with the logic tripping controller; its input is that (open is 0 for the folding condition of circuit breaker; be combined into 1) and the trip signal that comes from the wide area backup protection main website (normally be 0; tripping operation is 1); only have when the folding condition of circuit breaker is 1 entirely with the trip signal input that comes from the wide area backup protection main website, be output as 1 with the logic tripping controller, just the corresponding line-breaker of tripping.

Because network data transmission time-delay and main website centralized calculation time-delay, the at once trip signal that comes from wide area line backup protection main website can postpone than power line main protection on the spot approximately 300 milliseconds.The method of segmentation ladder time delay is taked in the traditional circuit backup protection in order to realize selectivity, one-level ladder time delay just needs 500 milliseconds usually, and multistage time delay may be up to the several seconds.Therefore, responsiveness of the present invention is slower than power line main protection, faster than the traditional circuit backup protection based on this locality amount decision-making.Realize thus the cooperation of power line main protection, the present invention and traditional circuit backup protection.

Table 1: the Calculation results of backup protection decision service when in the protection zone various fault type occuring

Fault type	The internal fault detection case	χ 5R /(km)	χ 4R /(km)	χ 3R /(km)	χ 2R /(km)	χ 1R /(km)	Fault branch is chosen
								The Bus1-P1 branch road is apart from the P1 point 35km BCG of place, 10 Ω	The BC phase fault	149.967	149.976	150.008	149.937	173.708	Bus1-P1
The Bus4-P4 branch road is apart from the P4 node 5km AB of place fault	The AB phase fault	350.254	355.26	250.048	249.841	149.803	Bus4-P4
								The Bus5-P4 branch road is apart from the P4 node 125km AG of place, 300 Ω	A phase high resistive fault	474.997	350.002	250.016	249.956	149.94	Bus5-P4
The Bus5-P4 branch road is apart from the Bus5 end 45km AG of place, 250 Ω	A phase high resistive fault	454.997	350.002	250.023	249.934	149.912	Bus5-P4
								The Bus2-P3 branch road is apart from the P3 node 15km CG of place, 200 Ω	C phase high resistive fault	249.845	249.844	349.798	364.785	147.970	Bus2-P3
The Bus2-P3 branch road is apart from the P3 node 35km AG of place, 200 Ω	A phase high resistive fault	249.884	249.882	349.848	384.825	148.460	Bus2-P3
								The Bus2-P3 branch road is apart from the P3 node 15km CG of place, 10 Ω	The C phase fault	249.845	249.844	349.798	364.784	147.970	Bus2-P3
The Bus2-P3 branch road is apart from the P3 node 35km AG of place, 300 Ω	A phase high resistive fault	249.884	249.882	349.848	384.825	148.46	Bus2-P3
								The Bus3-P3 branch road is apart from the Bus3 node 35km BC of place, 50 Ω	The BC phase fault	249.808	249.812	394.693	349.174	147.556	Bus3-P3
The Bus3-P3 branch road is apart from the P3 node 35km CG of place, 300 Ω	C phase high resistive fault	249.747	249.738	391.387	347.061	147.481	Bus3-P3
								The P1-BusR branch road is apart from the P1 node 3km AG of place, 300 Ω	The A phase fault	146.966	146.971	147.013	146.921	146.119	P1-BusR
The P1-BusR branch road is apart from the R end 15km AG of place, 300 Ω	The A phase fault	15.190	15.251	15.656	15.256	14.958	P1-BusR
								The P1-BusR branch road is apart from the R end 30km AG of place, 250 Ω	The A phase fault	30.256	30.346	30.950	30.327	29.935	P1-BusR
The P2-P4 branch road is apart from the P4 node 2.5km BC of place, 10 Ω	The BC phase fault	347.742	347.739	249.294	249.595	149.751	P2-P4
								The P2-P4 branch road is apart from the P2 node 2km BC of place, 10 Ω	The BC phase fault	252.396	252.631	250.100	249.731	149.586	P2-P4
The P1-P2 branch road is apart from the P2 node 18km AB of place phase fault	The AB phase fault	231.954	231.649	232.012	231.858	149.363	P1-P2
								The P1-P2 branch road is apart from the P1 node 5km CAG of place	The AC phase fault	154.920	154.440	154.684	154.428	149.186	P1-P2

The above; only for the better embodiment of the present invention, but protection scope of the present invention is not limited to this, anyly is familiar with those skilled in the art in the technical scope that the present invention discloses; the variation that can expect easily or replacement all should be encompassed within protection scope of the present invention.

Claims (1)

1. back-up protection method of multi-terminal high-voltage power transmission area based on WAMS, wide area backup protection comprises that the protection zone internal fault detects and fault branch is selected, realization is based on the multi-terminal high-voltage power transmission area backup protection of Wide-area Measurement Information, namely at first utilize the existing WAMS of multi-terminal high-voltage power transmission area to realize that all are equipped with the voltage of phasor measurement unit node to this zone, the synchronous real-time measurement of electric current phasor, computational analysis through main website and wide area backup protection server, accurately determine concrete fault phase and faulty line, and issue the execution substation that control command arrives each circuit in this zone; It is characterized in that, implementation method is as follows:

A) voltage, the electric current phasor at each phasor measurement unit mounting points place of collecting according to main website in real time of wide area backup protection server, adopt the wide area current differential protection to detect in the protection zone and whether break down, in finding the protection zone, break down and then determine the separate and transition resistance situation of concrete fault;

B) the wide area current differential protection of above-mentioned steps in a) comprises that the protection of wide area full current differential and wide area fault component based differential protection protect, the two replenishes the internal fault Detection task that is used for bearing multi-terminal high-voltage power transmission area mutually, wherein, the protection of wide area full current differential refers to that the wide area backup protection server directly carries out Phase-Sequence Transformation to the real-time measurement data of sending on each phasor measurement unit, the center of choosing multi-terminal high-voltage power transmission area is reference point, based on distributed parameter model, each order component of first and last end by multi-terminal high-voltage power transmission area is calculated each order differential current and each the order stalling current that obtains the reference point place to reference point respectively, then syntheticly obtain each corresponding differential current and stalling current, utilize at last ratio-restrained characteristic to consist of the full current differential protection; The protection of wide area fault component based differential protection refers to that the wide area backup protection server is just calculating each phasor measurement unit mounting points place, negative, residual voltage fault component and just, negative, the zero-sequence current fault component, the center of choosing multi-terminal high-voltage power transmission area is reference point, based on distributed parameter model, each order fault component of first and last end by multi-terminal high-voltage power transmission area is calculated each order fault component based differential protection electric current and each the order fault component braking electric current that obtains the reference point place to reference point respectively, then syntheticly obtain each corresponding fault component based differential protection electric current and fault component braking electric current, utilize at last ratio-restrained characteristic to consist of the fault component current differential protection;

C) break down in detecting the protection zone, then accurately determine faulty line according to the faulty line system of selection, then main website is to the execution substation sending action order of faulty line; Wherein, the faulty line system of selection refers to based on distributed parameter model, is calculated to reference edge respectively by each proper order component and obtains the solution χ that faulty line is selected equation _IR, I=1 wherein ..., N; If χ _IRSatisfy χ _IR＜χ _2R＜...＜χ _KR＜χ _K+1R=...=χ _NR, P then _K+1P _KLine fault; If χ _IR(I=1 ..., satisfy χ between N) _1R＜χ _2R＜... χ _K-1R＜χ _K+1R=...=χ _NR＜χ _KR, KP then _KLine fault; R is reference edge, and N is the node sum of multi-terminal high-voltage zone outermost; K+1, K, K-1 represent the numbering of multi-terminal high-voltage power transmission area external port node; P _K+1, P _K, P _K-1The numbering of expression multi-terminal high-voltage power transmission area internal node;

D) faulty line above-mentioned steps c) selects equation to refer to that its expression formula is based on the synchronous fault distance-finding method of the double line terminal of distributed parameter model Wherein

χ _IRCalculate the solution of the faulty line selection equation that obtains to reference edge R for rectified the order component by I, Positive sequence voltage, electric current for reference edge R;

Be P ₁Node is to the distance of reference edge R; For rectifying the order component to P by I ₁The P that reckoning obtains ₁Node voltage, P ₁Node outlet electric current; Z _C1, γ ₁Be transmission line positive sequence wave impedance and propagation constant.

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