CN109494697A - A method of the new energy station multiterminal pilot protection based on cosine similarity - Google Patents

A method of the new energy station multiterminal pilot protection based on cosine similarity Download PDF

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CN109494697A
CN109494697A CN201910015668.6A CN201910015668A CN109494697A CN 109494697 A CN109494697 A CN 109494697A CN 201910015668 A CN201910015668 A CN 201910015668A CN 109494697 A CN109494697 A CN 109494697A
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new energy
current
cosine similarity
protection
value
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CN109494697B (en
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贾科
郑黎明
毕天姝
杨哲
方煜
朱正轩
董雄鹰
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North China Electric Power University
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    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02HEMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00Emergency 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
    • H02H7/26Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
    • H02H7/28Sectionalised 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 meshed systems
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00Energy generation through renewable energy sources
    • Y02E10/50Photovoltaic [PV] energy
    • Y02E10/56Power conversion systems, e.g. maximum power point trackers

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  • Supply And Distribution Of Alternating Current (AREA)
  • Emergency Protection Circuit Devices (AREA)

Abstract

本发明公开了一种基于余弦相似度的新能源场站多端纵联保护的方法,针对通过电力电子换流器并网的新能源场站,结合常用的抑制负序电流的控制策略,获得新能源场站故障的暂态电流解析式以及新能源场站短路电流解析式;根据所述新能源场站短路电流解析式,分析获得新能源场站短路电路波形呈非工频衰减的正弦波与非工频正弦波叠加的特性,并由此构造出基于余弦相似度的新能源场站多端纵联保护判据;根据系统正常运行时的角度误差与幅值误差对所述多端纵联保护判据中的保护定值进行整定。上述方法不受新能源容量、运行方式影响,其具有高可靠性和灵敏性、且速动性好的特点,提高了规模化新能源并网系统运行的安全性和可靠性。

The invention discloses a method for multi-terminal longitudinal protection of new energy field stations based on cosine similarity. For new energy field stations connected to the grid through power electronic converters, combined with the commonly used control strategy for suppressing negative sequence current, a new method can be obtained. The transient current analytical formula of the fault of the energy station and the short-circuit current analytical formula of the new energy station; according to the short-circuit current analytical formula of the new energy station, the sine wave and The characteristics of non-power frequency sine wave superposition, and from this, a multi-terminal longitudinal protection criterion based on cosine similarity is constructed; according to the angle error and amplitude error of the system during normal operation, the multi-terminal longitudinal protection criterion is determined. Set according to the protection setting in . The above method is not affected by the new energy capacity and operation mode, and has the characteristics of high reliability, sensitivity, and good quickness, which improves the safety and reliability of the operation of a large-scale new energy grid-connected system.

Description

A method of the new energy station multiterminal pilot protection based on cosine similarity
Technical field
The present invention relates to new energy power grid protection technique field more particularly to a kind of new energy based on cosine similarity The method of source station multiterminal pilot protection.
Background technique
In order to solve increasingly serious energy crisis and problem of environmental pollution, the new energy power supply such as photovoltaic, wind-powered electricity generation is obtained It rapidly develops.Scale new energy station is mostly using grid-connected structure of boosting is concentrated, in order to save power equipment investment, new energy Source station is relatively common through T direct type topology in 110/220kV grid-connected route.Multiple new energy station T connect to be sent out in same Route, therefore protect incorrect operation bigger to systematic influence range, in order to improve the safety that new energy electric power utilizes, need electricity Net relay protection is reliable, rapidly cuts off failure, so the protection that research new energy station T direct type sends out route has important meaning Justice.
It is difficult that the power output of new energy power supply has many characteristics, such as that waveform, randomness cause fault characteristic value to extract, and due to New energy station generally uses power electronics inverter to be connected to the grid, and short circuit current shows amplitude limited, frequency shift (FS), abnormal The unique properties such as change, harmonic wave are completely different with the fault characteristic of synchronous generator.Above-mentioned reason causes traditional based on synchronous hair There is the adaptability problem of sensitivity decline, even there is mistake, tripping risk, traditional protection in the protection philosophy of electrical fault characteristic It faces the challenge, it is therefore necessary to study after the failure of new energy station short circuit current feature and construct and be suitable for new energy station T Connect the salvo of grid-connected system.
Summary of the invention
The method of the object of the present invention is to provide a kind of new energy station multiterminal pilot protection based on cosine similarity, should Method is not influenced by new energy capacity, the method for operation, has the characteristics that high reliability and sensitivity and quick-action is good, is improved The safety and reliability of scale new energy grid connection system operation.
The purpose of the present invention is what is be achieved through the following technical solutions:
A method of the new energy station multiterminal pilot protection based on cosine similarity, which comprises
Step 1, for by the grid-connected new energy station of power electronics inverter, in conjunction with the common negative-sequence current that inhibits Control strategy obtains the transient short circuit current analytic expression of new energy station failure;
Step 2, according to the new energy station transient short circuit current analytic expression, analysis obtains new energy station short circuit current The characteristic that waveform is superimposed in the sine wave of non-power frequency decaying with non-power frequency sine wave, and thus construct based on cosine similarity New energy station multiterminal pilot protection criterion;
Step 3, angular error when being operated normally according to system and amplitude error are in the multiterminal pilot protection criterion Protection definite value adjusted.
As seen from the above technical solution provided by the invention, the above method is not by new energy capacity, method of operation shadow It rings, has the characteristics that high reliability and sensitivity and quick-action is good, improve the peace of scale new energy grid connection system operation Full property and reliability.
Detailed description of the invention
In order to illustrate the technical solution of the embodiments of the present invention more clearly, required use in being described below to embodiment Attached drawing be briefly described, it should be apparent that, drawings in the following description are only some embodiments of the invention, for this For the those of ordinary skill in field, without creative efforts, it can also be obtained according to these attached drawings other Attached drawing.
Fig. 1 is the method stream of the new energy station multiterminal pilot protection provided in an embodiment of the present invention based on cosine similarity Journey schematic diagram;
Fig. 2 is that scale new energy station T direct type sends out line topological and abort situation signal in example of the present invention Figure;
Fig. 3 is that new energy station T direct type sends out circuit relay protection device connection schematic diagram in example of the present invention;
Fig. 4 is that (the event in area of protection act situation when A phase ground fault occurs for T junction in area in example of the present invention Barrier) schematic diagram;
Fig. 5 is protection act situation (in area when T junction generation BC two-phase short-circuit fault in area in example of the present invention Failure) schematic diagram;
Fig. 6 is protection act situation (in area when T junction generation BC double earthfault in area in example of the present invention Failure) schematic diagram;
Fig. 7 is that (the event in area of protection act situation when ABC three-phase fault occurs for T junction in area in example of the present invention Barrier) schematic diagram.
Specific embodiment
With reference to the attached drawing in the embodiment of the present invention, technical solution in the embodiment of the present invention carries out clear, complete Ground description, it is clear that described embodiments are only a part of the embodiments of the present invention, instead of all the embodiments.Based on this The embodiment of invention, every other implementation obtained by those of ordinary skill in the art without making creative efforts Example, belongs to protection scope of the present invention.
The embodiment of the present invention is described in further detail below in conjunction with attached drawing, is implemented as shown in Figure 1 for the present invention The method flow schematic diagram for the new energy station multiterminal pilot protection based on cosine similarity that example provides, which comprises
Step 1, for by the grid-connected new energy station of power electronics inverter, in conjunction with the common negative-sequence current that inhibits Control strategy obtains the transient short circuit current analytic expression of new energy station failure;
The detailed process of the step are as follows:
Firstly, new energy station grid-connected inverters loop equation indicates under dq coordinate system are as follows:
In formula, L is the equivalent inductance of grid-connected inverters topology;R is the substitutional resistance of grid-connected inverters topology;idFor dq seat D shaft current under mark system;iqFor the q shaft current under dq coordinate system;udFor the d shaft voltage of inverter outlet;uqFor inverter outlet Q shaft voltage;edFor power grid electromotive force d axis component;eqFor power grid electromotive force q axis component;ω is angular frequency;
When above-mentioned new energy station inverter uses voltage-to-current double-closed-loop control device, in the control for inhibiting negative-sequence current Under strategy, the governing equation of inverter be can be written as:
In formula, kip、kiiIt is current regulator ratio, integration time constant respectively;Respectively indicate d shaft current ginseng Examine value and q shaft current reference value;id, iqRespectively indicate d axis, q shaft current actual value;L is the equivalence electricity of grid-connected inverters topology Sense;edFor power grid electromotive force d axis component;eqFor power grid electromotive force q axis component.
It will disconnect outer voltage when inverter transient response, at this moment dq shaft current is mainly influenced by current control inner ring, PI Electric current loop only needs to track given reference value, can in conjunction with the loop equation and inverter control equation of grid-connected inverters To obtain inverter transient response equation are as follows:
In formula, kip、kiiIt is current regulator ratio, integration time constant respectively;Respectively indicate the reference of d shaft current Value and q shaft current reference value;id, iqRespectively indicate d axis, q shaft current actual value;L is the equivalent inductance of grid-connected inverters topology.
When due to operating normally, new energy station generally keeps rated power factor to run, so dq axis initial current id0 =1p.u., iq0=0p.u. solves the transient current analytic expression under the available dq axis of inverter transient response equation are as follows:
Wherein, id, iqRespectively indicate d axis, q shaft current actual value;Respectively indicate d shaft current reference value and q axis electricity Flow reference value;ξ is the damping ratio of second-order system, and value isωnAngular frequency, value are vibrated naturally for second-order system ForωdDamped oscillation frequency is represented, value isβ is drag angle, and value is
It is short that the transient current analytic expression is further converted to by the new energy station under ABC coordinate system by coordinate transform Road electric current analytic expression, is embodied as:
Wherein, iφFor the short circuit current of phase any in three-phase;θφInitial phase angle after representing three-phase fault;ω represents lock The angular frequency that phase ring detects;t0For failure start time.
Step 2, according to the new energy station short circuit current analytic expression, analysis obtains new energy station short circuit current waveform In the characteristic that the sine wave that non-power frequency decays is superimposed with non-power frequency sine wave, and thus construct the new energy based on cosine similarity Source station multiterminal pilot protection criterion;
In the step, the short circuit current analytic expression of conventional synchronization power supply is indicated are as follows:
In formula, i is the short circuit current of any phase in three-phase;Eq|0|And xdRespectively synchronous machine built-in potential and synchronous electricity It is anti-;x″dWith x 'd、T″dWith T 'dSynchronous machine reactance, AC compounent damping time constant in respectively secondary transient state and transient process; ω is power frequency angular frequency;TaIt is DC component damping time constant;For fault initial angle.
According to above formula it is found that conventional synchronization power supply short circuit current waveform shows as the power frequency exponentially to decay sine Wave;And the characteristic that the sine wave of non-power frequency decaying is superimposed with non-power frequency sine wave is presented in new energy station short circuit current waveform.This There are huge differences for two kinds of characteristics, and the new energy station multiterminal based on cosine similarity can be constructed using this species diversity Pilot protection criterion, specifically:
Line topological is sent out in conjunction with new energy station T direct type, it is synchronous that all T are connect the long internal clock of new energy station 10ms window Current sampling data it is corresponding be added, operation result is denoted as station side and current vector
In formula, N, which is represented, shares N number of new energy station access on T direct type submitting route;iwkFor k-th of new energy station The synchronous current sampling data vector of the long internal clock of 10ms window;N is the total number of all sampled points in 10ms window is long;
The synchronous current sampling data of the long internal clock of synchronization system side 10ms window is denoted as system side current vector, indicates are as follows: is =(is1,is2,…,isn);
Above-mentioned two current vector is substituted into following cosine similarity formula and is calculated again:
In formula, cos (iw,is) represent two current vectors cosine similarity calculate;
Wherein, when external area error occurs, the transient current waveform of station side and electric current and system side electric current is on the contrary, calculate Obtain two current vector coefficient of similarity cos (iw,is)=- 1;When troubles inside the sample space occurs, since new energy power supply and tradition are same It is different to walk power failure characteristic, two sides transient current wave-form similarity is poor, and the coefficient of similarity being calculated will be greater than -1;By It being directly grounded in the neutral point of main transformer in wind-powered electricity generation station, when ground fault occurring in area, zero-sequence current is larger in system, so that Thus the calculated value of cosine similarity constructs the new energy station multiterminal pilot protection based on cosine similarity and sentences near 1 According to expression are as follows:
cos(i,is) > cosset
In formula, subscript φ is any phase in ABC three-phase, calculates coefficient of similarity using the data of same famous prime minister;cossetFor Definite value is protected, value range is between [- 1,1].
Step 3, angular error when being operated normally according to system and amplitude error are in the multiterminal pilot protection criterion Protection definite value adjusted.
Here, the protection definite value in the multiterminal pilot protection criterion is carried out adjusting used formula are as follows:
Wherein, K is safety factor;KangFor angular error coefficient;KampFor amplitude error coefficient;KmarFor nargin coefficient; cossetTo protect definite value.
For example, angular error is mainly derived from pilot protection communication synchronization error and CT angular error, chooses electric current Reference direction is that bus is directed toward route, in the case where not considering angular error, station side and electric current and system side current waveform Completely on the contrary, cosine similarity calculated value is -1 at this time.In view of synchronous error is up to 0.5ms, corresponding 9 ° of power frequency angle;CT Angular error is generally considered as 7 °, so angular error is 16 ° total.When angular error is 16 °, corresponding cosine similarity is calculated Value is -0.960, and in order to escape angular error, the COEFFICIENT K about angular error is arrangedang
Other than angular error, amplitude error also will affect cosine similarity calculated value, be mainly derived from CT amplitude mistake Difference.Since CT precision is generally 5% or 10%, under 10% amplitude error, cosine similarity calculated value is -0.993.In order to hide Amplitude error is crossed, the COEFFICIENT K about amplitude error is setamp
In addition, under normal circumstances protection definite value setting in order to ensure reliability need to there are certain nargin, so setting about The COEFFICIENT K of narginmar
Such as can choose that angular error coefficient is 0.95, amplitude error coefficient is 0.99, nargin coefficient is 0.95, it calculates Obtaining safety factor K is 0.9, it is possible thereby to know that the setting valve of protection definite value is cosset=-1 × 0.9=-0.9.
It is described in detail below with process of the specific example to the above method, is illustrated in figure 2 the present invention and lifts in fact Scale new energy station T direct type sends out line topological and abort situation schematic diagram, a power electronics unit table in Fig. 2 in example Show a new energy station (general rated capacity is 50MW or 100MW), multiple new energy fields can be connect with T on a submitting route It stands, is then incorporated to external sync system through overhead line, the T direct type that voltage class is 220kV in Fig. 2, which is sent out, accesses two on route 100MW new energy station, wherein #1 new energy station is permanent magnetism wind power plant, and single machine rated capacity is 1.5MW, shares 99 typhoons Machine, set end voltage 0.69kV;#2 new energy station is double-fed fan motor field, and single machine rated capacity is 3MW, totally 33 Fans, machine End voltage is 0.69kV;Case becomes rated capacity 3.5MVA, no-load voltage ratio 35kV/0.69kV, Dyn wiring, short-circuit impedance 6.76%;It is equivalent Collect 0.11 Ω of line resistance, 409.5 μ H of inductance.Main transformer rated capacity 120MVA, no-load voltage ratio 220kV/35kV, YNd wiring, short circuit resistance Anti- 6%.Route overall length 40km is sent out, positive and negative sequence impedance is 0.076+j0.338 Ω/km, zero sequence impedance 0.284+ J0.824 Ω/km, T contact is located at route midpoint.Topological structure and above-mentioned parameter according to fig. 2 is in Real Time Digital Simulator New energy T is built in (Real time digital simulator, RTDS) connects grid-connected system electrical-magnetic model to verify this Invent the method proposed.
Abort situation at totally 6, is separately positioned on and sends out route W1、W2, the side S is externally ported and inner proximal, be denoted as respectively K11,K12,K13,K14,K15,K16.Fault type includes all 4 seed types, including the event of singlephase earth fault, two phase ground Barrier, two-phase short-circuit fault, three phase short circuit fault are grounded respectively with A phase, BC two phase ground, BC line to line fault and ABC three-phase shortcircuit For, above 4 kinds of fault types are abbreviated as AG, BCG, BC, ABC respectively.
It is illustrated in figure 3 new energy station T direct type in example of the present invention and sends out circuit relay protection device and connect and show It is intended to.It is as shown in Figure 3: to send out route W1Side, W2Side and the side S are mounted with protective relaying device W respectively1、W2And S, every suit protection Device independently measures this side three-phase current, and the sampled value of other two sides is obtained by communication channel.It proposes through the invention The new energy station multiterminal pilot protection criterion based on cosine similarity, utilize same famous prime minister station side and electric current and system side electricity It flows sampled value and carries out cosine similarity calculating, judge abort situation and send out trip signal to corresponding breaker.
It is illustrated in figure 4 in example of the present invention T junction in area and protection act situation when A phase ground fault occurs (troubles inside the sample space);It is illustrated in figure 5 in example of the present invention T junction in area and protection act when BC two-phase short-circuit fault occurs Situation (troubles inside the sample space);It is illustrated in figure 6 in example of the present invention T junction in area and protection when BC double earthfault occurs Action situation (troubles inside the sample space);It is illustrated in figure 7 in example of the present invention T junction in area and guarantor when ABC three-phase fault occurs It protects action situation (troubles inside the sample space).Wherein solid line is A phase cosine similarity calculated value, and dotted line is B phase cosine similarity calculated value, Chain-dotted line is C phase cosine similarity calculated value;In order to clearly illustrate Perfomance of protective relaying, it is fixed that protection has been marked with double dot dash line Value.0ms is that the moment occurs for failure in figure, and the cosine similarity coefficient calculated value of the 5ms after troubles inside the sample space, failure phase are just more than Definite value -0.9 is protected, and cosine similarity calculated value tends towards stability in 10~15ms, protection reliably, can be identified rapidly Area's internal and external fault, and act in circuit breaker trip.
It is former for different faults position shown in Fig. 2, difference for the validity for further verifying the proposed method of the present invention A large amount of simulation studies are carried out situations such as hindering type in Real Time Digital Simulator (RTDS), the following table 1 gives all emulation knots Fruit, cosine similarity in 20ms after " cosine similarity index variation range " is referred to from failure start time to failure in table 1 The variation range of coefficient;In the case that table 2 gives T junction through transition resistive short, the action performance of protection.In table 2 " cosine similarity calculated value " is the cosine similarity being calculated using all sampled values in failure the latter data window length; When the new energy station T direct type that table 3 gives different capabilities is sent out, the cosine similarity calculated value of T junction failure.In table 3 " cosine similarity calculated value " be using failure the latter data window it is long in the cosine that is calculated of all sampled values it is similar Degree.
Table 1
Table 2
Table 3
Above-mentioned simulation result shows that protection reliably can rapidly identify various types of area's internal and external faults, troubles inside the sample space 10~15ms protects cosine similarity calculated value to be greater than protection definite value -0.9 and tends towards stability afterwards, and protection quick-action is good;Protection It is not influenced by new energy station capacity and the method for operation, can guarantee higher sensitivity in various situations;It is short through transition resistance In the case where road, protection still has reliability, is resistant to high resistive fault.
It is worth noting that, the content being not described in detail in the embodiment of the present invention belongs to professional and technical personnel in the field's public affairs The prior art known.
In conclusion traditional protection sensitivity decline is even refused when the method for the embodiment of the present invention avoids troubles inside the sample space Dynamic situation, while when sending out route troubles inside the sample space, protection can action message, and can be realized complete fibre;This method is not It is influenced by new energy power supply capacity, the method for operation, and uncontrolled strategy influences.
The foregoing is only a preferred embodiment of the present invention, but scope of protection of the present invention is not limited thereto, Within the technical scope of the present disclosure, any changes or substitutions that can be easily thought of by anyone skilled in the art, It should be covered by the protection scope of the present invention.Therefore, protection scope of the present invention should be with the protection model of claims Subject to enclosing.

Claims (4)

1.一种基于余弦相似度的新能源场站多端纵联保护的方法,其特征在于,所述方法包括:1. a method for multi-terminal longitudinal protection of new energy field station based on cosine similarity, is characterized in that, described method comprises: 步骤1、针对通过电力电子换流器并网的新能源场站,结合常用的抑制负序电流的控制策略,获得新能源场站故障的暂态短路电流解析式;Step 1. For the new energy station connected to the grid through the power electronic converter, combined with the commonly used control strategy for suppressing negative sequence current, obtain the transient short-circuit current analytical formula of the fault of the new energy station; 步骤2、根据所述新能源场站暂态短路电流解析式,分析获得新能源场站短路电路波形呈非工频衰减的正弦波与非工频正弦波叠加的特性,并由此构造出基于余弦相似度的新能源场站多端纵联保护判据;Step 2. According to the analytical formula of the transient short-circuit current of the new energy station, analyze and obtain the characteristics of the superposition of the non-power-frequency attenuated sine wave and the non-power-frequency sine wave in the short-circuit circuit waveform of the new energy station. The multi-terminal longitudinal protection criterion of new energy stations based on cosine similarity; 步骤3、根据系统正常运行时的角度误差与幅值误差对所述多端纵联保护判据中的保护定值进行整定。Step 3: Set the protection setting value in the multi-terminal longitudinal protection criterion according to the angle error and the amplitude error during normal operation of the system. 2.根据权利要求1所述基于余弦相似度的新能源场站多端纵联保护的方法,其特征在于,在步骤1中,所获得的dq轴下的暂态电流解析式为:2. The method for multi-terminal longitudinal protection of new energy field stations based on cosine similarity according to claim 1, wherein in step 1, the obtained transient current analytical formula under the dq axis is: 其中,id,iq分别表示d轴、q轴电流实际值;分别表示d轴电流参考值与q轴电流参考值;ξ为二阶系统的阻尼比,其值为ωn为二阶系统自然振荡角频率,其值为ωd代表阻尼振荡频率,其值为β为阻尼角,其值为 Among them, i d , i q represent the actual values of the d-axis and q-axis currents, respectively; respectively represent the d-axis current reference value and the q-axis current reference value; ξ is the damping ratio of the second-order system, and its value is ω n is the natural oscillation angular frequency of the second-order system, and its value is ω d represents the damped oscillation frequency, and its value is β is the damping angle, and its value is 进一步通过坐标变换将所述暂态电流解析式转换为ABC坐标系下的新能源场站短路电流解析式,具体表示为:The transient current analytical formula is further converted into the new energy station short-circuit current analytical formula under the ABC coordinate system through coordinate transformation, which is specifically expressed as: 其中,iφ为三相中其中任一相的短路电流;θφ代表三相故障后的初相角;ω代表锁相环检测到的角频率;t0为故障开始时刻。Among them, i φ is the short-circuit current of any one of the three phases; θ φ represents the initial phase angle after the three-phase fault; ω represents the angular frequency detected by the phase-locked loop; t 0 is the start time of the fault. 3.根据权利要求1所述基于余弦相似度的新能源场站多端纵联保护的方法,其特征在于,在步骤2中,所述构造出基于余弦相似度的新能源场站多端纵联保护判据的过程具体为:3. The method for multi-terminal longitudinal protection of new energy field stations based on cosine similarity according to claim 1, characterized in that, in step 2, described constructing the multi-terminal longitudinal protection of new energy field stations based on cosine similarity The process of judgment is as follows: 结合新能源场站T接型送出线路拓扑,将所有T接新能源场站10ms窗长内时钟同步的电流采样值对应相加,运算结果记为场站侧和电流向量 Combined with the T-connected outgoing line topology of the new energy station, the current sampling values of the clock synchronization within the 10ms window length of all T-connected new energy stations are added correspondingly, and the calculation result is recorded as the station side and the current vector 式中,N代表T接型送出线路上共有N个新能源场站接入;iwk为第k个新能源场站10ms窗长内时钟同步的电流采样值向量;n为10ms窗长内所有采样点的总数目;In the formula, N represents that there are a total of N new energy stations connected to the T-connected outgoing line; iwk is the current sampling value vector synchronized by the clock within the 10ms window length of the kth new energy station; the total number of sampling points; 同步系统侧10ms窗长内时钟同步的电流采样值记作系统侧电流向量,表示为:is=(is1,is2,…,isn);The current sampling value synchronized by the clock in the 10ms window length of the synchronous system side is recorded as the current vector of the system side, expressed as: i s = (i s1 , i s2 ,...,is n ); 再将上述两个电流向量代入下面的余弦相似度公式中进行计算:Then substitute the above two current vectors into the following cosine similarity formula for calculation: 式中,cos(iw,is)代表两个电流向量的余弦相似度计算;In the formula, cos(i w , i s ) represents the cosine similarity calculation of two current vectors; 其中,当发生区外故障时,场站侧和电流与系统侧电流的暂态电流波形相反,计算得到两电流向量相似度系数cos(iw,is)=-1;当发生区内故障时,计算得到的相似度系数大于-1;由于风电场站内的主变中性点直接接地,在区内发生接地故障时,系统中零序电流较大,使得余弦相似度的计算值在1附近,由此构造出基于余弦相似度的新能源场站多端纵联保护判据表示为:Among them, when an out-of-area fault occurs, the transient current waveforms of the station-side sum current and the system-side current are opposite, and the similarity coefficient of the two current vectors cos(i w , i s )=-1 is calculated; when an intra-area fault occurs , the calculated similarity coefficient is greater than -1; since the neutral point of the main transformer in the wind farm is directly grounded, when a ground fault occurs in the area, the zero-sequence current in the system is large, so that the calculated value of the cosine similarity is 1 Nearby, the multi-terminal longitudinal protection criterion of new energy station based on cosine similarity is constructed and expressed as: cos(i,is)>cosset cos(i ,i s )>cos set 式中,下标φ为ABC三相中的任一相,利用同名相的数据计算相似度系数;cosset为保护定值,取值范围在[-1,1]之间。In the formula, the subscript φ is any phase in the ABC three-phase, and the similarity coefficient is calculated by using the data of the phase with the same name; cos set is the protection fixed value, and the value range is between [-1, 1]. 4.根据权利要求1所述基于余弦相似度的新能源场站多端纵联保护的方法,其特征在于,在步骤3中,对所述多端纵联保护判据中的保护定值进行整定所采用的公式为:4. The method for multi-terminal pilot protection of new energy power stations based on cosine similarity according to claim 1, wherein in step 3, the protection setting value in the multi-terminal pilot protection criterion is adjusted. The formula used is: 其中,K为可靠系数;Kang为角度误差系数;Kamp为幅值误差系数;Kmar为裕度系数;cosset为保护定值。Among them, K is the reliability coefficient; K ang is the angle error coefficient; K amp is the amplitude error coefficient; K mar is the margin coefficient; cos set is the protection fixed value.
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CN110165644A (en) * 2019-06-03 2019-08-23 华北电力大学 A kind of new energy station longitudinal protection method based on transient current time-frequency characteristic
CN111564828A (en) * 2020-06-11 2020-08-21 国网江西省电力有限公司电力科学研究院 Distance pilot protection method suitable for double-fed fan output line
CN111983376B (en) * 2020-07-03 2023-02-28 昆明理工大学 A Protection Method Based on Cosine Similarity for Internal and External Faults
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CN111981637A (en) * 2020-09-01 2020-11-24 珠海格力电器股份有限公司 Air conditioner short circuit abnormity detection method, computer device and computer readable storage medium
CN111981637B (en) * 2020-09-01 2021-11-19 珠海格力电器股份有限公司 Air conditioner short circuit abnormity detection method, computer device and computer readable storage medium
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CN113036729A (en) * 2021-04-12 2021-06-25 华中科技大学 Differential protection method, device and system based on Euclidean distance and pearson similarity
CN113054661A (en) * 2021-04-20 2021-06-29 华北电力大学 New energy station outgoing line pilot protection method based on Kaemphrara distance
CN114884032A (en) * 2022-05-18 2022-08-09 华北电力大学 High-speed protection method suitable for T-connection type outgoing line of new energy station and application thereof
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CN119189410A (en) * 2024-11-27 2024-12-27 成都正西液压设备制造有限公司 A method for visual imaging and detection of products on hydraulic presses

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