CN104979808B - A kind of inverter calculation of penetration level method counted and longitudinal difference protection influences - Google Patents
A kind of inverter calculation of penetration level method counted and longitudinal difference protection influences Download PDFInfo
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- CN104979808B CN104979808B CN201510394545.XA CN201510394545A CN104979808B CN 104979808 B CN104979808 B CN 104979808B CN 201510394545 A CN201510394545 A CN 201510394545A CN 104979808 B CN104979808 B CN 104979808B
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Abstract
The present invention relates to the inverter calculation of penetration level methods that meter and longitudinal difference protection influence, including：(1) longitudinal differential protection device is adjusted；(2) T connects in the Double-End Source system of inverse distributed power, according to grid entry point Voltage Drop to the voltage for obtaining DG grid entry points voltage and fault point in various degree；(3) under the maximum phase angle difference that system stable operation allows; it is connected to the grid maximum transition resistance under voltage class through inverse distributed power; according to the degree of grid entry point Voltage Drop; obtained single-phase short circuit difference current obtains the inverse distributed power that T connects different capabilities; difference current in different location single phase ground fault; and be compared it with the setting valve of protection, when the two is equal, corresponding minimum capacity is the allowed capacity of inverse distributed power.The present invention has higher directive significance in engineer application.
Description
Technical field
The present invention relates to field of relay protection in power, after being related to a kind of inverse distributed power T links, connection is indulged
Calculation of penetration level method under the influence of differential protection.
Background technology
A large amount of inverse distributed powers (IIDG) are incorporated into the power networks to original protection and control device in electric system
Reliability service produce influence.The allowed capacity for determining IIDG makes the protective device in electric system keep original coordination
Property, it is most important to the safe and stable operation of electric system.National policy help and technological progress promotion under, IIDG's and
Network capacity amount is increasing, and grid-connected voltage class is also higher and higher, and the network being incorporated to is no longer limited to radial low pressure and matches
Power grid.《Distributed generation resource accesses electric power network technique regulation》It points out, distributed generation resource accesses different voltages grade according to capacity difference
Power distribution network, when capacity is in 15MW or more, access 35kV and 110kV power grids.In addition《Distribution network planning designing technique directive/guide》
It points out in 110kV networks, DG can be connected to the grid in such a way that T connects.When IIDG access high-tension distributing lines form T links
When, become preferred plan using selectivity and the good longitudinal differential protection of quick-action.In the electricity that can not obtain DG grid entry points
Under the premise of gas information, the method for improving longitudinal differential protection setting valve can only be used, can just meet longitudinal differential protection selection
The requirement of property.But when the IIDG that T connects is more than certain capacity, short trouble occurs through transition resistance inside protection domain
When, since difference current is smaller, longitudinal differential protection tripping may be caused.
The present invention gives T to connect comparative indicator of the Double-End Source system of IIDG through transition resistance generation single-phase short circuit when
Formula is calculated, it is proposed that meter and the IIDG allowed capacity analysis methods of longitudinal differential protection influence..
Invention content
It is an object of the present invention to known T connects the grid-connected position of IIDG, and the operating status of IIDG and system operation mode
Under the premise of unknown, to ensure the reliability of longitudinal differential protection action, a kind of computational methods of IIDG allowed capacities are provided, it should
Method has obtained the access appearance of IIDG by comparing the size of difference current and longitudinal differential protection setting valve minimum when failure
Amount.The present invention considers the influence of abort situation, transition resistance, two side system phase angle differences to difference current, accurate and effective, to work
Cheng Yingyong has higher directive significance.
The present invention can be achieved through the following technical solutions：
A kind of inverter calculation of penetration level method counted and longitudinal difference protection influences, is made of following steps：
(1) longitudinal differential protection device is adjusted, setting valve is：
Iunb=0.1KnpKsamIk.max+2IN (1)
Wherein, Ik.maxFor longitudinal differential protection range external fault when maximum through current, KsamFor the electricity no more than 1
Current transformer homotype coefficient, KnpFor the influence coefficient of aperiodic component, value is between 1.5~2, INFor inverse distributed electricity
The rated current in source；
(2) T connects in the Double-End Source system of inverse distributed power, and circuit AB is longitudinal differential protection installation site, M
Point be inverse distributed power grid entry point, grid entry point Voltage Drop to it is different degrees of when, due to inverse distributed power
Output characteristics it is different, therefore to calculate formula also different for obtained difference current, when through transition resistance single-phase earthing occurs for system
When short-circuit, it can obtain：
When grid entry point Voltage Drop to 0.9UNWhen above
When grid entry point Voltage Drop to 0.1-0.9UNBetween when
When grid entry point Voltage Drop to 0.1UNWhen following
Voltage Drop to it is different degrees of when, respectively by formula (2)~(4) and formula (5) simultaneous, you can obtain DG grid entry points
VoltageWith the voltage of fault point
And then the difference current of failure phase is when obtaining single-phase short circuit
Wherein, UNFor system nominal voltage, INFor inverse distributed power rated current, P is inverse distributed power
Output power,WithThe respectively system equivalent potential of the both sides circuit AB,Phase angle is δ,Phase angle is 0 °；It is inverse
The positive sequence voltage of modification distributed generation resource grid entry point, phase angle are For the positive sequence voltage of fault point, phase angle θ；Circuit
The positive-negative sequence impedance of AM is Z1, zero sequence impedance Z10, grid entry point M to the positive-negative sequence impedance between short circuit trouble point is Zf1,
Resistance is Rf1, reactance Xf1, zero sequence impedance Zf10, the positive-negative sequence impedance of short circuit trouble point to busbar B is Zf2, zero sequence impedance
For Zf20；Z3For failure Deng Zhi Zu Pit, value Z in compound sequence network3=(Z1+Zf1)//Zf2+(Z10+Zf10)//Zf20+3ZD；r(x)
It is to take imaginary-part operation to take real part operation, im (x)；
(3) it under the maximum phase angle difference that system stable operation allows, is connected to the grid voltage etc. through inverse distributed power
Maximum transition resistance under grade is selected public by the corresponding calculating provided in step (2) according to the degree of grid entry point Voltage Drop
Formula, obtained single-phase short circuit difference current obtain the inverse distributed power that T connects different capabilities, occur in different location single-phase
Difference current when ground short circuit, and it is compared with the setting valve of protection, when the two is equal, corresponding minimum capacity
The as allowed capacity of inverse distributed power.
The present invention has the advantage that compared with the prior art：
First, the present invention is simple and effective, and considers abort situation, transition resistance, two side system phase angle differences comprehensively to difference
The influence of streaming current so that the computational methods of IIDG allowed capacities are more accurate and reliable.Secondly, meter of the present invention and IIDG's is low
Voltage ride-through output characteristics so that the calculating of difference current is more in line with engineering reality.Finally, the present invention meets IIDG to assessment T
There is directive significance to the configuration of the influence of circuit longitudinal differential protection and protection afterwards, when the IIDG capacity that T connects holds less than access
When measuring calculated value, it is only necessary to original longitudinal differential protection setting valve is improved, can ensure the selectivity and reliability of protection,
Otherwise, it needs to use new protection scheme.
Description of the drawings
Fig. 1 is the NETWORK STRUCTURE PRESERVING POWER SYSTEM figure that T connects inverse distributed power；
Fig. 2 is the compound sequence network that single-phase short circuit occurs through transition resistance.
Specific implementation mode
It is described in detail below in conjunction with embodiment and with reference to attached drawing to the technical solution of the invention.
The present embodiment is by taking structure chart shown in FIG. 1 as an example, and circuit AB is the circuit that T connects inverse distributed power in figure,
System voltage grade be 110kV, circuit AB long 120km, circuit positive-negative sequence impedance be 0.21+j0.419 Ω/km, zero sequence impedance
It is connected to the midpoint of circuit AB for 0.63+j1.257 Ω/km, inverse distributed power T.
The inverse distributed power calculation of penetration level method that meter using the present invention and longitudinal differential protection influence.Packet
Include following steps：
(1) longitudinal differential protection device is adjusted, setting valve is：
Iunb=0.1KnpKsamIk.max+2IN(1)
Wherein, Ik.maxFor longitudinal differential protection range external fault when maximum through current, KsamFor the electricity no more than 1
Current transformer homotype coefficient, KnpFor the influence coefficient of aperiodic component, general value is between 1.5~2.INFor the specified of IIDG
Electric current.
(2) different through maximum transition resistance under the voltage class under the maximum phase angle difference that system stable operation allows
When the single phase ground fault of position, relational expression of the difference current with IIDG volume changes is obtained.
When in Fig. 1 f points through transition resistance ZDWhen single phase ground fault, compound sequence network as shown in Figure 2 is obtained.In figureFor the positive sequence voltage of IIDG grid entry points,For the positive sequence voltage of fault point,WithThe respectively system etc. of the both sides circuit AB
It is worth potential, M points are the grid entry point of DG, and the positive-negative sequence impedance of circuit AM is Z1, zero sequence impedance Z10, grid entry point M to short-circuit event
Positive-negative sequence impedance between barrier point is Zf1, zero sequence impedance Zf10, the positive-negative sequence impedance of short circuit trouble point to busbar B is
Zf2, zero sequence impedance Zf20。
According to fig. 2 and Kirchhoff's second law can obtain following relational expression：
Wherein, Z3Failure Deng Zhi Zu Pit as in compound sequence network shown in Fig. 2 in dotted line frame.Its value is Z3=(Z1+Zf1)//
Zf2+(Z10+Zf10)//Zf20+3ZD。The as output characteristics of IIDG accesses electricity according to photo-voltaic power generation station and wind power plant
The technical stipulation of Force system obtains following output characteristics：
Wherein, P is the output power of IIDG, UTFor the grid entry point voltage of IIDG, UNFor system nominal voltage.It can by above formula
Know, when grid entry point voltage is in 0.9UNWhen above, IIDG output currents and voltage in phase, active power of output；When voltage falls
Fall on 0.9UNWhen following, 90 ° of output current and the voltage phase difference of IIDG, output reactive power；When Voltage Drop to 0.1UNWith
When lower, under the action of current limit link, IIDG output currents are steady state value 2IN。
Assuming thatFormula (2) can be converted to scalar equation group.
The first two equation is related to the output characteristics of IIDG in equation group (2), during failure when grid entry point voltage difference, output characteristics
Also it can change correspondingly.
When grid entry point Voltage Drop to 0.9UNWhen above, it can obtain
When grid entry point Voltage Drop to 0.1-0.9UNBetween when, can obtain
When grid entry point Voltage Drop to 0.1UNWhen following, it can obtain
The third equation of equation group (3) is unrelated with grid entry point voltage, is converted into scalar equation and is
When Voltage Drop to it is different degrees of when, solve DG grid entry point voltages using formula (4)-(7)With fault point
VoltageThe difference current of failure phase is when single-phase short circuit known to and then
(3) both sides system equivalent potential phase angle difference is set as 60 ° of the maximum value allowed when stable operation, transition resistance setting
For maximum 100 Ω of transition resistance of 110kV circuits.Formula is calculated using the single-phase short circuit difference current obtained in step (2), is obtained
Different capabilities inverse distributed power is connect to T, difference current when different location breaks down is carried out with the setting valve of protection
Compare, when the two is equal, corresponding minimum capacity 18MW is the allowed capacity of inverse distributed power.
The above content is only the embodiment of the present invention, and purpose is not intended to system and method proposed by the invention
Limitation, protection scope of the present invention are subject to claim.Without departing from the spirit and scope of the present invention, this field
Technical staff without departing from the scope and spirit of the invention, it is carried out about the various aobvious of form and details and
The modification or variation being clear to should all be fallen within the scope and spirit of the invention.
Claims (1)
1. a kind of inverter calculation of penetration level method that meter and longitudinal difference protection influence, is made of following steps：
(1) longitudinal differential protection device is adjusted, setting valve is：
Iunb=0.1KnpKsamIk.max+2IN (1)
Wherein, Ik.maxFor longitudinal differential protection range external fault when maximum through current, KsamIt is mutual no more than 1 electric current
Sensor homotype coefficient, KnpFor the influence coefficient of aperiodic component, value is between 1.5~2, INFor inverse distributed power
Rated current；
(2) T connects in the Double-End Source system of inverse distributed power, and circuit AB is longitudinal differential protection installation site, and M points are
The grid entry point of inverse distributed power, grid entry point Voltage Drop to it is different degrees of when, it is defeated due to inverse distributed power
Go out characteristic difference, therefore obtained difference current calculating formula is also different, when system is through transition resistance single phase ground fault
When, it can obtain：
When grid entry point Voltage Drop is to higher than 0.9UNWhen
When grid entry point Voltage Drop to 0.1-0.9UNBetween when
When grid entry point Voltage Drop is to less than 0.1UNWhen
Voltage Drop to it is different degrees of when, respectively by formula (2)~(4) and formula (5) simultaneous, you can obtain DG inverse types be distributed
The positive sequence voltage of formula power grid pointWith the positive sequence voltage of fault point
And then the difference current of failure phase is when obtaining single-phase short circuit
Wherein, UNFor system nominal voltage, INFor inverse distributed power rated current, P is the defeated of inverse distributed power
Go out power,WithThe respectively system equivalent potential of the both sides circuit AB,Phase angle is δ,Phase angle is 0 °；Phase angle be Phase angle is θ；The positive-negative sequence impedance of circuit AM is Z1, zero sequence impedance Z10, grid entry point M is to positive and negative between short circuit trouble point
Sequence impedance is Zf1, resistance Rf1, reactance Xf1, zero sequence impedance Zf10, the positive-negative sequence impedance of short circuit trouble point to busbar B is equal
For Zf2, zero sequence impedance Zf20；Z3For failure Deng Zhi Zu Pit, value Z in compound sequence network3=(Z1+Zf1)//Zf2+(Z10+
Zf10)//Zf20+3ZD；R (x) is to take real part operation, and im (x) is to take imaginary-part operation, ZDFor transition resistance；
(3) it under the maximum phase angle difference that system stable operation allows, is connected to the grid under voltage class through inverse distributed power
Maximum transition resistance is selected according to the degree of grid entry point Voltage Drop by the corresponding calculation formula provided in step (2),
Obtained single-phase short circuit difference current obtains the inverse distributed power that T connects different capabilities, and single-phase connect occurs in different location
Difference current when ground short circuit, and it is compared with the setting valve of protection, when the two is equal, corresponding minimum capacity is
For the allowed capacity of inverse distributed power.
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| CN108336733A (en) * | 2018-03-30 | 2018-07-27 | 贵州电网有限责任公司 | The distributed generation resource capacity collocation method minimum suitable for distribution network protection and loss |
| CN109149643A (en) * | 2018-09-28 | 2019-01-04 | 中国石油大学(华东) | A kind of photovoltaic access capacity improved under dotted network reverse-power protection determines method |
| CN110518555B (en) * | 2019-08-09 | 2022-07-01 | 浙江双成电气有限公司 | Method for realizing random power supply access power distribution network differential protection |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101562332A (en) * | 2009-05-27 | 2009-10-21 | 天津大学 | Self-adaptive current fast tripping protection method for distribution network comprising inverse distributed power |
| CN104077449A (en) * | 2014-07-02 | 2014-10-01 | 中国南方电网有限责任公司 | Method for calculating inverse DG penetration level on basis of particle swarm optimization |
| CN104242348A (en) * | 2014-09-24 | 2014-12-24 | 天津大学 | Calculation method for penetration level of inverter-based DG (distributed generation) |
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| US8775104B2 (en) * | 2007-12-17 | 2014-07-08 | Jose R. Marti | Method and system for protecting an electrical power transmission network |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101562332A (en) * | 2009-05-27 | 2009-10-21 | 天津大学 | Self-adaptive current fast tripping protection method for distribution network comprising inverse distributed power |
| CN104077449A (en) * | 2014-07-02 | 2014-10-01 | 中国南方电网有限责任公司 | Method for calculating inverse DG penetration level on basis of particle swarm optimization |
| CN104242348A (en) * | 2014-09-24 | 2014-12-24 | 天津大学 | Calculation method for penetration level of inverter-based DG (distributed generation) |
Non-Patent Citations (2)
| Title |
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| DG容量对配电网电流保护的影响及对策研究;冯希科等;《电力***保护与控制》;20101116;第38卷(第22期);全文 * |
| 考虑配电网保护约束的IIDG准入容量及对策分析;李亚辉等;《中国电力》;20130331;第46卷(第3期);全文 * |
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