CN204044261U - A kind of electrical network resistance characteristic test device frequently - Google Patents
A kind of electrical network resistance characteristic test device frequently Download PDFInfo
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- CN204044261U CN204044261U CN201420456796.7U CN201420456796U CN204044261U CN 204044261 U CN204044261 U CN 204044261U CN 201420456796 U CN201420456796 U CN 201420456796U CN 204044261 U CN204044261 U CN 204044261U
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Abstract
The utility model discloses a kind of electrical network resistance characteristic test device frequently, be made up of DC energy storage device (D), single-phase inverter (B), single-phase isolating transformer (T), voltage transformer (VT) (V), current transformer (A), top level control device (C) etc., top level control device (C) controls the harmonic current that single-phase inverter (B) exports non-characteristic frequency, power network monitoring point (M) is injected through single-phase isolating transformer (T), the harmonic current value injecting monitoring point measured by current transformer (A), the harmonic voltage value of monitoring point measured by voltage transformer (VT) (V), deduct the impact of the transport function of known current transformer (A) and voltage transformer (VT) (V), top level control device (C) calculates the resistance value of power network monitoring point, the resistance family curve frequently of the power network monitoring point comprising characteristic frequency is simulated again according to resistance value.
Description
Technical field
The utility model relates to a kind of electrical network resistance characteristic test system frequently, particularly the on-line testing technique of electrical network resistance frequency characteristic.
Background technology
The develop rapidly of Power Electronic Technique, improve mains supply performance, provide strong support to the technology such as extensive, extra long distance and super high voltage direct current electricity transmission, and be applied in the various fields of national economy more and more widely, but meanwhile, in electrical network, the use of these power electronics (non-linear) equipment also result in the harmonic problem that can not be ignored, and day by day serious.
Harmonic wave can produce much harm to electrical network, mainly comprises: (1) dielectric breakdown or idle overload and make Capacitor banks fault; (2) disturb ripple control carrier wave system, cause the operation exception of remote control, spatial load forecasting and remote measurement; (3) grid loss is caused to increase; (4) network resonance causes superpotential or excess current; (5) harmonic wave superpotential causes the dielectric breakdown of insulated cable; (6) to the inductive disturbance of communication system; (7) induction meter error in dipping is caused; (8) cause signal disturbing and false protection, particularly solid-state version with microcomputer type; (9) large-size machine control system and power plant's excitation system is disturbed; (10) mechanical vibration of induction motor or synchronous motor are caused; (11) cause and to detect based on voltage zero-cross or the irregular operation of trigger circuit of locking, etc.
In order to control the harmonic pollution in utility network, national standard " quality of power supply utility network harmonic wave " defines user's harmonic emissions limit value.It is also proposed a kind of rewards and punishments scheme in the world, i.e. system and user's arm's length transaction in specified scope, if system can not ensure power supply quality, user should obtain an indemnity; If the contamination index of user worsens, then system will collect extra rejection penalty in guarantee under the prerequisite of user's normal power supply; If user absorbs harmonic power extra in system, system should give the certain compensation of user and encouragement.The prerequisite that the program is implemented smoothly reasonably assesses at the harmonic emission level of points of common connection to system and user, and assessment mainly launches around to system and user-side harmonic analysis of Impedance Characteristic.As everyone knows, electrical network is a network containing inductance, electric capacity, resistance and source element, and the resistance frequency characteristic of electrical network is intrinsic, wherein, and its resonance characteristic most important.When harmonic source to the harmonic frequency that this network injects equal or both close to network resonant frequency time, this network of excitation is produced resonance or Harmonics amplification.Resonance is divided into parallel resonance and series resonance.Resonance can cause harmonic wave in electrical network to increase sharply, and produces the phenomenons such as harmonic wave excess current, superpotential, and the power supply of harm system, consumer, also can affect the safe and reliable operation of electrical network time serious.In recent years, along with friendship orthogonal train widely using in electric railway, harmonic resonance causes the power-supply unit of electric railway to damage, and even impact case that is normal, safe operation happens occasionally.Therefore, be necessary to measure the resistance frequency characteristic of system, grasp its resonance rule, more targetedly the harmonic wave situation of system is assessed and administered, avoid dysgenic generation and development.
Chinese scholars is devoted to the research of system resistance frequency characteristic measurement method always, and the method for proposition mainly contains: switched capacitor method, switching thyristor branching and harmonic current source injection method.All there is the incomplete and uncontrollable problem of harmonic content in first two, easily by the impact of noise signal, reduce the accuracy of measurement, and the employing of harmonic current source injection method is inject characteristic harmonic current, the interference being subject to electrical network background harmonics (being also characteristic harmonics) is affected its measuring accuracy again by this, and even true and false difficulty is distinguished.
For this reason, a kind of electrical network resistance characteristic test method frequently that the applicant proposes, its technical scheme is: a kind of electrical network resistance characteristic test method frequently, in the system formed primarily of DC energy storage device (D), single-phase inverter (B), single-phase isolating transformer (T), voltage transformer (VT) (V), current transformer (A), top level control device (C) etc.; Top level control device (C) controls the harmonic current that single-phase inverter (B) exports non-characteristic frequency, power network monitoring point (M) is injected through single-phase isolating transformer (T), the harmonic current value injecting monitoring point measured by current transformer (A), the harmonic voltage value of this monitoring point respective frequencies measured by voltage transformer (VT) (V) simultaneously, and the harmonic current value recorded and harmonic voltage value are delivered to top level control device (C); Top level control device (C) calculates with the harmonic current value recorded, harmonic voltage value according to the transport function of voltage transformer (VT) (V) known under this non-characteristic frequency with current transformer (A), draw the resistance value of power network monitoring point, the resistance family curve frequently of further acquisition power network monitoring point, key step is:
(1) top level control device (C) controls the sequence harmonic current that single-phase inverter (B) exports one group of non-characteristic frequency, corresponding sequence harmonic voltage value measured by voltage transformer (VT) (V), deduct the impact of the transport function of known voltage transformer (VT) (V) and current transformer (A), top level control device (C) calculates the sequence resistance value of power network monitoring point;
(2) top level control device (C) simulates the resistance family curve frequently comprising characteristic frequency according to this sequence resistance value; On corresponding resistance frequency family curve, impedance maximum value is parallel resonance frequency, and impedance is minimizing is series resonance frequency; If need more accurately measuring of tuning-points, go to step (3), otherwise, go to step (5);
(3) top level control device (C) controls single-phase inverter (B) and exports another group and concentrate on non-characteristic frequency sequence harmonic current near parallel resonance and series resonance frequency, wherein, retain a harmonic current identical with size with a upper class frequency, be called calibration harmonic current, voltage transformer (VT) (V) is measured should the harmonic voltage value of sequence, deduct the impact of the transport function of known voltage transformer (VT) (V) and current transformer (A), top level control device (C) calculates the sequence resistance value of power network monitoring point;
(4) corresponding calibration harmonic current, if the deviation of the resistance value that step (3) and step (2) calculate is in allowed band, then think that now power system operating mode is stablized, and goes to step (2), otherwise, go to step (1);
(5) power network monitoring point resistance family curve is frequently exported.
Characteristic frequency refers to the frequency of power frequency integral multiple, and as 100Hz, 150Hz, 200Hz, 250Hz, 300Hz, 350Hz etc., non-characteristic frequency refers to the frequency beyond characteristic frequency.
Utility model content
The purpose of this utility model provides a kind of electrical network to hinder characteristic test device frequently for said method, realizes the on-line testing of electrical network resistance frequency characteristic.Its concrete means are:
A kind of electrical network resistance characteristic test device frequently, primarily of DC energy storage device (D), single-phase inverter (B), single-phase isolating transformer (T), voltage transformer (VT) (V), current transformer (A), top level control device (C) composition.Described top level control device (C) is connected with single-phase inverter (B), and single-phase isolating transformer (T) is connected between single-phase inverter (B) and power network monitoring point (M); Top level control device (C) controls the harmonic current that single-phase inverter (B) exports non-characteristic frequency, power network monitoring point (M) is injected through single-phase isolating transformer (T), the harmonic current value injecting monitoring point measured by current transformer (A), the harmonic voltage value of this monitoring point respective frequencies measured by voltage transformer (VT) (V) simultaneously, and the harmonic current value recorded and harmonic voltage value are delivered to top level control device (C); Top level control device (C) calculates with the harmonic current value recorded, harmonic voltage value according to the transport function of voltage transformer (VT) (V) known under this non-characteristic frequency with current transformer (A), draws the resistance value of power network monitoring point.
Principle of work of the present utility model is: electrical network is the network be made up of elements such as generator, transformer, power transmission line and loads.Each element all can come equivalently represented by inductance, electric capacity, resistance and power supply and connecting relation thereof.Generator can be represented by fundamental voltage source and series impedance thereof; The equivalent electrical circuit that transformer, power transmission line can be made up of inductance, electric capacity, resistance represents; Load is divided into linear in nonlinear, the equivalent electrical circuit that the former can be made up of inductance, electric capacity, resistance represents, the latter take power electronic equipment as representative, and produce the characteristic harmonics of power frequency integral multiple frequency, wherein, the characteristic harmonic current source-representation of the equivalent electrical circuit that electronic power rectification device can be made up of inductance, electric capacity, resistance and parallel connection, the characteristic harmonics voltage source of the equivalent electrical circuit that electronic power inversion device can be made up of inductance, electric capacity, resistance and series connection represents.So the passive equivalent electrical circuit that electrical network can be made up of inductance, electric capacity, resistance and the equivalent network that fundamental voltage source, characteristic harmonics voltage source and characteristic harmonic current source form represent.When uncharacteristic harmonics beyond characteristic frequency acts on electrical network, fundamental voltage source voltage in the equivalent network of electrical network is 0 (short circuit), characteristic harmonics voltage source voltage is 0 (short circuit), characteristic harmonic current source electric current is 0 (open circuit), so electrical network just can be represented by the passive network of this only power supply effect of uncharacteristic harmonics.Obviously, the electric network impedance value of the uncharacteristic harmonics application point (monitoring point) now recorded and the resistance that obtains thus frequently characteristic do not affect by fundamental voltage source, characteristic harmonics voltage source and characteristic harmonic current source.
Electrical network gives timing, and its resistance frequently characteristic is exactly fixing.In resistance frequently family curve, what impedance maximum value place occurred is parallel resonance, and what impedance minimal value place occurred is series resonance.Research shows: parallel resonance, the series resonance of electrical network increase along with frequency and occur successively; Frequency range is can not occur 2 times in power frequency (50Hz) scope and more parallel resonance or series resonance, in other words, when the non-characteristic frequency interval of the sequence harmonic current that single-phase inverter (B) exports is less than 1/2nd (25Hz) of power frequency (50Hz), the resistance obtained frequently characteristic just can comprise whole parallel resonances and series resonance.
By this requirement, inject the sequence harmonic current of the one group of non-characteristic frequency in monitoring point, its non-characteristic frequency interval is less than 1/2nd (25Hz) of power frequency (50Hz), measure corresponding sequence harmonic voltage value, just can calculate the sequence resistance value of power network monitoring point, and simulate the resistance family curve frequently comprising characteristic frequency according to this sequence resistance value.
The transport function (hindering characteristic frequently) of testing current transformer used and voltage transformer (VT) can record in advance and should deduct, to ensure test, the computational accuracy of resistance value.
Research electrical network resistance frequently characteristic the most important thing is research parallel resonance and series resonance.The size injecting the non-characteristic frequency interval of the sequence harmonic current of monitoring point can affect the resistance the comprising characteristic frequency characteristic precision frequently simulated, non-characteristic frequency interval is less, fitting precision is higher, but simultaneously, when total test frequency scope is constant, harmonic current quantity in sequence can increase, and required injecting power is also larger.Therefore, test at upper one group, calculate, simulate the resistance frequently family curve obtain on the basis of parallel resonance, series resonance comprising characteristic frequency, another group that is necessary to reinject concentrates on non-characteristic frequency sequence harmonic current near parallel resonance and series resonance frequency, measure corresponding sequence harmonic voltage value, calculate the sequence resistance value of power network monitoring point, thus resistance characteristic frequently can be obtained more accurately when not increasing harmonic current quantity and required injecting power in sequence.
Certainly, the change of power system operating mode just means the change of the structure and parameter of equivalent network, and the resistance value of corresponding monitoring point will change.In test, calculating, introduce the concept of calibration harmonic current, an i.e. harmonic current identical with size with a upper class frequency, the resistance value of twice corresponding calibration harmonic current relatively, judge whether power system operating mode changes according to its deviation, and determining whether test repeats, this has just taken into account real-time and the stability of test.
Thus, the utility model can by the harmonic current injection power network monitoring point of non-characteristic frequency, in conjunction with the harmonic voltage of test corresponding frequencies, deduct the impact of the transport function of known voltage transformer (VT) and current transformer, obtain the resistance value of this point, then simulate the resistance characteristic frequently comprising characteristic frequency according to these resistance values recorded.
Compared with prior art, the beneficial effects of the utility model are:
One, electrical network resistance frequency characteristic test device of the present utility model is with uncharacteristic harmonics pulse current injectingt power network monitoring point, the interference of existing feature (background) harmonic wave in electrical network can not be subject to, in other words, feature (background) harmonic wave and uncharacteristic harmonics are independent of each other.Meanwhile, deduct the impact of the transport function of known voltage transformer (VT) and current transformer, ensure test better, calculate and simulate high-precision resistance family curve frequently.
Two, the utility model is by introducing the concept of calibration harmonic current, an i.e. harmonic current identical with size with a upper class frequency, the resistance value of twice corresponding calibration harmonic current relatively, judge whether power system operating mode changes according to its deviation, taken into account real-time and the stability of test.
Three, electrical network resistance frequency characteristic test device of the present utility model can be arranged on means of transport, as the ingredient of electric energy quality test system, possesses good maneuverability.
Below in conjunction with the drawings and specific embodiments, the utility model will be further described.
Accompanying drawing explanation
Fig. 1 is the structural representation of the utility model embodiment.
Fig. 2 is the resistance characteristic formation frequently process flow diagram that the utility model is implemented.
Embodiment
Embodiment
Fig. 1 illustrates, a kind of embodiment of the present utility model is: a kind of electrical network resistance characteristic test device frequently, is made up of DC energy storage device (D), single-phase inverter (B), single-phase isolating transformer (T), voltage transformer (VT) (V), current transformer (A), top level control device (C) etc.; Top level control device (C) controls the harmonic current that single-phase inverter (B) exports non-characteristic frequency, power network monitoring point (M) is injected through single-phase isolating transformer (T), the harmonic current value injecting monitoring point measured by current transformer (A), the harmonic voltage value of this monitoring point respective frequencies measured by voltage transformer (VT) (V) simultaneously, and the harmonic current value recorded and harmonic voltage value are delivered to top level control device (C); Top level control device (C) calculates with the harmonic current value recorded, harmonic voltage value according to the transport function of voltage transformer (VT) (V) known under this non-characteristic frequency with current transformer (A), draw the resistance value of power network monitoring point, the resistance family curve frequently of further acquisition power network monitoring point, concrete steps are:
(1) select one group of non-characteristic frequency of p=1, such as, be: f
p(k)=100-x+10k, Hz, x=5, k=0,1,2,3 ..., n (its upper limit is determined by the most higher harmonics number of times needing to test), top level control device (C) controls the sequence harmonic current I that single-phase inverter (B) exports
pk (), corresponding sequence harmonic voltage value U measured by voltage transformer (VT) (V)
pk (), the sequence harmonic current after deduction current transformer (A) transport function is designated as Ir
pk (), the sequence harmonic voltage after the transport function of deduction voltage transformer (VT) (V) is designated as Ur
pk (), top level control device (C) calculates the sequence resistance value of power network monitoring point, Z
p(k)=Ur
p(k)/Ir
p(k).
(2) top level control device (C) simulates the resistance family curve frequently comprising characteristic frequency according to this sequence resistance value; On corresponding resistance frequency family curve, impedance maximum value is parallel resonance frequency, and impedance is minimizing is series resonance frequency; If need more accurately measuring of tuning-points, go to step (3), otherwise, go to step (5).
(3) select another group (p+1) to concentrate on non-characteristic frequency near parallel resonance and series resonance frequency, be designated as: f
p+1j (), top level control device (C) controls single-phase inverter (B) output sequence harmonic current I
p+1j (), wherein, retains a harmonic current identical with size with a upper class frequency, is called calibration harmonic current, voltage transformer (VT) (V) is measured should the harmonic voltage value U of sequence
p+1j (), the sequence harmonic current after deduction current transformer (A) transport function is designated as Ir
p+1k (), the sequence harmonic voltage after the transport function of deduction voltage transformer (VT) (V) is designated as Ur
p+1k (), top level control device (C) calculates the sequence resistance value of power network monitoring point, Z
p+1(k)=Ur
p+1(k)/Ir
p+1(k);
(4) corresponding calibration harmonic current, if the resistance value that calculates of step (3) and step (2) Pian differ from Jue Dui Zhi ∣ Z
p(0)-Z
p+1(0) ∣ in allowed band, then thinks that now power system operating mode is stablized, and goes to step (2), otherwise, go to step (1).
(5) power network monitoring point resistance family curve is frequently exported.
Fig. 2 is resistance characteristic formation frequently process flow diagram.
Obviously, the resistance of above-described 3 cover single-phase electrical network frequently characteristic test device be connected into star or triangle is connected to resistance frequency characteristic test and the analysis that electrical network just can carry out three phase network.
When single-phase inverter (B) electric pressure is consistent with the electric pressure of monitoring point, single-phase isolating transformer (T) can be save.
Claims (1)
1. electrical network resistance characteristic test device frequently, primarily of DC energy storage device (D), single-phase inverter (B), single-phase isolating transformer (T), voltage transformer (VT) (V), current transformer (A), top level control device (C) composition, it is characterized in that, top level control device (C) is connected with single-phase inverter (B), and single-phase isolating transformer (T) is connected between single-phase inverter (B) and power network monitoring point (M); Top level control device (C) controls the harmonic current that single-phase inverter (B) exports non-characteristic frequency, power network monitoring point (M) is injected through single-phase isolating transformer (T), the harmonic current value injecting monitoring point measured by current transformer (A), the harmonic voltage value of this monitoring point respective frequencies measured by voltage transformer (VT) (V) simultaneously, and the harmonic current value recorded and harmonic voltage value are delivered to top level control device (C); Top level control device (C) calculates with the harmonic current value recorded, harmonic voltage value according to the transport function of voltage transformer (VT) (V) known under this non-characteristic frequency with current transformer (A), draws the resistance value of power network monitoring point.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106199284A (en) * | 2016-08-17 | 2016-12-07 | 云南电网有限责任公司电力科学研究院 | The resonance method for early warning of capacitor switching and system |
| CN107402334A (en) * | 2017-07-10 | 2017-11-28 | 清华大学 | The frequency domain identification method and system of power system time/supersynchronous coupled impedance model |
| CN109164319A (en) * | 2018-08-31 | 2019-01-08 | 深圳供电局有限公司 | A kind of building user power utilization abnormality determination method |
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2014
- 2014-08-14 CN CN201420456796.7U patent/CN204044261U/en not_active Expired - Fee Related
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106199284A (en) * | 2016-08-17 | 2016-12-07 | 云南电网有限责任公司电力科学研究院 | The resonance method for early warning of capacitor switching and system |
| CN106199284B (en) * | 2016-08-17 | 2023-04-21 | 云南电网有限责任公司电力科学研究院 | Resonance early warning method and system for capacitor switching |
| CN107402334A (en) * | 2017-07-10 | 2017-11-28 | 清华大学 | The frequency domain identification method and system of power system time/supersynchronous coupled impedance model |
| CN107402334B (en) * | 2017-07-10 | 2019-08-09 | 清华大学 | Electric system time/supersynchronous coupled impedance model frequency domain identification method and system |
| CN109164319A (en) * | 2018-08-31 | 2019-01-08 | 深圳供电局有限公司 | A kind of building user power utilization abnormality determination method |
| CN109164319B (en) * | 2018-08-31 | 2021-01-29 | 深圳供电局有限公司 | Method for judging abnormal electricity utilization of building user |
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