CN101719656A - Adjusting method of differential protection during voltage adjustment of on-load transformer - Google Patents

Abstract

The invention discloses an adjusting method of differential protection during voltage adjustment of an on-load transformer, which comprises the steps of: obtaining real-time gear information of a tap switch of the transformer by a transformer differential protection device; judging whether a real-time gear of the tap switch is a target gear or not, if so, adopting the original differential protection action criterion as an operating differential protection action criterion, if not, computing imbalance differential current caused by the gear adjustment of the gap switch of the transformer, computing a temporary differential protection action criterion as the operating differential protection action criterion, then rejudging until the real-time gear of the tap switch is the target gear; completing the adjustment period, and recording the gear information of the tap switch of the transformer after the adjustment. The adjusting method of differential protection during voltage adjustment of the on-load transformer can be used in a protection device for a double-winding transformer and a three-winding transformer.

Description

The method of adjustment of differential protection in the voltage adjustment of on-load transformer process

Technical field

The present invention relates to the technical field of transformer relay protecting, specifically is a kind of method of adjustment that proposes at differential protection in the voltage adjustment of on-load transformer process.

Background technology

Electric power system adopts the adjustment sub-connecting switch of transformer that working voltage is maintained a reasonable levels under the situation of reactive power abundance usually.Particularly with the voltage adjustment of on-load transformer since the advantage that can under load-carrying situation, adjust voltage and voltage adjusting range broad be subjected to more and more widely using.But in the process of band voltage adjustment of on-load, protective device reduces the selectivity of fault judgement, possible malfunction, thus cause power outage.

Summary of the invention

The objective of the invention is to propose the method for adjustment of differential protection in a kind of voltage adjustment of on-load transformer process in order to overcome the defective in the above protection scheme.Described method realizes by the following technical solutions, comprises step:

Step 1: the transformer differential protection device detects the state of sub-connecting switch of transformer, obtains the real-time gear information of sub-connecting switch of transformer;

Step 2: whether the real-time gear of judging shunting switch is the target gear, if then adopt the differential protection operating criterion of the original operating criterion of differential protection as operation, enters step 4 then, if otherwise enter step 3 adjustment;

Step 3: according to the no-load voltage ratio n of transformer both sides current transformer _TA1And n _TA2, last record sub-connecting switch of transformer gear Δ U _N-1And the target gear Δ U of this sub-connecting switch of transformer adjustment _nCalculate the material unaccounted for streaming current that this sub-connecting switch of transformer gear adjustment causes

And calculate the differential protection operating criterion of the interim operating criterion of differential protection as operation, return step 2 then and judge again;

Step 4: finish adjustment cycle, and write down the sub-connecting switch of transformer gear information of adjusting after finishing;

The material unaccounted for streaming current that above-mentioned this sub-connecting switch of transformer gear adjustment causes ${\stackrel{\&CenterDot;}{I}}_{\mathrm{unb}\&CenterDot;t}=[1-\frac{{\mathrm{<figure-callout\; id="1"\; label="n\; TA"\; filenames="H2009102436940E00011.png"\; state="\{\{state\}\}">n</figure-callout>}}_{\mathrm{TA}}\&CenterDot;n_T\&CenterDot;(1+{\mathrm{\&Delta;U}}_n-\mathrm{\&Delta;}{U}_{n-1})}{n_{\mathrm{TA}2}}]\&CenterDot;\frac{{\stackrel{\&CenterDot;}{I}}_1}{{\mathrm{<figure-callout\; id="1"\; label="n\; TA"\; filenames="H2009102436940E00011.png"\; state="\{\{state\}\}">n</figure-callout>}}_{\mathrm{TA}}},$ Δ U wherein _nBe the target gear that this sub-connecting switch of transformer is adjusted, Δ U _N-1For the last time is adjusted the sub-connecting switch of transformer gear that finishes the back record,

Be the former avris electric current of transformer, n _TA1, n _TA2Be respectively the former secondary side of transformer mutual inductor ratio, n _TBe transformer voltage ratio;

The interim operating criterion of differential protection is:

$I_{d\&CenterDot;\mathrm{traditional}}\&GreaterEqual;(a\&CenterDot;I_{b\&CenterDot;\mathrm{traditional}}+b+K_{\mathrm{rel}}|{\stackrel{\&CenterDot;}{I}}_{\mathrm{unb}\&CenterDot;t}\left|\right),$ I wherein _DtraditionalAnd I _BtraditionalBe the differential current and the stalling current of original transformer differential protection, a and b are the value coefficient in original differential protection principle, K _RelBe safety factor.

The present invention can obtain following beneficial effect: calculate the material unaccounted for streaming current that this sub-connecting switch of transformer gear adjustment causes according to the no-load voltage ratio of transformer both sides current transformer, the sub-connecting switch of transformer gear of last record and the object gear information of this sub-connecting switch of transformer adjustment.In the process of sub-connecting switch of transformer adjustment, the transformer differential protection criterion is made amendment, improved the reliability of protective device in the shunting switch adjustment process.

Description of drawings

Fig. 1 is a double winding step-down transformer differential protection schematic diagram;

Fig. 2 is the schematic flow sheet of the inventive method.

Embodiment

With double winding step-down transformer shown in Figure 1 is example, and the differential protecting method of the introducing transformer tapping switch information that the present invention proposes is to realize by following principle:

Calculate the material unaccounted for streaming current that this sub-connecting switch of transformer gear adjustment causes according to the no-load voltage ratio of transformer both sides current transformer, gear and this object gear information of the last record of sub-connecting switch of transformer:

${\stackrel{\&CenterDot;}{I}}_{\mathrm{unb}\&CenterDot;t}=[1-\frac{{\mathrm{<figure-callout\; id="1"\; label="n\; TA"\; filenames="H2009102436940E00011.png"\; state="\{\{state\}\}">n</figure-callout>}}_{\mathrm{TA}}\&CenterDot;n_T\&CenterDot;(1+{\mathrm{\&Delta;U}}_n-\mathrm{\&Delta;}{U}_{n-1})}{n_{\mathrm{TA}2}}]\&CenterDot;\frac{{\stackrel{\&CenterDot;}{I}}_1}{n_{\mathrm{TA}1}}---\left(1\right)$

Wherein:

The material unaccounted for streaming current that causes for this sub-connecting switch of transformer gear adjustment,

Δ U _nThe target gear of adjusting for this sub-connecting switch of transformer (example: when gear is-5%, Δ U _n=-0.05),

Δ U _N-1Adjust to finish the sub-connecting switch of transformer gear (example: adjust gear after finishing for-2.5% time when the last time, Δ U of back record for the last time _N-1=-0.025),

Be the former avris electric current of transformer (having carried out the phase place adjustment),

n _TA1, n _TA2Be respectively the former secondary side of transformer mutual inductor ratio,

n _TBe transformer voltage ratio.

The inventive method is not made amendment to the differential current and the stalling current computational process of original transformer differential protection.If original differential current of tranformer protection and stalling current result of calculation are respectively I _DtraditionalAnd I _Btraditional, and original operating criterion is:

I _{d·traditional}≥a·I _{b·traditional}+b (2)

Wherein: a and b are former differential protection operating characteristics broken line design factor, in the desirable different value of different sections.Its value computational process has several different methods, belongs to former differential protection and calculates, and does not do description at this.

Then in the sub-connecting switch of transformer adjustment process, the interim operating criterion of differential protection is adjusted into:

$I_{d\&CenterDot;\mathrm{traditional}}\&GreaterEqual;(a\&CenterDot;I_{b\&CenterDot;\mathrm{traditional}}+b+K_{\mathrm{rel}}|{\stackrel{\&CenterDot;}{I}}_{\mathrm{unb}\&CenterDot;t}\left|\right)---\left(3\right)$

Wherein:

K _RelBe safety factor, preferred value 0.8～1.2,

The value of a and b is not changed according to former differential protection.

As shown in Figure 2, the method for adjustment that the present invention proposes differential protection in the voltage adjustment of on-load transformer process realizes that by the following technical solutions described method comprises step:

At first from step S101, protective device detects the state of sub-connecting switch of transformer, obtains the real-time gear information of sub-connecting switch of transformer.

Step S102 judges whether the real-time gear of shunting switch is the target gear.If real-time gear is the target gear then enters step S106, if real-time gear is not the target gear then enters step S103.

Step S103 reads last recorded information of regulating after finishing.

Step S104 calculates the material unaccounted for streaming current that this gear adjustment causes

Step S105 adopts the differential protection operating criterion of the interim operating criterion of differential protection as operation, returns step S102 then.

Step S106 adopts the differential protection operating criterion of the original operating criterion of differential protection as operation.

Step S107 finishes adjustment cycle, and writes down the sub-connecting switch of transformer gear information of adjusting after finishing.

Step S108 process ends.

Because realizing said method among the present invention is to realize in concrete device; to electric current sample, detect the sub-connecting switch of transformer gear information, former differential protection computational process can be realized by various piece of the prior art; therefore, above-mentioned device here there is no need to further describe.The present invention is the method for adjustment of differential protection in a kind of voltage adjustment of on-load transformer process, can be used for the protective device to two winding transformer and three-winding transformer.

According to above-mentioned description, those skilled in the art can merge or decompose each step of the present invention, and these concrete variations all should be within claims restricted portion of the present invention.

Claims (1)

1. the method for adjustment of differential protection in the voltage adjustment of on-load transformer process, described method comprises step:

Step 1, the transformer differential protection device detects the state of sub-connecting switch of transformer, obtains the real-time gear information of sub-connecting switch of transformer;

Step 2 judges whether the real-time gear of shunting switch is the target gear, if then adopt the differential protection operating criterion of the original operating criterion of differential protection as operation, enters step 4 then, if otherwise enter step 3 adjustment;

Step 3 is according to the no-load voltage ratio n of transformer both sides current transformer _TA1And n _TA2, last record sub-connecting switch of transformer gear Δ U _N-1And the target gear Δ U of this sub-connecting switch of transformer adjustment _nCalculate the material unaccounted for streaming current that this sub-connecting switch of transformer gear adjustment causes

And calculate the differential protection operating criterion of the interim operating criterion of differential protection as operation, return step 2 then and judge again;

Step 4 is finished adjustment cycle, and writes down the sub-connecting switch of transformer gear information of adjusting after finishing;

The material unaccounted for streaming current that above-mentioned this sub-connecting switch of transformer gear adjustment causes ${\stackrel{\&CenterDot;}{I}}_{\mathrm{unb}\&CenterDot;t}=[1-\frac{n_{\mathrm{TA}1}\&CenterDot;n_T\&CenterDot;(1+\mathrm{\&Delta;}{U}_n-\mathrm{\&Delta;}{U}_{n-1})}{n_{\mathrm{TA}2}}]\&CenterDot;\frac{{\stackrel{\&CenterDot;}{I}}_1}{n_{\mathrm{TA}1}},$ Δ U wherein _nBe the target gear that this sub-connecting switch of transformer is adjusted, Δ U _N-1For the last time is adjusted the sub-connecting switch of transformer gear that finishes the back record,

Be the former avris electric current of transformer, n _TA1, n _TA2Be respectively the former secondary side of transformer mutual inductor ratio,

n _TBe transformer voltage ratio;

The interim operating criterion of differential protection is:

$I_{d\&CenterDot;\mathrm{traditional}}\&GreaterEqual;(a\&CenterDot;I_{b\&CenterDot;\mathrm{traditional}}+b+K_{\mathrm{rel}}|{\stackrel{\&CenterDot;}{I}}_{\mathrm{unb}\&CenterDot;t}\left|\right),$ I wherein _DtraditionalAnd I _BtraditionalBe the differential current and the stalling current of original transformer differential protection, a and b are the value coefficient in original differential protection principle, K _RelBe safety factor.

Images