CN109116110A - A method of calculating Yyn type distribution transformer low voltage electric network phase voltage phase - Google Patents
A method of calculating Yyn type distribution transformer low voltage electric network phase voltage phase Download PDFInfo
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- CN109116110A CN109116110A CN201810979536.0A CN201810979536A CN109116110A CN 109116110 A CN109116110 A CN 109116110A CN 201810979536 A CN201810979536 A CN 201810979536A CN 109116110 A CN109116110 A CN 109116110A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R25/00—Arrangements for measuring phase angle between a voltage and a current or between voltages or currents
Abstract
The invention discloses a kind of methods for calculating Yyn type transformer low voltage power grid phase voltage phase, it chooses and uses extraction system sample point data, obtain the famous value of three-phase voltage, consider practical operation situation, carry out the equal hypothesis of three-phase line voltage, establish the equation in relation to phase voltage phase, it is solved using MATLAB, low pressure phase voltage phase can be obtained, so that the dynamic loss for carrying out Yyn type transformer under the conditions of imbalance calculates, this is energy-saving for power quality controlling and power grid with important directive significance.
Description
Technical field
The invention belongs to power quality controlling and Power System Analysis technical field, a kind of particularly calculating Yyn type
The method of distribution transformer low voltage electric network phase voltage phase.
Background technique
In the low-voltage network of three-phase four-wire system, distribution transformer three-phase imbalance operating status is generally existing, three-phase
Imbalance can make transformer generate added losses, not only reduce the service life of transformer, also will increase the electric energy loss of power grid,
Larger economic loss is caused to electric system.Dynamic loss calculating is carried out to the Yyn type distribution transformer of three-phase four-wire system
When, when especially calculating under the conditions of three-phase imbalance, existing calculation method requires the phase of necessary known step down side
Otherwise the phase of electric current can not carry out quantum chemical method, and the phase of phase current can be derived by the phase of phase voltage, therefore close
Key is the solution of phase voltage phase.
When carrying out energy consumption quantum chemical method to distribution transformer, generally to be in terms of data basis carries out with the data of extraction system
It calculates, but is no voltage and current phase with the status of extraction system, only three-phase current, the famous value of voltage and three-phase are active
Power and reactive power value, so that can not be right directly using the dynamic loss for calculating Yyn type distribution transformer with extraction system data
The Energy Efficiency Analysis of transformer causes certain difficulty.
Summary of the invention
A method of Yyn type distribution transformer low voltage electric network phase voltage phase is calculated, is included the following steps:
Step 1: choosing a sampled point for using extraction system, obtain the famous value of three-phase voltage of distribution transformer low-pressure side
Ua、Ub、Uc；
Step 2: the famous value equilibrium relationships of phase voltage and line voltage are established according to the cosine law,
Uab、Ubc、UcaFor low-pressure side three-phase line voltage,For the phase difference of three-phase phase voltage；
Step 3: according between the phase difference of three-phase phase voltage relationship and equilibrium relationships establish ternary quadratic nonlinearity
Equation group；
Step 4: ternary implicit function is established by ternary quadratic equation group；
Step 5: ternary implicit function being solved using fsolve function in MATLAB.
Further, according to hypothesis U after step 2ab=Ubc=UcaThe equilibrium relationships established to step 2 simplify, and obtain
It arrives:
Further, the ternary quadratic nonlinearity equation group that step 3 is established are as follows:
Further, it enablesThe implicit function that step 4 is established are as follows:
Q=f (x, y, z)
Further, with UaPhase is reference, i.e.,WhereinFor low-pressure side a phase voltage phase, then have:
WhereinFor low-pressure side b phase voltage phase,For low-pressure side c phase voltage phase.
The beneficial effects of the invention are as follows for being lacked at present with voltage, current phase in extraction system data, electricity can not be obtained
The vector of pressure, electric current leads to not the dynamic loss calculating that Yyn type transformer is calculated under the conditions of actual three-phase imbalance
Problem proposes a kind of calculation method based on extraction system data calculating Yyn type distribution transformer low voltage electric network phase voltage phase,
It only needs to consider that actual conditions carry out condition hypothesis in original data basis, establishes the equation in relation to phase voltage phase, benefit
It is solved with MATLAB.The method is energy-saving to loss calculation of the low-voltage network under three-phase imbalance and power grid
Have great importance.
Detailed description of the invention
Fig. 1 is Yyn type transformer neutral point variation figure.
Specific embodiment
It elaborates in the following with reference to the drawings and specific embodiments to the present invention.
For the existing data basis with extraction system, the present invention proposes a kind of calculating Yyn type distribution transformer low voltage electric network
The method of phase voltage phase.
What this method needed to be calculated is to calculate Yyn type distribution transformer low voltage electric network phase voltage phase, is solved first
The phase difference of low-pressure side three-phase phase voltageThen assumed condition through the invention obtains corresponding phase
Position.AndIt then needs to utilize the famous value U of three-phase voltage with extraction systema、Ub、UcAnd Yyn type transformer exists
When three-phase imbalance line voltage with calculate the characteristics of phase voltage.
When real-life experience shows the three-phase load unbalance of Yyn type transformer, since zero sequence impedance is hindered much larger than negative phase-sequence
Anti-, the negative sequence voltage very little of generation can be ignored.Phase voltage imbalance at this time is primarily due to neutrality caused by zero-sequence component
Point variation, as shown in Figure 1, three-phase imbalance leads to Yyn it can be seen from Yyn type transformer neutral point variation
Type transformer neutral point variation, but line voltage is kept substantially symmetrically.Three-phase line voltage amplitude phase is assumed according to this feature
Deng can list three equations, the phase difference of phase voltage can be solved, and then find out phase voltage phase.
Calculation method of the invention is carried out on using the data basis with extraction system.
1) sampled point for using extraction system is chosen, the famous value U of three-phase voltage of the Yyn type transformer point is obtaineda、Ub、
Uc；
2) it according to real-life experience and electric circuit characteristic, needs to carry out it is assumed that assumed condition has:
1. low-pressure side three-phase line voltage is symmetrical, amplitude is equal, it may be assumed that
Uab=Ubc=Uca (1)
Uab、Ubc、UcaFor low-pressure side three-phase line voltage.
2. transformer negative sequence voltage is zero；
3. with UaPhase is reference, i.e.,WhereinFor low-pressure side a phase voltage phase；
3) the famous value equilibrium relationships of phase voltage and line voltage are established.According to the cosine law:
Wherein,For UaAdvanced UbPhase,For UbAdvanced UcPhase,For UaAdvanced UcPhase.
Substitution formula (1), square abbreviation can obtain simultaneously on both sides:
4) ternary quadratic nonlinearity equation group is established.
It is known:
Therefore ternary quadratic nonlinearity equation group is constituted by formula (5)-(7):
5) ternary implicit function is established by ternary quadratic equation group.
It is required according to MATLAB, establishes the implicit function that can be solved, enabled Then implicit function to be asked
Are as follows:
6) solution is iterated to implicit function using the fsolve function in MATLAB, obtains the phase difference of three-phase phase voltage
x、y、z。
3. from the hypothesis in step 2)Then have:
WhereinFor low-pressure side b phase voltage phase,For low-pressure side c phase voltage phase.
Calculation method of the invention is illustrated with specific example below.
1) the famous value of three-phase voltage of known certain transformer one sampled point of extraction system are as follows:
Ua=225.3V, Ub=222.6V, Uc=233.2V
2) modeling method of the solution three-phase phase voltage phase proposed according to the present invention, it is as follows to obtain equation group:
3) implicit function q=f (x, y, z) is set up according to equation,
4) implicit function is solved to obtain using fsolve function in MATLAB:
Being scaled angle, that phase voltage phase difference is made is as follows:
IfIt can be obtained according to formula (11), (12):
The foregoing is only a preferred embodiment of the present invention, but scope of protection of the present invention is not limited thereto,
In the technical scope disclosed by the present invention, 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 scope of protection of the claims
Subject to.
Claims (5)
1. a kind of method for calculating Yyn type distribution transformer low voltage electric network phase voltage phase, includes the following steps:
Step 1: choosing a sampled point for using extraction system, obtain the famous value U of three-phase voltage of distribution transformer low-pressure sidea、Ub、
Uc；
Step 2: the famous value equilibrium relationships of phase voltage and line voltage are established according to the cosine law,
Uab、Ubc、UcaFor low-pressure side three-phase line voltage,For the phase difference of three-phase phase voltage；
Step 3: according between the phase difference of three-phase phase voltage relationship and equilibrium relationships establish ternary quadratic nonlinearity equation
Group；
Step 4: ternary implicit function is established by ternary quadratic equation group；
Step 5: ternary implicit function being solved using fsolve function in MATLAB.
2. a kind of method for calculating Yyn type distribution transformer low voltage electric network phase voltage phase according to claim 1, special
Sign is, according to hypothesis U after step 2ab=Ubc=UcaThe equilibrium relationships established to step 2 simplify, and obtain:
3. a kind of calculation method based on extraction system data calculating low voltage electric network phase voltage phase according to claim 2,
It is characterized in that, the ternary quadratic nonlinearity equation group that step 3 is established are as follows:
4. a kind of calculation method based on extraction system data calculating low voltage electric network phase voltage phase according to claim 3,
It is characterized in that, enablingThe implicit function that step 4 is established are as follows:
Q=f (x, y, z)
5. a kind of calculation method based on extraction system data calculating low voltage electric network phase voltage phase according to claim 4,
It is characterized in that, with UaPhase is reference, i.e.,WhereinFor low-pressure side a phase voltage phase, then have:
WhereinFor low-pressure side b phase voltage phase,For low-pressure side c phase voltage phase.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005033848A (en) * | 2003-07-07 | 2005-02-03 | Tm T & D Kk | Method for calculating phase angle difference of power system, method for calculating phase angle of power system, and power system analyzer |
| CN101788597A (en) * | 2010-03-29 | 2010-07-28 | 福建师范大学 | Three-phase three-wire system phase voltage measuring method |
| CN104931781A (en) * | 2015-05-29 | 2015-09-23 | 国家电网公司 | Method and device for measuring electric quantity phase angle of three-phase four-line circuit |
| CN108303606A (en) * | 2018-01-02 | 2018-07-20 | 国网江西省电力有限公司电力科学研究院 | A kind of distribution transformer capacity online evaluation method |
-
2018
- 2018-08-27 CN CN201810979536.0A patent/CN109116110A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005033848A (en) * | 2003-07-07 | 2005-02-03 | Tm T & D Kk | Method for calculating phase angle difference of power system, method for calculating phase angle of power system, and power system analyzer |
| CN101788597A (en) * | 2010-03-29 | 2010-07-28 | 福建师范大学 | Three-phase three-wire system phase voltage measuring method |
| CN104931781A (en) * | 2015-05-29 | 2015-09-23 | 国家电网公司 | Method and device for measuring electric quantity phase angle of three-phase four-line circuit |
| CN108303606A (en) * | 2018-01-02 | 2018-07-20 | 国网江西省电力有限公司电力科学研究院 | A kind of distribution transformer capacity online evaluation method |
Non-Patent Citations (2)
| Title |
|---|
| 江宁强 等: "基于fsolve的电力系统潮流计算", 《电气电子教学学报》 * |
| 马学亮 等: "多单元高压变频器中点漂移法分析", 《变压器世界》 * |
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| CB03 | Change of inventor or designer information | ||
| CB03 | Change of inventor or designer information |
Inventor after: Tao Shun Inventor after: Sun Zhipeng Inventor after: Zhang Miao Inventor before: Tao Shun Inventor before: Sun Zhipeng |
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Application publication date: 20190101 |