# Research on Electronic Voltage Transformer for Big Data Background

^{1}

^{2}

^{3}

^{*}

## Abstract

**:**

## 1. Introduction

## 2. Principle and Structure

_{h}and the parasitic capacitance C

_{e}to the ground. Figure 1 is a schematic of the distribution of C

_{h}and C

_{e}. C

_{h}is usually smaller than C

_{e}, and the combination of the two capacitances is equivalent to a smaller parasitic capacitance to the ground, which is usually called the equivalent parasitic capacitance C

_{ed}to the ground. Part of the current will flow through the parasitic capacitance C

_{e}to the ground because of the existence of C

_{ed}, which will cause a change in measurement accuracy and make the anti-electromagnetic interference poor. Although the increase of the capacitance can reduce this effect, the price and size will increase sharply [13].

_{1}of the high-voltage side is formed by the capacitor ring and the primary conductor. Its output is transmitted to the low-voltage side by a shield cable. Its value can be given as:

_{1}is the diameter of the capacitor ring (m).

_{2}is the diameter of the primary conductor (m).

_{1}.

## 3. High-Precision Digital Integrator

- (1)
- Improving the sampling frequency has obvious effects on improving the amplitude characteristic of the digital integrator.
- (2)
- The complex Simpson formula is more accurate than the complex trapezoidal formula, and the error is reduced faster [15].

^{−4}, and the precision is high in the 0.95π. At the same time, the form of Formula (8) is simple and easy to design, and the phase is −90 degree in the whole frequency band, so the error of the phase characteristic is unnecessary to consider.

^{−3}using Formula (10) to construct a traditional digital integrator, and the error is reduced to 5.7389 × 10

^{−5}after the error compensation channel is added on the basis of Figure 7. The results of Table 1 show that the dual -hannel digital integrator has the characteristics of simple design and high accuracy. Meanwhile, the program design of the integral link can also be reduced, which can improve the computation speed and reduce the computation time.

## 4. Performance Analysis

#### 4.1. Analysis of Position Influence of the SF_6 Coaxial Capacitor

_{1}and R

_{2}, and R

_{2}> R

_{1}. The length of the cylinder is l. Suppose l >> (R

_{2}− R

_{1}), the capacitance between the two cylindrical conductor shells can be obtained:

#### 4.1.1. Calculation of Off-Axis Capacitance

#### 4.1.2. Calculation of the Deflection Angle Capacitance

_{2}− R

_{1}:

#### 4.1.3. Off-Axis Distance Allowed in Practice

_{1}= 45 mm and R

_{2}= 135 mm. The simulation results are shown in Figure 9.

#### 4.2. Analysis of Temperature Performance and Pressure Performance of the Coaxial Capacitor

^{3}).

^{−23}J/K.

#### 4.2.1. The Relationship between the Capacitance and the Temperature When the Density Does Not Change

^{3}. The relationship between P and T can be obtained by Formula (21).

_{1}and R

_{2}are the inner and outer radii.

#### 4.2.2. The Relationship between the Capacitance and the Temperature When the Density Changes

## 5. Experimental Results and Analysis

#### 5.1. Basic Accuracy Test

#### 5.2. Partial Discharge Test

#### 5.3. EMC (Electromagnetic Compatibility) Test

#### 5.4. Temperature Cycle Test

## 6. Conclusions

## Author Contributions

## Funding

## Conflicts of Interest

## Nomenclature

C_{h} | parasitic capacitance for the high-voltage side (F); |

C_{e} | parasitic capacitance to the ground (F); |

C_{ed} | equivalent parasitic capacitance to the ground (F); |

C_{1} | capacitance C_{1} of the high-voltage side (F); |

ε_{0} | permittivity of vacuum (8.85 × 10^{−12} F/m); |

l | width of the capacitor ring (m); |

D_{1} | diameter of the the capacitor ring (m); |

D_{2} | diameter of the primary conductor (m); |

i | capacitance current (A); |

u | primary voltage (V); |

R_{1} | inner radius of the coaxial cylindrical conductor shells (m); |

R_{2} | outer radius of the coaxial cylindrical conductor shells(m); |

P | pressure (MPa); |

T | temperature (K); |

ρ | density (Kg/m^{3}); |

k | Boltzmann constant (1.38 × 10^{−23} J/K); |

$a$ | molecular radius of the SF_6 gas (2.27 × 10^{−10} m). |

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**Figure 1.**Schematic sketch of the distribution of the parasitic capacitance for the high-voltage side (C

_{h}) and the parasitic capacitance to the ground (C

_{e}).

**Figure 2.**Basic structure of the SF_6 gas-insulated transformer. 1, explosion-proof slice; 2, high-voltage shell; 3, primary connection terminal; 4, insulating sleeve; 5, gas density meter; 6, primary conductor; 7, grounding guide rod; 8, base; 9, metal shield; 10, metal tube; 11, capacitor ring; 12, secondary connection boxes; 13, nameplate.

**Figure 3.**SF_6 coaxial capacitor structure. 1, metal shield; 2, capacitor ring; 3, primary conductor; 4, high-voltage shell; 5, ground electrode; 6, insulating layer.

n | Complex Rectangular Formula R_{(n)(0)} | Complex Trapezoid Formula R_{(n)(1)} | Complex Simpson Formula R_{(n)(2)} | |||
---|---|---|---|---|---|---|

$\alpha $ = 0.7 | $\alpha $ = 0.95 | $\alpha $ = 0.7 | $\alpha $ = 0.95 | $\alpha $ = 0.7 | $\alpha $ = 0.95 | |

0 | 0.5771 | 0.8215 | 0.0273 | 0.0754 | 0.0035 | 0.32223 |

1 | 0.13902 | 0.19056 | 1.5769 × 10^{−3} | 4.0266 × 10^{−3} | 5.4254 × 10^{−6} | 5.7389 × 10^{−5} |

Standard Requirements | Test Results of the Tested Electronic Voltage Transformer |
---|---|

Preload voltage: 230 kV | Preload voltage: 230 kV |

Test frequency: 50 Hz | Test frequency: 50 Hz |

Measurement voltage: 126 kV | Measurement voltage: 126 kV |

Allowable partial discharge: ≤10 pC | apparent charge: 3 pC |

Measurement voltage: 87 kV | Measurement voltage: 87 kV |

Allowable partial discharge: ≤5 pC | apparent charge: 2 pC |

Detection Project | Performance Evaluation |
---|---|

Voltage variations immunity tests | A |

Voltage dips and short interruptions immunity tests | A |

Surge immunity test | A |

Electrical fast transient/burst immunity test | A |

Damped oscillatory wave immunity test | A |

Electrostatic discharge immunity test | A |

Power frequency magnetic field immunity test | A |

Pulse magnetic field immunity test | A |

Damped oscillatory magnetic field immunity test | A |

Radiated, radio-frequency, electromagnetic field immunity test | A |

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**MDPI and ACS Style**

Li, Z.-H.; Wang, Y.; Wu, Z.-T.; Li, Z.-X.
Research on Electronic Voltage Transformer for Big Data Background. *Symmetry* **2018**, *10*, 234.
https://doi.org/10.3390/sym10070234

**AMA Style**

Li Z-H, Wang Y, Wu Z-T, Li Z-X.
Research on Electronic Voltage Transformer for Big Data Background. *Symmetry*. 2018; 10(7):234.
https://doi.org/10.3390/sym10070234

**Chicago/Turabian Style**

Li, Zhen-Hua, Yao Wang, Zheng-Tian Wu, and Zhen-Xing Li.
2018. "Research on Electronic Voltage Transformer for Big Data Background" *Symmetry* 10, no. 7: 234.
https://doi.org/10.3390/sym10070234