CN204241684U - Capacitance type potential transformer error checking arrangement - Google Patents

Abstract

The utility model belongs to power measurement field, discloses a kind of capacitance type potential transformer error checking arrangement, comprises operational amplifier, adjustable resistance , adjustable resistance , fixed value resistance with thyristor-controlled reactor TCR; Described adjustable resistance one end is connected on the positive polarity input end of described operational amplifier, and an end is connected on the output terminal b of device; Described adjustable resistance one end is connected on the positive polarity input end of described operational amplifier, and an end is connected on the output terminal of described operational amplifier; Described fixed value resistance one end is connected on the negative polarity input end of described operational amplifier, and an end is connected on the output terminal of described operational amplifier; Described thyristor-controlled reactor TCR mono-end is connected on the output terminal a of device, and an end is connected on the negative polarity input end of described operational amplifier.The utility model device is applicable to capacitance type potential transformer error checking, is installed in series at the output terminal of capacitance type potential transformer, can improves the measuring accuracy of capacitance type potential transformer.

Description

Capacitance type potential transformer error checking arrangement

Technical field

The utility model belongs to power measurement field, relates to a kind of capacitance type potential transformer error checking arrangement.

Background technology

Due to capacitance type potential transformer simple structure, cheap, it is widely used in voltage measurement and relay protection in electric system.Capacitance type potential transformer is a capacitive divider in essence, when from viewed from the output terminal of capacitance type potential transformer to when the impedance of input end is zero or the in parallel impedance of output terminal of capacitance type potential transformer is infinitely-great ammeter, the reading of mutual inductor is only accurately.But this is very inaccessible often, so will verify the error of capacitance type potential transformer.Existing capacitance type potential transformer error checking method has at its output terminal string one inductance to offset the capacitive reactance of mutual inductor self, and this type of method of calibration does not consider the ohmic loss of mutual inductor self.Or the output terminal of capacitance type potential transformer is connect table again to reduce outgoing side electric current after voltage transformer (VT) step-down, this type of method of calibration needs extra voltage transformer (VT), and economy is poor.

Utility model content

For the deficiency that prior art exists, the utility model provides a kind of reliable effective, simple, lower-cost capacitance type potential transformer error checking arrangement of structure.

In order to solve the problems of the technologies described above, the utility model adopts following technical scheme:

A kind of capacitance type potential transformer error checking arrangement, comprises operational amplifier, adjustable resistance R ₃, adjustable resistance R ₂, fixed value resistance R ₁with thyristor-controlled reactor TCR; Described adjustable resistance R ₃one end is connected on the positive polarity input end of described operational amplifier, and the other end connects the output terminal of wire as this device; Described adjustable resistance R ₂one end is connected on the positive polarity input end of described operational amplifier, and the other end is connected on the output terminal of described operational amplifier; Described fixed value resistance R ₁one end is connected on the negative polarity input end of described operational amplifier, and the other end is connected on the output terminal of described operational amplifier; Described thyristor-controlled reactor TCR mono-end is connected on the negative polarity input end of described operational amplifier, and the other end connects wire another output terminal as this device.

Described thyristor-controlled reactor TCR (4) be after two thyristor inverse parallels with inductance L, resistance R _lin series; One end after described two thyristors (1) inverse parallel and inductance L (2), resistance R _l(3) connect, the other end connects the output terminal of wire as this device.

Technique effect of the present utility model is: capacitance type potential transformer error checking arrangement is installed in series at the output terminal of capacitance type potential transformer, verify by producing the error of an adjustable impedance to capacitance type potential transformer, thus improve the measuring accuracy of capacitance type potential transformer.

Accompanying drawing explanation

Accompanying drawing 1 is electrical block diagram of the present utility model;

Accompanying drawing 2 is a kind of mounting structure schematic diagram of the present utility model;

Accompanying drawing 3 is the equivalent circuit diagrams after the utility model access capacitance type potential transformer;

Accompanying drawing 4 is circuit connection diagrams of the utility model determination parameter.

In figure, 1-two thyristors, 2-inductance L, 3-resistance R _l, 4-thyristor-controlled reactor (TCR), 5-adjustable resistance R ₃, 6-adjustable resistance R ₂, 7-fixed value resistance R ₁, 8-operational amplifier, 9-electric capacity C, 10-resistance R, 11-capacitance type potential transformer error checking arrangement, the load of 12-output terminal.

Embodiment

Below in conjunction with accompanying drawing, the utility model is described further.

As Fig. 1, capacitance type potential transformer error checking arrangement, comprises operational amplifier 8, adjustable resistance R ₃5, adjustable resistance R ₂6, fixed value resistance R ₁7.With described inductance L 2, resistance R after described two thyristors 1 inverse parallel _l3 series connection, form thyristor-controlled reactor TCR (Thyristor Controlled Reactor) 4 structures, resistance R _l3 represent the loss that inductance L 2 exists.Thyristor-controlled reactor TCR mono-end is connected on the output terminal a of device, and an end is connected on the negative polarity input end of described operational amplifier; Described adjustable resistance R ₃5 one ends are connected on the positive polarity input end of described operational amplifier, and an end is connected on the output terminal b of device; Described adjustable resistance R ₂one end is connected on the positive polarity input end of described operational amplifier, and an end is connected on the output terminal of described operational amplifier; Described fixed value resistance R ₁one end is connected on the negative polarity input end of described operational amplifier, and an end is connected on the output terminal of described operational amplifier.

As Fig. 1, described capacitance type potential transformer error checking arrangement can produce a dynamic adjustable impedance, can the internal impedance of building-out capacitor formula voltage transformer (VT) at the output terminal of mutual inductor by its series connection, thus verify error.The impedance of TCR (4) can be expressed as formula (1), and wherein, α is the Trigger Angle of two thyristors (1), and controlled range is 90 °-180 °, and L is the value of inductance 2, and ω is angular frequency.

$Z_{\mathrm{TCR}}\left(\mathrm{\α}\right)=R_L+\frac{\mathrm{j\ωL}}{2-\frac{2\mathrm{\α}}{\mathrm{\π}}+\frac{\sin 2\mathrm{\α}}{\mathrm{\π}}}---\left(1\right)$

As Fig. 1, described capacitance type potential transformer error checking arrangement to be broken principle by the short void of the void of operational amplifier 8, can try to achieve the equiva lent impedance Z of a, b end _eqfor formula (2).Visible, by regulating adjustable resistance R ₂, R ₃, control the Trigger Angle α of two thyristors (1), get final product the size of dynamic adjustments impedance.This impedance is perception, but resistance value is negative.

$Z_{\mathrm{eq}}=-\frac{R_1}{R_2}{R}_3+Z_{\mathrm{TCR}}\left(\mathrm{\α}\right)---\left(2\right)$

If Fig. 2 is a kind of mounting structure schematic diagram of the present utility model, c, d end left side is the capacitance type potential transformer of non-error checking, and electric capacity C is the single electric capacity of capacitance type potential transformer 9, and resistance R 10 is the loss of the single electric capacity of capacitance type potential transformer.Input voltage be added on (k+1) individual electric capacity, output terminal c, d are the voltage on 1 electric capacity.The series connection of capacitance type potential transformer error checking arrangement at output terminal, as in figure a, b end shown in.Z _lD12 is output terminal load, is generally the potential winding of measurement instrument or relay, and its impedance is very large, is approximately open circuit, Z _lD12 are connected on b, d end.

If Fig. 3 is the equivalent circuit diagram that the utility model accesses after capacitance type potential transformer, and Z _ibe from the Thevenin's equivalence parameter to capacitance type potential transformer viewed from c, d port in Fig. 2, and parameter can be expressed as formula (3), (4).When the impedance of capacitance type potential transformer error checking arrangement 11 can offset impedance Z _i, then Z _lDvoltage on 12 for , namely there is not error in value.

${\stackrel{\·}{U}}_i=\frac{1}{k+1}{\stackrel{\·}{U}}_1---\left(3\right)$

$Z_i=(\mathrm{kR}+j\frac{k}{\mathrm{\ωC}})//(R+j\frac{1}{\mathrm{\ωC}})---\left(4\right)$

As the circuit connection diagram that Fig. 4 is the utility model determination parameter.To treat the input end short circuit of the capacitance type potential transformer of error checking to add power frequency test voltage at output terminal c, d measure output end current then Z _itry to achieve by formula (5), the impedance of capacitance type potential transformer error checking arrangement is set to formula (6).What namely formula (5) was tried to achieve is capacitive reactances, and capacitance type potential transformer error checking arrangement offsets the capacitive reactances of capacitance type potential transformer by generation induction reactance and negative resistance.

$Z_i=\frac{{\stackrel{\·}{U}}_t}{{\stackrel{\·}{I}}_t}---\left(5\right)$

$Z_{\mathrm{eq}}=-\frac{{\stackrel{\·}{U}}_t}{{\stackrel{\·}{I}}_t}---\left(6\right)$

Obtain Z _eqafter can determine adjustable resistance R ₂, R ₃with the value of Trigger Angle α, these values are carried out device set the error that can verify capacitance type potential transformer.

Therefore, the utility model can carry out error checking to the capacitance type potential transformer of onsite application, and implementation is simple and reliable.

Claims (2)

1. a capacitance type potential transformer error checking arrangement, is characterized in that: comprise operational amplifier (8), adjustable resistance (5), adjustable resistance (6), fixed value resistance (7) and thyristor-controlled reactor TCR (4), described adjustable resistance (5) one ends are connected on the positive polarity input end of described operational amplifier (8), and the other end connects the output terminal of wire as this device; Described adjustable resistance (6) one ends are connected on the positive polarity input end of described operational amplifier (8), and the other end is connected on the output terminal of described operational amplifier (8); Described fixed value resistance (7) one ends are connected on the negative polarity input end of described operational amplifier (8), and the other end is connected on the output terminal of described operational amplifier (8); Described thyristor-controlled reactor TCR (4) end is connected on the negative polarity input end of described operational amplifier (8), and the other end connects wire another output terminal as this device.

2. a kind of capacitance type potential transformer error checking arrangement according to claim 1, is characterized in that: described thyristor-controlled reactor TCR (4) be after the inverse parallel of two thyristors (1) with inductance (2), resistance (3) in series; One end after described two thyristors (1) inverse parallel and inductance (2), resistance (3) connect, the other end connects the output terminal of wire as this device.