KR20110004563A - Appratus and method for measuring electric power - Google Patents

Abstract

PURPOSE: A power measuring method and a method thereof are provided to accurately measure received power or transmitting power. CONSTITUTION: A first power measuring part(210) measures the electric energy of a Y connection side. A second power measuring part(220) measures the neutral point circulating power amount of the Y connection side. A calculating part(240) determines the used electric energy by subtracting the measured value from the second power measuring part from the measured value from the first power measuring part.

Description

Power measuring method and power measuring device {APPRATUS AND METHOD FOR MEASURING ELECTRIC POWER}

The present invention relates to a power measuring method and a measuring apparatus, and in order to accurately measure the amount of power to be measured when receiving power from an electric service provider or surplus power of a consumer to a power provider in a transmission and transmission facility connected in a Wi-Delta method. It relates to a measuring method and a measuring device.

In general, large-capacity consumers who receive ultra-high voltage of 154Kv or more receive power directly generated by electricity providers through primary substations, and most have their own power generation facilities to change load power and secure reserve power. Due to the characteristics of the power system, electricity is supplied from the electricity supplier or the electricity is exchanged between the customer and the electricity provider. .

Therefore, the measurement of power transmitted and received between the customer and the utility is also very important, and the electricity bill generated by the electricity transaction can also have a significant impact on the management of the customer and the utility. It is common to measure by the mutual agreement and the method of measuring the line power is also described in the literature except for the single phase, when the power is supplied to the load by n wires in multi-phase exchange. If one is considered to be a common return, and if n-1 power meters are installed between this and other n-1 wires, the sum of the powers indicated by these power meters is equal to the power supplied to the load. ' According to Brondel's theorem, it is desirable to measure the load power in a proper way according to the characteristics of the power receiving system. Even if the wiring (Y · △ connection), the unbalance of the load and the voltage and current waveform are non-sinusoidal, the cycles have the same period, and usually, two-element power meter method (2CT, 3PT) or three-element power meter method (3CT, 3PT) The bills are measured and mutually settled.

As shown in FIG. 4, in a transmission and reception facility such as a transformer of a Y-delta connection method, the neutral point current In causes the power system on the wire connection side to be asymmetric to generate an image voltage at the neutral point, and cause the image current to circulate toward the ground. And a current that can circulate inside the corresponding delta connection and flow to ground through the neutral point. The neutral point current In is present regardless of the delta load side load currents Ial, Ibl, and Icl, and according to the magnitude of the neutral point current even when there is no load, that is, Ial + Ibl + Icl = 0. Wye-side power is to be measured.

Therefore, there is a problem that the charge is settled by the amount of power added to the unnecessary power by the neutral point current together with the actual power used on the load side.

In addition, there is a generator 10 on the side of the delta connection mentioned above, even when the electric power is generated and transmitted to the wire connection side, the amount of unnecessary power is generated by the neutral point current, including the problem that the power bill is settled. do.

An object of the present invention for solving the above problems is to provide a power measuring device and a power measuring method that can measure only the power actually supplied to the load.

In order to achieve the above object, as a power measurement method of a power transmission and reception facility connected in the w-delta method of the present invention, as a power measurement method of a power transmission and reception facility connected in the wye-delta method, the amount of power is determined on the wire connection side. The first step to do; A second step of determining an amount of circulating power circulated through the neutral point of the wire connection side; And a third step of determining the actual amount of power by subtracting the amount of power of the first step according to the determined amount of circulating power of the neutral point of the second step. It includes.

In addition, the power amount determined in the first step in the power measurement method of the power transmission equipment connected by the Wi-Delta method of the present invention is characterized in that the sum of the power of each phase of the wire connection side.

(P₁ : 와이 결선측 전력량, I_a, I_b, I_c : 와이결선의 각 상 전류, V_a, V_b, V_c : 와이결선의 각 상 전압, θ_a, θ_b, θ_c : 와이결선 각 상의 전류와 전압의 위상차)에 의해서 결정되는 것을 특징으로 한다.In addition, the power amount (P ₁ ) of the first step in the power measurement method of the power transmission equipment connected in the Y-delta method of the present invention is

(P ₁ : power of wire connection side, I _a , I _b , I _c : current of each phase of wire connection, V _a , V _b , V _c : voltage of each phase of wire connection, θ _a , θ _b , θ _c : And the phase difference between the current and the voltage of each phase of the wire connection.

(P₀ : 중성점 순환 전력량, I_a, I_b, I_c : 와이결선의 각 상 전류, V_a, V_b, V_c : 와이결선의 각 상 전압, θ_an, θ_bn, θ_cn : 와이결선의 각 상 전압과 중성점 중성점 전류와의 위상차)에 의해서 결정되는 것을 특징으로 한다. In addition, in the power measurement method of the power transmission and reception equipment connected in the Y-delta method of the present invention, the circulating power amount P ₀ of the second step is

(P ₀ : Neutral circulating power, I _a , I _b , I _c : Current of each phase of the wire, V _a , V _b , V _c : Voltage of each phase of the wire, θ _an , θ _bn , θ _cn : W Phase difference between the voltage of each phase of the connection and the neutral point current of the neutral point.

(P_w : 실제전력량, P₁ : 와이 결선측 전력량, P₀ : 중성점 순환 전력량, I_a, I_b, I_c : 와이결선의 각 상 전류, V_a, V_b, V_c : 와이결선의 각 상 전압, θ_a, θ_b, θ_c : 와이결선 각 상의 전류와 전압의 위상차, θ_an, θ_bn, θ_cn : 와이결선의 각 상전압과 중성점 순환 전류와의 위상차)에 의해서 결정되는 것을 특징으로 한다.In addition, in the power measurement method of the transmission and reception facilities wired in the Y-delta method of the present invention, the actual amount of power P _{w in} the third step is

(P _w : actual power, P ₁ : power of wire connection side, P ₀ : neutral cycle power, I _a , I _b , I _c : current of each phase of wire, V _a , V _b , V _c : wire of wire Each phase voltage, θ _a , θ _b , θ _c : phase difference between the current and voltage of each wire in the wire connection, θ _an , θ _bn , θ _cn : phase difference between each phase voltage and neutral point circulating current of the wire It is characterized by.

On the other hand, the power meter of the transmission and reception facilities wired by the Wi-Delta method of the present invention, the first power measuring unit for measuring the amount of power on the wire connection side; A second power measurement unit configured to measure a neutral point circulating power amount on the wire connection side; And a calculating unit which subtracts the measured value of the second power measuring unit from the measured value of the first power measuring unit and determines the actual amount of power used. Characterized in that it comprises a.

In addition, in the power meter of the transmission and reception facilities wired in the wa-delta method of the present invention, the second power measurement unit, at least one current transformer (CT) for measurement; A plurality of measuring transformers PT; The at least one measuring current transformer is characterized in that for detecting the neutral current (I _n ) of the neutral ground line of the wire connection side.

In addition, the plurality of measuring transformers (PT) in the power meter of the power transmission equipment connected in the Wi-Delta method of the present invention is characterized in that for measuring the voltage of each phase of the wire.

(P₁ : 와이 결선측 전력량, I_a, I_b, I_c : 와이결선의 각 상 전류, V_a, V_b, V_c : 와이결선의 각 상 전압, θ_a, θ_b, θ_c : 와이결선 각 상의 전류와 전압의 위상차)에 의해서 측정값(P₁)을 결정하는 것을 특징으로 한다. In addition, the first power measuring unit in the power meter of the power transmission and transmission facilities wired in the wa-delta method of the present invention

(P ₁ : power of wire connection side, I _a , I _b , I _c : current of each phase of wire connection, V _a , V _b , V _c : voltage of each phase of wire connection, θ _a , θ _b , θ _c : The measured value P ₁ is determined by the phase difference between the current and the voltage of each of the wires.

(P₀ : 중성점 순환 전력량, I_n : 와이결선의 중성점 순환 전류, V_a, V_b, V_c : 와이결선의 각 상 전압, θ_an, θ_bn, θ_cn : 와이결선의 각 상전압과 중성점 순환 전류와의 위상차)에 의해서 측정값(P₀)을 결정하는 것을 특징으로 한다. In addition, the second power measuring unit in the power meter of the power transmission and transmission facilities wired in the Y-delta method of the present invention

(P _0: neutral circulation amount of power, I _n: a wire connection neutral point circulating _{current, V a, V b, V} c: each phase voltage of the Y _{connection, θ an, θ bn, θ} cn: each phase voltage of the Y connection and It is characterized in that the measured value (P ₀ ) is determined by the phase difference with the neutral point circulating current.

(P_w : 실제전력량, P₁ : 와이 결선측 전력량, P₀ : 중성점 순환 전력량, I_a, I_b, I_c : 와이결선의 각 상 전류, V_a, V_b, V_c : 와이결선의 각 상 전압, θ_a, θ_b, θ_c : 와이결선 각 상의 전류와 전압의 위상차, θ_an, θ_bn, θ_cn : 와이결선의 각 상전압과 중성점 순환 전류와의 위상차)을 이용하여 실제 사용 전력량(P_w)으로 결정하는 것을 특징으로 한다. In addition, the calculation unit in the power meter of the power transmission and transmission facilities wired in the Y-delta method of the present invention

(P _w : actual power, P ₁ : power of wire connection side, P ₀ : neutral cycle power, I _a , I _b , I _c : current of each phase of wire, V _a , V _b , V _c : wire of wire Each phase voltage, θ _a , θ _b , θ _c : phase difference between the current and voltage of each phase of the wire, θ _an , θ _bn , θ _cn : phase difference between each phase voltage of the wire and the neutral circulating current) Characterized in that the amount of power (P _w ) used.

The power measurement method and power meter of the present invention as described above has the advantage that can prevent the over-measurement and under-measurement of the receiving power or transmission power by eliminating the error caused by the neutral point current to enable a fair trade. In particular, consumers and electricity providers can bill the power bill without error in the measurement of power reception and transmission power, thereby increasing the transparency of transactions.

Hereinafter, with reference to the accompanying drawings 1 to 3 will be described in detail a preferred embodiment according to the present invention. Note that the same components in the drawings are denoted by the same reference numerals and symbols as much as possible even if shown in different drawings. In addition, in describing the embodiments of the present invention, when it is determined that the detailed description of the related known functions or configurations may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

1 is a view for explaining a power measurement method of the calculation unit according to a first embodiment of the present invention, a simplified view of a three-element power meter.

The power meter 100 of FIG. 1 includes a measuring transformer PT _a , PT _b , PT _c for measuring the respective phase voltages of the wire connection, and a current transformer for measuring the phase currents of the wire connection. _a , CT _b , CT _c , a plurality of connection terminals 1S, P1, 2S, P2, 3S, P3, P0, 3L, 2L, 1L, and the measuring transformer PT _a , PT _b , PT _c ) and a calculation unit 110 that receives the output of the measuring current transformers CT _a , CT _b , CT _c to determine the actual amount of power. Determination of the calculation unit 110 means measurement or calculation.

The calculating unit 110 determines the actual amount of power by subtracting the amount of circulating power by the neutral point from the sum of the amount of each phase power of the wire connection. This series of processes are pre-logicized and stored in the calculating unit 110, and IC It is calculated by the IC and the microcomputer (not shown).

The sum P ₁ of the amount of power of each phase of the wire connection is determined by Equation 1 below.

[Equation 1]

(P ₁ : power of wire connection side, I _a , I _b , I _c : current of each phase of wire connection, V _a , V _b , V _c : voltage of each phase of wire connection, θ _a , θ _b , θ _c : Phase difference between current and voltage of each wire

Hereinafter, each current and each voltage represent a phaser vector.

In addition, the amount of circulating power P ₀ by the neutral point is determined by Equation 2 below.

[Equation 2]

(P ₀ : Neutral circulating power, I _a , I _b , I _c : Current of each phase of the wire, V _a , V _b , V _c : Voltage of each phase of the wire, θ _an , θ _bn , θ _cn : W Phase difference between each phase voltage of the connection and the neutral point current of the neutral point)

이 흐르게 된다. 따라서, 중성점의 순환전력량은

이 된다. 상기 도 1의 전류방향을 기준으로 상기 중성점에서의 유출되거나 유입되는 전류의 합은 키리히 호프의 법칙에 의해서 Ia + Ib + Ic + In = 0 이 되므로, 상기 중성점 중성점 전류 In = - (Ia + Ib + Ic)이 되고, 위 식에 대입하여 정리하면 수학식 2와 같이 정리되는 것이다. Since the current circulating in the delta connection side circulates the same current in each phase, the neutral point circulating current (In) is equally distributed in each phase of the wire connection side.

Will flow. Therefore, the amount of circulating power at the neutral point

Becomes Based on the current direction of FIG. 1, the sum of the current flowing out or flowing in the neutral point becomes Ia + Ib + Ic + In = 0 according to Kirchhoff's law, and thus the neutral point current In =-(Ia + Ib + Ic), and substituting by the above equation will be arranged as in Equation 2.

Therefore, the final amount of power to be used must be subtracted from the sum P ₁ of the amount of power of each phase and the amount of circulating power P ₀ due to the neutral current is determined as in Equation 3 below.

&Quot; (3) "

(P _w : actual power, P ₁ : power of wire connection side, P ₀ : neutral cycle power, I _a , I _b , I _c : current of each phase of wire, V _a , V _b , V _c : wire of wire each phase _{voltage, θ a, θ b, θ} c: wire connection phase difference between the current and voltage of each phase, _an θ, θ _{bn, cn} θ: phase difference between each of the Y wiring phase voltage and the neutral point current cycle)

As described above, when the logic 1 to 3 is written into the calculation unit 110 and the measured values of the current transformer and the transformer for the instrument are calculated, the actual amount of power used by subtracting the circulating power due to the neutral point current is calculated. There is an advantage that can be easily measured.

In the present embodiment, the high-voltage power transmission line having the instrument current transformer and the instrument transformer has been described as an example, but is not limited thereto. In other words, the conventional power meter includes the functions of the instrument current transformer and the instrument transformer, because of the limitation of the capacity to install a separate instrument current transformer and instrument transformer for measuring the amount of power of the high-voltage transmission line. Therefore, in the low-voltage transmission and reception line, the above-described embodiment can be sufficiently operated by a power meter including the calculation unit 110 in which Equations 1 to 3 are logic.

FIG. 2 is a block diagram of a power meter according to a second embodiment of the present invention, and FIG. 3 is a detailed view of the block diagram of FIG. 2.

The power meter 200 according to the present embodiment includes a first power measurement unit 210 for measuring the amount of power on the wire connection side, and a second power measurement unit 220 for measuring the neutral point circulating power amount on the wire connection side. And, the first and second power measuring unit (210, 220) includes a calculation unit 240 for determining the actual amount of use excluding the circulating power amount by receiving the calculation value. The first power measuring unit 210 includes a first current sensing unit 212 for measuring each phase current on the wire connection side, a voltage sensing unit 230 for measuring each phase voltage, And a first measuring unit 211 which receives the values of the first current detecting unit 212 and the voltage detecting unit 230 and calculates the amount of power on the wire connection side. The second power measuring unit 220 includes a second current sensing unit 221 for measuring a neutral point current on the wire side, a voltage sensing unit 230 for measuring each phase voltage, and each of the second current sensing units. And a second measurement unit 222 that receives the values of the unit 221 and the voltage detector 230 and calculates the amount of circulating power by the neutral point current. That is, the measuring current transformer and the second measuring unit 220 for measuring the neutral point current in the three-element power measuring devices 3CT and 3PT are further provided, and the voltage detecting unit 230 is commonly used.

The calculation unit 240 receives the total power amount of each phase of the wire connection calculated by the first measurement unit 211 and the cyclic power amount by the neutral point current calculated by the second measurement unit 222 to calculate and determine the final power consumption. It is. The series of processes are pre-logiced and stored in the operation unit 240, and are calculated and determined by IC or microcomputer (not shown).

The sum P1 of the amount of power of each phase of the wire connection calculated by the first measurement unit 211 is determined by Equation 4 below.

&Quot; (4) "

(P ₁ : power of wire connection side, I _a , I _b , I _c : current of each phase of wire connection, V _a , V _b , V _c : voltage of each phase of wire connection, θ _a , θ _b , θ _c : Phase difference between current and voltage of each wire

The amount of circulating power P ₀ by the neutral point calculated by the second measurement unit 222 is determined by Equation 5 below.

[Equation 5]

(P _0: neutral cycle energy, I _n: a wire connection neutral point circulating _{current, V a, V b, V} c: each phase voltage of the Y _{connection, θ an, θ bn, θ} cn: each phase voltage of the Y connection and Phase difference from neutral circuit current)

이 흐르게 된다. 이때에는 각각의 계측용 변류기(CT_a, CT_b, CT_c, CT_n)에 의해 중성점으로 향하는 전류를 측정하게 되므로, 동일한 방향의 전류값으로 처리된다. 따라서, 중성점의 순환전력량은

이 된다. 상기 중성점에서의 유출되거나 유입되는 전류의 합은 키리히 호프의 법칙에 의해서 Ia + Ib + Ic + In = 0 이 되므로, 상기 중성점 전류 In = -(Ia + Ib + Ic) 이되고, 위 식에 대입하여 정리하면 수학식 5와 같이 정리되는 것이다. Since the current circulating in the delta connection side circulates the same current in each phase, the neutral point circulating current (In) is equally distributed in each phase of the wire connection side.

Will flow. At this time, since the currents toward the neutral point are measured by the current transformers CT _a , CT _b , CT _c , and CT _n , the current values in the same direction are processed. Therefore, the amount of circulating power at the neutral point

Becomes Since the sum of the current flowing out or flowing in the neutral point becomes Ia + Ib + Ic + In = 0 according to Kirchhoff's law, the neutral current In =-(Ia + Ib + Ic) becomes Substituting and arranging will be arranged as in Equation 5.

Therefore, the final amount of power to be used must be subtracted from the sum P ₁ of the amounts of power of each phase and the amount of circulating power P ₀ due to the neutral current is determined as shown in Equation 6 below.

&Quot; (6) "

(P _w : actual power, P ₁ : power of wire connection side, P ₀ : power of neutral point, I _a , I _b , I _c : current of each phase of wire, V _a , V _b , V _c : wire of wire each phase _{voltage, θ a, θ b, θ} c: wire connection phase difference between the current and voltage of each phase, _an θ, θ _{bn, cn} θ: phase difference between each of the Y wiring phase voltage and the neutral point current cycle)

As described above, the neutral point current is directly detected, and the actual amount of power is determined by subtracting the amount of circulating power by the neutral point based on the detected value, thereby providing accurate measurement.

One embodiment of the present invention described above should not be construed as limiting the technical spirit of the present invention. The protection scope of the present invention is limited only by the matters described in the claims, and those skilled in the art can change and change the technical idea of the present invention in various forms. Therefore, such improvements and modifications will fall within the protection scope of the present invention as long as it will be apparent to those skilled in the art.

1 is a view for explaining a power measurement method of the calculation unit according to a first embodiment of the present invention

2 is a block diagram of a power meter according to a second embodiment of the present invention.

3 is a detailed view of the power meter shown in FIG.

4 is a schematic diagram of a typical Wye-delta connection transformer

Claims (11)

As a power measurement method of power transmission and transmission facilities connected by Y-delta method, A first step of determining an amount of power at the wire connection side; A second step of determining an amount of circulating power circulated through the neutral point of the wire connection side; And A third step of determining an actual power amount by subtracting the power amount of the first step according to the determined cyclic power amount of the neutral point of the second step; Power measurement method comprising a. The method of claim 1, The amount of power determined in the first step is the sum of the power of each phase of the wire connection side, the power measurement method. The method of claim 1, The power measurement method of the first step (P ₁ ) is characterized in that determined by the following equation. [Equation]

(P ₁ : power of wire connection side, I _a , I _b , I _c : current of each phase of wire connection, V _a , V _b , V _c : voltage of each phase of wire connection, θ _a , θ _b , θ _c : Phase difference between current and voltage of each wire The method of claim 1, The cyclic power amount (P ₀ ) of the second step is determined by the following equation. [Equation]

(P ₀ : Neutral circulating power, I _a , I _b , I _c : Current of each phase of the wire, V _a , V _b , V _c : Voltage of each phase of the wire, θ _an , θ _bn , θ _cn : W Phase difference between each phase voltage of the connection and the neutral point current of the neutral point) The method of claim 1, The actual power amount P _w of the third step is determined by the following equation. [Equation]

(P _w : actual power, I _a , I _b , I _c : each phase current of wire connection, V _a , V _b , V _c : each phase voltage of wire connection, θ _a , θ _b , θ _c : wire connection Phase difference between current and voltage of each phase, θ _an , θ _bn , θ _cn : phase difference between each phase voltage and neutral point cyclic current of wire connection) W-Delta is a power meter for transmission and transmission facilities. A first power measurement unit measuring an amount of power on the wire connection side; A second power measurement unit configured to measure a neutral point circulating power amount on the wire connection side; And A calculator configured to subtract the measured value of the second power measurer from the measured value of the first power measurer to determine an actual amount of power used; Power meter comprising a. The method of claim 6, The second power measuring unit, At least one instrument current transformer (CT); A plurality of measuring transformers PT; Including, And the at least one current transformer for measuring measures the neutral current (I _n ) of the neutral ground line on the wire connection side. The method of claim 7, wherein The plurality of measuring transformer (PT) is a power meter, characterized in that for measuring the voltage of each phase of the wire connection. The method of claim 6, The first power measuring unit is a power meter, characterized in that for determining the measured value (P ₁ ) by the following equation. [Equation]

(P ₁ : power of wire connection side, I _a , I _b , I _c : current of each phase of wire connection, V _a , V _b , V _c : voltage of each phase of wire connection, θ _a , θ _b , θ _c : Phase difference between current and voltage of each wire The method of claim 6, And the second power measurement unit determines a measurement value (P ₀ ) by the following equation. [Equation]

(P _0: neutral cycle energy, I _n: a wire connection neutral point circulating _{current, V a, V b, V} c: each phase voltage of the Y _{connection, θ an, θ bn, θ} cn: each phase voltage of the Y connection and Phase difference from neutral circuit current) The method of claim 6, The calculation unit is a power meter, characterized in that to determine the actual amount of power (P _w ) using the following equation. [Equation]

(P _w : actual power, I _a , I _b , I _c : each phase current of wire connection, V _a , V _b , V _c : each phase voltage of wire connection, θ _a , θ _b , θ _c : wire connection Phase difference between current and voltage of each phase, θ _an , θ _bn , θ _cn : phase difference between each phase voltage and neutral point cyclic current of wire connection)

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