JPS62254217A - Controller for electric power-factor - Google Patents

Abstract

PURPOSE:To secure a constant level of average power-factor and to improve the power-factor in terms of a long period of time, by correcting automatically the set value of reactive power based on the past value of achievements. CONSTITUTION:The power factor Pf is first set at the power receiving point of a demander by a power-factor setting part 1. This set factor Pf is led to a reactive power value arithmetic means 3 together with the electric power value WH obtained by a power value generating part 2 on the previous day. Thus the reactive power value VarH1 is obtained. An overs/shorts arithmetic means 3 obtains the reactive power value VarH3 undergone overs/shorts on the previous day from said value VarH1 and the reactive power value VarH2 obtained on the previous day through a reactive power generating part 4. In a overs/shorts mode the value VarH3 is delivered to a converting part 8 to be converted into the instantaneous reactive power Var2 and multiplied by a weight coefficient K3 to be delivered to a reactive power setting means 9 for today. The means 9 obtains the set reactive power value Var3 of today from the reactive power value Var1 obtained in an application mode of a phase advance capacitor and K3.Var2 and delivers it.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a power power factor control device for detecting reactive power at a power receiving point and improving the received power factor based on the detected value.

(B) Summary of the Invention The present invention provides a power factor control device that does not fix the reactive power setting value, but automatically corrects the reactive power setting value based on the past actual value. This makes it possible to maintain a constant average power factor and improve the power factor over the long term.

(O Conventional technology The power receiving point of electrical equipment where most of the loads are electric motors, such as water treatment equipment, has a lagging power factor, so in order to compensate for this lagging power factor and improve the power factor, the power receiving point is capacitor control is being performed.

Figure 2 shows a single line diagram for power factor control.
Phase advance capacitors SC1 to SCn are connected in parallel with loads L1 to Ln at the power receiving point, and the reactive power (instantaneous value) obtained through transformer PT and current transformer G is transferred to relay RY.
The switches 81 to Sn are selected depending on whether or not the detected reactive power is larger than the set reactive power, and control for closing or tripping is performed. Note that CB and CB, to CBn are circuit breakers, and SR1 to SRn are series reactors.

Figure 3 shows the control mode of the phase advance capacitor.
B is the set reactive power trip line, B is the set reactive power input line, and when the reactive power at the receiving point detected by the reactive power relay RY is larger than the set reactive power B (lag), connect the phase advance capacitor. Insert it, and when it is smaller than A, [proceed] and pull it out. In other words, the amount of reactive power at the power receiving point is always the set reactive power width W
controlled to be located within.

■) Problems that the invention aims to solve The benefits obtained by improving the power factor include reducing power loss, reducing power drop, and reducing the capacity of the main transformer, but this is a major need for consumers. The key is to reduce electricity costs. Conventionally, in controlling reactive power for such purposes, reactive power settings A and B shown in FIG.
Since it is fixed, it has the following problems.

(1) Past actual results are not reflected in the set reactive power.

(2) Since it is not possible to improve the low power factor (low reactive power) when the power used is low, there is a limit to the improvement of the average power factor.

(3) Since the power used fluctuates from moment to moment and its fluctuation pattern is not constant, it is not possible to keep the average power factor constant.

(4) Since stable control is not possible, the number of closing and tripping ports increases, shortening the life of the capacitor.

In addition to having the above-mentioned problems, from the point of view of electricity rate discounts, discounts are given at the monthly average rate, so long-term power factor improvement based on actual values is preferable to short-term power factor improvement. In particular, stable control can be expected.

The present invention has been made in view of this point, and its purpose is to provide a control device for long-term power factor improvement.

(g) Means for solving the problem This invention calculates the reactive power amount at the time of deer rate setting from the power factor setting value and the previous day's power amount in order to automatically correct the reactive power setting by the daily vehicle position. a reactive power amount calculation means for setting a power factor; an excess/deficiency calculation means for calculating an excess or deficiency of reactive power in the previous H from the reactive power amount obtained by this calculation means and the reactive power amount of the previous day; It is provided with a reactive power setting means for calculating today's reactive power setting value based on the surplus/deficiency amount determined by the calculation means and the reactive power setting value at the time of turning on.

(j Calculate the excess or deficiency reactive energy on the day between the reactive energy at the time of setting the active power factor and the actual reactive energy of the previous day. Subtract this excess or deficiency from the reactive power setting value at the time of power-on. Accordingly, today's reactive power setting value (input) can be determined.

(G) Example An example of the present invention will be described below in detail with reference to FIG. In the figure, reference numeral 1 denotes a power factor setting section where the power factor Pf is set. 2
is a power generation unit for the previous day, and this generation unit 2 is a pulse totalizer, an analog totalizer, or a setting device that newly sets wH for the current day. 3 is a reactive power amount calculation means which calculates the reactive power amount varH1 at the time of deer rate setting based on the power factor setting value Pf and the previous day's power amount. 4 is a reactive power generation unit for the previous day, 5 is an excess/deficiency calculation means, and this calculation unit 5 calculates the reactive power amount Var I(5) that was excessive or insufficient on the previous day. 6 is a determination unit, and 7 is a reactive power In the setting section, this setting section 7 sets the reactive power value Var1 when the phase advance capacitor is turned on.
is set. 8 is a conversion unit, 9 is a reactive power setting means for calculating today's reactive power setting value, lO is a reactive power setting means for setting the reactive power width VarD, and l is a subtraction unit. sets the reactive power for removing phase advance capacitor 1.

The operation of the present invention configured as above will be explained.

At the time of initialization, the amount of reactive power is separately set and that value is used, but the following explanation assumes that the operation is continued.

First, the power factor Pf of the power receiving point of the consumer is set in advance by the power factor setting section 1, and this set value Pf and the power amount wH obtained by the power amount generating section 2 on the previous day are calculated by the reactive power amount calculation means. 3 and calculate the equation (1) to obtain the reactive power amount VarH1 at the time of setting the power factor.

VarH1=WH1-(Pf)”/Pf ”・・””・
(1) The determined value VarH1 is output to the excess/deficiency calculation means 5. The calculation means 5 includes the previous day's reactive power amount calculation means 4, which is a pulse integrator or the like, and the previous day's reactive power amount v.
arH2 is also applied, and these people are also applying VarH5.
=VarHl -VarH2·=-f21 is calculated to find the reactive power amount VarH5 which was surplus or insufficient on the previous day. The obtained VarH5 is introduced into the determination unit 6, and if VarH5 is negative, 1VarH51>KL, then insufficient VarH3 is positive, then 1VarH5l), and if K2, it is determined to be excessive. Further, when the conditions are other than the above, it is determined that VarH5=0. Here, 1 is a constant for the insensitivity side dead zone, and K2 is a constant for the overabundance side dead zone.

If the judgment result is NO, that is, VarH5=O
In the case of , it remains as it is, but in the case of Yes, that is, when an excess or deficiency occurs, VarH5 is output to the converter 8 and converted to instantaneous reactive power Var2, and the weighting coefficient is set by 3.
is multiplied and output to today's reactive power setting means 9. The reactive power setting means 9 is supplied with the reactive power value Var1 from the setting section 7 at the time of power-on.
......Calculate (3) and get today's set reactive power value Var
Find 3.

However, a limiter is provided for Var5, and Mar
When 5≦4, Var5 = 4. When Var5≧5, Var5- is set to 5. Here, K11 is the set minimum value of reactive power, and K5 is the set maximum value of reactive power.

On the other hand, the set reactive power amount VarlI for tripping is calculated by the subtraction unit 1
1, using the value VBrl set by the setting unit 7 and the reactive power VarD set by the setting unit IO, Var+4 = Varl, −VarD ・=−=・
Find the calculation in (4). (Varp) Control Capacitor Capacity) 0 Effects of the Invention According to the present invention, (1) By automatically correcting the setting value of the reactive power, the past actual value can be changed from the past actual value at one day's vehicle position. reflected in the power factor.

(2) Low power factor (low reactive power) when less power is used
The average value can also be improved by being reflected in past performance values.

(3) Since the set power factor is used as the standard, the reactive power setting means is used to control the power factor at a constant value, so the average power factor does not vary due to fluctuations in power consumption, etc. (4) Long-term power As a result, stable control with reduced frequency of capacitor closing and tripping is possible, and the life of the capacitor can be extended.

(5) Although the capacitor capacitance to be controlled is stepped, the set value of the reactive power is corrected to an arbitrary value, so the capacitor capacitance control is isometrically as if it were continuous.

It has the following advantages.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention, FIG. 2 is a single connection diagram of a conventional power factor control device, and FIG. 3 is an explanatory diagram of capacitor control. 1 is a power factor setting section, 2 is a previous day's power generation section, 3 is a reactive power amount calculation means, 4 is a previous day's reactive power generation section, 5 is an excess/deficiency calculation means, 6 is a determination section, and 7 is a reactive power The setting section 9 is a reactive power setting means.

Claims (1)

[Claims] A power factor setting for setting the power factor of the power receiving point in a device that connects a phase advancing capacitor in parallel with the load and controls turning on and off of the phase advancing capacitor according to the amount of reactive power at the power receiving point. , the previous day's power generation section, the previous day's reactive power generation section, the setting value set in the power factor setting section, and the amount of power generated by the previous day's power generation section. a reactive power amount calculating means for calculating the amount of reactive power; and calculating an excess or deficiency of the reactive power amount of the previous day based on the reactive power amount obtained by the calculating means and the reactive power generated from the reactive power generating section of the previous day. The present invention is characterized by comprising an excess/deficiency calculation means, and a reactive power setting means for setting today's reactive power amount based on the calculation result of the calculation means and the input reactive power setting value when an excess/deficiency occurs. Power power factor control device.