SU1376177A1 - Three-phase variable filter - Google Patents

Abstract

The invention relates to industrial power engineering, in particular, to methods and means of providing quality indicators of electrical energy in power supply systems of industrial enterprises with non-linear, varying in time over a wide range of current components, such as arc furnaces, controlled by thyristors electric drives, powerful welding installations. The goal is to increase reliability by eliminating the mutual parallel resonance between the filter capacitor branches. With a higher level of reactive power filter generated into the network by contacts 4 and 5 are closed and at the same time contacts 6 are switched "(

Description

A1

WITH

05

The apparatus provides for the connection of the reactors with 3 triangles. In this case, there is no parallel connection between the two condenser-reactor legs, which are tuned to the same frequency, which eliminates the parallel mutual resonance between the individual sections of the filter and thereby ensures the electromagnetic compatibility of the filter1

The invention relates to industrial power engineering, in particular, to methods and means of providing electrical energy quality indicators (voltage quality) in power supply systems of industrial enterprises (SESP) with non-linear, varying in time in a wide range of component currents of electric arc type loads, thyristors controlled electric drives, powerful welding equipment and can be used in SESP independently, in the form of a separate step-adjustable filter, of a certain harmonic (like Emer, 5 ohms), or as a constituent unit in a controlled-frequency filter-mnogochas devices (RFKU) or static five- ristornyh) .kompensatorah reactive power or TKRM STK).

The aim of the invention is to increase reliability by eliminating mutual parallel resonance between the reactor-capacitor branches of the filter.

FIG. Figures 1 and 2 show the basic three-phase controlled filter circuits; options 4

The device contains two three-phase capacitor banks 1 and 2, the power of the first of which 1 is two times less than the second 2; a three-phase group of reactors 3 connected in series with capacitor banks 1 and 2, an independent switch 4 for connecting (disconnecting) a battery of capacitors 2 to the network, a switch 5 for connecting to the network

ra with a power supply network and increase of reliability of its work, reduces energy losses in a network and the filter. Stepwise control of the filter power is provided using a single group of reactors. The range of the step power control of a three-phase controlled filter is 3: 1. 2 Il.

2

batteries 1 and two-position three-phase switching apparatus 6 for switching the connection between reactors 3 from a star to a triangle 5 (upper position of contacts 6) or from a triangle to a star (lower position of contacts 6).

The device works as follows.

0 With a higher level of reactive power generated in the network by the filter, pins 4 and 5 are closed and at the same time pins 6 of the switching device provide a connection scheme between the reactors 3 by a triangle. At a lower power level of the filter, the contacts of the switch 4 are open and at the same time the contacts 6 of the switching apparatus switch the connection scheme between the sockets of reactors 3 from a triangle to a star. B device (Fig.1) as when the battery is disconnected capacitors 2 and the interconnection of the reactors 3 star, and at. capacitor bank

2and interconnecting reactors

3 triangle, there is no parallel connection between the two capacitor-reactor branches, tuned to the same frequency, which eliminates the parallel mutual resonance between the individual sections of the filter and ensures the electromagnetic compatibility of the filter with the power supply

5 network and higher reliability

work, reduces energy losses in the network and filter.

Step-wise filter power control is provided using 5

0

one group of reactors. Switching the connection of a group of reactors between themselves from a star to a triangle leads to a decrease in their equivalent resistance by a factor of three x-, XP / 3. The step power control range of the three-phase controlled filter is 3: 1.

The three-phase controlled filter (Fig. 2) provides a wider range of control of the generated power and contains two three-phase capacitor banks 1 and 2, the power of the first of which 1 is three times less than the second battery 2 (to provide the specified control range of 1: 4). In series with capacitor banks 1 and 2, two three-phase groups of reactors 3 and 7 of the same type are connected, which are interconnected by a closed hexagon. In addition, the device contains three three-phase independent switches 5, 6 and 4, the contacts of the first of which are connected in series with the second capacitor bank 2 (providing connection or disconnection of this section to the phase terminals of the supply network A, B, C). Switch 4 connects the battery of capacitors 1 to the network, and the contacts of the switching device 6 are connected between the vertices (through one) of the hexagons of the same type reactors 3 and 7, thereby switching the connection between the two three-phase groups of reactors 3 and 7 from serial to parallel (when the contacts 6) or from parallel to serial (when opening contacts 6)

The device works as follows.

At a lower step of the reactive power generated by the controlled filter, contacts 6 and 4 of the independent isolators are open, the battery of capacitors 2 is disconnected, and the battery of capacitors 1 is connected in series with reactors 3 and 7, which are connected in series in the form of a hexagon; 6 and 4 independent isolators - zamlnu and the battery of capacitors 2 are connected to the phase terminals of the mains A, B, C and connected in parallel to the capacitor battery 1. Reactors 3 and 7 are connected succession

five

0

five

0

five

0

five

0

five

They are connected to capacitor batteries 1 and 2 and are connected in parallel in the form of two triangles. The equivalent power of each phase of the filter when the contacts 6 are closed has increased 4 times, since the power of the connected battery 2 is three times greater than the power of the first capacitor bank 1. When switching the connection circuit between one and the same type reactors 3 and 7 from serial to parallel, their total equivalent resistance has also decreased in four times. To change the power level of the filter, they simultaneously tighten the contacts 6 and 4 and at the same time, connect (disconnect) the capacitor bank 2 and change the connection circuit between the three-phase groups of reactors 3 and 7 from the serial to the parallel. At any stage of power three-phase control. No filter in it, there are no interconnected reactor-capacitor branches tuned to the same harmonics. This is a necessary condition for eliminating mutual parallel resonance between the sections of the reactive filter elements, reduces the energy losses in the filter and the power supply network, increases the reliability of the three-phase filter and ensures its electromagnetic compatibility with the power supply network. Using single-type reactors reduces the cost of the filter, simplifies its configuration.

Claims (1)

Invention Formula A three-phase controlled filter containing two three-phase capacitor banks connected to the network through two independent switches, and a three-phase group of reactors connected in series with the first capacitor battery and tuned to it at a given resonant frequency, characterized in that, in order to increase reliability by eliminating mutual parallel resonance between the reactor-capacitor branches of the filter, the second terminals of the second three-phase capacitor battery are connected at the junction points of the first terminal capacitor bank battery and reactors, the filter additionally introduced vzhlyuchatel phase. 513761776 providing a change in the connection circuit to resonance when the reactor is connected to the network to adjust the filter of the second capacitor bank. FIG. 2