ELEKTROTEHNI KO PODJETJE Leskoπkova cesta 12, 1000 Ljubljana, SLOVENIA

Transcription

1 d.o.o. ELEKTROTEHNI KO PODJETJE Leskoπkova cesta 12, 1000 Ljubljana, SLOVENIA

2 SETTING UP REACTIVE POWER COMPENSATION DEVICES SELECTING A REACTIVE POWER COMPENSATION DEVICE To effectively compensate the reactive power in the network, first we have to determine the active power/reactive power ratio. The easiest way to do this is to measure it in an active network. In the second example (the planning phase) the expected reactive power based on the technical data of loads is determined. In Fig. 1 a diagram on reactive power flow through the network is displayed and the basic principle of reactive power compensation is shown. In Fig. 2 the basic formula for the calculation of reactive power is displayed. NETWORK Active power Economization Active power Reactive power CONSUMER Figure 1: The principle of reactive power compensation. Q C = P (tanϕ 1 - tanϕ 2 ) Where is: P Q C ϕ 1 ϕ 2 Active power [kw] Reactive power to compensate [kvar] Measured or calculated network phase angle Phase angle at a desired cosϕ Figure 2: The basic reactive power calculation from the power diagram. The desired cosϕ is usually set between the legal minimum value cosϕ=0,95 and maximum value cosϕ=1. This calculation can be simplified by calculating the value (tanϕ1-tanϕ2). The factor K can be looked up in the table 1 on page 3: 2

3 SETTING UP REACTIVE POWER COMPENSATION DEVICES SELECTING A REACTIVE POWER COMPENSATION DEVICE 3 Table 1: Calculated values for K = (tanϕ 1 - tanϕ 2 ). 3,18 2,96 2,77 2,59 2,43 2,29 2,16 2,04 1,93 1,83 1,73 1,64 1,56 1,48 1,40 1,33 1,30 1,27 1,23 1,20 1,11 1,08 1,05 1,02 0,99 0,96 0,94 0,91 0,88 0,86 0,83 0,80 0,78 0,75 0,72 0,70 0,67 0,65 0,62 0,59 0,57 0,54 0,51 0,48 0,46 0,43 0,40 0,36 0,33 0,29 0,30 0,32 0,34 0,36 0,38 0,40 0,42 0,44 0,46 0,48 0,50 0,52 0,54 0,56 0,58 0,60 0,61 0,62 0, 0,64 0,67 0,68 0,69 0,70 0,71 0,72 0,73 0,74 0,75 0,76 0,77 0,78 0,79 0,80 0,81 0,82 0,83 0,84 0,85 0,86 0,87 0,88 0,89 0,90 0,91 0,92 0,93 0,94 0,95 0,96 2,43 2,21 2,02 1,84 1,68 1,54 1,41 1,29 1,18 1,08 0,98 0,89 0,81 0,73 0,65 0,58 0,55 0,52 0,48 0,45 0,36 0,33 0,30 0,27 0,24 0,21 0,19 0,16 0,13 0,11 0,08 0,05 0,03 2,56 2,34 2,15 1,97 1,81 1,67 1,54 1,42 1,31 1,21 1,11 1,02 0,94 0,86 0,78 0,71 0,68 0,65 0,61 0,58 0,49 0,46 0,43 0,40 0,37 0,34 0,32 0,29 0,26 0,24 0,21 0,18 0,16 0,13 0,10 0,08 0,05 0,03 2,70 2,48 2,28 2,10 1,95 1,81 1,68 1,56 1,45 1,34 1,25 1,16 1,07 1,00 0,92 0,85 0,81 0,78 0,75 0,72 0, 0,59 0,56 0,54 0,51 0,48 0,45 0,42 0,40 0,37 0,34 0,32 0,29 0,27 0,24 0,21 0,19 0,16 0,14 0,11 0,08 0,06 0,03 2,75 2,53 2,34 2,17 2,01 1,87 1,73 1,61 1,50 1,40 1,31 1,22 1,13 1,05 0,98 0,91 0,87 0,84 0,81 0,77 0,68 0,65 0,62 0,59 0,57 0,54 0,51 0,48 0,46 0,43 0,40 0,38 0, 0,32 0,30 0,27 0,25 0,22 0,19 0,17 0,14 0,11 0,09 0,06 0,03 2,85 2, 2,44 2,26 2,11 1,96 1,83 1,71 1,60 1,50 1,40 1,31 1,23 1,15 1,08 1,00 0,97 0,94 0,90 0,87 0,78 0,75 0,72 0,69 0,66 0,64 0,61 0,58 0,55 0,53 0,50 0,47 0,45 0,42 0,40 0,37 0,34 0,32 0,29 0,26 0,24 0,21 0,18 0,16 0,13 0,10 0,07 0,03 2,98 2,76 2,56 2,39 2,23 2,09 1,96 1,84 1,73 1,62 1,53 1,44 1,36 1,28 1,20 1,13 1,10 1,06 1,03 1,00 0,90 0,88 0,85 0,82 0,79 0,76 0,73 0,71 0,68 0,65 0, 0,60 0,57 0,55 0,52 0,49 0,47 0,44 0,42 0,39 0,36 0,34 0,31 0,28 0,25 0,22 0,19 0,16 0,13 0,09 3,18 2,96 2,77 2,59 2,43 2,29 2,16 2,04 1,93 1,83 1,73 1,64 1,56 1,48 1,40 1,33 1,30 1,27 1,23 1,20 1,11 1,08 1,05 1,02 0,99 0,96 0,94 0,91 0,88 0,86 0,83 0,80 0,78 0,75 0,72 0,70 0,67 0,65 0,62 0,59 0,57 0,54 0,51 0,48 0,46 0,43 0,40 0,36 0,33 0,29 EXISTENT DESIRED VALUE COSϕ tanϕ cosϕ 0,80 0,85 0,90 0,92 0,95 0,98 1,00

4 SETTING UP REACTIVE POWER COMPENSATION DEVICES SELECTING A REACTIVE POWER COMPENSATION DEVICE 1. Calculation example: Determine the required capacity of the compensation device, which would compensate reactive power to cosϕ 2 =1 in a network with the following characteristics: Peak power: 120kW Cosϕ 1 : 0,73 Peak power Apparent power = = 120 kw =164,38kVA cosϕ 1 0,73 K for the desired cosϕ 2 = 1 at cosϕ= 0,73 is 0,94. (Find the relevant K factor in table 1.) The capacity of the compensation device = peak power x factor K = 120kW x 0,94 = 112,8 kvar. For the compensation of the reactive power to cosϕ 1 =1 we need a compensation device of at least 112,8 kvar. Find the most appropriate device in the catalogue. In our case it would be the 120kvar device. 2. Calculation example: Determine the required capacity of the compensation device, which would compensate reactive power to cosϕ 2 = 0,98 in a network with the following characteristics: Peak power: 180kW Active power: 780kWh Reactive power: 23879kvarh reactive power tanϕ = = 23879k var h =0,67 active power 780kwh K for the desired cosϕ 2 = 0,98 at tanϕ= 0,67 is 0,47. (Find the relevant K factor in table 1.) The capacity of the compensation device = peak power x factor K = 180kW x 0,47 = 84,6 kvar. For the compensation of the reactive power to cosϕ 2 =0,98 we need a compensation device of at least 84,6kvar. Find the most appropriate device in the catalogue. In our case it would be the 90kvar device. 4

5 SETTING UP REACTIVE POWER COMPENSATION DEVICES HIGH HARMONICS IN THE NETWORK AND HARMONIC FILTERS WHERE DO HIGH HARMONICS APPEAR? High harmonics are generated in a network by non-linear loads, such as: frequency regulators, rectifiers, uninterruptible power sources, fluorescent lamps, welding devices, computers etc. DISTORTIONS, CAUSED BY HIGH HARMONICS Non-linear elements in devices e.g. thyristors generate harmonics in the current. As a result, high harmonics in the voltage occur, which cause overloads of capacitor units in compensation devices, ripple control signal interferences and unreliable actuator work in electronic devices, which use the voltage zero crossing. Additionally, they strain mains leads, energy transformers, fuses and switching devices and cause interference in telephone systems. Harmonics are additionally increased by parallel and serial resonances, which can magnify single high harmonics to a multiple value. WHY DO HIGH HARMONICS REDUCE CAPACITOR LIFE? High harmonics are to be seen as an increase of the effective value of the current, which runs through the capacitor. This phenomenon causes heating of the capacitor thus reducing its life. Additionally, parallel and serial resonance circuits between capacitors and network inductances can cause a multiple increase of a single high harmonic and with it distortions, which additionally magnify the current that runs through the capacitor. At what frequency the high harmonics resonate depends on the size of capacitors and network characteristics. REACTIVE POWER COMPENSATION WITH HARMONIC FILTERS When using a harmonic filtering system, a harmonic filter is connected in series with the capacitor unit. This filter together with the capacitor forms a series oscillating circuit, which tunes the frequency below the lowest high harmonic that is still occurring in the network. In Fig. 3 we can see, that on the area of harmonics we have achieved a resonance circuit of inductive nature and therefore resonance conditions cannot occur. In this way we have prevented uncontrolled magnification of single harmonics in the network due to resonance conditions and related distortions. The commonly used frequencies in harmonic filters are: 134Hz, 141Hz, 176Hz, 189Hz and 214Hz. They are described with the factor p: 5

6 SETTING UP REACTIVE POWER COMPENSATION DEVICES HIGH HARMONICS IN THE NETWORK AND HARMONIC FILTERS Figure 3: Impedance characteristics of a series oscillating circuit in the harmonic filtering. Impedance Z inductance frequency capacitance cap. SUPPRESSION OF HIGH HARMONICS WITH HARMONIC FILTERS From the shown impedance characteristics it is clear that the series oscillating circuit has the lowest impedance values on the area of high harmonics, which most commonly occur in the network (3rd, 5th, 7th harmonic). As a result, high harmonics are being absorbed out of the network. That means, harmonic filters also suppress high harmonics in the network. The degree of suppression depends on the selected resonance frequency of the filter. Example: a filter with a frequency of 214Hz suppresses the 5th harmonic for approx. 50%; a filter with a frequency of 189Hz suppresses the 5th harmonic for approx. 25%. But when using a filter with a frequency of 134Hz, the absorption of the 5th harmonic is negligible. With the increase of absorption of high harmonics out of the network also the thermal load of the oscillating circuit is increased. This has to be considered when planning a compensation device. Of course, values of single high harmonics in the on-site measured network, which is to be filtered, are of major importance. HARMONIC FILTERS IN NETWORKS WITH A RIPPLE CONTROL SIGNAL As mentioned above, the filter circuit is absorbing harmonics in the area near the resonance frequency. If a ripple control signal is present in the same area, it is also suppressed. The degree of suppression depends on the capacity of the energy transformer, size of the compensation device, filter circuit frequency and ripple control signal frequency. It is to be said that this problem appears also with common compensation devices i.e. at higher frequencies of the ripple control signal. If there is no other possibility, the ripple control signal is to be improved using a stop filter, which is connected in series with the compensation device. 6

7 SETTING UP REACTIVE POWER COMPENSATION DEVICES HIGH HARMONICS IN THE NETWORK AND HARMONIC FILTERS WHEN SHOULD I USE A HARMONIC FILTER? Due to the stated facts it is obvious that many factors decide about the type of the selected reactive power compensation device. At first: harmonic filtering yes or no; what should be the filter frequency like; do we have a ripple control signal in the network; which harmonics are mostly expressed in the network; what about the resonance? When making plans to install compensation devices for a specific situation, all of these factors have to be considered. Besides, the legal regulative and standards e.g. GUIDANCE ON SYSTEMATIC OPERATION OF THE ELECTRICITY DISTRIBUTION SYSTEM (Official gazette of the R of Slovenia: 15/2) and the standard on quality of electrical power SIST EN 50160, where the limits for single harmonics are defined, have to be taken into consideration. All of the above questions cannot be answered equally. But we can use the following guidelines: When looking at a new building and a new transformer station, we do not know, in which conditions the compensation device will operate. Besides, we are not informed about the values of single high harmonics. Still, we can classify the consumers with defining the percentage of non-linear loads in respect to facility load. A harmonic filter is recommended, if more than 15% of the facility load is non-linear! At the same time we have to consider, which of these non-linear loads are connected when electricity consumption is lowest (at week ends), as then resonance conditions may be amplified due to low network suppression as a result of minimally activated loads. When setting the filtering frequency, a compromise between the following factors is needed: suppression of high harmonics in the network, suppression of the ripple control signal and prevention of resonance. In cases, where the value of high harmonics in the middle-voltage range (10, 20 and kv) is known, the following guidelines can be used: Harmonic filtering is needed, if the 5th harmonic in the voltage exceeds 2% in respect to the fundamental harmonic, or when the overall voltage distortion exceeds 3% in respect to the fundamental harmonic. It is hard to give a clear answer to the last question as resonance conditions in the network are hardly defined accurately, due to the continuously changing network impedances (e.g. automatic compensation capacitance). Resonance conditions are prevented by using a harmonic filter! ADVANTAGES OF HARMONIC FILTERS reliable reactive power compensation in networks with high harmonics protecting energy transformers, fuses, switching devices and mains leads suppression of high harmonics in the voltage suppression of the effective current value due to suppressed high harmonics prevention of resonance conditions in the network 7

8 AUTOMATICALLY CONTROLLED REACTIVE POWER COMPENSATION DEVICE Type: ASK - technical data Nominal voltage and frequency: Max. allowed over-voltage: Max. allowed over-current: Nominal values of measuring el. circuits: Operating temperature range: Cooling of compensation fields: Power losses: V, 50Hz-power circuit; 230 V, 50Hz-control circuits 1,1xUn (nominal voltage), max. eight hours per day 1,3xIn (nominal current) constant voltage measuring input: 230V, 50Hz current measuring input: 5A (through the current measuring transformer) Average 24-hours temperature: + C Max. temperature: +40 C Min. temperature: -10 C Relative humidity:max. 95% (condensation not allowed) Natural airing Capacitors: max. 0,5 W/kvar Compensation device: max. 2 W/kvar Mechanical protection IP: IP 31 IP 54 (optional) Colour: RAL 7032 In compliance with IEC and -2, SIST EN Table with technical data for single types: Nominal power [kvar] 15 17, , Programme 1:1:2:2 1:2:2:2 1:1:1:1 1:2:2 1:1:2 1:2:2:2 1:1:2:2 1:2:2:2 1:2:4:8 1:2:2:2 1:1:2:2 1:2:2:2... 1:2:2:2 1:2:2:2... 1:2:2:2... 1:2:2:2... 1:2:2:2... Type ASK1-15/ ASK1-17,5/ ASK1-20/ ASK1-25/ ASK1-30/ ASK2-/ ASK2-45/ ASK2-52,5/ ASK2-60/ ASK2-70/ ASK2-75/ ASK3-90/ ASK3-105/ ASK3-120/ ASK3-1/ ASK3-150/ ASK4-165/ ASK4-180/ ASK4-210/ ASK5-240/ ASK5-270/ ASK5-300/ ASK5-345/ ASK5-390/ ASK6-450/ ASK6-480/ ASK7-540/ ASK7-/ ASK7-660/ ASK7-720/ ASK7-780/ Configuration of capacitor units [kvar] 2 x 2,5+2 x 5 1 x 2,5+3 x5 4 x 5 1 x 5+2 x 10 2 x 7,5+1 x 15 1 x 5+3 x 10 2x 7,5+2 x 15 1 x 7,5+3 x 15 1 x 5+1x10+1x15+1x30 1x10+3x20 2x12,5+2x25 1x10+4x20 1x15+3x30 2x15+3x30 1x15+4x30 2x15+4x30 1x15+5x30 2x15+5x30 2x15+6x30 2x15+7x30 2x15+8x30 2x15+9x30 1x15+11x30 2x15+12x30 1x30+7x60 2x30+7x60 2x30+8x60 2x30+9x60 2x30+10x60 2x30+11x60 2x30+12x60 Feed cable cross-section Cu [mm 2 ] 4 x 6 4 x 10 4 x 10 4 x 25 3 x /16 3 x 70/ 3 x 70/ 3 x 95/50 3 x 95/50 3 x 120/70 3 x 120/70 3 x 150/70 3 x 185/95 3 x 185/95 3 x 240/120 2x(3 x 150/70) 2x(3 x 185/95) 2x(3 x 185/95) 2x(3 x 240/120) 2x(3 x 240/120) 4x(3 x 120/70) 4x(3 x 120/70) 4x(3 x 185/95) 4x(3 x 185/95) 4x(3 x 240/120) 4x(3 x 240/120) 4x(3 x 240/120) Fuses [A] x 2 x 2 x x x 0 2 x 0 2 x x x 800 8

9 SET COMPUTER 8d-96 cos I (A) I(Ax10) d% Alarm SET SET COMPUTER 8d-96 cos I (A) I(Ax10) d% Alarm COMPUTER 8d-96 cos I (A) I(Ax10) d% Alarm AUTOMATICALLY CONTROLLED REACTIVE POWER COMPENSATION DEVICE Type: ASK - figures and dimensions ASK ASK ASK

10 AUTOMATICALLY CONTROLLED REACTIVE POWER COMPENSATION DEVICE Type: ASK - figures and dimensions ASK4-... ASK6-... ASK ASK

11 DIRECTLY CONTROLLED REACTIVE POWER COMPENSATION DEVICE Type: DSK - technical data and figures Nominal voltage and frequency: Max. allowed over-voltage: Max. allowed over-current: Operating temperature range: Cooling of compensation fields: Power losses: V, 50Hz-power circuit; 1,1xUn (nominal voltage), max. eight hours per day 1,3xIn (nominal current) - constant Average 24-hours temperature: + C Max. temperature: +40 C Min. temperature: -10 C Relative humidity:max. 95% (condensation not allowed) Natural airing Capacitors: max. 0,5 W/kvar Compensation device: max. 2W/kvar Mechanical protection IP: IP 31 IP 54 (optional) Colour: RAL 7032 In compliance with IEC and -2, SIST EN Table with technical data for single types: DSK1-... Nominal power [kvar] Type DSK1-10/ DSK1-15/ DSK1-20/ DSK1-25/ DSK1-30/ DSK2-40/ DSK2-50/ DSK2-60/ DSK2-75/ DSK2-90/ Feed cable cross-section Cu [mm 2 ] 4 x 6 4 x 6 4 x 10 3 x /16 3 x 70/ 3 x 95/50 Fuses [A] DSK Table with technical data for single types: (types with a fuse switch disconnector) Nominal power [kvar] Type DSK1-10/V DSK1-15/V DSK1-20/V DSK1-25/V DSK1-30/V DSK2-40/V DSK2-50/V DSK2-60/V DSK2-75/V DSK2-90/V Feed cable cross-section Cu [mm 2 ] 4 x 6 4 x 6 4 x 10 3 x /16 3 x 70/ 3 x 95/50 Fuses [A] DSK1-.../V DSK2-.../V 11

12 AUTOMATICALLY CONTROLLED HARMONIC FILTER Type: FASK - technical data Nominal voltage and frequency: 440V, 50Hz-power circuits for p= 5,5, 7, 8% 525 V, 50Hz-power circuits for p=12,5, 14% ;230 V, 50Hz-control circuits Max. allowed over-voltage: 1,1xUn (nominal voltage), max. eight hours per day Max. allowed over-current: 1,3xIn (nominal current) - constant Nominal values of measuring el. circuits: voltage measuring input: 230V, 50Hz current measuring input: 5A (through the current measuring transformer) Operating temperature range: Average 24-hours temperature: + C Max. temperature: +40 C Min. temperature: -10 C Relative humidity:max. 95% (condensation not allowed) Cooling of compensation fields: Ventilators Power losses: Capacitors: max. 0,5 W/kvar Compensation device: max 5W/kvar Mechanical protection IP: IP 31 IP 54 (optional) Colour: RAL 7032 In compliance with IEC and -2, SIST EN Filter circuit frequency 134(14%), 141(12,5%), 176(8%), 189(7%), 214(5,5%)Hz Table with technical data for single types: Nominal power [kvar] 25 31, , , Programme Type (*) 1:2:2 1:2:2 1:2:2:2... 1:2:2:2... FASK1-25/440-7 FASK1-31,25/440-7 FASK1-50/440-7 FASK1-62,5/440-7 FASK2-75/440-7 FASK2-87,5/440-7 FASK2-100/440-7 FASK2-/-7 FASK3-150/440-7 FASK3-175/440-7 FASK3-/440-7 FASK4-250/440-7 FASK4-275/440-7 FASK4-300/440-7 FASK4-0/440-7 FASK5-/440-7 FASK5-450/440-7 FASK6-500/440-7 FASK6-550/440-7 FASK6-/440-7 FASK6-650/440-7 FASK6-720/440-7 Configuration of capacitor units [kvar] 2x6,25+1x12,5 1x6,25+2x12,5 2x6,25+3x12,5 2x6,25+4x12,5 2x12,5+2,25 1x12,5+3x25 2x12,5+3x25 2x12,5+4x25 2x12,5+5x25 2x12,5+6x25 2x25+3x50 2x25+4x50 1x25+5x50 2x25+5x50 2x25+6x50 2x25+7x50 2x25+8x50 2x25+9x50 2x25x10x50 2x25+11x50 2x25+12x50 14x50 Feed cable cross-section Cu [mm 2 ] 3 x 70/ 3 x 95/50 3 x 95/50 3 x 120/70 3 x 150/70 3 x 185/95 3 x 240/120 2x(3 x 150/70) 2x(3 x 185/95) 2x(3 x 185/95) 2x(3 x 240/120) 2x(3 x 240/120) 4x(3 x 120/70) 4x(3 x 120/70) 4x(3 x 185/95) 4x(3 x 185/95) 4x(3 x 240/120) 4x(3 x 240/120) *Note: the stated types relate to the harmonic filter with the mostly used frequency of 189Hz. For other frequencies contact our technical department. Figures and dimensions are shown on pages 13 and 14. Fuses [A] x 2 x 2 x x x 0 2 x 0 2 x x

13 SET COMPUTER 8d-96 cos I (A) I(Ax10) d% Alarm AUTOMATICALLY CONTROLLED HARMONIC FILTER Type: FASK - figures and dimension FASK FASK

14 AUTOMATICALLY CONTROLLED HARMONIC FILTER Type: FASK - figures and dimension FASK3-... FASK5-... FASK FASK

15 DIRECTLY CONTROLLED HARMONIC FILTER Type: FDSK - technical data and figures Nominal voltage and frequency: 440V, 50Hz-power circuit for p=5,5 7, 8% 525V,50Hz-power circuit for p=12,5, 14% Max. allowed over-voltage: 1,1xUn (nominal voltage), max. eight hours per day Max. allowed over-current: 1,3xIn (nominal current) - constant Operating temperature range: Average 24-hours temperature: + C Max. temperature: +40 C Min. temperature: -10 C Relative humidity:max. 95% (condensation not allowed) Cooling of compensation fields: Natural airing Power losses: Capacitors: max. 0,5 W/kvar Compensation device: max. 5W/kvar Mechanical protection IP: IP 31 IP 54 (optional) Colour: RAL 7032 In compliance with IEC and -2, SIST EN Filter circuit frequency 134(14%), 141(12,5%), 176(8%), 189(7%), 214(5,5%)Hz Table with technical data for single types: Nominal power Type [kvar] 10 FDSK1-10/ FDSK1-15/ FDSK1-20/ FDSK1-25/ FDSK1-30/ FDSK1-40/ FDSK2-50/-7 60 FDSK2-60/ FDSK2-75/ FDSK2-90/ FDSK2-110/440-7 Feed cable cross-section Cu [mm 2 ] 4 x 6 4 x 6 4 x 10 3 x /16 3 x 70/ 3 x 95/50 3 x 120/70 Fuses [A] (*) Note: The stated types relate to the harmonic filter with the mostly used frequency of 189Hz. For other frequencies contact our technical department. FDSK FDSK

16 OUR SERVICES: Manufacturing: low-voltage compensation devices high-voltage compensation devices low-voltage switching systems, module and traditional types for industry and transformer stations Setting up: electrical power equipment managing electrical power installations transformer stations Service of: electrical power installations compensation devices Measuring: energy quantities and implementing registration of high harmonics in the network in terms of a correct setting of compensation and other devices Constructing: low-voltage switching systems d.o.o. ELEKTROTEHNI KO PODJETJE Leskoπkova cesta 12, 1000 Ljubljana, Slovenia Tel.: , Fax: , Mobil.: / , / enerprom@siol.net