DIPLOMA THESIS. AGH University of Science and Technology

Transcription

1 AGH University of Science and Technology Faculty of Electrical Engineering, Automatics, Computer Science and Biomedical Engineering Department of Power Electronics and Energy Conversion Systems Automation Postgraduate Studies Electrical Power Quality DIPLOMA THESIS Analysis of the Power Network at the Point of Connection of Two Hoist Machines Converter Drives Name: Place of employment: MSc Eng. Klaudiusz Borkowski Polkowice-Sieroszowice" Mine KGHM S.A. Thesis supervisor: Prof. Zbigniew Hanzelka, PhD Eng. Andrzej Firlit, PhD Eng. Krzysztof Piątek Kraków 2012/2013

2 Contents: 1. Introduction The objective of the Thesis Power quality assessment criteria Methods for filtering high harmonics in power systems supplying thyristor converters of hoist machines drives Passive LC filters Description of the investigated plant The east shaft compartment hoist machine harmonic filter The west shaft compartment hoist machine harmonic filter Measurements Results of measurements at the point of connection of the east compartment hoist machine to 6 kv network Results of measurements at the point of connection of the west compartment hoist machine to 6 kv network Summary and conclusions Appendix References

3 1. Introduction The analysis of electrical power quality is aimed at improving power systems performance. A reliable analysis of power quality allows determining investment needs and their scope, so that a network could be operated continuously and in compliance with relevant standards. A correct analysis and measurements require the use of both the adequate instrumentation and measurement algorithms. Hoist machines are the most important and the largest electrical loads in underground copper mines. They are used for both men and material transport. Since rated powers of hoist machines are of the order of megawatts, their impact on a power network shall not be neglected. They are chiefly DC drives supplied from thyristor converters having a considerable impact on the power supply network. Hence the topic of this diploma thesis: "Analysis of a Power Network at the Point of Connection of Two Hoist Machines Converter Drives" has been proposed. 2. The objective of the Thesis The objective of this thesis are measurements and analysis of the power network key parameters and assessment of electrical power quality at the points of connection of two hoist machines drives to 6 kv grid, as well as the assessment of operation of two harmonic filters of different configurations and operating with identical drive systems. 3. Power quality assessment criteria According to the definition of the Advisory Committee on Electromagnetic Compatibility (IEC) the quality of electrical power is a set of technical parameters describing the process of power delivery to a consumer under normal operating conditions, characterizing the supply voltage (magnitude, symmetry, frequency, waveform). Relevant procedures, standards and regulations: Polish Standard PN-EN "Voltage characteristics of electricity supplied by public distribution networks", Polish Standard, PN-IEC , PN-IEC and PN-IEC , The Regulation of the Minister of Economy of May 4, 2007 on detailed conditions for the operation of the power system (Dz.U. [Journal of Laws] No. 93, item 623 of May 29, 2007). The quality of power is determined by the set of parameters of the supply voltage at the consumer's terminals. Measurements performed in order to evaluate/asses the quality of 3

4 transient states overvoltages power utilize advanced instrumentation (power quality analysers/recorders) that measure and record a large amount of data over a specified period of time (days, weeks, months). The measurement results are processed in order to determine power quality parameters that are not "directly" available from voltage and current measurements, e.g. total harmonic distortion (THD). THD where: U 1, U i rms value of the first and i-th harmonic, respectively. U i 2 U U 1 2 i Power quality recorders from all manufacturers are compliant with relevant standards that specify the methods for computing power quality factors. Using the collected voltage and current samples power quality recorders compute the measured quantities root mean square, minimum, average and maximum values over various time intervals: 200 ms, 3 s, 1 min, 10 min. In terms of the quality of electrical power it is necessary to know the values averaged in 10-minute intervals, according to the standard PN EN A graphical representation of disturbances in the coordinate system: the disturbance time vs. voltage amplitude, as per standard PN EN , is shown in Fig Urms[%] 110% temporary power frequency overvoltages 90% voltage magnitude variations (quantile 95%) voltage dip 1% short supply interruption 0, long supply interruption t [s] Fig Classification of voltage disturbances with respect to their duration and the voltage rms value The most important values and parameters needed for a correct power quality analysis are: rms voltage value, long-term flicker indicator P LT, supply voltage asymmetry, total harmonic voltage distortion factor THD U, supply voltage harmonics, supply voltage frequency. 4

5 Usually a report prepared after the analysis includes also: total harmonic current distortion factor THD I, current harmonics, active, reactive and apparent power, power factors: tgφ, PF, DPF. The parameters that, according to standard PN EN 50160, may be additionally included into the power quality analysis report do not confirm the quality of power but can be useful for locating the sources of an event and/or a disturbance. Also the power factor tgφ is not a power quality index. The electricity supplier is obliged to comply with contractual power quality indices as specified in the so-called "System regulation" (Regulation of the Minister of Economy of May 4, 2007 on detailed conditions for the operation of the power system) provided that that reactive power consumed by a customer shall be not greater than the contracted power at the power factor tgφ not exceeding Methods for filtering high harmonics in power systems supplying thyristor converters of hoist machines drives DC Converter drives of hoist machines have a considerable impact on the power supply network due to their principle of operation. They are non-linear loads that generate high harmonics and emit voltage disturbances to distribution network. A large-power hoist machine drive comprises two series-connected 6-pulse thyristor bridges (Fig. 4.1). Each bridge is supplied from a separate transformer having different connection group. Such configuration provides 12-pulse influence on supply network and thus reduces negative impact on the network. Normally both bridges are controlled simultaneously, i.e. thyristor control angles (delay angles) are equal. The lowest order harmonic of the source current of such converter is the 11-th harmonic, and converter generates the source current characteristic harmonics of orders: h = 12m ± 1, where m=1,2,.. 5

6 Fig Schematic diagram of a complex 12-pulse converter Thyristor converters supplying DC motors, particularly those of large powers, adversely impact the supply network and give rise to unwanted effects: Increased reactive power consumption. The reactive power varies with time because its value is a function of the rectified voltage average value. During a motor start, when the motor voltage is close to zero, occurs the so-called power surge, with magnitude exceeding the motor rated power that which considerably loads the supply network. Current harmonics in feeder lines due to the current waveform distortion. Commutation notches in the line voltage caused by converter operation. It can be assumed that adverse impact on the supply network is directly proportional to the converter drive power and inversely proportional to the supply network short-circuit capacity and also to the distance between the source and the load. A number of solutions can be employed to mitigate the adverse impact of a converter drive on the supply network, e.g.: modification of the converter drive configuration complex converters, e.g. 12- pulse, appropriate control of converter bridges the sequence control, high-order harmonics filters, follow-up compensation of reactive power. 6

7 Harmonic reduction methods Increased short-circuit capacity at PCC Activ Harmonics filters Passive Appropriate transformer Reduction of high-order harmonics in load current e.g. converters Hybrid Active input interfaces Converter current shaping Passive circuits Active input current shaping Magnetic methods Unity power factor converters Multi-pulse converters Fluxes compensation Fig Methods for mitigation of harmonics effects There are practically two types of technical solutions for high-order harmonics elimination and reactive power compensation in power networks supplying converters of large-power hoist machines drives: passive LC filters, active filters, less often. 4.1 Passive LC filters One of the methods for high-order harmonics filtering consists in connecting passive LC filters in parallel with the supply network; each LC filter comprises a series-connected reactor and capacitor (Fig. 4.3). Selection of L and C elements parameters depends on their series resonant frequency, adjusted to the filtered harmonic order. Filters and supply network impedance supply network impedance Fig A passive LC filter and its frequency characteristic 7

8 Since under the series resonance conditions the impedance of LC filter branch is very small (it approximately equals the reactor winding resistance), harmonic currents with frequencies close to the resonant frequency are to a large extent flowing in the converter filter branch circuit. The resonance frequency of an LC filter is: 1 f R 2 L C The reactance of series-connected L and C elements is: X ( h) X X where: h - the harmonic order j, hx X h X 2 2 h F h F C F L C L C 2 F 2 - the filter natural relative frequency F = X C /X L, X C - the filter capacitor reactance for the fundamental harmonic, - the filter reactor reactance for the fundamental harmonic. X L An LC resonant filter with parameters adjusted to the fundamental harmonic presents a capacitive load for harmonics of orders lower than the resonant frequency and for higher order harmonics it presents an inductive load. The resonant frequency current flows in the filter - converter circuit and not in the power network. For the fundamental harmonic the high frequency filter has a capacitive character and it thus functions as a reactive power compensator. 5. Description of the investigated plant Each hoist machine drive is supplied from two converter transformers with rated powers of 2.5 MVA and connection groups Dyn11 and Dd0. Trnsformers are connected by means of busbars with thyristor converters of ABB make, type DCS600, connected in series that supply an armature of a 3 MW separately excited DC motor of the hoist machine. The motor field winding is supplied from a thyristor reversible converter, which by means of reversing the excitation current enables reversing the direction of the hoist machine rotation. Functions of the hoist machine logical control and the speed control are performed by master computer software. The trigger pulses phase-shift of each converter is digitally controlled and set by software in the internal electronic pulse angle control system. One of the converters functions as master and generates control signals, whereas the second converter (slave) operates according to the master control signals. 8

9 Fig Schematic diagram of both hoist machines drive system 5.1 The east shaft compartment hoist machine harmonic filter For the purposes of filtering the harmonics generated by the east compartment hoist machine drive has been installed in 2000 a passive filter bank consisted of three 5-th, 7-th and 11-th harmonic filters. The filter bank total power is 2.2 MVA at rated voltage of 6.3 kv. Detailed filter parameters are provided below. The 5-th harmonic filter: Total reactive power generated by the 5-th harmonic filter is 847 [kvar] at 6.3 [kv], 50 [Hz]. Table 1. The 5-th harmonic filter capacitor bank ratings: Nominal power 1.05 [Mvar] Nominal voltage Configuration 6.65 [kv] Y (The capacitor bank comprises 3 single-phase capacitors impregnated with impregnating compound, under brand name FARADOL 600) Table 2. The 5-th harmonic filter capacitor ratings: Nominal capacitance Nominal power Nominal voltage Nominal current [μf] 1 x [kvar] [kv] 86.9 [A] Table 3. The 5-th harmonic reactor ratings: Nominal voltage Nominal current Nominal inductance 6.0 [kv] 86.0 [A] [mh] 9

10 The 7-th harmonic filter: Total reactive power generated by the 7-th harmonic filter is 434 [kvar] at 6.3 [kv], 50 [Hz]. Table 4. The 7-th harmonic filter capacitor bank ratings: Nominal power 0.49 [Mvar] Nominal voltage 6.69 [kv] Configuration Y Table 5. The 7-th harmonic filter capacitor ratings: Nominal capacitance Nominal power Nominal voltage Nominal current 34.6 [μf] 1 x [kvar] [kv] 42.0 [A] Table 6. The 7-th harmonic reactor ratings: Nominal voltage Nominal current Nominal inductance 6.0 [kv] 42 [A] [mh] The 11-th harmonic filter: Total reactive power generated by the 7-th harmonic filter is 863 [kvar] at 6.3 [kv], 50 [Hz]. Table 7. The 11-th harmonic filter capacitor bank ratings: Nominal power 1.05 [Mvar] Nominal voltage Configuration 6.95 [kv] Y Table 8. The 11-th harmonic filter capacitor ratings: Nominal capacitance Nominal power [μf] 1 x [kvar] Table 9. The 11-th harmonic reactor ratings: Nominal voltage Nominal current Nominal inductance 6.0 [kv] 87 [A] [mh] 10

11 Fig Schematic diagram of the harmonic filter FA The west shaft compartment hoist machine harmonic filter For the purposes of filtering harmonics generated by the west compartment hoist machine drive has been installed in 2002 a two-branch passive filters bank comprising two branches: the 11-th and 13-th harmonic filters. The total filter bank power is 1.8 MVA at rated voltage of 6.3 kv. Detailed filter parameters are provided below. The 11-th harmonic filter: Total reactive power generated by the 5-th harmonic filter is 847 [kvar] at 6.3 [kv], 50 [Hz]. Table 10. The 11-th harmonic filter capacitor bank ratings:: Capacitance [μf] Nominal power Nominal voltage Nominal current Configuration 1046 [kvar] 7 [kv] [A] Y Table 11. The 11-th harmonic filter capacitor ratings: Nominal capacitance Nominal power Nominal voltage [μf] [kvar] 4.01 [kv] Table 12. The 11-th harmonic reactor ratings: Nominal voltage Nominal current Nominal inductance 6.0 [kv] 100 [A] 1.2 [mh] 11

12 The 13-th harmonic filter: Total reactive power generated by the 13-th harmonic filter is 847 [kvar] at 6.3 [kv], 50 [Hz]. Table 13. The 13-th harmonic filter capacitor bank ratings: Capacitance [μf] Nominal power 1046 [kvar] Nominal voltage Nominal current Configuration 7 [kv] [A] Y Table 14. The 13-th harmonic filter capacitor ratings: Nominal capacitance Nominal power Nominal voltage [μf] [kvar] 4.01 [kv] Table 15. The 13-th harmonic reactor ratings: Nominal voltage Nominal current Nominal inductance 6.0 [kv] 100 [A] 0.9 [mh] Fig Schematic diagram of high-order harmonics filter FB.1 12

13 6. Measurements The measurements were carried out in two switchgear fields supplying the hoist machines 6 kv switchgear and also in outgoing feeders to harmonic filters. In order to investigate the influence of hoist machines drives on the 110 kv measurements were also carrid out at metering points in the 110/6 kv transformer substation. Measurement point B Measurement point B.1 Measurement point A Measurement point A.1 Fig Diagram of the examined 110/6 kv network with indicated measurement points 13

14 Further below 6.1 Results of measurements at the point of connection of the east compartment hoist machine to 6 kv network General information Location of measurements Feeder section 1 of 6 kv switchgear Hoist machine - east compartment Analyzer PQM-701 Measurements Start: 18: Duration: Stop: 18: week Number of samples 998 Type of network IT Frequency 50 Hz Nominal line voltage 6 kv General statistical data Supplementary information - events OVERVOLTAGES Parameter Unit L1 L2 L3 Comments Number none Maximum value V none Maximum duration s none VOLTAGE DIPS Parameter: Unit L1 L2 L3 Comments Number Maximum value V Maximum duration s

15 Analysis of recorded voltage dips: According to the standard specification the duration of a voltage dip is 10 ms to 1 minute. During the measurements were recorded two successive voltage dips with duration of 90 ms and separated by a time interval of 1 s. During these dips the line voltage in phases L1 and L2 was reduced to the residue voltage value of 1997 V (57% U n ). In result of these dips one of three currently operating fans at the shaft main ventilation fan station was turned out. Fig The instantaneous and rms values of the voltage and current during the first voltage dip Fig The instantaneous and rms values of the voltage and current during the second voltage dip From the above time characteristics it is evident that along with the voltage reduction the current also decreases thus the dip source is located upstream the measurement point. During the measurements were also recorded overvoltages with magnitudes approaching +10%U n. They resulted mostly from the hoist machine stop (no load) and FA.1 filter energizing. Figure 6.4 shows the instant of the harmonic filter FA.1 switching to power supply network. 15

16 Fig The instantaneous and rms values of the voltage and current during and overvoltage (switching-on FA.1) Time characteristics and spectra of selected recorded parameters: 16

17 rms harmonic value FWH wyłączony 32A 11A 20A 9,8A Fig Spectra of voltage and current harmonics in the incoming feeder of the east compartment hoist machine feeder field (harmonic filter switched OFF) Table 16 Effectiveness of the filter FA.1 Filter FA.1 No. Harmonic Off On Effectiveness [A] [A] 1 5-th None 2 7-th None 3 11-th % 4 13-th % 5 23-th % 6 THD I 55% 8% 85% Comments FWH załączony 2A 6A 5A Fig Spectra of voltage and current harmonics in the incoming feeder of the east compartment hoist machine (harmonic filter switched ON) 17

18 Figure 6.5 confirms that with the filter FA.1 switched-off only characteristic harmonics, generated by the hoist machine drive, occur in the voltage and current supplying section 1 of the 6 kv switchgear. When the filter FA.1 is switched-on the characteristic harmonics are effectively attenuated. Figure 6.7 shows the voltage and current harmonics recorded in the outgoing feeder to FA.1. It is evident that the filter works correctly and harmonic currents are flowing through it I H11 = 32A (practically 100% of the generated harmonic current) I H13 = 16A. 32A 16A 7A Fig Spectra of voltage and current harmonics in the outgoing feeder to FA.1 Fig Waveforms of selected harmonics recorded in the incoming feeder of the east compartment hoist machine with filter FA.1 switched-off 18

19 Fig Waveforms of selected harmonics recorded in the incoming feeder of the east compartment hoist machine with filter FA.1 switched-on The voltage and current harmonics waveforms and their rms values (Fig. 6.8 FA.1 switched off and Fig.6.9 FA.1 switched on) illustrate the variability in time of generated harmonics and confirm the converter drive dynamics and its influence on the supply network. After switching the harmonics filter on, the 11-th harmonic (attenuated by the filter) is no longer the predominant one. The largest is the next characteristic harmonic, i.e. the 13-th harmonic, which is not attenuated by the filter. Fig The active and reactive power measured in the incoming feeder of the east compartment hoist machine with filter FA.1 switched off Figure 6.10 shows the active and reactive power recorded at the hoist machine 6 kv switchgear incoming feeder. Variation of these powers is strongly correlated with the hoist machine operating cycle. At the instant of start occurs a reactive power surge up to its maximum value. As follows from the recorded waveforms, the reactive power compensation is at the 2 Mvar level (approximately equal to the capacitor bank rated power). 19

20 Reactive power increases the loading of transmission line. After switching-on the harmonic filter the current at the hoist machine 6 kv switchgear incoming feeder has decreased by about 100 A during a steady phase of the operating cycle, whereas during the machine starting it has decreased from an average value of 600A to 450A (the start duration is 23s). Fig The current in the hoist machine switchgear incoming feeder 6.2 Results of measurements at the point of connection of the west compartment hoist machine to 6 kv network General information Location of measurements Feeder section 2 of 6 kv switchgear Hoist machine - west compartment Analyzer PQM-701 Measurements Start: 18:12: Duration: Stop: 18:12: week Number of samples minute averaging Type of network IT Frequency Nominal line voltage 50 Hz 6 kv General statistical data 20

21 Wavef orms below Supplementary information - events OVERVOLTAGES Parameter: Unit L1 L2 L3 Comments Number Maximum value: V Maximum duration s SHORT SUPPLY INTERRUPTIONS Parameter: Unit L1 L2 L3 Comments Number none Maximum duration s none LONG SUPPLY INTERRUPTIONS Parameter: Unit L1 L2 L3 Comments Number none Maximum duration s none VOLTAGE DIPS Parameter: Unit L1 L2 L3 Comments Number none Minimum value V none Maximum duration s none 21

22 Analysis of overvoltages at busbars of section 2 of the 6 kv switchgear supplying the west compartment hoist machine. Fig The voltage and current rms values and waveforms recorded during an overvoltage Figure 6.12 shows the overvoltage that occurred probably at the instant of switchingon the filter FB.1. The overvoltage duration is short but its amplitude attains the value close to the capacitors' rated voltage (U N = 4 kv) that may lead to the FB.1 filter capacitor bank failure. 22

23 Waveforms of selected recorded parameters: 10-minute averaging Fig Variation of THD U at the measurement point B Variation of total harmonic distortion factor THD after switching off the filter FB.1 illustrate a high distortion level due to the current harmonics generated by the hoist machine drive system. During 95% of the recording time period the harmonic current distortion factor THD I is 76% and harmonic voltage distortion factor THD U is 9%. When the filter is switchedon, a considerable reduction in harmonic distortion factors is observed: THD I to CP95 value 18% and THD U CP95 value 2.6%. The power network voltage and current harmonic content of the power network voltage and current shows that the hoist machine thyristor converter generates solely characteristic harmonics, dominant in the harmonic spectrum. When the filter FB.1 is switched-off the I h11 constitutes ca. 10% of I h01 and I h13 ca. 6% of I h01. After switching-on the filter FB.1 characteristic harmonics are significantly reduced, whereas magnification of the 5- th harmonic, and particularly of the 7-th harmonic, is observed. 23

24 rms harmonic value FWH wyłączony 17A 1,2A 4,6A Fig Spectrum of voltage and current harmonics at the measurement point B the filter FB.1 switched off FWH wyłączony 17A 1,2A 4,6A Fig Spectrum of voltage and current harmonics at the measurement point B - the filter FB.1 switched on Table 17 Effectiveness of the filter FB.1 Filter FB.1 No. Harmonic Off On Effectiveness Comments [A] [A] 1 5-th None 2 7-th 1 17 Amplification 3 11-th % 4 13-th % 5 23-th % 6 THD I 76% 18% 76% CP95 24

25 From the harmonic spectrum of the current flowing from the 6 kv field it can be found that the filter effectively attenuates characteristic harmonics whereas the 7-th harmonic, which in this circuit is practically negligible, is amplified. 34A 18A 21A 9A Fig Spectrum of the voltage and current harmonics recorded at the measurement point B1 From the data listed in table 17 it is evident that the filter FB.1 efficiently reduces characteristic harmonics generated by the hoist machine drive. The filter branches tuned to the 11-th and 13-th harmonic attenuate 96% and 77% of these harmonics, respectively. The waveforms of current harmonics with the filter FB.1 switched off are shown in Fig The most clearly visible waveforms are those of the 11-th, 13-th, 23-th and 25-th harmonics, strongly correlated with the with the hoist machine operating cycle and the fundamental harmonic current waveform. Upon switching the filter FB.1on, these harmonics are reduced, whereas the 7-th harmonic is amplified, cf. Fig

26 Fig The current harmonics waveforms recorded in the switchgear field No. 9 with the filter FB.1switched off Fig The current harmonics waveforms recorded in the switchgear field No. 9 with the filter FB.1 switched on Because the filter FB.1 branches are tuned to the 11-th and 13-th harmonics, a parallel resonance for lower order harmonics, i.e. the 5-th and 7-th, may occur. 26

27 Harmonic filter ON FWH załączony FWH wyłączony Harmonic filter OFF Fig The active and reactive powers and cos recorded at the measurement point B 7. Summary and conclusions The performed measurements and analyses demonstrate that the stated objectives have been achieved. Analysis of measurement results allows concluding that the installed filters enable to mitigate the converter's adverse impact on the supply network. In the case of the west compartment hoist machine drive all parameters contained in the power quality report have met the requirements of standard PN EN 50160, whereas in the case of the east compartment hoist machine drive only the long term flicker severity index P LT has not been contained within the limits specified in the standard. Two different approaches to the filtering problem have been adopted by the companies that in supplied the hoist machines drive systems together with harmonic filters. The first one consist in erection of the 5-th, 7-th and 11-th harmonic filter for the east compartment hoist machine has reduced the FA.1 role to reactive power compensation, rather than high order harmonics filtering (the 5-th, 7-th do not occur in the power network). This solution, though it may be considered conservative, is a safe solution due to the filter detuning from a possible occurrence of a dangerous resonance in the network. The second approach consists in installing the filter of two characteristic harmonics, i.e. the 11-th and 13-th harmonics generated by the hoist machine 12-pulse converter drive. That solution, however, did not enable avoiding magnification of the not filtered 7-th harmonic, whose magnitude increased considerably after switching the FB.1 filter on. Both filters function as reactive power compensators that have beneficial influence on the power network and increase transmission lines capacity. Figure 7.1 shows the current at the 6 kv switchgear sections 1 and 2 incoming feeder with filters FA.1 and FB.1 switched on and off It can be seen that the current has been reduced by ca A. 27

28 ,7 0,6 0,5 [ka] Wyłączony FA.1 OFF filtr Załączony FA.1 ON filtr [ka] FB.1 OFF FB.1 ON 0,4 0,3 0,2 0,1 0 East compartment West compartment Fig. 7.1 The 6 kv switchgear incoming feeder current The difference between maximum current values during the hoist acceleration period, results from the thyristor converters currents limits set at 150% I n for the east compartment and 140% I n for the west compartment (where I n is the hoist machine DC motor rated current, equal 4050 A). During further modernizations FC+TCR systems it may be taken into consideration, which apart of harmonics filtering provide follow-up compensation of reactive power with the response time of ca. 1.6ms to reactive load changes. 28

29 8. Appendix Thyristor Kąt wysterowania control angle tyrystorów Armature Prąd twornika current Armature Napięcie twornika voltage Prędkość Speed napędu Fig Correlated time characteristics of the control angle and reactive power during a single operating cycle of the east compartment hoist machine As follows from figure 8.1, at the instant of the hoist machine start the control angle is ca. 82 and the surge of reactive power (exceeding the motor rated power) occurs. 29

30 Armature voltage Armature current Prąd twornika Napięcie twornika Speed Prędkość Thyristor control angle Kąt wysterowania tyrystorów Fig Correlated time characteristics of the control angle and reactive power during a single operating cycle of the west compartment hoist machine Figure 8.2 illustrates a situation similar to that shown in Fig. 8.1 but for the west compartment hoist machine drive. Also in this case the reactive power surge occurs at the instant of the hoist machine start. 30

31 9. References 1. Zbigniew Hanzelka - Jakość energii elektrycznej (Power Quality)- Parts 1-6 Seminar Materials, 2. Stanisław Piróg - Energoelektronika - układy o komutacji sieciowej i o komutacji twardej, 3. Ludgier Szklarski, Jacek Zarudzki - Elektryczne maszyny wyciągowe, 4. PN EN Voltage characteristics of electricity supplied by public distribution networks, 5. PN-EN Electromagnetic compatibility (EMC) - Part 2-4: Environment - Compatibility levels in industrial plants for low-frequency conducted disturbances, 6. PN-EN Electromagnetic Compatibility (EMC) Part 4-30: Testing and Measurement Techniques - Power Quality Measurement Methods, 7. PN-EN Electromagnetic compatibility (EMC) Part 4: Testing and measurement techniques. Section 15: Flickermeter Functional and design specifications, 8. PN-EN Electromagnetic Compatibility (EMC) Part 4-7: Testing and measurement techniques General guide on harmonics and interharmonics measurements and instrumentation, for power supply systems and equipment connected thereto, 9. ABB Company materials - Power factor correction and harmonic filtering in electrical plants - 1SDC007107G0201, 10. Ryszard Strzelecki, Henryk Supronowicz - Filtracja harmonicznych w sieciach zasilających prądu przemiennego, &cHash=fef671a066&type=98, 12. Piotr Nowak - Pasywne filtry wyższych harmonicznych The ELMA capacitors Company, 13. Klempka Ryszard - Projektowanie grupy filtrów prostych, 14. Marcin Szlosek - Zastosowanie sieci neuronowych do rozpoznawania zaburzeń elektromagnetycznych i pomiaru ich ilościowych wskaźników 31