Electrical Power Distribution (CDEE)

Transcription

1 Lecturer: Ing. Martin Paar, Ph.D. Transmission and distribution networks in the Czech Republic Electrical Power Distribution (CDEE) e-power - Inovace výuky elektroenergetiky a silnoproudé elektrotechniky formou e-learningu a rozší ení prakticky orientované výuky, íslo: CZ.1.07/2.2.00/

2 Power System in the Czech Republic

3

4 Level of voltage in the Czech Republic UHV ( kv) 400 kv HV ( kv) 220 kv HV ( kv) 110 kv MV (1-52 kv) 22 (35) kv 10 kv 6 kv LV ( V) 0,4 kv Transmission networks supergrid Distribution networks Distribution and transmission character

5 Installed power Total installed capacity in the Czech Republic 20,520 MW ( ) From: Energy regulatory office

6 Installed power (2010) From: EPS, a.s.

7 Installed power Abbreviations: TPS - Thermal Power Station (coal only) CCGT - Power Station with Combine Cycle Gas Turbine SCGT - Power Station with Simple Cycle Gas Turbine NPS - Nuclear Power Station HPS - Hydro Power Station (without PSPS) PSPS Pumping Storage Power Stations (hydro) FPS Photovoltaic Power Station WPS Wind Power Station

8 Electricity generation in the Czech Republic From: Energy regulatory office

9 Development of electricity consumption the national economy by sector [GWh] From: Energy regulatory office

10 From: EPS, a.s. The gross energy production in the CR since 1986

11 Monthly maximum and minimum consumption in year 2012 [MW] Annual load maximum: 11,324 GW at 12 p.m. on 7 February Annual load minimum: 4,447 GW at 6 a.m. on 12 August From: Energy regulatory office

12 Development of electricity exports and imports (billed values) From: Energy regulatory office

13 Gross consumption on annual peak load days between 2005 and 2012 From: Energy regulatory office

14 The International co-operation annual energy flows in 2010 From: EPS, a.s.

15 Basic parameters of power system

16 Load Diagram (Load Curve) Shows the power (input) curve in dependence on time: - year (8760 hours), - month (720 hours), - week (168 hours), - day (24 hours). The amount of consumed energy is proportional to the curve area: W T 0 P( t) dt

17 Characteristic values of yearly load diagram

18 Maximum load P m - mean value of power during a period of 15 minutes in which the highest amount of electrical energy has been supplied Average load P s - the average power in a monitored period by which the same amount of energy would be taken off: P s T P( t) dt 0 T

19 Characteristic values of yearly load diagram

20 Peak demand utilization hours T m - the time during which (with demanded P m ) the same amount of energy would be taken off as during the time variable take-off in a given period: T P dt t P T dt t P T P m T m T m m 0 0 ) ( ) (. Utilization time of power losses T - the time during which maximum demanded current causes the same losses as the time variable current in a monitored period: max max ) ( ) ( ) ( ) (... m T T T P dt t P I dt t I T dt t R I T R I

21 Transmission and Distribution Lines

22 Transmission-Line Design two basic types: overhead lines cable lines overhead lines consist of conductors insulators support structures shield wires

23 Electrical lines Overhead lines in transmission systems that means voltage levels 400 kv, 220 kv, 110 kv, in distribution lines it means voltage levels 110 kv, 35 kv, 22kV The line consist from - towers construction (casket, cat, portal, ) function(guyed tower, stright-line tower, ) - conductors AlFe, Al and Cu ropes

24 Conductors aluminum or copper or steel steel-reinforced aluminum conductor (ACSR)

25 Bundled conductors are used for ultra-high voltage lines (220 kv and more) have more than one conductor per phase Bundled conductors have a lower electric field strength at the conductor surfaces, which limits corona a smaller series reactance

26 Support structures (poles or towers) construction (casket, cat, portal, ) function (guyed tower, straight-line tower, ) material of towers (wood, concrete, steel)

27

28 Latticed steel towers: 110-kV-line tower 400-kV-line tower

29 Cat - guyed (tension) tower

30 Delta - straight-line tower

31 Casket - straight-line tower

32 Detail of straight-line tower hanger

33 Detail of guyed tower hanger

34 MV Guyed tower with the artificial earth fault

35 Shield wires protect the phase conductors against lightning, they are grounded to the tower usually steel, with smaller cross section than the phase conductors

36 Cable line (MV, HV, UHV) Divide e.g.: voltage level material of core (Al, Cu) number of cores (one-core, three-cores) material and performance of insulation - oil impregnated paper - compressive oil and gas cables - XLPE cables type of shielding (Cu thin wires, belts) external insulation (PE,PVC + flame retardant)

37 HV Cables Three core 15 kv XLPE Cable Single core XLPE 12,7/22 kv Cable 2500 mm kv XLPE cable

38 HV Cable

39 Cables

40 Line design Transmission and distribution line design is based on optimization of: electrical factors mechanical factors environmental factors economic factors

41 Electrical design type, size and number of bundle or single conductors per phase phase conductors are selected to have sufficient thermal capacity to meet continuous, emergencyoverload and short-circuit current ratings number of bundle conductors per phase is selected to control the voltage gradient at conductor surfaces in order to reduce or eliminate corona

42 Electrical design Conductor spacing, types and sizes determine: the series impedance (affecting line-voltage drops, I 2 R losses and stability limits) the shunt admittance (affecting line-charging currents that inject reactive power into the power system)

43 Mechanical design strength of conductors, insulator strings and support structures conductors must support a specified thickness of ice and a specified wind in addition to their own weight

44 Environmental factors land usage visual impact biological effects of prolonged exposure to electric and magnetic field near transmission lines

45 Economic factors Optimum line design meets all the technical design criteria at lowest overall cost (including the total installed cost of the line and the cost of line losses over the operating life of the line)

46 Transmission-Line Parameters Longitudinal impedance Transversal admitance Four line parameters series resistance (R [ ]) series inductance (L [H]) shunt conductance (G [S]) shunt capacitance (C [F])

47 These four parameters can be expressed in form of two complex parameters series impedance Z R j L R jx angular velocity [rad.s -1 ] X inductive reactance [ ] shunt admittance Y G j C G jb S B capacitive susceptance [S]