例子pscad讲座-武汉

1、Introduction to HVDC Seminar周铮,王学恭Nov 2008Agenda HVDC Background and History HVDC Configuration and Equipment HVDC Basic Definitions / Equations HVDC AC system requirements Basic Conversion Process Simple Conversion Demo HVDC Controls and Power Transfer PSCAD Demo HVDC Controls System PSCAD demo sho

2、wing Control actions Why Use DC Transmission HVDC History 1929, 1950, 1954 Mature Technology and large worldwide interest (Show HVDC project Listings_IEEE) Smaller tower: 2 versus 3 conductors DC Lower Transmission Losses AC Line effects in overhead lines or Cables Control of Power Flow Directly Con

3、nect Areas with different freq. Or Freq Phase Control / Stability system support options Separation of Large Areas into Regions. USA blackout 2003 - did not impact Quebec RectifierInverter1 Valve group2 AC Filter3 Converter transformer4 DC filter5 Ground/sea electrode or metallic6 Receiving ac syste

4、m7 Sending ac system1345276+-PowerIdIdVd or EdManitoba Henday +/- 500 kV 2000 MW Cigre 2008 :Paper B4:117 Why Not Use DC High Cost of Conversion equipment Transformation and tapping power is not easy or possible Possible Harmonic Interference with Communication Circuits Ground currents (electrode) H

5、igh Reactive Power Requirements at each terminal Lack of skilled “specialty” workforce. HVDC Configurations Monopolar, Bipolar, with overhead line and / or cable Series groups, Parallel Poles Back to Back BTB Multi - terminal Voltage source (VSC) VSC HVDC VSC Voltage Sourced ConverterOperates into l

6、ow short circuit or even “dead” ac networks.IGBT technology today would allow hundreds megawatts. Both ABB HVDC Light and Siemens HVDC Plus are talking about 1000-2000MW VSC schemes Thyristor Characteristics Positive voltage Anode to Cathode Gate or Firing Pulse Cannot stop current except at current

7、 zeroFundamentals of Convertor Operation Three Phase Graetz Bridge 3 Phase 6 Pulse Bridge Basic HVDC Building Block Go to Commutation PresentationDiode Natural Commutation V1 +, V2-, V3 +, V4 -, V5+, V6-, V1 + Defined as Alpha = 0 Ideal Waveforms, No Delay 6P Operation Use Simple6P ExampleBasic Wave

8、forms 6PIncludes Effect of Commutation Reactance Current cannot change Instantly Effective voltage drop Adds Notching to Voltage Waveforms Why do we need commutation Reactance? Firing Angle Thyristors = Delay in firing, as long as voltage is positive anode to cathode. Delay angle Alpha 0 Alpha 90 Re

9、ctifier 90 Alpha 2.5 Low 1.5 2.5 Very Low 1.5 AC System Impacts System Strength Definitions Show Build Current controller with 12 Pulse Rect case HVDC Control SystemsIdXcEllVd*cos(*35. 1 =aBasic HVDC Transmission SystemId = (Vrec-Vinv / Rline) Pd = Vd * Id Vd Id CharacteristicsVdId = minRectifier and inverterConstant =18 Id=.1 PuHVDC Control DiagramsVDCOL (Voltage Dependent Current Order Limit) Overall Block Diagram Use HVDC 1 case Sources of Reactive Power AC Filters Shunt Capac