HOWARD LECTURES: THE DISTRIBUTION OF POWER FROM CENTRAL STATIONS
THE BASIC ELEMENTS OF A POWER SYSTEM ARE SHOWN IN FIGURE 1 1 EACH OF THE ELEMENTS IS EQUIPPED WITH DEVICES FOR MANEUVERING, MEASUREMENT, PROTECTION, AND CONTROL THE NOMINAL FREQUENCY VALUE IS TYPICALLY 50 HZ (IN EUROPE) OR 60 HZ (IN THE UNITED STATES); THE MAXIMUM NOMINAL VOLTAGE RANGES 20–25 KV (LINE-TO-LINE VOLT- AGE) AT SYNCHRONOUS MACHINE TERMINALS; OTHER VOLTAGE LEVELS PRESENT MUCH LARGER VALUES (UP TO 1000 KV) FOR TRANSMISSION NETWORKS, THEN DECREASE FOR DISTRIBUTION NETWORKS AS DEPICTED IN FIGURE 1 1 GENERATION IS PREDOMINANTLY ACCOMPLISHED BY THERMAL POWER PLANTS EQUIPPED WITH STEAM TURBINES USING “TRADITIONAL” FUEL (COAL, OIL, GAS, ETC ) OR NUCLEAR FUEL, AND/OR HYDROELECTRIC PLANTS (WITH RESERVOIR OR BASIN, OR ?UENT-WATER TYPE) GENER- ATION ALSO CAN BE ACCOMPLISHED BY THERMAL PLANTS WITH GAS TURBINES OR DIESEL ENGINES, GEOTHERMAL POWER PLANTS (EQUIPPED WITH STEAM TURBINES), AND OTHER SOURCES (E G , WIND, SOLAR, TIDAL, CHEMICAL PLANTS, ETC ) WHOSE ACTUAL CAPABILITIES ARE STILL UNDER STUDY OR EXPERIMENTATION THE TRANSMISSION SYSTEM INCLUDES AN EXTENSIVE, RELATIVELY MESHED NETWORK A SINGLE GENERIC LINE CAN, FOR EXAMPLE, CARRY HUNDREDS OR EVEN THOUSANDS OF MEGAWATTS (POSSIBLY IN BOTH DIRECTIONS, ACCORDING TO ITS OPERATING CONDITIONS), POSSIBLE INTERCONNECTIONS TRANSMISSION EHV HV STEP-UP TRANSFORMER STEP-DOWN TRANSFORMER GENERATOR TURBINE SUPPLY SYSTEM AND VALVES EXCITATION SYSTEM GENERATION DISTRIBUTION USERS LV MV HV EXAMPLES OF NOMINAL LINE-TO-LINE VOLTAGES EHV TRANSMISSION HV DISTRIBUTION (OR SUBTRANSMISSION) MV DISTRIBUTION LV DISTRIBUTION HV TRANSMISSION 380 KV 220 KV 150 KV 132 KV 60 KV 30 KV 20 KV 15 KV 10 KV 380 KV 220 KV FIGURE 1 1 BASIC ELEMENTS OF AN ELECTRIC POWER SYSTEM (EHV, HV, MV, LV MEAN, RESPECTIVELY, EXTRA-HIGH, HIGH, MEDIUM, AND LOW VOLTAGE) HOWARD LECTURES: THE DISTRIBUTION OF POWER FROM CENTRAL STATIONS