Comprehensive Notes – Electrical Power Systems, Generation Technologies, Transmission & Instrumentation

1. Overview of an Electrical Power System (Sistem Tenaga Listrik)

• A single, integrated arrangement of generation units, transmission lines, distribution networks and loads designed to supply electrical energy to end-users.

• High-level block (see Figure 1 in transcript):

  • Generation (Pembangkit)

  • Transmission (Transmisi)

  • Distribution (Distribusi)

  • Load/Beban (Utilization)

• Principal objectives: reliability, quality (stable $V$ & $f$), safety, economy.

2. Major Components and Their Functions

2.1 Generation (Pembangkit Tenaga Listrik)

2.1.1 Hydroelectric Power Plant (PLTA)

• Energy source: potential & kinetic energy of water (head $H$ & flow $Q$).

• Basic energy chain: Water → Turbine → Generator → Electricity (3-φ, AC).

• Prime movers (“runner”):

  • Pelton (impulse) – H > 300\,\text{m}, small $Q$.

  • Francis – medium/large $Q$, medium–high $H$.

  • Kaplan (propeller, adjustable blades) – large $Q$, low $H$.

• Core subsystems:

  • Reservoir (waduk/KTH)

  • Water conveyors: tunnel (underground) & penstock (steel, surface)

  • Powerhouse machinery: Turbine, Generator, Transformer, Auxiliaries

  • Tail race (water return)

• Plant layouts:

  • Run-of-River, With Daily Pond (Kolam Tando), With Large Reservoir, Lake Outlet, Tidal, Pumped-Storage, Cascade (multi-plant series)

• Generator thrust-bearing configurations: Biasa, Payung, Semi-Payung, Penunjang Bawah (Saguling uses Semi-Payung).

• Main hydropower civil structures & auxiliaries:

  • Dam categories: Concrete (Gravitational, Arch, Hollow), Earth-fill, Rock-fill, Steel, Timber.

  • Spillway (must pass $1.2\,Q_{\text{flood}}$), Bottom Outlet, Intake & Trash Rake, Headrace Tunnel, Surge Tank, Penstock, Powerhouse.

  • Turbine auxiliary systems: Lubrication, Cooling, Hydraulic, Compressed-air, Jack, Brake, Drainage.

2.1.2 Steam Power Plant (PLTU)

• Three-stage energy conversion:

  1. Chemical energy (fuel) → Thermal energy (steam) in Boiler.

  2. Steam enthalpy → Shaft power in Turbine.

  3. Shaft power → Electricity in Synchronous Generator.

• Working fluid circulates in a closed Rankine cycle (idealised on $T-s$ diagram):

  • $a\rightarrow b$ : feed-water pressurisation (isentropic pumping)

  • $b\rightarrow c$ : sensible heating (economiser/heaters)

  • $c\rightarrow d$ : evaporation (isobaric)

  • $d\rightarrow e$ : superheating

  • $e\rightarrow f$ : isentropic expansion in turbine

  • $f\rightarrow a$ : condensation (isobaric, $T\approx$ saturation)

• Main equipment:

  • Boiler, Steam Turbine, Condenser, Generator.

• Typical auxiliary systems:

  • Desalination / Reverse Osmosis, Pre-treatment, Demineraliser, H₂-Generator (for generator cooling), Chlorination, Auxiliary Boiler, Coal-Handling, Ash-Handling.

2.1.3 Combined Cycle Gas-Steam Plant (PLTGU)

• Hybrid of Brayton (Gas-Turbine, open cycle) + Rankine (Steam-Turbine, HRSG) → higher $\eta$.

• Gas-turbine exhaust (~$500–600\,^{\circ}\text{C}$) heats HRSG; generated steam drives ST.

• $T-s$ combination: Brayton states $(1'\to4')$, Rankine states $(1\to4)$.

• Block configurations:

  • Single-shaft (1 GT + 1 ST + 1 HRSG, common generator)

  • Multi-shaft 1-on-1, 2-on-1, 3-on-1, etc.

2.1.4 Geothermal Plant (PLTP)

• Uses hydrothermal fluids T>225^{\circ}\text{C} (high-T) or $150–225^{\circ}\text{C}$ (medium-T).

• Key considerations: temperature, 25–30 yr resource, near-neutral pH, well depth <3\,\text{km}, low hydrothermal-eruption risk.

• Process chain:

  1. Production well → separator (cyclone) → demister → steam turbine.

  2. Exhaust → jet-spray condenser → cooling tower → reinjection.

• Steam-field equipment: Well-head valves (Master, Service, Bypass, Bleed), Separator, Silencer, Demister.

• Power-island: Turbine (back-pressure or condensing), Condenser (direct contact), Gas-extraction (ejector or vacuum pump), Cooling Tower (mechanical or natural), Reinjection system.

2.1.5 Diesel Power Plant (PLTD)

• Prime mover: internal-combustion diesel engine (2-stroke or 4-stroke).

• Operating cycle (4-stroke): Intake → Compression → Power → Exhaust.

• $P-V$ indicator diagrams and valve-timing charts define performance.

• Support systems:

  • Lubrication (sump, pump, filters, cooler, relief valve)

  • Cooling (radiator, fan, pump, thermostat)

  • Fuel (tanks, filters, feed pump, injection pump, injectors)

  • Air-intake & exhaust (filters, intercooler, turbocharger, silencer)

  • Starting (battery/motor-starter or compressed-air)

  • Control & Protection (governor, safety shut-downs)

2.2 Transmission System (Saluran Transmisi)

• Function: carry bulk power from generation centres to load centres.

• Media & voltage classes:

  • Overhead (conductor + insulators) – 70$–150\,\text{kV}$(SUTT),$>150$to$750\,\text{kV}$(SUTET),$>750\,\text{kV}$(SUTUT).</p></li><li><p>Underground cable.</p></li><li><p>Sub-marine cable.</p></li></ul></li></ul><h4 id="c6e700e5-60b0-4d2a-aef3-c687a9573dd4" data-toc-id="c6e700e5-60b0-4d2a-aef3-c687a9573dd4" collapsed="false" seolevelmigrated="true">2.3 Distribution System (Saluran Distribusi)</h4><ul><li><p>Delivers energy from substations to individual consumers.</p></li><li><p>Voltage levels:</p><ul><li><p>Medium voltage$\approx20\,\text{kV}$(between GI, GI → customer TM, GI → distribution transformer TR).</p></li><li><p>Low voltage$220/380\,\text{V}$to end-users.</p></li></ul></li></ul><h4 id="7dd3ccf8-a42f-4271-a235-7031326f8b17" data-toc-id="7dd3ccf8-a42f-4271-a235-7031326f8b17" collapsed="false" seolevelmigrated="true">2.4 Electrical Loads (Beban Listrik)</h4><ul><li><p>Resistive (R) – lamps, heaters, irons.</p></li><li><p>Inductive (L) – motors, pumps;$I{\text{start}} \approx 3 I{\text{rated}}$.</p></li><li><p>Capacitive (C) – capacitor banks for$\cos\varphi correction.

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  3. Reliability & Power-Quality Requirements

  • Voltage: keep within statutory tolerance; tap-changing or AVR.

  • Frequency: governor control; deviation limited to narrow band (e.g. \pm0.2\,\text{Hz}$for$50\,\text{Hz}).

  • Continuity: minimise outages via protection, redundancy, automation.

  • Safety: standards-compliant equipment, proper grounding, protective devices.

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  4. Single-Line Diagrams (SLD) in Power Plants

  • Condensed representation of 3-phase circuits; shows sources, buses, transformers, switchgear, key feeders.

  • Two broad sections on SLD of a plant:

    • External network & switch-yard interconnection.

    • Internal auxiliary power system (Works Power):

    • Unit Board (critical auxiliaries) – fed by unit trafo during normal run; fed through inter-connector from Station Board during start-up.

    • Station Board (service auxiliaries) – fed from grid via Station Transformer.

  • Essential (emergency) supply:

    • DC battery systems 110\,\text{V}$/$220\,\text{V}$.</p></li><li><p>Inverters, DC-motor-generator sets.</p></li><li><p>Diesel generator set for black-start / safe-shutdown loads.</p></li></ul></li><li><p>Typical rating selection: Station trafo sized for$P{\text{service}} + P{\text{one-unit-start}}.

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    5. Piping & Instrumentation Diagram (P&ID) Essentials

    • Graphical depiction of process flow, equipment, piping, instrumentation & control philosophy (ISO 10628).

    • Key drafting pre-requisites: available PFD, understanding of unit operations, control & safety.

    5.1 Line & Signal Symbols

    • Process: solid line; Utility: dashed line; Instrument impulse: thin; Electrical trace, thermal lagging, jacketed etc.

    • Signal types: electrical, pneumatic, hydraulic, software (dotted); mechanical linkage (chain line).

    5.2 Valve & Actuator Symbols

    • Isolation: gate, globe, ball, plug.

    • Check: swing, lift.

    • Safety: spring-loaded PSV, rupture disk, breather.

    • Control valve with various actuators: pneumatic diaphragm, electric motorised, hydraulic, solenoid.

    5.3 Equipment Symbols (selected)

    • Pumps: gear, screw, centrifugal.

    • Compressors & blowers.

    • Heat-exchangers: shell-&-tube, plate, air-cooler, cooling tower.

    • Filters: cartridge, strainer, cyclone, electrostatic precipitator.

    • Vessels, mixers, silencers, burners, separators.

    5.4 Piping Fittings & Misc.

    • Reducers, flanges, nozzles, orifice plates, spectacle blinds, sight-glasses, siphons, bellows, insulation.

    5.5 Instrumentation Identification (ISA / ISO)

    • Tag format: \text{Letter}{\text{variable}} \text{Letter}{\text{function}}$+ sequence no.</p><ul><li><p>First letter (measured variable):$P, T, F, L, Q, Z, V, S$etc.</p></li><li><p>Second letter (function):$I$(indicate),$T$(transmit),$C$(control),$A$(alarm),$H/L$(high/low),$S$(switch)…</p></li></ul></li><li><p>Examples:</p><ul><li><p>FE – Flow Element (sensor)</p></li><li><p>FT – Flow Transmitter (4–20 mA)</p></li><li><p>FI – Flow Indicator</p></li><li><p>PDI – Differential-Pressure Indicator</p></li><li><p>TIC – Temperature Indicating Controller</p></li><li><p>ZS – Position Switch.</p></li></ul></li></ul><div data-type="horizontalRule"><hr></div><h3 id="f483aa9a-c96d-49b8-8d24-ea4895fd3e1a" data-toc-id="f483aa9a-c96d-49b8-8d24-ea4895fd3e1a" collapsed="false" seolevelmigrated="true">6. Mathematical / Numerical References (selected)</h3><ul><li><p>Hydro head classification: Pelton$H>300\,\text{m}$; Kaplan$H<25\,\text{m}$(typical).</p></li><li><p>Spillway sizing:$Q{spill} \ge 1.2\,Q{\text{flood peak}}$.</p></li><li><p>Diesel valve-timing diagram sample:$\text{Intake-open}=10^{\circ}\,\text{BTDC}$,$\text{Intake-close}=49^{\circ}\,\text{ABDC}$→$239^{\circ}$crank angle open.</p></li><li><p>Indicator Mean Effective Pressure relates to$\int PdV$area of$P!-
      !V diagram.

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    7. Ethical, Practical & Safety Considerations

    • Renewable vs fossil: PLTA & PLTP offer low emissions; PLTU & PLTD emit \text{CO}2$,$\text{SO}x$,$\text{NO}_x; efficiency improvements (combined-cycle, pollution control) mitigate impacts.

    • Hydropower dams impact ecosystems & displacement; cascade systems optimise river use.

    • Geothermal: reinjection minimises subsidence, contamination; risk of thermal breakthrough & enthalpy decline.

    • Reliability = social responsibility: voltage/frequency deviations damage consumer equipment; prolonged outages harm economic activity.

    • P&ID & SLD clarity crucial for safe construction, commissioning, O&M; consistent symbols & tagging prevent human error.

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    8. Quick Revision Checklist

    • Can you draw the Rankine T-s path & state each component?

    • Identify which hydro turbine fits H=50\,\text{m}, Q=200\,\text{m}^3/\text{s}$$.

    • List five auxiliaries that must stay online during PLTU blackout.

    • Explain why opening IGV on GT lowers exhaust temperature.

    • Decode tag “PDT-101H” & locate it on a P&ID.