Dauda na Maimakon HVDC Daga HVAC a Ingancin Karamin Kirki?

HVDC da HVAC na gane mafi yawan kula?

Karamin shirya yana tafi masu sarki don hankali. Makarantun shirya, da yake daɗe, suke bayar shirya tun daga fadin mita zuwa filayen kayan adawa. Tashidar shirya da mutumai mai tsawon tsari na iya haɓaka karfin cikin hanyar, amma HVDC ta da muhimmanci a tashidar shirya.

Zaɓuwar tashidar shirya shine haɓaka karfi da abincin kuɗi. Hakan ya haɗa da nuna, HVDC ta da muhimmanci a tashidar shirya. Littafin yaɗa zai ba da muhimmancin HVDC da HVAC:

Abincin Kuɗi Na Tashidar
Abincin kuɗi na tashidar suna ƙunshi abincin ƙarfafin tsarin tsari, kadan/kudin takardun kamar, girman takalma, da kuma karfi. HVAC ta yi ƙarfafa tsarin tsari a kan transformas, wanda ya fi ƙara da kawai da HVDC na ƙarfafin thyristor, wanda shi ne babban muhimmancin abinci.

HVAC ta buƙatar da takamai 3 don tashidar 3-phase. HVDC, wanda ya yi ƙarfafa tsarin tsari a kan ƙasa, ta buƙatar da takama 1 (monopolar) ko 2 (bipolar), wanda ke haɓaka abinci. Kuma ƙarin 3-phase take iya bar shirya dubuwa a kan HVDC double bipolar links.

HVAC ta buƙatar da girman ƙarin da ƙasa da ƙarin phase-to-ground, wanda ke buƙata takalma ƙarin da ƙasa. Takalmun HVDC sun haɓaka abincin kuɗi. HVDC tana da karfi ƙarin ƙarin, wanda yake da muhimmanci a tashidar shirya.

Abincin kuɗin tashidar zai iya rarrabawa a ƙarin kungiyoyi: abincin kuɗin terminal station da abincin kuɗin tashidar. Abincin kuɗin terminal station shine ƙarin da ba biyuwa ga tashidar, amma abincin kuɗin tashidar yana ƙarin da biyuwa ga tashidar. Abincin kuɗin terminal AC su ne ƙarin, amma abincin kuɗin terminal HVDC su ne ƙarin da ƙarin. Amma, abincin kuɗin 100 km na HVAC tana da ƙarin da ƙarin da abincin kuɗin 100 km na HVDC. Saboda haka, abincin kuɗin HVAC da HVDC ke magana a matsayin break-even distance.

Break-even distance shine tashidar da za suka ƙarin da ƙarin abincin kuɗin HVAC ya ƙarin da abincin kuɗin HVDC. Wannan tashidar yana ƙarin da ƙarin da tashidar: kusan mita 400-500 (600-800 km) don tashidar ƙasa, 20-50 km don tashidar ƙare, da 50-100 km don tashidar ƙasa. Daga baya wannan ƙarfafin, HVDC tana da muhimmanci a tashidar shirya da ƙarin ƙarin.

Tashidar HVDC tana da karfi ƙarin ƙarin da tashidar HVAC, wanda ke da muhimmanci a ƙarin ƙarin:

Babu Karfi Reactive Power

Tashidar HVAC tana da karfi reactive power, wanda ke ƙarin da ƙarin da tashidar, tsarin tsari, da kuma inductive loads a ƙarin. Wannan karfi tana haɓaka effective power transfer da kuma waste energy, wanda ke ƙarin da ƙarin da tashidar da ƙarin ƙarin HVAC. Don ƙara wannan, HVAC systems ta yi series da shunt compensation don ƙara VARs (volt-ampere reactive) da kuma ƙara stability.

Amma, HVDC tana yi aiki da ƙarfin tsarin tsari ko charging current, wanda ke ƙara karfi reactive power da ƙarin. Wannan tana ƙara abubuwan ƙara measures.

Karfi Corona Ƙarin Ƙarin

Idan tsarin tashidar ta ƙarin da ƙarin da tsarin corona inception voltage, air molecules a cikin conductors ke ionize, wanda ke ƙara sparks (corona discharge) da ke waste energy. Karfi corona tana ƙarin da ƙarin da tsarin level da tsarin tsari. Idan DC tana da tsarin tsari 0, karfi corona na HVDC tana ƙarin da ƙarin da tashidar da ƙarin ƙarin HVAC systems.

Babu Skin Effect

Current AC tana ƙara skin effect, inda current tana ƙarfin da ƙarin da ƙasa, wanda ke haɓaka core. Wannan distribution ta ƙarfin da ƙarin tana haɓaka effective cross-sectional area na conductor, ƙara resistance (da resistance tana ƙarin da ƙarin da area) da kuma ƙara I²R losses a tashidar HVAC. HVDC, da current direct tana ƙara wannan effect, tana ƙara distribution uniform across the conductor da kuma ƙara resistive losses.

Babu Radiation Ko Induction Losses

Tashidar HVAC tana da radiation da induction losses saboda magnetic fields da ke ƙarin da ƙarin. Radiation losses tana faru saboda tashidar AC tana ƙara antennas, wanda ke radiate energy da ba a iya kofin. Induction losses tana faru saboda currents induced a cikin conductors nearby by the alternating field.A cikin HVDC systems, magnetic field tana ƙarfin da ƙarin, wanda ke ƙara both radiation and induction losses entirely.

Karfi Charging Current Ƙarin Ƙarin

Cables ƙasa da ƙare tana da parasitic capacitance, wanda ke buƙatar charging before they can transmit power. Capacitance tana ƙarin da ƙarin da tashidar, da kuma charging current tana ƙarin da ƙarin da tashidar.

A cikin systems AC, cables tana charge da discharge multiple times per second, drawing additional current from the source to maintain this cycle. Wannan extra current tana ƙara I²R losses a cikin cable.HVDC cables, on the other hand, only require charging once during initial energization or switching. This eliminates losses associated with continuous charging currents.

Babu Dielectric Heating Losses

Alternating electric field a cikin systems AC tana ƙara insulation materials a tashidar, causing them to absorb energy and convert it into heat—a phenomenon known as dielectric loss. This not only wastes energy but also shortens insulation lifespan.HVDC systems generate a constant electric field, avoiding dielectric losses and the associated insulation heating issues.

3) Thinner Conductors

Skin effect a cikin AC tana ƙara current to concentrate near the conductor surface, requiring thicker conductors to increase surface area and accommodate higher currents.HVDC, free from the skin effect, allows current to distribute uniformly across the conductor cross-section. This enables the use of thinner conductors while maintaining the same current-carrying capacity, reducing material costs and weight.

4) Line Length Limitations

HVAC lines suffer from reactive power losses that increase directly with line length. This imposes a critical limit on HVAC transmission distance: beyond approximately 500 km for overhead lines, reactive power losses become excessively high, destabilizing the system.HVDC transmission, by contrast, has no such length restrictions, making it suitable for ultra-long-distance power delivery.

5) Reduced Cable Rating Requirements

Cables are rated for maximum tolerable voltage and current. In AC systems, peak voltage and current are roughly 1.4 times higher than their average values (which correspond to actual power delivered). However, conductors must be rated for these peak values.In DC systems, peak and average values are identical. This means HVDC can transmit the same power using cables with lower voltage and current ratings compared to HVAC. In fact, HVAC systems effectively waste about 30% of a conductor’s capacity due to their higher peak requirements.

6) Narrower Right-of-Way

"Right-of-way" refers to the land corridor required for transmission infrastructure. HVDC systems require a narrower right-of-way because they use smaller towers and fewer conductors.HVAC, by contrast, needs taller towers to support more conductors and larger insulators (rated for AC peak voltages), which demand stronger structural support. This broader footprint increases material, construction, and land costs—making HVDC superior in terms of right-of-way efficiency.

7) Superior Cable-Based Transmission

Underground and submarine cables consist of multiple conductors separated by insulation, creating parasitic capacitance between them. These cables cannot transmit power until fully charged, and capacitance (and thus charging current) increases with length.AC systems repeatedly charge and discharge cables (50–60 times per second), amplifying I²R losses and limiting cable length. HVDC cables, however, only charge once (during initial energization or switching), eliminating such losses and length restrictions.This makes HVDC the preferred choice for offshore, underwater, and underground cable transmission.

8) Bipolar Transmission

HVDC supports versatile transmission modes, with bipolar transmission being a widely used and cost-effective option. It features two parallel conductors with opposite polarities, their voltages balanced relative to the earth.If one line fails or breaks, the system seamlessly switches to monopolar mode: the remaining line continues supplying current, using the earth as the return path.

9) Controllable Power Flow

HVDC converters, based on solid-state electronics, enable precise control over power flow in AC networks. Their rapid switching capability (operating multiple times per cycle) enhances harmonic performance, dampens power swings, and optimizes the network’s power supply capacity.

10) Fast Fault Clearance

Fault currents—abnormal currents from electrical faults—pose significant risks. In HVAC systems, high fault currents can damage transmission lines, stations, generators, and loads.HVDC minimizes such risks: fault currents are lower, limiting damage to specific sections, and its fast-switching operation ensures rapid fault response, enhancing system resilience.

11) Asynchronous Grid Interconnection

HVDC enables interconnection of asynchronous AC grids with differing parameters (e.g., frequency, phase).Regions often use distinct frequencies (e.g., 50 Hz in Europe vs. 60 Hz in the U.S.), and grids may have phase differences, making direct AC interconnection impossible. HVDC, operating without frequency or phase constraints, easily links these independent systems.

12) Enabling Smart Grids

Smart grids integrate small-scale generators (solar, wind, nuclear) into a unified network with intelligent power flow control.This is feasible with HVDC, which supports asynchronous interconnection of generation units and provides full control over power distribution, aligning with smart grid requirements.

13) Reduced Noise Interference

HVDC causes far less noise interference to nearby communication lines compared to HVAC.HVAC generates audible buzzing, radio, and TV interference, with intensity tied to its frequency. HVDC, with zero frequency, produces minimal noise. Additionally, HVAC noise increases in bad weather, while HVDC noise diminishes, ensuring more stable operation.