--- title: "Methods of load forecasting" subject: "Transmission and Distribution System Design" chapter: 6 key: "semester_8/transmission_and_distribution_system_design:load-forecasting-methods" source: https://www.bctengineer.com/q/semester_8/transmission_and_distribution_system_design/load-forecasting-methods site: BCT Engineering --- # Methods of load forecasting Transmission and Distribution System Design · Chapter 6: Electrical Load Characteristics and Load Forecast - Asked in: 2078 Chaitra, 8 marks - Video: [METHODOLOGY OF LOAD FORECASTING](https://www.youtube.com/watch?v=GCPZ5SiIjtw) — ELECTRICAL ELECTRONICS - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_8/transmission_and_distribution_system_design/load-forecasting-methods - Whole chapter: https://www.bctengineer.com/md/semester_8/transmission_and_distribution_system_design/chapter-6 ## Question What are the different methods of load forecasting? Describe briefly. ## Short answer Main methods are trend extrapolation, econometric regression on economic variables, end-use method built from appliance consumption, time-series models (ARIMA), simulation/land-use for spatial forecasting, judgmental Delphi, and AI methods. They are often combined. ## Answer **Load forecasting** is the prediction of future peak demand (kW) and energy (kWh) of a system or area, needed for planning generation, transmission and distribution. Methods differ by time horizon and approach. #### By time horizon | Type | Horizon | Use | |---|---|---| | Very short / short term | minutes to 1 week | Unit commitment, dispatch | | Medium term | 1 week to 1 year | Maintenance, fuel planning | | Long term | 1 to 20 years | Expansion of generation, T&D | #### Main methods 1. **Trend analysis (extrapolation)**: past load data are fitted with a curve (linear $P = a + bt$, exponential $P = a e^{bt}$, polynomial, Gompertz S-curve) and extended into the future. Simple and cheap; suitable for large areas with smooth growth. It ignores causes of growth and fails when conditions change. 2. **Econometric (regression) method**: load is expressed as a function of factors such as GDP, population, per-capita income, electricity price and number of consumers, e.g. $E = a + b\,(GDP) + c\,(Pop)$. Coefficients come from regression on past data. Explains causes but needs forecasts of the economic variables. 3. **End-use method**: total demand = Σ (number of appliances/consumers × use per appliance × hours). Built up from consumer classes (domestic, commercial, industrial). Good for new areas and demand-side studies; the load-centre method used by NEA (consumer number × consumption × growth × coverage) is an end-use type method. Needs detailed survey data. 4. **Time-series methods**: autoregressive (AR), moving-average (MA), combined ARMA/ARIMA and exponential smoothing models of hourly/daily load. Mainly for short-term forecasting. 5. **Simulation (land-use) method**: for small-area/spatial forecasting. Land is divided into small cells; land-use change (residential, commercial, industrial) is simulated and converted to load using load density per land-use class. Gives where and when load will appear. 6. **Judgmental / Delphi method**: opinions of experts are collected and refined in rounds. Used when data are lacking. 7. **Artificial intelligence methods**: artificial neural networks, fuzzy logic and machine learning models trained on historical load and weather data; mostly for short-term forecasting. In practice, a combination is used: trending/econometric for the national system, end-use and simulation for distribution areas. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. What is the main weakness of trend analysis? A. It needs detailed appliance data B. It ignores the causes of growth and fails when conditions change C. It cannot be used for large areas D. It needs expert opinion Answer: B. Trending extrapolates past data with a fitted curve and is best for large areas with smooth growth. (Key point: Trend analysis) 2. The econometric method expresses load as: A. A function of factors like GDP, population, income and price, with coefficients from regression B. A sum of land-use cells C. An expert vote D. A neural network of weather Answer: A. It explains causes but needs forecasts of the economic variables. (Key point: Econometric method) 3. Which pairing is correct? A. End-use is for small-area spatial forecasts; simulation is for national totals B. End-use builds demand from consumers x use per consumer; simulation uses land-use change and load density per class C. Both use only past load curves D. Simulation uses ARIMA models Answer: B. End-use sums consumer class demand; simulation models land-use development to give where and when load appears. (Key point: Simulation vs end-use) 4. Which methods are mainly used for short-term forecasting? A. Delphi and land-use simulation B. Time-series (AR, ARMA, ARIMA, smoothing) and AI methods like neural networks C. Econometric regression on GDP only D. Trend analysis over 20 years Answer: B. Time-series and AI models trained on hourly or daily load and weather suit short horizons. 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