SGT Cheatsheets

Cheatsheet Content

R-APDRP Programme of Govt. of India Restructured Accelerated Power Development and Reforms Programme (R-APDRP): AT&C loss reduction (Feeder Separation, Load Balancing, Use of Aerial Bunch Cables). Adoption of IT in energy accounting, consumer care. Strengthening of Distribution network of State Power Utilities. Establishment of supervisory control & data acquisition system (SCADA). Smart Grid Drivers and Challenges Smart Grid Drivers Policy and Legislative: Economic Competitiveness, Energy Reliability and Security, Electricity Market Rules, State Regulations. Economic Benefits: New businesses, reduced labor costs (manual meter reading), reduced T&D losses, defer capital expenditures. Reliability: Decreased outage duration and frequency, improved billing accuracy, prevention of theft. Customer Empowerment: Control over energy usage, options to save money by shifting loads. Indian Drivers: Utilities: AT&C loss reduction, peak load management, reduced power purchase cost, better asset management, self-healing grid, renewable energy integration. Customers: 24x7 power, improved reliability/quality, user-friendly interface, increased choice (green power), "Prosumer" enablement. Government & Regulators: Satisfied customers, financially sound utilities, tariff modernization, emission reduction. Smart Grid Challenges Policy and Regulation: Lack of defined standards, need for new frameworks. Cost: High implementation costs, replacement of old equipment, financial burden. Lack of Awareness: Consumers, policymakers, utilities need better understanding. Cyber Security and Data Privacy: Vulnerability to attacks, privacy concerns with consumption data. Smart Grid Initiatives in India National Missions: Jawaharlal Nehru National Solar Mission: Aim for 100,000 MW by 2022. R-APDRP: (See above). Rajiv Gandhi Grameen Vidyutikaran Yojana (RGGVY): Rural electrification. Puducherry Smart Grid Project: Phase 1: Automatic Metering (Smart Meters, Remote Connect/Disconnect, GPRS communication). Phase 2: Renewable Energy Integration. Phase 3: Making Smart City. PMU, Functionality, and Comparison with SCADA Limitations of SCADA: Limited real-time visibility and time resolution. Phasor: Representation of time-varying sinusoidal functions $x(t) = X_m \cos(2\pi f_0 t + \phi)$. PMU (Phasor Measurement Unit): Building block of Wide Area Monitoring System (WAMS). Time-synchronizes measurements using GPS satellites. Provides real-time phasor (angle and magnitude) data (voltage and current). High precision data acquisition: $ Functionality: Measures busbar voltage magnitudes/phases, current flows, aids in Power System State Estimation, Monitoring & Warning, Event Analysis. Block Diagram: GPS receiver, PLL, Phasor Processor, Modem, A/D conversion. Comparison: "SCADA is like X-Ray, Synchrophasor Technology is like MRI." PMU data offers significantly higher time-resolution and dynamic information compared to SCADA. Features of Smart Meters Automated and remote meter reading. Remote connection and disconnection of energy supply. Outage detection and reporting. Tamper detection to identify energy theft. Monitoring of power quality. Interface for in-home display units showing current consumption, cost, and tariff. Interface for load control devices to remotely switch appliances. Supply capacity control (circuit breaker) to disconnect if demand exceeds set value. Capability to record both energy imported (consumption) and exported (e.g., from PV). Smart Substations & IEC 61850 Smart Substations Elements: Protection, Monitoring and Control devices (IEDs), Sensors, SCADA System. IEDs (Intelligent Electronic Devices): Microprocessor-based devices exchanging data/control signals. Perform protection, monitoring, control, data acquisition. Key to substation automation, multifunctional, IEC 61850 compatible. Sensors: Collect data from power equipment (e.g., transformers, circuit breakers). Optical/fiber based sensors offer high accuracy, no saturation, reduced size. SCADA in Substation: Collects sensor data, sends to central system for management/control. Real-time monitoring/control (1-5s). Smart Devices: Intelligent breaker (digital interface, internal controller), Intelligent transformer (sensors for oil temp, voltage/current, dissolved gases). IEC 61850 - Communication Standard for Substation Automation Purpose: Universal standard to ensure interoperability among IEDs from different vendors. Equipment Levels: Process Level: CT, PT, Sensors, CB. Extracts info, executes commands. Bay Level: IEDs. Acquires data, acts on primary equipment. Station Level: HMI, Communication Unit. Acts on data from multiple bays, interfaces with local/remote operators. Benefits: Reduced cabling, improved reliability, enhanced interoperability. Communication Protocols: MMS (Manufacturing Messaging Specification): Client-Server, IEDs to SCADA. GOOSE (Generic Object-Oriented Substation Events): Publisher-Subscriber/Multicasting, IED to IED, for tele-protection tripping. SMV (Sampled Measured Values): Fast, reliable communication of measurements from CT/VT. SCL (Substation Configuration Language): XML-based language for describing substations (ICD, SCD, SSD files). Different Energy Storage Technologies (Utility Level) Batteries: Lead-acid, Sodium Sulfur (NaS): Used for large utility applications (MW-size), smoothing wind/solar output. Lithium Ion (Li-ion), Nickel Cadmium (NiCd): Used in distributed applications (kW-MW size). Flow Batteries: Zinc Bromide, Vanadium Redox. Flywheel: Stores kinetic energy. Superconducting Magnetic Energy Storage (SMES): Stores energy in a magnetic field. Super/Ultra Capacitors: High power density, fast charge/discharge. Pumped Hydro: Stores energy by pumping water to a higher reservoir. Compressed Air Energy Storage (CAES): Stores energy by compressing air. Demand Response (DR) Definition: Encourages consumers to alter consumption patterns based on price or utility request to reduce bills or manage grid. Why DR? Utility: Reduces peak demand, defers infrastructure investment, improves reliability, integrates renewables. Consumer: Lower electricity bills, energy independence, environmental benefits. Steps Involved: Price Signals/Utility Request: Consumers receive real-time pricing, critical peak pricing, or direct utility commands. Decision Making: Consumers (or automated systems like HEMS) decide to reduce/shift load. Load Adjustment: Appliances are turned off, shifted, or curtailed. Feedback: Consumers receive feedback on savings, and utility observes reduced demand. Customer Load Control: Utility directly controls non-essential loads (e.g., HVAC, water heaters) during peak times. Home Energy Management System (HEMS): Intelligent system for residential load management, responding to DR signals. Difference between Demand Response and Energy Efficiency Energy Efficiency: Focuses on lowering overall energy consumption over time (e.g., using LED bulbs instead of incandescent). It's about "doing more with less energy" or "using less energy to achieve the same output." Demand Response: Focuses on shifting or reducing energy consumption at specific times, usually in response to price signals or grid conditions (e.g., turning off the AC during a critical peak price event). It's about "when" energy is consumed, not necessarily "how much" overall. CPP and ToD Tariff Time of Use (TOU) Pricing: Electricity prices vary by time of day, day of week, and season. Higher prices during peak demand periods, lower during off-peak. Encourages shifting consumption. Critical Peak Pricing (CPP): High prices are triggered during a few critical peak hours (e.g., 10-15 days a year) when demand is exceptionally high or supply is constrained. Consumers are typically notified in advance. Prices during these events are significantly higher than TOU peak prices. Monthly Electricity Bill Computation Example (Simplified) Given: Load profile (kW per interval), Tariff structure (e.g., TOU prices for different blocks of time), Fixed charges, Taxes. Calculate Energy Consumption per Interval: Multiply average power (kW) by duration of interval (hours) to get kWh. Apply Time-of-Use (TOU) Rates: Sum kWh consumed in each TOU period (e.g., On-peak, Off-peak, Mid-peak) and multiply by the respective rates. Apply Critical Peak Pricing (CPP) (if applicable): If any consumption falls into a CPP event, apply the higher CPP rate for those hours. Calculate Energy Charges: Sum all consumption costs. Add Fixed Charges: Include monthly service fees, demand charges (if any, based on peak kW). Add Taxes/Surcharges: Apply any applicable government taxes or surcharges. Total Bill: Sum all charges. Example Formula: $Total Bill = \sum (kWh_{period} \times Rate_{period}) + Fixed Charges + Demand Charges + Taxes$ Impacts of Residential EV Charging Increased Supply Demand: EVs add significant load to the grid, especially with high penetration. Greater Impact on Peak Demand: Uncontrolled charging can significantly increase peak demand, requiring grid infrastructure upgrades. Overloading of Distribution Transformers: High EV penetration can overload local distribution transformers (e.g., 5% EV penetration could overload 4% of transformers). Increased Power Loss: Higher currents due to charging lead to increased $I^2R$ losses. Voltage Fluctuations: Large, sudden loads can cause voltage sags, especially in weak distribution networks. Harmonic Distortions: EV chargers (especially DC fast chargers) can introduce harmonics into the grid, affecting power quality. Need for Network Reinforcements: Requires significant investment in grid and generation capacities. Priority Based Residential Charging A strategy to manage EV charging to mitigate negative impacts on the grid, especially transformer overloading. Concept: EVs are charged based on a priority scheme rather than all at once or at random. Priorities can be based on: Battery State of Charge (SoC): Lower SoC EVs get higher priority. Desired Departure Time: EVs needing to be fully charged by an earlier time get higher priority. Grid Conditions: Charging can be delayed or throttled if the local transformer is approaching overload or if grid prices are high. User Preference/Cost: Users can set preferences for faster charging (at higher cost) or slower charging (at lower cost). Mechanism: Charging rates are dynamically adjusted or charging is paused/resumed based on the established priorities and real-time grid conditions. Benefits: Prevents transformer overloading, reduces peak demand, minimizes voltage fluctuations, optimizes energy cost for consumers, and defers infrastructure upgrades. Feed-in Tariff (FiT), Difference between P2P and P2G Feed-in Tariff (FiT): A policy mechanism designed to accelerate investment in renewable energy technologies. It offers long-term contracts to renewable energy producers, typically based on the cost of generation of each technology, providing a guaranteed payment for the electricity they produce and feed into the grid. P2G (Peer-to-Grid) Energy Transaction: Model: Prosumers (consumers who also produce energy, e.g., with solar panels) trade their net power independently with the utility. Flow: If a prosumer has excess power, they sell it to the utility at the FiT rate. If they have a deficit, they buy from the utility at the retail price. Centralized: The utility acts as the central intermediary for all transactions. Limitations: Declining FiT prices can reduce investment incentives for DERs. P2P (Peer-to-Peer) Energy Transaction: Model: A paradigm shift where participants (prosumers and consumers) directly trade their excess/deficit power with each other within a localized community (e.g., neighborhood), often facilitated by a Locality Electricity Trading System (LETS). Flow: Prosumers can sell excess power directly to nearby consumers, bypassing the utility as the sole intermediary for local trades. The utility still acts as a backup and for balancing. Decentralized: Promotes local energy markets, increased community self-sufficiency. Advantages: Reduced electricity prices for consumers, better returns for prosumers, endorsement of green power, increased customer participation, reduced load burden on local transformers, contributes to smart city objectives (zero pollution, lower energy prices). Requirements of Communication Network for Smart Grid Reliability: Must provide communications that equal or exceed the reliability of the power grid. Scalability: Must support an ever-increasing number of devices and last for decades. Availability: High uptime with protection mechanisms, redundancy, and self-healing. Security: End-to-end security, privacy from unauthorized access, and confidentiality. Low Latency: Critical for some applications (e.g., 10 ms for teleprotection). Hard QoS (Quality of Service): Guaranteed performance for critical applications. Cost Effectiveness: Low capital and operational expenditures. Standards & Interoperability: Developed standards to enable different devices/systems to work together. IP-based: Primarily uses Internet Protocol (IPv6 recommended). Communication Technologies in HAN and NAN Home Area Network (HAN) / Premises Network Purpose: Connects appliances and equipment within customer premises. Requirements: Low power, low cost, low latency, secure. Technologies: ZigBee (IEEE 802.15.4): Wireless, low power, low cost, 10-75m range, star/tree/mesh topologies. HomePlug (IEEE 1901): Wired (power lines). HomePlug AV for broadband, HomePlug GP for HEM. Z-wave: Low power wireless for home automation. Wi-Fi (IEEE 802.11): Wireless, 11-248 Mbps, 30-100m range. Ethernet: Wired (twisted pair), 10 Mbps-1 Gbps, 100m range. Neighborhood Area Network (NAN) / Field Area Network (FAN) / AMI Network Purpose: Connects smart meters, field devices, and distributed resources; backhauls to WAN. Technologies: WiMAX (IEEE 802.16): Wireless broadband, 5km range, high capacity, low latency (10-50ms), connection-oriented, QoS ensured. Cellular (3G/4G LTE): For mobile services and data (WCDMA, HSPA, HSDPA, LTE), high capacity, low latency, all IP-based. Wired: Ethernet, Power Line Communication (PLC), DOCSIS (Data Over Cable Service Interface Specification) as complementary options. Difference between WiFi and WiMAX Feature Wi-Fi (IEEE 802.11) WiMAX (IEEE 802.16) Technology Type Wireless Fidelity Wireless Interoperability for Microwave Access Standard IEEE 802.11 IEEE 802.16 Frequency Band Unlicensed ISM band, 2.4 GHz (also 5 GHz) Licensed band 2.3 GHz, 2.5 GHz, 3.5 GHz (higher bands too) Deployment End-user technology (users configure) Mostly deployed by service providers Range Short Range: 30 m – 100 m Long Range: up to 5 km (fixed WiMAX much further) Protocols Connection-less CSMA/CA Connection-oriented protocols QoS Not inherently ensured Ensured through scheduling algorithm SG Preference Preferred for HAN Preferred for NAN/backhaul Features and Applications of Modbus, STTP, DLMS, and IEEE 2030.5 Protocols Modbus Protocol: Features: Messaging structure for intelligent devices (master-slave). Used for industrial devices (controllers, sensors). Limitations: Limited security, no standardized addressing, limited data types, slow communication, single master, no built-in error handling, difficult integration with modern systems. Streaming Telemetry Transport Protocol (STTP) (IEEE 2664-2024): Features: Designed to transport huge streaming data (e.g., PMU data) over IP. Built for real-time measurements and continuous data flow. Includes security, lossless data compression, publish-subscribe architecture. Applications: Real-time monitoring and control in power systems, especially for synchrophasor data. DLMS (Device Language Message Specification) / IEC 62056: Features: Facilitates communication between utility control centers, data concentrators, and smart meters. Brand/communication technology independent. Adaptable to various physical mediums (PLC, RF, cellular). Applications: Smart metering infrastructure, automated meter reading, data exchange between utility devices. IEEE 2030.5 Protocol: Features: Connects and leverages distributed energy resources (DERs). Built for Internet-based communications for a large number of small devices. Rich data model, uses IoT concepts. Applications: Exchanges pricing, demand response, and energy usage information. Enables integration of smart thermostats, meters, EVs, smart inverters, and smart appliances.