{
  "node": {
    "id": "term:frequency-regulation",
    "type": "Term",
    "label": "Frequency regulation",
    "properties": {
      "id": "frequency-regulation",
      "name": "Frequency regulation",
      "aka": [
        "ancillary services",
        "frequency response"
      ],
      "section": "topic-applications",
      "definition": "Rapidly injecting or absorbing power to hold the grid frequency at 50 or 60 Hz, a service batteries do better than any generator because they respond in milliseconds. It cycles the battery shallowly but very often.",
      "related": [
        "stationary-storage",
        "energy-arbitrage",
        "specific-power",
        "equivalent-full-cycle",
        "rate-of-change-of-frequency"
      ],
      "url": "https://lemonergy.com/learn/glossary/frequency-regulation/",
      "mentions": []
    }
  },
  "edges": [
    {
      "id": "edge:3158",
      "source": "term:frequency-regulation",
      "target": "topic:topic-applications",
      "type": "belongsTo",
      "properties": {
        "sourceFile": "terms.json"
      }
    },
    {
      "id": "edge:3159",
      "source": "term:frequency-regulation",
      "target": "term:stationary-storage",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:3160",
      "source": "term:frequency-regulation",
      "target": "term:energy-arbitrage",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:3161",
      "source": "term:frequency-regulation",
      "target": "term:specific-power",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:3162",
      "source": "term:frequency-regulation",
      "target": "term:equivalent-full-cycle",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:3163",
      "source": "term:frequency-regulation",
      "target": "term:rate-of-change-of-frequency",
      "type": "relatedTo",
      "properties": {
        "sourceFile": "terms.json",
        "meaning": "Related context; not a causal claim"
      }
    },
    {
      "id": "edge:3164",
      "source": "term:frequency-regulation",
      "target": "reference:doe-storage",
      "type": "cites",
      "properties": {
        "sourceFile": "wiki-references.json",
        "scope": "direct technical reference"
      }
    }
  ],
  "neighbors": [
    {
      "id": "topic:topic-applications",
      "type": "Topic",
      "label": "Applications and market",
      "properties": {
        "id": "topic-applications",
        "name": "Applications and market",
        "lede": "Where batteries are used, and the terms used to buy, size and compare them.",
        "context": "Start with mission energy, peak power and operating conditions.",
        "example": "20 kWh total energy and a ten-second 100 kW peak constrain different design aspects.",
        "lesson_url": "https://lemonergy.com/learn/fundamentals/capacity-and-c-rate/",
        "lesson_label": "Open energy and power"
      }
    },
    {
      "id": "term:stationary-storage",
      "type": "Term",
      "label": "Stationary storage",
      "properties": {
        "id": "stationary-storage",
        "name": "Stationary storage",
        "abbr": "BESS",
        "aka": [
          "battery energy storage system",
          "ESS"
        ],
        "section": "topic-applications",
        "definition": "Batteries installed in a fixed place — a container at a solar farm, a cabinet in a home — to shift energy in time or support the grid. LFP cells dominate because cost per cycle and safety matter more than mass.",
        "related": [
          "lfp",
          "energy-management-system",
          "inverter",
          "energy-arbitrage",
          "long-duration-storage",
          "ul-9540a"
        ],
        "url": "https://lemonergy.com/learn/glossary/stationary-storage/",
        "mentions": []
      }
    },
    {
      "id": "term:energy-arbitrage",
      "type": "Term",
      "label": "Energy arbitrage",
      "properties": {
        "id": "energy-arbitrage",
        "name": "Energy arbitrage",
        "aka": [
          "peak shaving",
          "load shifting"
        ],
        "section": "topic-applications",
        "definition": "Charging a battery when electricity is cheap and discharging when it is expensive, the simplest revenue of grid storage. Peak shaving is the same idea applied to a site’s demand charges.",
        "related": [
          "stationary-storage",
          "energy-management-system",
          "frequency-regulation",
          "levelized-cost-of-storage"
        ],
        "url": "https://lemonergy.com/learn/glossary/energy-arbitrage/",
        "mentions": []
      }
    },
    {
      "id": "term:specific-power",
      "type": "Term",
      "label": "Specific power",
      "properties": {
        "id": "specific-power",
        "name": "Specific power",
        "aka": [
          "power density"
        ],
        "section": "topic-ratings",
        "definition": "Deliverable power per unit mass, in watts per kilogram; power density is the same per litre. A cell is designed for energy or for power, rarely both: thin electrodes give power, thick ones give energy.",
        "unit": "W/kg",
        "related": [
          "power",
          "specific-energy",
          "ragone-plot",
          "areal-loading",
          "power-cell-energy-cell"
        ],
        "url": "https://lemonergy.com/learn/glossary/specific-power/",
        "mentions": []
      }
    },
    {
      "id": "term:equivalent-full-cycle",
      "type": "Term",
      "label": "Equivalent full cycle",
      "properties": {
        "id": "equivalent-full-cycle",
        "name": "Equivalent full cycle",
        "abbr": "EFC",
        "section": "topic-ratings",
        "definition": "Total charge throughput divided by nominal capacity, so that many shallow cycles count as the equivalent number of full ones. It lets cycle life be compared across different duty cycles.",
        "formula": "EFC = ΣQ_throughput / (2·Q_nominal)",
        "related": [
          "cycle-life",
          "depth-of-discharge",
          "cycle"
        ],
        "example": {
          "title": "Count partial throughput",
          "text": "For a 5 Ah reference capacity, 20 Ah of total absolute charge-plus-discharge throughput corresponds to 20/(2 × 5) = 2 EFC. If counting discharge throughput only, use its matching convention without the factor of two."
        },
        "url": "https://lemonergy.com/learn/glossary/equivalent-full-cycle/",
        "mentions": [
          "nominal-capacity",
          "energy-throughput"
        ]
      }
    },
    {
      "id": "term:rate-of-change-of-frequency",
      "type": "Term",
      "label": "Rate of change of frequency",
      "properties": {
        "id": "rate-of-change-of-frequency",
        "name": "Rate of change of frequency",
        "abbr": "RoCoF",
        "section": "topic-applications",
        "definition": "How fast grid frequency moves after a sudden imbalance such as a large generator tripping. Grids with less rotating inertia see steeper slopes; Great Britain has relaxed its loss-of-mains protection settings from 0.125 Hz/s to 0.5–1 Hz/s. Fast battery response and grid-forming inverters that emulate inertia help keep it within limits.",
        "formula": "RoCoF = df/dt",
        "unit": "Hz/s",
        "related": [
          "frequency-regulation",
          "inverter",
          "stationary-storage",
          "islanding"
        ],
        "example": {
          "title": "Measure a frequency slope",
          "text": "If measured grid frequency falls from 50.0 Hz to 49.8 Hz over 0.5 s, the average RoCoF is −0.4 Hz/s. Reporting windows and filtering affect the observed value."
        },
        "url": "https://lemonergy.com/learn/glossary/rate-of-change-of-frequency/",
        "mentions": []
      }
    },
    {
      "id": "reference:doe-storage",
      "type": "Reference",
      "label": "DOE/EPRI 2013 Electricity Storage Handbook in Collaboration with NRECA",
      "properties": {
        "title": "DOE/EPRI 2013 Electricity Storage Handbook in Collaboration with NRECA",
        "publisher": "Sandia National Laboratories",
        "url": "https://www.sandia.gov/ess/publications/eshb/doe-epri-nreca",
        "type": "Technical handbook",
        "scope": "Storage technologies and grid services. The publisher notes that its historical cost and deployment figures are outdated.",
        "year": 2013,
        "accessed": "2026-10-27"
      }
    }
  ]
}