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20 changes: 14 additions & 6 deletions _wiki/adequacy.md
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Expand Up @@ -4,21 +4,29 @@ description: The ability to supply the demand and energy requirements of the end
tags:
- reliability
- nerc
related: []
related:
- reliability
authors:
- name: Jinning Wang
url: https://jinningwang.github.io
version: 1.0.0
version: 1.0.1
date: 2025-03-15
lastmod: 2025-11-29
generated: 2025-12-02
lastmod: 2026-01-18
generated: 2026-01-18
---

### Definition by NERC

Source: <d-cite key="nerc2013terminology"></d-cite>
Source: <d-cite key="nerc2024glossary"></d-cite>

> The ability of the electric system to supply the aggregate electrical demand and energy requirements of the end-use customers at all times, taking into account scheduled and reasonably expected unscheduled outages of system elements.

<!-- prettier-ignore-start -->

> The previous reference <d-cite key="nerc2013terminology"></d-cite> is no longer available.
{: .block-danger }

> The ability of the electricity system to supply the aggregate electrical demand and energy requirements of the end-use customers at all times, taking into account scheduled and reasonably expected unscheduled outages of system elements.
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### Definition in a European Union Regulation

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4 changes: 2 additions & 2 deletions _wiki/cascading.md
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Expand Up @@ -12,7 +12,7 @@ authors:
version: 1.0.0
date: 2025-03-15
lastmod: 2025-06-20
generated: 2025-12-02
generated: 2026-01-18
---

### Definition by NERC
Expand All @@ -24,6 +24,6 @@ Source: <d-cite key="nerc2024glossary"></d-cite>
<!-- prettier-ignore-start -->

> This version is approved by FERC on 1/21/2016. Another version of the term "Cascading" was approved by FERC on 3/16/2007 and became inactive on 6/30/2016. The term "Cascading Outages" was remanded by FERC on 12/27/2007.
> {: .block-tip }
{: .block-tip }

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8 changes: 5 additions & 3 deletions _wiki/dynamic-stability.md
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Expand Up @@ -14,13 +14,15 @@ related:
- frequency-stability
- voltage-stability
- rotor-angle-stability
- small-signal-stability
- participation-factor
authors:
- name: Jinning Wang
url: https://jinningwang.github.io
version: 1.0.1
version: 1.0.2
date: 2025-12-02
lastmod: 2025-12-03
generated: 2025-12-03
lastmod: 2026-01-18
generated: 2026-01-18
---

### Definition by PJM
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17 changes: 14 additions & 3 deletions _wiki/frequency-stability.md
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Expand Up @@ -8,6 +8,7 @@ tags:
- article
- european-union
- europe
- China
related:
- stability
- fast-frequency-response
Expand All @@ -20,10 +21,10 @@ related:
authors:
- name: Jinning Wang
url: https://jinningwang.github.io
version: 1.0.1
version: 1.0.2
date: 2025-03-15
lastmod: 2025-11-28
generated: 2025-12-02
lastmod: 2026-01-18
generated: 2026-01-18
---

### Definition in an Article by a Task Force
Expand All @@ -37,3 +38,13 @@ Source: <d-cite key="kundur2004stability"></d-cite>
Source: <d-cite key="eu2017guideline"></d-cite> p6

> 'frequency stability' means the ability of the transmission system to maintain frequency stable in the N-situation and after being subjected to a disturbance;

### Definition in China grid operation code

Source: <d-cite key="gbt2022"></d-cite> p8

> 频率稳定:电力系统受到扰动后,系统频率能够保持或恢复到允许的范围内,不发生频率振荡或崩溃的能力。

Translation:

Frequency Stability: The ability of a power system to maintain or restore system frequency within an allowable range after being subjected to a disturbance, without the occurrence of frequency oscillation or collapse.
14 changes: 11 additions & 3 deletions _wiki/oscillation.md
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Expand Up @@ -4,13 +4,16 @@ description: A repetitive motion that can be either undamped, positively damped,
tags:
- event
- oscillation
related: []
related:
- resonance-stability
- subsynchronous-resonance
- subsynchronous-oscillation
authors:
- name: Jinning Wang
url: https://jinningwang.github.io
version: 1.0.0
version: 1.0.1
date: 2025-03-15
lastmod: 2025-06-18
lastmod: 2026-01-18
generated: 2025-12-02
---

Expand All @@ -27,3 +30,8 @@ Source: <d-cite key="powerworld2020oscillations"></d-cite>
> - Inter-area oscillations: From 0.15 to 1 Hz
> - Slower dynamics: Such as AGC, less than 0.15 Hz
> - Subsynchronous resonance: 10 to 50 Hz (less than synchronous)

<!-- prettier-ignore-start -->
In the context of power systems, Oscillation is an umbrella term that includes resonance.
{: .block-tip }
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13 changes: 8 additions & 5 deletions _wiki/participation-factors.md
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Expand Up @@ -4,14 +4,15 @@ description: One definition is about dispath and another is about small-signal s
tags:
- sensitivity
- book
related: []
related:
- small-signal-stability
authors:
- name: Jinning Wang
url: https://jinningwang.github.io
version: 1.0.0
version: 1.0.1
date: 2025-03-15
lastmod: 2025-06-18
generated: 2025-12-02
lastmod: 2026-01-18
generated: 2026-01-18
---

### Definition by NERC
Expand All @@ -26,7 +27,9 @@ Source: <d-cite key="kundur1994Power"></d-cite> p716-717, first edition

> One problem in using right and left eigenvectors individually for identifying the relationship between the states and the modes is that the elements of the eigenvectors are dependent on units and scaling associated with the state variables. As a solution to this problem, a matrix called the **participation matrix** ($P$), which combines the right and left eigenvectors as follows is proposed in reference 2 as a measure of the association between the state variables and the modes.

More details from the book are excerpted below for reference:
More elaboration can be found in <d-cite key="sun2021smallsignal"></d-cite>.

More details from the book are also excerpted below for reference:

$$ P = [ P_1 \quad P_2 \quad \dots \quad P_n ] $$ (12.49A)

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23 changes: 20 additions & 3 deletions _wiki/reliability.md
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Expand Up @@ -11,10 +11,10 @@ related:
authors:
- name: Jinning Wang
url: https://jinningwang.github.io
version: 1.0.0
version: 1.0.1
date: 2025-03-15
lastmod: 2025-06-22
generated: 2025-12-02
lastmod: 2026-01-18
generated: 2026-01-18
---

### Definition in an Article by a Joint Task Force of IEEE and CIGRE
Expand All @@ -29,3 +29,20 @@ Source: <d-cite key="kundur2004stability"></d-cite>
Source: <d-cite key="nerc2013terminology"></d-cite>

> NERC defines the reliability of the interconnected Bulk-Power System in terms of two basic and functional aspects, [adequacy](/wiki/adequacy), and [operating reliability](/wiki/operating-reliability).

### Definition by NREL

Source: <d-cite key="geocaris2022assessing"></d-cite>

> To frame the issue of reliability, researchers at the National Renewable Energy Laboratory (NREL) use the "three Rs of power system reliability": resource adequacy, operational reliability, and resilience.

### Definition by FERC

Source: <d-cite key="ferc2023reliability"></d-cite>

> The grid remains functional even during unanticipated but common system disturbances, such as loss of a source of energy generation from an energy provider or failure of some other system element. When something fails, the grid has to be able to isolate the problem and keep functioning.
>
> Grid reliability is based on two key elements:
>
> 1. Reliable operation – A reliable power grid has the ability to withstand sudden electric system disturbances that can lead to blackouts.
> 2. Resource adequacy - Generally speaking, resource adequacy is the ability of the electric system to meet the energy needs of electricity consumers. This means having sufficient generation to meet projected electric demand.
21 changes: 20 additions & 1 deletion _wiki/security.md
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Expand Up @@ -7,6 +7,7 @@ tags:
- ieee-task-force
- cigre
- article
- China
related:
- stability
- reliability
Expand All @@ -16,7 +17,7 @@ authors:
version: 1.0.0
date: 2025-03-15
lastmod: 2025-06-22
generated: 2025-12-02
generated: 2026-01-18
---

### Definition in an Article by a Joint Task Force of IEEE and CIGRE
Expand All @@ -25,3 +26,21 @@ Source: <d-cite key="kundur2004stability"></d-cite>

> Security of a power system refers to the degree of risk in its ability to survive imminent disturbances (contingencies) without interruption of customer service.
> It relates to robustness of the system to imminent disturbances and, hence, depends on the system operating condition as well as the contingent probability of disturbances.

### Definition in China grid operation code

Source: <d-cite key="gbt2022"></d-cite> p8

> 电力系统安全性:电力系统在运行中承受扰动(例如突然失去电力系统的元件,较大功率波动或短路故障等)的能力。 通过两个特性表征:
>
> a) 电力系统能承受住扰动引起的暂态过程并过渡到一个可接受的运行工况;
>
> b) 在新的运行工况下,各种约束条件得到满足。

Translation:

Power System Security: The ability of a power system to withstand disturbances during operation (such as the sudden loss of system components, significant power fluctuations, or short-circuit faults). It is characterized by two specific attributes:

a) The power system can withstand the transient processes caused by the disturbance and transition to an acceptable operating state;

b) Under the new operating state, various constraints are satisfied.
10 changes: 6 additions & 4 deletions _wiki/small-signal-stability.md
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Expand Up @@ -4,14 +4,16 @@ description: The ability to maintain synchronism when subjected to small disturb
tags:
- stability
- book
related: []
related:
- dynamic-stability
- participation-factor
authors:
- name: Jinning Wang
url: https://jinningwang.github.io
version: 1.0.0
version: 1.0.1
date: 2025-03-15
lastmod: 2025-06-19
generated: 2025-12-02
lastmod: 2026-01-18
generated: 2026-01-18
---

### Definition in a Textbook
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22 changes: 22 additions & 0 deletions _wiki/subsynchronous-oscillation.md
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@@ -0,0 +1,22 @@
---
title: Subsynchronous Oscillation
description: SSO.
tags:
- stability
related:
- oscillation
- subsynchronous-resonance
authors:
- name: Jinning Wang
url: https://jinningwang.github.io
version: 1.0.0
date: 2026-01-18
lastmod: 2026-01-18
generated: 2026-01-18
---

### Defintion in an Article

Source: <d-cite key="ieee1985terms"></d-cite>

> Subsynchronous oscillation is an electric power system condition where the electric network exchanges significant energy with a turbine-generator at one or more of the natural frequencies of the combined system below the synchronous frequency of the system following a disturbance from equilibrium. The above excludes the rigid body modes of the turbine-generator rotors.
8 changes: 5 additions & 3 deletions _wiki/subsynchronous-resonance.md
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Expand Up @@ -3,13 +3,15 @@ title: Subsynchronous Resonance
description: SSR. A condition involving energy exchange at natural frequencies below the synchronous frequency.
tags:
- stability
related: []
related:
- oscillation
- subsynchronous-oscillation
authors:
- name: Jinning Wang
url: https://jinningwang.github.io
version: 1.0.0
version: 1.0.1
date: 2025-03-15
lastmod: 2025-06-20
lastmod: 2026-01-18
generated: 2025-12-02
---

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21 changes: 18 additions & 3 deletions _wiki/voltage-stability.md
Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,7 @@ tags:
- article
- european-union
- europe
- China
related:
- stability
- frequency-stability
Expand All @@ -16,10 +17,10 @@ related:
authors:
- name: Jinning Wang
url: https://jinningwang.github.io
version: 1.0.0
version: 1.0.2
date: 2025-03-15
lastmod: 2025-06-20
generated: 2025-12-02
lastmod: 2026-01-18
generated: 2026-01-18
---

### Definition in an Article by a Task Force
Expand All @@ -28,8 +29,22 @@ Source: <d-cite key="hatziargyriou2021stability"></d-cite>

> Voltage stability refers to the ability of a power system to maintain steady voltages close to nominal value at all buses in the system after being subjected to a disturbance.

> Short-term voltage stability involves dynamics of fast acting load components such as induction motors, electronically controlled loads, HVDC links and inverter-based generators. The study period of interest is in the order of several seconds, similar to rotor angle stability or converter-driven stability (slow interaction type). Accordingly, models with the same degree of detail as for the above stability classes must be used. In addition, for short-term voltage stability, the dynamic modeling of loads is essential, and short circuit faults near loads are the main concern.

> Long-term voltage stability involves slower acting equipment such as tap-changing transformers, thermostatically controlled loads, and generator current limiters. It usually occurs in the form of a progressive reduction of voltages at some network buses. The maximum power transfer and voltage support are further limited when some of the generators hit their field and/or armature current time-overload capability limits. The study period of interest may extend to several minutes, and long-term simulations are required for analysis of system dynamic performance.

### Definition in a European Union Regulation

Source: <d-cite key="eu2017guideline"></d-cite> p6

> 'voltage stability' means the ability of a transmission system to maintain acceptable voltages at all nodes in the transmission system in the N-situation and after being subjected to a disturbance;

### Definition in China grid operation code

Source: <d-cite key="gbt2022"></d-cite> p8

> 电压稳定:电力系统受到扰动后,系统电压能够保持或恢复到允许的范围内,不发生电压崩溃的能力。

Translation:

Voltage Stability: The ability of a power system to maintain or restore system voltage within an allowable range after being subjected to a disturbance, without the occurrence of voltage collapse.
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