Hi Matthew, I will help explain the practical application of reactive power in managing grid and voltage stability.

Fundamentally, as I think it's been explained in the earlier replies, reactive power is key to managing the voltages on the power grid. Too much reactive power and voltages increase, and too little and voltages drop. Therefore, reactive power on a power grid needs to be actively monitored and controlled to ensure voltages remain stable and within limits. In GB, the voltages are managed on the transmission network to within the Security & Quality of Supply Standards (SQSS) limits.

To ensure reactive power (as denoted by "VAr") can be controlled, and therefore voltages can be managed, requires a mix of equipment and technologies, some of the key ones include:

- Shunt Capacitors (these inject reactive power).
- Shunt Reactors (these absorb reactive power).
- SVC or STATCOM or Synchronous Condensers (these absorb and inject reactive power, responding dynamically to the need of each to help maintain steady voltages).
- Transformers (tap changers enable the control of voltages at the LV/MV terminal).
- Generators (while generators tend to be thought of as just MW producers, they play an important role in helping to manage voltages locally to their connection point - at transmission level they are required to be able to achieve at least 0.95 power factor (lead / lag)).

Furthermore, voltage can also be controlled to a certain extent by controlling the power flow on the grid. This is also crucial to ensuring voltage stability following an outage / contingency. You can observe how voltage on the grid changes under varying power flow scenarios, due to the relationship between voltage drop and current level, length & type of transmission line. Examples of equipment to help direct/redirect power flow include Quadboosters, Series Reactor/Capacitor, and Static Synchronous Series Compensators.

Hi Matthew, I will help explain the practical application of reactive power in managing grid and voltage stability.

Fundamentally, as I think it's been explained in the earlier replies, reactive power is key to managing the voltages on the power grid. Too much reactive power and voltages increase, and too little and voltages drop. Therefore, reactive power on a power grid needs to be actively monitored and controlled to ensure voltages remain stable and within limits. In GB, the voltages are managed on the transmission network to within the Security & Quality of Supply Standards (SQSS) limits.

To ensure reactive power (as denoted by "VAr") can be controlled, and therefore voltages can be managed, requires a mix of equipment and technologies, some of the key ones include:

- Shunt Capacitors (these inject reactive power).
- Shunt Reactors (these absorb reactive power).
- SVC or STATCOM or Synchronous Condensers (these absorb and inject reactive power, responding dynamically to the need of each to help maintain steady voltages).
- Transformers (tap changers enable the control of voltages at the LV/MV terminal).
- Generators (while generators tend to be thought of as just MW producers, they play an important role in helping to manage voltages locally to their connection point - at transmission level they are required to be able to achieve at least 0.95 power factor (lead / lag)).

Furthermore, voltage can also be controlled to a certain extent by controlling the power flow on the grid. This is also crucial to ensuring voltage stability following an outage / contingency. You can observe how voltage on the grid changes under varying power flow scenarios, due to the relationship between voltage drop and current level, length & type of transmission line. Examples of equipment to help direct/redirect power flow include Quadboosters, Series Reactor/Capacitor, and Static Synchronous Series Compensators.