I am working on reactive power control of the IEEE 30 bus system. I would like to make some analysis to obtain the required reactive power required by a bus when the system voltage goes out of the preset boundary. I am trying to do some voltage sensitivity analysis on the IEEE test system to know what bus is prone to instability and the amount of reactive power that would be required to restore the bus voltage. I am not particularly sure how to go about the programming in MATLAB. I have already done the load flow for the test system, I am just not sure how to proceed form there. Thanks in advance for all the suggestions.