Have you been able to check this plethora of IEEE standards for the power grid? http://standards.ieee.org/findstds/prod/cds/pwrtrandist.pdf
Also, there is a standard, the IEC 61850, used for data interchange for configuration of Intelligent Electronic Devices in automation systems for electric substations, so that they will be able to communicate with each other. While it is not an IEEE one, IEC and IEEE work closely with each other, to the point that they offer standards derived from their combined efforts (for example, ISO/IEC/IEEE 42010 for software architectures)