Is it permissible for a woman in a synagogue to address the congregation during a Kiddush?

If you are referring to an Orthodox synagogue, ask the rabbi of the congregation. His decision is binding. If the congregation has no rabbi, the Gabbaim should address the question to a rabbi whose decision they all agree to accept as binding, If the question is addressed to a number of rabbis by various members of the congregation, the potential for creating a Machloket in the community outweighs any possible benefit.