Local servo systems are presently used to position the 9 photon beams in SPEAR. Each servo drives a 3‐magnet orbit bump with a 50 Hz closed‐loop bandwidth. We plan to add an orbit feedback system to stabilize the beam globally. In the first stage, the global feedback will run at slow speed (<1 Hz). The long‐term goal is to combine the local and global feedback into a unified system with bandwidth exceeding 50 Hz.In this paper, we report work on initial studies of the global feedback system for SPEAR. In particular, we describe components of a comprehensive accelerator simulation program used to assess the performance of harmonic and eigenvector orbit control algorithms. This program has also been used to choose new bpm sites, and can simulate the interaction between global and local orbit feedback systems. A prototype on‐line version used for SPEAR is discussed. © 1994 American Institute of Physics