A heat recovery steam generation system, comprising: at least one superheater (60, 62) or reheater in a steam path for receiving a steam flow and configured to produce a superheated steam flow; an inter-stage attemperator for injecting an attemperation fluid into the steam path; a control valve coupled to the inter-stage attemperator, the control valve configured to control flow of the attemperation fluid to the inter stage attemperator; and a controller comprising a feedforward controller configured to determine a desired amount of flow of the open loop attemperation fluid and a trimming feedback controller configured to compensate for inaccuracies in the determined amount of flow of the open loop attemperation fluid to determine a net desired amount of flow of attemperation fluid through the control valve into an inlet of the inter-stage attemperator based upon an outlet temperature of steam from the superheater; wherein the controller is further configured to: determine a control valve demand based upon flow to valve characteristics; manipulate the control valve of the inter-stage attemperator, and inject the desired amount of flow via the inter-stage attemperator to perform attemperation upstream of an inlet into the superheater, the system characterized by: an anti-quench controller decoupled from the controller and configured to maintain steam temperature at inlet of a finishing superheater above a saturation temperature; and wherein the controller is configured to bypass attemperation whenever an inlet temperature of steam into the finishing superheater does not exceed a saturation temperature of steam by a pre-determined safety value. at least one superheater (60, 62) or reheater in a steam path for receiving a steam flow and configured to produce a superheated steam flow; an inter-stage attemperator for injecting an attemperation fluid into the steam path; a control valve coupled to the inter-stage attemperator, the control valve configured to control flow of the attemperation fluid to the inter stage attemperator; and a controller comprising a feedforward controller configured to determine a desired amount of flow of the open loop attemperation fluid and a trimming feedback controller configured to compensate for inaccuracies in the determined amount of flow of the open loop attemperation fluid to determine a net desired amount of flow of attemperation fluid through the control valve into an inlet of the inter-stage attemperator based upon an outlet temperature of steam from the superheater; wherein the controller is further configured to: determine a control valve demand based upon flow to valve characteristics; manipulate the control valve of the inter-stage attemperator, and inject the desired amount of flow via the inter-stage attemperator to perform attemperation upstream of an inlet into the superheater, the system characterized by: an anti-quench controller decoupled from the controller and configured to maintain steam temperature at inlet of a finishing superheater above a saturation temperature; and wherein the controller is configured to bypass attemperation whenever an inlet temperature of steam into the finishing superheater does not exceed a saturation temperature of steam by a pre-determined safety value. determine a control valve demand based upon flow to valve characteristics; manipulate the control valve of the inter-stage attemperator, and inject the desired amount of flow via the inter-stage attemperator to perform attemperation upstream of an inlet into the superheater, the system characterized by: an anti-quench controller decoupled from the controller and configured to maintain steam temperature at inlet of a finishing superheater above a saturation temperature; and wherein the controller is configured to bypass attemperation whenever an inlet temperature of steam into the finishing superheater does not exceed a saturation temperature of steam by a pre-determined safety value. an anti-quench controller decoupled from the controller and configured to maintain steam temperature at inlet of a finishing superheater above a saturation temperature; and wherein the controller is configured to bypass attemperation whenever an inlet temperature of steam into the finishing superheater does not exceed a saturation temperature of steam by a pre-determined safety value.