The positive and negative effects of a regulator used in a control loop are common sense among self-control professionals, and there is nothing new here. But Fisher-Rosemount's PROV () XDCS products use this concept different. It must be aware of its differences before it is possible to form the correct control loop on the DCS. At the heart of this concept is the introduction of an Implied Valve Position (IVP) concept that implies valve position. use this. The concept of IVP replaces the traditional concept of regulator output signal, and the concept of its regulator's positive and negative effects is different. The significance of this IVP always represents the opening value of the control valve commanded by the output signal of the regulator, but it is not the valve opening measured by the actual valve position transmitter of the control valve. Instead, the output signal of the regulator is sent to After the control valve, the valve should have the opening value. Therefore, it is called implied valve position. To understand this concept of IVP, the new concept of regulator positive and negative effects is not difficult to understand. This is the role is that when the regulator deviation (measured as positive, set to negative) increases, the regulator required by the command valve opening also increases; the other hand, when the regulator increases the deviation, Regulator control valve opening is reduced, it is the reaction. By this definition, this concept is simpler and clearer than the original concept of the traditional concept. Confirming the positive and negative effects of the regulator in the control loop is easy and fast. The salient feature of this concept is that when determining the positive and negative effects of the regulator in the circuit, the "add on" (FC, conventionally referred to as air-open) and "increase-close" (FO) The performance of the set aside, so that the idea is simple. Of course, in the actual control process, the control valve FC and FO performance is not allowed to put aside, it is only a complex problem is broken down into two simple problems to deal with. Here, the control valve FC and FO performance as a regulator of the parameters to handle, that is, the regulator configuration, you must fill in the regulator under the command of the control valve is "increase open" or "increase off" ( FC or FO type) content. After the regulator learns about this FC or FO message, the signal is internally processed - reversed for FO and not for FC. This ensures the correctness of the signal sent to the control valve and ensures that the IVP signal of the regulator seen on the screen by the operator always represents the desired opening of the control valve it directs - Open, O% valve closed. So that operators do not have to keep in mind the FC and FO of each control valve, so that the control of the composition of the control loop can easily determine the positive and negative effects of the regulator. This concept is obvious for the advantages of a control system that commands only one control valve (or output signal is sent to only one successor unit - regulator, auxiliary unit, etc.); while for more than one control valve for one regulator , There may be some troubles, problems such as inconsistent FC or FO of two (several) control valves or inconsistent requirements of two (several) valves on the regulator, and the like. For similar problems, the first must ensure that the control function is correct; the first two on the control valve FC and FO and the positive and negative effects of the regulator, according to the characteristics of the control loop, the operator's operating habits, with one of the control valve Quasi, filled in the regulator configuration of positive and negative effects and control valve FC and FO content. For other control valve, although the regulator configuration can not meet the FC and FO and positive and negative effects of matching, but must be used to meet the correctness of its control functions. The PROVOX system has many features to meet this requirement. If more difficult, but also through I. CP point FST programming function to achieve.
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