JPH04128504A - Speed signal input circuit - Google Patents

Abstract

PURPOSE:To obtain a speed signal input circuit for eliminating influence of noise with no influence on control property by providing, in the input part of a control device a self-diagnostic judging circuit for eliminating influence of a signal caused by noise so as to transmit an optimum signal to the control device. CONSTITUTION:The revolution of a turbine is detected by a revolution number detector 1 so that a pulse signal is generated and the pulse signal is converted by a signal converter 11 so that a speed signal (S) is obtained. In a judging circuit 12, the speed signal (S) is compared with a speed increase control amount (A), a load set value (L), and a turbine inlet pressure (P) so as to judge whether the speed signal (S) is in the control range of each of control signals (A), (L), and (P). As a result, if the speed signal (S) is considered to have an optimum input value, it is outputted as a control signal (S1). On the other hand, when the speed signal (S) is considered to have an abnormal input value outside the control range, the speed signal (S) is neglected to estimate an optimum input value by each of control signals (A), (L), and (P) so that it can be outputted as the control signal (S1). An operating signal (V) is outputted from a speed increase control unit 16, and a constant speed control unit 17 by the control signal (S1).

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a speed signal input circuit in a control device.

[Conventional technology]

An example of a power generation turbine control device (turbine governor control) is shown in FIG. The turbine control device 3 detects the teeth of a gear attached to the turbine shaft as a pulse signal using a speed pickup (electromagnetic detector) 1, and counts the number of pulses using a converter 11 to obtain a turbine speed signal (rotation speed). S is detected and the speed-up control circuit 1 is controlled based on the value.
6. The constant speed control circuit 17 operates the regulating valve provided at the turbine steam inlet using the operation signal (2) to change the steam flowing into the turbine, thereby controlling the speed of the turbine. The initial pressure limiting circuit 19 adjusts the operating signal V to correspond to changes in generator load and turbine inlet pressure, thereby controlling the turbine. In addition, if the turbine suddenly accelerates due to an accident or erroneous operation, the acceleration detection circuit 4 detects the sudden acceleration and outputs a control valve quick closing signal Q, which quickly closes the control valve and controls the amount of inflow steam. At the same time as narrowing down the load, the generator side also disconnects the load (stops power generation)
This protects the turbine.

Therefore, if a high-frequency signal due to noise induced by the solenoid valve 2 is generated on the transmission path between the detector 1 and the converter 1-1, the turbine control device receives a higher speed than the actual speed, so the acceleration detector 14 Due to the sudden acceleration, the power generation plant was forced to stop generating electricity and was severely affected.

In addition, noise from solenoid valves, etc. at the five power stations differs depending on the installation conditions of the tester and each device, and protection by shielding the transmission line alone is insufficient, and removal by a single-frequency filter can also be applied to the input signal itself. , from several KHz to more than ten KH
This is impossible due to the high frequency of z.

For this reason, conventionally, the latest technology for noise countermeasures (published on July 30, 1986) published by General Technology 8th Edition, pages 279 to 281
The digital filter unit 3 is used to prevent the acceleration detection circuit 14 from malfunctioning due to noise.

[Problem to be solved by the invention]

The above conventional technology smoothes signals sampled within a certain period of time by averaging them, so if the sampling time is increased, the response becomes slower and the acceleration detection circuit 14 is unable to respond when it should normally operate. Furthermore, if the sampling time is shortened, there is a problem in that it is not effective against sudden noise caused by an electromagnetic contactor or the like. Furthermore, even if the sampling time is made long enough to prevent malfunction of the acceleration detection circuit 14 due to noise, the speed signal S increases due to the influence of noise, as shown in FIG. In order to lower the speed, the control valve is closed using the operation signal ■, and the actual rotational speed of the turbine is reduced. When the influence of noise disappears, the actual rotational speed has decreased, so the speed signal S decreases, and this causes the control The circuit had a problem in that it erroneously opened the control valve using the operation signal V in order to restore the speed to its original speed, which affected the plant.

An object of the present invention is to provide a speed signal input circuit that eliminates the influence of noise without affecting controllability.

[Means to solve the problem]

The above problem is that the input circuit determines whether the current input value is a value due to correct control based on changes in each control signal, and if it is determined that the input value is abnormal due to noise etc., the control signal is This can be solved by providing a self-diagnosis determination circuit that provides a correction value, continues normal control, and determines whether an abnormal input value is caused by noise L or an abnormality in the plant itself.

[Effect]

The determination circuit according to the present invention estimates the current input value based on changes in each control signal. This compares it with the current input value to determine whether the input value is abnormal due to the influence of noise or the like, and if it is abnormal, provides the estimated appropriate input value to the control circuit. Furthermore, if abnormal input values continue, the transition is analyzed and it is determined whether the abnormality is due to an abnormality in the plant itself or noise.

As described above, it is possible to remove the influence of noise and obtain an appropriate speed signal.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of a block diagram of a turbine control device according to the present invention. In this figure, a rotation speed detector 1 detects the rotation of the turbine and generates a pulse signal, and a converter 11 converts the pulse signal and provides a speed signal S. The determination circuit 12 according to the present invention compares the speed signal S with the speed increase control amount A, the load setting value, and the turbine inlet pressure P, and determines that the speed signal S is within the control range of each control signal A, L, and P. If the input value is appropriate, it is output as the control signal Ss. If the input value is abnormal outside the control range, the speed signal S is ignored and each control signal A, L, P is used to output the appropriate input value. The value is estimated and output as a control signal S1.

Speed increase control 13. The constant speed control 14 outputs the operation signal V based on the control signal S1.

FIG. 2 shows a flowchart of the determination circuit according to the present invention. In this figure, judgments 21 and 22 indicate that the operation signal V is currently changing depending on any one of the speed increase control amount A, the load setting value, and the turbine inlet pressure P, and is influenced by the speed signal S. Determine whether In determinations 23, 24, and 25, the rate of change ΔS of the rotational speed signal S is the rate of change ΔA of each control rate A, L, and P.

Appropriate control II for ΔL and ΔP! Determine whether the value is within the range. Here, if it is an abnormal value, the speed signal S is ignored, and each control signal change rate ΔA,
Δ11. The value determined by ΔP is added to the value that is currently estimated to be appropriate, and the control signal S1 is output, and if the value is within the appropriate control range, the speed signal S is output as is as the control signal S1. In addition, in judgment 30, it is judged whether the abnormal value continues for more than N sampling periods (1), and if it continues (2), in judgment 31, it is determined from the transition of the speed signal S that it is due to noise or an abnormality in the plant itself. Determine whether Here, the speed input is N
If the value returns to normal within the sampling period or if it is determined that the problem is due to noise based on the judgment 3 above, necessary abnormality processing 33 such as outputting a warning to operating equipment is carried out, and the abnormality is determined to be in the plant itself. In this case, depending on the transition of the speed signal S, plant abnormality processing 32 such as acceleration detection circuit operation is performed.

According to this embodiment, even if the speed signal S becomes an abnormal input value due to the influence of noise, as shown in time chart 1- of FIG. 4, a proper input value S1 is output to the control circuit.2. This has the effect of being able to obtain a normal operating signal (■) and eliminating the effects of noise on the plant.

〔Effect of the invention〕

According to the present invention, a speed input circuit that is highly reliable against noise can be realized without adding any special device, and a highly reliable control device can be obtained.

[Brief explanation of drawings]

3 is a block diagram of a turbine control device according to an embodiment of the present invention, FIG. 2 is a block diagram of a conventional turbine control device, and FIG. 3 is a flowchart of the determination circuit 12 of FIG. 15.
Figure 4 is a time chart of a conventional turbine control device.
FIG. 5 is a time chart of an embodiment of the present invention. 1. Rotation speed detector, 2. Pressure detector, 3. Turbine control device, 11. Converter, 12. Judgment circuit according to the present invention, 13 to 16. Control block 2S. Speed signal, A.
- Speed up control signal, L...Load setting value, ■) Turbine inlet steam pressure, ■... Operation signal.

Claims (1)

[Claims] 1. Consists of a speed detector that sends a speed (rotation speed) measurement value using a pulse signal, a converter that converts the pulse signal into a specific analog value, and a control device that performs control using the converted analog value. 1. A speed signal input circuit characterized in that the pulse input circuit is provided with a self-diagnosis determination circuit in the control device input section for removing the influence of noise on the signal and providing an appropriate signal to the control device.