FIELD OF THE INVENTION :
The present invention generally relates to a method for operating a drive control module
for Proportional valve, more particularly a method is implemented to control and protect
the operation of proportional valve in High Pressure Bypass (HPBP) system.
BACKGROUND OF THE INVENTION:
High Pressure Bypass system is to allow the steam pressure at the HP turbine inlet to be
controlled before and during turbine start-up as well as during trip and shutdown
conditions by bypass valve. The system is capable of reducing the main steam pressure
and temperature to a level normally encountered in cold reheat line with or without
turbine in operation. During short trip, HP Bypass system is used to bypass the steam
from inlet to turbine, allowing boiler and turbine to operate independently. In low load
operations or transient demand, HP bypass system is to maintain the inlet to turbine.
There are four major control loops available in HPBP system as given below,
1. Pressure Master Controller
2. Temperature Controller
3. Spray Water Isolation control valve
4. Fast opening system
Out of the four control loops, the conditions for fast opening HPBP system are as follows:
a) Generator Circuit breaker Open
b) Turbine load Shedding Relay Operated
c) Turbine TRIP
d) Emergency Push Button Operated
e) Pressure deviation High

HPBP valve opens within 3 seconds on energizing fast opening solenoid. The valve is
actuated by the hydraulic actuator for achieving quick and fine control. The oil supply unit
provides the required oil under pressure for operating the hydraulic actuators. The oil is
flown through many HPBP valves.
As HPBP is a critical system, it should operate reliably, even on controller failure and I/O
Bus Failure. In the prior art, Servo valves are used in HPBP system.
Due to technology up gradation, servo valves are replaced by proportional valves for its
robust nature and as the oil quality required for the proportional valve need not be as
high as required for servo valve. To control the function of the proportional valve, Control
software was implemented in DCS (Distributed Control System). However, the operation
was not smooth and reliable, and unable to implement many protection features.
There are many drawbacks are found in the prior art method. A few are as listed below:
1. there is no system to identify for loop monitor fault annunciation,
2. there is no system to find for enabling or disabling valve in case of oil shortage,
3. there is no option for manual operation
4. there is no system to ensure operation of valve when there is no blocking element
is energized.
Hence, there is a need of a method for controlling and monitoring the operation of
proportional valve in HPBP system in such a manner so that, the above mentioned
drawbacks of conventional system are addressed.

OBJECTS OF THE INVENTION:
It is therefore, the object of the invention to overcome the aforementioned and other
drawbacks existing in prior arts.
The primary object of the present invention is to propose a method to control and monitor
the operation of proportional valve in HPBP system.
Another object of the present invention is to propose a method to control and protect the
proportional valve’s operation both in automatic mode and manual mode.
Still another object of the present invention is to monitor various operation of the drive
control module of the system like output current monitoring, current loop wire break
monitoring, output selection option, PS (Power supply) to blocking element, BE (Blocking
element) current monitoring and etc.
Yet another object of the present invention is to determine fault annunciation of the
module by using the monitoring circuit, so that preventive measure can be taken.
These and other objects and advantages of the present invention will be apparent to
those skilled in the art after a consideration of the following detailed description taken in
conjunction with the accompanying drawings in which a preferred form of the present
invention is illustrated.

SUMMARY OF THE INVENTION:
One or more drawbacks of conventional arts for controlling the Proportional valve function
in HP Bypass system are overcome, and additional advantages are provided through the
present invention as disclosed. Additional feature and advantages are realized through
the technicalities of the present disclosure. Other embodiments and aspects of the
disclosure are described in detail herein and are considered to be part of the claimed
disclosure.
In the embodiment of the present invention, A method for controlling and monitoring the
operation of proportional valve in a HPBP system, wherein the HPBP system includes a
plurality of proportional valves for controlling the flow of oil to the solenoid valve using a
blocking element to control and monitoring the operation of proportional valve by using
a drive control module which consists of at least one position feedback transmitter, at
least one current to voltage converter, at least one voltage to current converter, at least
one summing amplifier unit , at least a logic circuit , at least one Blocking Element control
and monitoring unit, at least one circuit breaker, at least one blocking element, at least
a voltage scaling circuit, at least one jumper, at least one power supply to Blocking Element,
at least one monitoring circuit, at least one proportional valve and including associated
circuitry, the method comprising the steps of: receiving a plurality of current signals as
position feedback signal from a position feedback transmitter and getting a position
reference signal from DCS (Distributed control System); providing the position feedback
signal to at least a current to voltage converter , to generate a scaled positive feedback
voltage signal after conversion; providing the position feedback voltage signal to at least
a voltage to current converter and to generate a current signal after converting from a
position feedback voltage signal, for monitoring at distributed control system; getting a
reference signal (demand signal) from distributed control system; converting the
reference signal into voltage signal by using at least a current to voltage converter to

feed to a summing amplifier unit ; providing a plurality of inputs as at least three positive
voltage inputs, at least a demand voltage signal, at least a buffered reference voltage
signal and also position feedback voltage signal to the summing amplifier and then to PI
control circuit for final control output i.e position deviation signal; providing a plurality of
input signals to the logic circuit which operates mainly at least in two mode specially in
automatic mode and generating a plurality of output signal from the logic circuit and also
generating a control signal which is fed to a blocking element unit, and scaling and
converting the output signal from the logic circuit by using at least a voltage scaling circuit
and at least a voltage to current converter and fed to the proportional valve.
In an embodiment, the current and voltage inputs from the transmitter lies within either
of 5mA to 15mA or 4mA to 20mA and 2.5V to 12.5V voltage range. A position feedback
current signal is fed to the current to voltage converter and output of the current to
voltage converter is scaled and converted to a voltage signal within 0V to 10V range.
Further the position feedback voltage signal is converted to a current signal within 4mA
to 20mA range by using a voltage to current converter. The monitoring of the position
feedback signal for short circuits, lower and upper range (change of current/voltage),
and annunciating fault is identified by using a monitoring circuit. The demand signal
(reference) is within the range of 4-20mA and converted to 0V to 10V using current to
voltage converter. The summing amplifier unit comprises a low pass filter with a cut-off
frequency of 4Hz and 15Hz and a PI control. The amplification of position deviation signal
is carried out using at least a potentiometer between 6 and 20. The blocking element
which is a poppet valve, is powered through a circuit breaker with 24V voltage and 1.3A
current signal for opening and closing the poppet valve. The output signal from the logic
circuit (6) is scaled between 0V to 10V by using a voltage scaling circuit and further
output voltage signal is converted to current signal by using a voltage to current converter
and wherein, the output signal is, either voltage output between range -10V to +10V or
current output between range 4mA to 20mA, selected by using at least a jumper (11)
and fed to the proportional valve (14).

In an embodiment, monitoring circuit is used to indicate the total operation of the drive
control module. Normal operation of the drive control module is indicated by green LED
display, faulty operation is indicated by red LED display and Automatic mode of operation
is indicated by using Auto mode LED display. The present invention is widely used in
Power plants to control and monitor the operation of Proportional valve in HPBP system.
Various objects, features, aspects and advantages of the inventive subject matter will
become more apparent from the following detailed description of preferred embodiments,
along with the accompanying drawing figures in which like numerals represent like
components.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
The illustrated embodiments of the subject matter will be best understood by reference
to the drawings, wherein like parts are designated by like numerals throughout. The
following description is intended only by way of example, and simply illustrates certain
selected embodiments of shrouds that are consistent with the subject matter as claimed
herein, wherein:
Fig 1 - illustrates the schematic block diagram of the proposed method for controlling and
monitoring the proportional valve’s operation by using a drive control module according
to the present invention.
Fig 2 - illustrates the front view of the drive control module according to the present
invention.
The figures depict embodiments of the disclosure for purposes of illustration only. One
skilled in the art will readily recognize from the following description that alternative
embodiments of the structures illustrated herein may be employed without departing
from the principles of the disclosure described herein.

DETAILED DESCRIPTION OF THE INVENTION:
While the embodiments of the disclosure are subject to various modifications and
alternative forms, specific embodiment thereof have been shown in the figures and will
be described below. It should be understood, however, that it is not intended to limit the
disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover
all modifications, equivalents, and alternative falling within the scope of the disclosure.
The figures illustrate only those specific details that are pertinent to understand the
embodiments of the present disclosure, so as not to obscure the disclosure with details
that will be clear to those of ordinary skill in the art having benefit of the description
herein.
The purpose of High Pressure Bypass system is to allow the steam pressure at the HP
turbine inlet to be controlled before and during turbine start-up as well as during trip and
shutdown conditions by bypass valve. The system is capable of reducing the main steam
pressure and temperature to a level normally encountered in cold reheat line with or
without turbine in operation. During short trip, HP Bypass system is used to bypass the
steam from inlet to turbine, allowing boiler and turbine to operate independently. In low
load operations or transient demand, HP bypass system is to maintain the inlet to turbine.
There are four major control loops available in HPBP system, given as Pressure Master
Controller, Temperature Controller, Spray Water Isolation control valve and Fast opening
system.
Out of the four control loops, the conditions for fast opening HPBP system are given as
follows:
a) Generator CB (Circuit breaker) Open
b) Turbine LSR (load Shedding Relay) Operated
c) Turbine TRIP
d) Emergency PB (Push Button) Operated
e) Pressure DEVN. High

HPBP valve opens for 3 seconds for energizing fast opening of solenoid solenoid valve.
The valve is actuated by the hydraulic actuator for achieving quick and fine control. The
oil supply unit provides the required oil under pressure for operating the hydraulic
actuators. The oil is flown through individual proportional valves and blocking elements
for opening and closing of proportional valves.
In the prior art, Servo valve is used and further servo valves are replaced by proportional
valves in the HPBP System and the conventional system, used for servo valve, is not
suitable for proportional valve. Initially the control operation is done through DCS
software which is not suitable and many features are not accomplished by the software.
Hence a dedicated control module is configured to control the proportional valve
operation and also the control the operation of blocking element.
The present invention is directed towards a method for controlling and monitoring the
operation of proportional valve by using a drive control module in HP Bypass system. The
drive control module consists of position feedback transmitter(1) , at least one current to
voltage converter (2,4) , at least one voltage to current converter (3,10), at least one
summing amplifier unit (5), at least one logic circuit (6) for Auto and manual operation
for selection and enabling blocking element control and monitoring unit (7), analog
controller circuit, output limiting circuit unit (upper and lower limits), analog controller
output (either current or voltage), at least one jumper (11,12), at least one power supply
to blocking element (app. 1.3A) through circuit breaker(8), at least a filter (16), and at
least a DC-DC converter (17), at least a monitoring circuit (13), at least one blocking
element(15), at least one proportional valve(14) at least a blocking element wire break
current monitoring circuit, valve open or close indication signal, a provision to set the
output value using front plate potentiometers during manual operation and other
associated circuitry and a plurality of channels of field signals, and DCS signals (X10-1
to X10-16 and X11-1 to X11-16 and X2-1 to X2-4) for connecting said functional parts of
the drive control module.

The present invention is directed towards a method for controlling and monitoring the
operation of proportional valve by using a drive control module in HP Bypass system. The
system includes various sub-parts and functions of each sub-part is illustrated as per
fig-1.
Fig 1 illustrates the overall block diagram of the present invention. The module is received
the position feedback signal from transmitter (1) (SG-10) (SGP, SG2) and position
reference signal (demand) (4-20mA) (X10-1 & X10-2) from DCS and then converted into
0-10V. The corresponding control signal is generated to control the operation of the valve.
The system can receive different current and voltage such as 5...15mA, 4...20 mA &
2.5...12.5V as inputs (optional). Power supply to the transmitter is provided by the
module. Presently, the system receives only 5-15mA current inputs from the transmitter.
Fig 1 illustrates about the position feedback signal measurement unit. The signal i.e. the
position feedback signals are received from the transmitter(1) and converted by using
current to voltage (I/V) converter(2) and scaled to (0-10V) over the complete stroke of
the valve. Further, voltage input is fed to the voltage to current converter (3) and the
current output is about 4-20mA. The position feedback voltage signal is converted into
4-20mA current signal and used for monitoring at Distributed Control System (DCS).
Moreover, the position feedback signal is monitored for short circuits and lower and upper
range and if any fault is found, the fault is annunciated. The output from the current to
voltage converter (2) are send to the summing amplifier unit (5). Another current to
voltage (4) converter is used to convert the position demand signal (reference signal)
which is a current signal, to voltage signal as illustrated in fig-1.
In the present invention, Fig-1 illustrates also current to voltage converter unit in which
a demand signal (4-20mA) from distributed control system as a reference signal is given
to the current to voltage converter(4) by using two inputs channel (X10-1 and X10-2).
The demand signal is converted into 0-10V for further processing. The output can be
adjusted using two offset and gain potentiometer. The output of the current to voltage

converter (4) i.e. the voltage signal (0-10V) is fed to the summing amplifier unit (5)
through a jumper (12).
In the present invention further, Fig -1 illustrates about this summing amplifier unit (5)
in details. The summing amplifier unit comprises a low pass filter and a PI control. There
are three voltage inputs and position feedback voltage signals and demand voltage
signals are fed as input to the summing amplifier unit using ((P2, P3, P4) channel, AP
channel and position demand signal (current to voltage converted signal available at X10-
3 . VP is used to limit the position feedback signal using potentiometer. A buffered
reference voltage can be added to position feedback signal by using N2 (X10-4) channel.
Initially the low pass filter is having a cut-off frequency of 4Hz. Internally the bridge LK2
can be cut out, which increases the cut-off frequency to 15Hz. This adds a new feature
of the system by adding fast positioning circuits. The position deviation signal can be
amplified between 6 and 120 using potentiometer. The position deviation signal is
indicated a voltage signal which is the difference between the position feedback signal
and position demand signal (reference signal). The summing amplifier unit (5) comprises
proportional integral (PI) control circuit. Position demand signal and position feedback
signal are both applied to Proportional integral control circuit and both the signals are
compared and difference between those signals is taken out as a position deviation signal
which is further applied to the logic circuit (6). The output of the summing amplifier unit
(5) is fed to the logic circuit (6) as illustrated in below.
Moreover, in the present invention, Fig-1 illustrates about the logic circuit (6) which has
a plurality of inputs, a plurality of outputs and at least a control signal. The output of the
summing amplifier unit (5) is fed to the logic circuit (6). Input signal for logic circuits as
given (Auto, oil, enable, open, close) are fed to the logic circuit by using (X11-1, X11-2,
X11-3, X11-4, X11-5) channels and Output signal/command of the logic circuits are open,
close, control signal for blocking element, Auto signal indication using relay and LED for
automatic controlling purpose and signal to variable gain amplifier and limiting circuit.
Any fault is detected, which will be indicated by using red LED as shown in monitoring
circuit (13). The reference voltages (+15V) and (-15V) are fed to the logic circuit for

choosing the manual process either open or close of the valve operation. The output
from the logic circuit (6) is used to provide current output to the proportional valve(14)
and also control signals for blocking element control and monitoring unit(7).
In the present invention, Fig-1 illustrates about the blocking element control and
monitoring unit in detail. The blocking element (15) i.e. poppet valve is mounted on the
proportional valve (14) to control the oil flow to solenoid valves. The Poppet valve is the
entry point for oil to flow into the proportional valve. Poppet valve is energised through
this drive control module under healthy condition to allow the valve to modulate based
on the control demand. In case of any faulty condition such as wire breakage, poppet
valve will be de-energized directly from the drive control module so that the oil entry is
blocked and valve will be put in stay-put condition until the next command is given. For
proper functioning of the proportional valve, pressurized oil is supplied from the
Accumulation which is the source of oil. After the usage, oil is returned to the oil storage
bank.
In the present invention, as figure 1 illustrates the blocking element (15) requires 24V
(app. 1.3A) power supply for operation. The power supply (24V and 1.3A current) is
driven through a circuit breaker and controlled and monitored by using a blocking element
control and monitoring unit (7). The current flowing to the blocking element unit is
monitored. Blocking element is energized to deblock or to opening the valve. Control
signal for Blocking element is derived through logic circuit (6) as illustrated in the fig-1.
Power supply to the blocking element is given through a circuit breaker (8), 2A rating.
The circuit breaker trips with the delay of <30 sec, whenever the load current exceeds
1.35A. When the circuit breaker (8) trips, it breaks both ends of the line cutting off power
supply as well as ground connection to the load and isolates load from power supply.
Once the fault is cleared, the circuit breaker can be reset manually by pressing “Reset”
push button on the front panel as shown in the fig 2. The output signal from the blocking
element control and monitoring unit (7) is fed to blocking element or poppet valve (15)
for smooth operation by using X10-15 and X10-16 channels.

The input power of the circuit breaker (8) is filtered by using Filter (16) to prevent
unwanted harmonics. The output of the circuit breaker (8) is fed to the DC-DC converter
(17). The DC-DC converter provides a plurality of DC power as (24V (for blocking
element), ±15V, and 5V).
Furthermore, in the present invention, Fig 1 illustrates about the output unit in detail. At
least one output from the logic circuit is fed to variable gain amplifier and limiting circuit
(18). Further, the position deviation signal (-10V to +10V) is scaled to (0V to 10V) by
using voltage scaling circuit (9).
The scaled voltage signal is fed to a voltage to current converter (10) and the output
current signal is fed to jumper (11) and further fed to the proportional valve (14) by using
X11-15 and X11-16 channel. Voltage to current converter (10) converts the position
deviation voltage signal from (0 to 10V) to current (4-20mA) signal. The position deviation
signal can be limited, the limiting values for the output signal can be set with internal
potentiometers. The output from the jumper (11) can be selected either voltage output
(±10V) through (choosing 2 and 3 pin) jumper (11) or current output (4-20mA) through
(choosing 1 and 2 pin) jumper (11) as output signal. Voltage and current outputs are
monitored for loop break by using monitoring circuit (13) as illustrated in fig-1 and Red
LED (on the front plate as shown in fig-1) will glow when there is a fault.
Moreover, in the present invention, Fig 1 and also Fig-2 illustrates about the monitoring
circuit (13). The module can be operated either in an AUTO mode or in a MANUAL mode
depending on the various conditions. The selection of Auto and manual mode can be Auto
mode selection, manual mode selection (open or close), control signal for blocking
element, control signal when oil is low and are generated using Logic circuits in the
module. Analog switch is used to switch the signals from Auto mode to Manual by opening
or closing valve depending on the control logic. Auto command and manual command
inputs are given below.

AUTO command input:
The module is in Auto mode whenever input at Auto signal is high (24V).
a. Auto signal always supersedes the manual signals.
b. The Auto mode of operation is indicated by yellow color 'AUTO' LED on the Front
Panel.
c. AUTO input cannot be blocked by MANUAL OPEN / CLOSE commands.
Manual command input:
Logic circuits are provided for changing Auto mode to Manual mode.
The open and close signal in a manual mode can be set using potentiometers available
at the front plate.
a. Open and Close commands are interlocked internally to prevent any action
when both open and close commands are issued.
b. The manual commands are valid only if AUTO is off
c. OPEN and Close commands are valid if issued with the Enable signal.
There is a possible to trip the power supply unit manually in case of emergency.
Whenever the trip power supply is to be turned off only in case of emergency, the
'Emergency trip' knob of CB (circuit breaker) on the front plate can be pressed.
In the present invention, the fault due to various parts of drive control module can be
detected by using fault annunciation unit (Monitoring Circuit (13)). The current output
signal as selected by using the jumper is monitored by using the monitoring circuit as
shown in the fig-1 and fig-2.
Further, in the monitoring circuit, the green LED indicates the operation of the module is
normal indicated as (OK) as shown in the fig-1 and fig-2. Any fault is indicated by using
RED LED display as shown in the fig-1 and fig-2. Auto mode of operation is also indicated
by using LED display) as shown in the fig-1 and fig-2.

The following fault signals are generated in the proposed system during the operational
stage:
1. Position feedback fault
2. Fault due to Output current open loop indication
3. Fault in the Blocking Element, open loop indication
The Power supply unit is dedicated for the drive control module which provides a
different kind of power to the respective unit in the drive control module. The module
receives only +24V input, which is protected by resettable fuse. A DC-DC converter
(17) blocks are used to derive +15V,-15V, +24V and 5V regulated voltages required for
internal circuits as shown in the fig 1.
The drive control module can be widely used in power plants and other industries where
proportional valves are used. The module can be used in HPBP system of power plants
to control the main steam pressure at HP turbine inlet and CRH downstream temperature.
Advantages:
1. Double protection mode is used to control the operation of proportional valve.
2. Auto Mode and Manual mode is used to control the operation of proportional
valve to avoid any damage.
3. The drive control module can be widely used in power plants and other
industries where proportional valves are used.

WE CLAIM :
1. A method for controlling and monitoring the operation of proportional valve in a
High pressure Bypass (HPBP) system, wherein the HPBP system includes a plurality
of proportional valves for controlling the flow of oil to the solenoid valve using a
blocking element to control and monitoring the operation of proportional valve by
using a drive control module which consists of at least one position feedback
transmitter (1) , at least one current to voltage converter (2,4) , at least one
voltage to current converter(3,10), at least one summing amplifier unit (5) , at
least a logic circuit (6), at least one blocking element control and monitoring unit
(7), at least one circuit breaker (8), at least a voltage scaling circuit (9), at least
one jumper (11,12), at least one monitoring circuit (13), at least one proportional
valve (14), at least one blocking element (15) and including associated circuitry,
the method comprising the steps of:
• receiving a plurality of current/voltage signals as position feedback signal from
a position feedback transmitter (1);
• getting a position reference signal from DCS (Distributed Control System);
• providing the position feedback signal to at least a current to voltage converter
(2), to generate a scaled positive feedback voltage signal after conversion;
• providing the position feedback voltage signal to at least a voltage to current
converter (3) and to generate a current signal after converting from a position
feedback voltage signal, for monitoring at distributed control system;
• converting the reference signal into voltage signal by using at least a current
to voltage converter (4) to feed to the summing amplifier unit (5);

• providing a plurality of inputs as at least three positive voltage inputs, at least
a demand voltage signal, at least a buffered reference voltage signal and also
position feedback voltage signal to the summing amplifier unit(5) to at least a
logic circuit (6);
• providing a plurality of input signals to the logic circuit (6) which operates at
least in two mode specially in automatic mode and generating a plurality of
output signal from the logic circuit and also generating a control signal which
is fed to a blocking element (7) unit for opening and closing the valve (15),
and
• scaling and converting the output signal from the logic circuit (6) by using at
least a voltage scaling circuit (9) and at least a voltage to current converter
(10) and fed to the proportional valve(14).

2. The method as claimed in claim 1, wherein the current and voltage inputs from
the transmitter (1) lies within either of 5mA to 15mA or 4mA to 20mA and 2.5V to
12.5V voltage range.
3. The method as claimed in claim 1, wherein the position feedback signal is scaled
and converted to a voltage signal within 0V to 10V range.
4. The method as claimed in claim 1, wherein the position feedback voltage signal is
converted to a current signal within 4mA to 20mA range.
5. The method as claimed in claim 1, wherein monitoring of the position feedback
signal for short circuits, lower and upper range, and annunciating fault by using a
monitoring circuit (13).

6. The method as claimed in claim 1, wherein the demand signal (reference) is within
the range of 0V to 10V.
7. The method as claimed in claim 1, wherein the summing amplifier unit (5)
comprises of a summing amplifier, a low pass filter with a cut-off frequency of 4Hz
and 15Hz and a Proportional Integral (PI) control.
8. The method as claimed in claim 1, wherein the amplification of position deviation
signal is carried out using at least a potentiometer between 6 and 20.
9. The method as claimed in claim 1, wherein the blocking element which is a poppet
valve is powered through a circuit breaker(8) and blocking element control and
monitoring unit with 24V voltage and 1.3A current signal for opening and closing
the poppet valve(15).
10.The method as claimed in claim 1, wherein the output signal from the logic circuit
(6)is scaled between 0V to 10V by using a voltage scaling circuit (9) and further
output voltage signal is converted to current signal by using a voltage to current
converter (10) and wherein,
- the output signal is, either voltage output between range -10V to +10V
or current output between range 4mA to 20mA, selected by using at
least a jumper (11) and fed to the proportional valve (14).