Data logging in a voltage regulator controller

A voltage regulator controller including three types of data logs which are operator selectable and configurable. An operator can enable data logging to occur at specific times and intervals. The voltage regulator controller includes a real time clock/calendar and interval timer to support this function. In a preferred embodiment, the controller includes an event log, a snapshot interval log and a minimum/maximum metered parameter log. Advantageously, the event log can be programmed to monitor configuration changes made from the voltage regulator controller's front panel or from a remote device. The voltage regulator controller also includes a memory card interface which enables the log contents to be uploaded to a removable PCMCIA standard memory card.

I. Cross Reference to Related Applications 
This application is related to U.S. patent application Ser. No. 07/950,402; 
filed on Sep. 23, 1992; and U.S. patent application Ser. No. 08/101,133; 
filed on Aug. 2, 1993 now U.S. Pat. No. 5,455,505. 
II. Background of the Invention 
a. Field of the Invention 
This invention relates to voltage regulators and related control systems. 
b. Related Art 
A step-type voltage regulator is a device which is used to maintain a 
relatively constant voltage level in a power distribution system. Without 
such a regulator, the voltage level of the power distribution system could 
fluctuate significantly and cause damage to electrically powered 
equipment. 
A step-type voltage regulator can be thought of as having two parts: a 
transformer assembly and a controller. A conventional step-type voltage 
regulator transformer assembly 102 and its associated controller 106 are 
shown in FIG. 1. The voltage regulator transformer assembly can be, for 
example, a Siemens JFR series. The windings and other internal components 
that form the transformer assembly 102 are mounted in an oil filled tank 
108. A tap changing mechanism (not shown) is commonly sealed in a separate 
chamber in the tank 108. 
The various electrical signals generated by the transformer are brought out 
to a terminal block 110 and external bushings S, SL, L for access. The 
terminal block is preferably covered with a waterproof housing. An 
indicator 112 is provided so that the position of the tap as well as its 
minimum and maximum positions can be readily determined. 
A cabinet 114 is secured to the tank to mount and protect the voltage 
regulator controller 106. The cabinet 114 includes a door (not shown) and 
is sealed in a manner sufficient to protect the voltage regulator 
controller 106 from the elements. Signals carried between the transformer 
or tap changing mechanism and the voltage regulator controller 106 are 
carried via an external conduit 116. 
The tap changing mechanism is controlled by the voltage regulator 
controller 106 based on the controller's program code and programmed 
configuration parameters. In operation, high voltage signals generated by 
the transformer assembly 102 are scaled down for reading by the controller 
106. These signals are used by the controller 106 to make tap change 
control decisions in accordance with the configuration parameters and to 
provide indications of various conditions to an operator. 
SUMMARY OF THE INVENTION 
In accordance with an embodiment of the present invention, a voltage 
regulator controller is provided with a log memory and control software 
for storing and maintaining data logs which are operator selectable and 
configurable. An operator can enable data logging to occur upon the 
occurrence of one or more predefined events and at specific times and 
intervals. 
According to one aspect of the present invention, a voltage regulator 
controller includes an interface which couples the voltage regulator 
controller to a regulator transformer; a processor for monitoring 
electrical parameters present in the regulator transformer and for 
providing control signals to the regulator transformer responsive to at 
least one of the electrical parameters; an operator interface for 
receiving configuration data from an operator of the voltage regulator 
controller; a log memory; and a log task for capturing, in the log memory, 
data indicative of at least some of the electrical parameters when 
conditions specified by the configuration data occur. 
According to another aspect of the present invention a method of operating 
a voltage regulator controller includes the steps of receiving 
configuration data including information indicative of a log triggering 
condition, from an operator of the voltage regulator controller; 
monitoring the voltage regulator controller and a regulator transformer 
whose operation is controlled by the voltage regulator controller, for 
occurrence of the log triggering condition; monitoring electrical 
parameters present in the regulator transformer; and, capturing data 
indicative of at least some of the electrical parameters in a memory when 
the log triggering condition is detected.

IV. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
An embodiment of the present invention will now be described by reference 
to FIGS. 2 through 4. 
A step-type voltage regulator and its associated controller according to an 
embodiment of the present invention are shown in FIG. 3. The voltage 
regulator transformer assembly 302 can be, for example, a Siemens JFR 
series but in any event is of a conventional type which includes a 
multi-tap transformer 402 and an associated tap changer 404. The tap 
changer 404 is controlled by the voltage regulator controller 306 which 
receives signals indicative of voltage and current in the windings of the 
transformer 402 and conventionally generates tap control signals in 
accordance with operator programmed set-points and thresholds for these 
signals. The voltage regulator 302 can also be provided with a personality 
module 126 which stores statistics and historical information relating to 
the voltage regulator. 
The voltage regulator controller 306 includes a processor section 406, a 
high voltage interface 408, a memory card interface 138 (which can be of 
the PCMCIA type), an I/O expansion chassis 412 which is coupled to the 
processor section 406 by way of an SPI bus 414 and a front panel 416 which 
is coupled to the processor section. 
The front panel 416 provides an operator interface including a keypad 417, 
a character display 510, indicators 421 for various regulator conditions 
and a serial communications port connector 524. A user interface task 
("usint") 434 running under the mcp monitors activity on the keypad 417 
and provides responses to the character display 510 as needed. The front 
panel 416, its associated operator interface and the user interface task 
434 can be of the type described in United States patent application Ser. 
No. 07/950,402; filed on Sep. 23, 1992, which is incorporated by reference 
in its entirety as if printed in full below. 
The processor section 406 is controlled by a microprocessor (uP) 502. The 
processor section 406 generates digital control signals based on internal 
program code and operator selected parameters entered (by an operator) via 
the controllers front panel 416. In operation, high voltage signals are 
generated by the voltage regulator transformer 402. These signals are 
scaled down via internal transformers (not shown) and provided to the high 
voltage interface 408. The high voltage interface 408, in turn, further 
scales the transformed down signals for reading by an analog to digital 
converter 502c (shown in FIG. 4) within the processor section 406. The 
data fed back from the voltage regulator 402 is used by the processor 
section 406 to make tap change control decisions and to provide indication 
of various conditions to an operator. 
The memory card interface 138 is disposed in the controller housing so that 
it is externally accessible via a slot formed in the controller housing 
wall. A voltage regulator controller having a suitable memory card 
interface is described, for example, in copending U.S. patent application 
Ser. No. 08/101,133; filed on Aug. 2, 1993 now U.S. Pat. No. 5,455,505, 
which is incorporated by reference in its entirety as if printed in full 
below. 
In accordance with an embodiment of the present invention, the processor 
section 406 includes a log memory 422 and control software (log task) 424 
for storing and maintaining data logs which are operator selectable and 
configurable. An operator can enable data logging to occur at specific 
times and intervals as will be described in more detail later. The 
processor section 406 also includes an internal real time clock, calendar 
and interval timer (collectively referred to as the rtc 532) to support 
this function. The real time clock/calendar is supported with a 
conventional self-recharging auxiliary power source back-up 426. The 
auxiliary power source 426 is rated so that time is kept for a suitable 
minimum outage period, for example 72 hours. 
There are three data logs which are stored and maintained in the log memory 
422. These include an event log 428, a snapshot/interval log 430 and a 
minimum/maximum (min/max) log 432. 
The event log 428 stores present readings when an event occurs. Events 
which will trigger the event logging function are defined in log set-up 
configuration items entered via the keypad 417. Events which can be 
specified to trigger event logging (trigger events) include controller 
power up; parameter (setting) changes (entered, for example, by way of the 
front panel or a communications port); alert conditions such as high 
voltage or low current. Voltage Reduction Control (VRC) operations; 
Voltage Limit Control (VLC) operations; the reaching of 
operator-specified, pre-defined tap positions and power flow direction 
changes. Those of skill in the art will recognize that other events, such 
as relay conditions as status input changes, could be monitored as well. 
Entries stored in the event log 428 can be retrieved via the display 510 
or via a communications port such as the front panel serial communications 
port 524. Optionally, events can be time/data stamped by using the real 
time clock/calendar 532. 
The snapshot/interval log 430 stores present readings at specific times and 
or intervals which are defined in the configuration settings. Entries 
stored in the snapshot/interval log 430 can be retrieved via the display 
510 or via a communications port (e.g. 524). As will be described in more 
detail later, the snapshot/interval log is used in conjunction with the 
real time clock/calendar 532. 
The min/max log 432 stores minimum and maximum values for metered 
parameters. These parameters can be viewed via the display 510 under 
keypad control and/or can be communicated via a communications port. Once 
interrogated, the min/max values are resetable one at a time. The 
displayed value reverts to the present value upon reset and integration is 
restarted. Optionally, the minimum and/or maximum values for any metered 
parameter can be time/date stamped using the real time clock/calendar 532. 
The log task 424 is a software task which runs under the microprocessor's 
main control program (mcp) 433. One function of the log task 424 monitors 
the voltage regulator controller and transformer assembly for the operator 
specified event conditions (e.g. by monitoring signals coming from the 
high voltage interface 408). When the log task 424 detects occurrence of 
an operator specified trigger event, it captures the parametric data for 
that event in the event log 428. 
An operator activates event logging by depressing a unique key sequence on 
the keypad 417. When event logging is activated, the log task 424 performs 
the activities required to detect occurrence of the trigger event. Log 
task activities include: 1) tracking tap position, 2) monitoring 
conditions for VLC and imposing VLC when conditions warrant, 3) monitoring 
conditions for VRC and imposing VRC when conditions warrant, 4) monitoring 
power flow direction, 5) determining occurrence of power up, 6) 
determining when configuration changes are made and 7) determining when 
alert conditions occur. 
Each entry in the event log includes a code which identifies the cause of 
the event (e.g. tap change, power up, specified configuration change, 
etc.); the event number (e.g identification of the logged entry as the 
first, second, third . . . event to occur since event logging was 
commenced); parametric data associated with an event such as instantaneous 
values for the load voltage, load current, power factor, real power, 
reactive power, apparent power, source voltage and the instantaneous tap 
position; and a time/data stamp from the rtc. The parametric data are 
updated periodically by a metering task 435 running under the main control 
program 433. 
The operator enables data logging by configuring the voltage regulator 
controller 306 via the front panel 416. The operator enters configuration 
data via the keypad 417 while viewing the configuration data on the 
display 510. When the operator changes the configuration data (e.g. event 
log set-up), the user interface task 434 modifies the corresponding 
configuration data. This revised configuration data is then accessible by 
the log task 424 (e.g. for determining which events to record in the event 
log 428). 
According to an embodiment of the present invention, the event log 
definitions can be set up so that future configuration changes made by an 
operator are time and date stamped and recorded in the event log 428. When 
this option is invoked by an operator (via a keystroke sequence on the 
keypad) the operator interface task 434 notifies the log task 424 about 
the occurrence and type of any operator programmed configuration changes. 
The log task 424, in turn, adds a time and date stamp to the configuration 
change data (using the rtc 532) and stores the time/date stamped 
configuration change information in the event log 428. 
The snapshot/interval log 430 operates under a similar principle, storing 
snapshots of operator specified data at operator specified times (the data 
and time specifications all being passed through to the log task 424 by 
the operator interface task 434). Once the operator sets the interval 
period and enables interval logging via the operator interface, the log 
task begins timing the specified interval using the rtc. When the interval 
time has elapsed (or the snapshot time/date has occurred), values of the 
parametric working data are stored in the snapshot/interval log 428 and 
the log task starts timing out the next interval. 
Each entry in the snapshot/interval log 430 includes the interval number; 
the time and date of the interval snapshot; the minimum, maximum, 
instantaneous and demand values for the load voltage, load current, real 
power, reactive power and apparent power; the instantaneous power factor; 
the power factor at minimum and maximum apparent power; the instantaneous 
minimum and maximum tap position; and the total operations count. Many 
other combinations of interval parameter storage could also be performed 
if desired. 
Log data for both intervals and events can be accessed by way of the 
display 510 (under control of the keypad 417) or remotely via a 
communications port. Similarly, the log set-up information can be 
configured remotely via a communications port. 
The log task 424 monitors the values of metered parameters and compares the 
new values to previously stored minimum and maximum values. If a new value 
for a metered parameter falls below the stored minimum value, then the new 
value is stored as the new minimum value. Similarly, if a new value for a 
metered parameter rises above the stored maximum value, the new value is 
stored as the new maximum value. The operator can individually clear each 
stored minimum and maximum value by selecting the minimum or maximum value 
for display and then pressing the reset key on the front panel keypad. 
The log task 424 maintains the minimum/maximum data in the min/max log 432. 
The working parameters (the instantaneous metered values) are periodically 
updated by the metering task 435. The log task compares the minimum and 
maximum log data to the working parameters and updates the min./max. log 
entries as required. 
Minimum/Maximum logging is essentially always enabled when the voltage 
regulator controller is turned on. 
The operator can view the min/max log data via the display 510 under 
control of the keypad 417. Using the keypad, the operator first displays 
the instantaneous value for the parameter of interest. Then by pressing a 
Max/Min key, the operator can view either the minimum or the maximum value 
for the parameter. Through further key press sequences, the operator can 
also view the time and date of occurrence for each minimum or maximum 
value. 
Min/Max log data as well as the time and data of their occurrence can be 
accessed remotely via a communications port. 
Any or all of the logs 428, 430, 432 can be uploaded to a memory card 140 
by way of the memory card interface 138. This is accomplished by an 
operator plugging a PCMCIA standard memory card into the memory card 
interface and invoking an "UPLOAD" command from the keypad 417. When the 
UPLOAD command is invoked, the microprocessor causes the memory card 
interface to assert a write enable signal to the memory card and copies 
the contents of the logs 428,430, 432 to the memory card 140 via the 
memory card interface 138. 
The operation and scheduling of the various data logging functions are 
shown in FIG. 2. As explained previously, data logging is enabled by an 
operating setting the appropriate configuration parameters by way of the 
front panel or via a communications port. The user interface task 434 
stores these parameters in the processor's memory where they are available 
to the mcp 433 and the log task 424. The configuration parameters specify 
which logging functions are to be enabled. In step 202 these parameters 
are read by the mcp 433 which, in turn, in step 204 schedules program 
tasks for each of the enabled logging functions. The scheduler (step 206) 
ensures that each of the enabled logging functions is executed by the 
microprocessor 502 using conventional time-sharing algorithms. 
Each of the logging functions starts (in steps 208-212) by reading its 
associated configuration parameters as specified by the operator and 
stored by the operator interface task 434. 
For the snapshot/interval log, the associated configuration data includes 
the operator specified interval and can optionally include data indicative 
of which working parameters to store in the snapshot log when the 
specified interval has elapsed. Alternatively, the working parameters to 
be captured can be a fixed set specified by the log task's programming 
code. In any event, in step 214 the snapshot log program code updates the 
interval timer. During the first pass, this includes programming the 
interval timer with the initial interval. During subsequent passes, this 
includes modifying the specified interval and reinitializing the timer 
when the specified interval has been changed by the configuration data. In 
step 216, the snapshot log program code checks the interval timer to 
determined if the interval has expired. If so, in step 218 the program 
code records the specified snapshot data and restarts the interval timer 
in step 214. If no, the program code again updates the interval timer as 
needed in step 214. 
Similar to the snapshot/interval log, the event configuration data 
specifies one or more triggering events and can optionally specify the 
working parameters to be captured in the event log when the specified 
events occur. Alternatively the working parameters can be fixed by the log 
task program code as described for the snapshot/interval log. The event 
configuration data also includes an indicator as to whether the occurrence 
of the specified triggering events are to be time stamped. 
In step 220 the event log program code commences monitoring the working 
parameters used to determine occurrence of the event triggers specified by 
the event conditions. If any of the event triggers occur, this is detected 
in step 222 and the event data is recorded in step 224. The monitoring of 
step 220 continues throughout the process. 
Unlike snapshot and event logging, the processor tracks new minimum and 
maximums of metered parameters whether the logging function is enabled or 
not. However, when the min/max log is enabled all new occurrences of 
minimums and maximums specified by the configuration parameters are time 
stamped and stored in the minimum/maximum log. In step 226, the min/max 
program compares the working parameters to their previously stored minimum 
and maximum values. If any new minimums or maximums are detected in step 
228, they are time stamped and recorded in the event log in step 230. 
The present invention may be embodied as an improvement to the base 
circuitry and programming of an existing microprocessor based voltage 
regulator controller. An example of a controller having suitable base 
circuitry and programming is the Siemens MJX voltage regulator controller, 
available from Siemens Energy and Automation, Inc. of Jackson, Miss. 
A more detailed block diagram of the processor section 406 and its 
interconnection other elements of the voltage regulator controller is 
illustrated in FIG. 4. 
The processor section 406 includes the microprocessor 502 (for example, a 
Motorola 68HC16) which is coupled to the other processor elements by way 
of a common bus 504. An electrically erasable programmable read only 
memory (EEPROM) 506 includes the microprocessor's program instructions 
(including the mcp 433, the user interface task 434, the metering task 435 
and the log task 424) and default configuration data. 
A static type random access memory (SRAM) 508 stores operator programmed 
configuration data and includes an area for the microprocessor 502 to 
store working data. The SRAM also include a memory space for the data logs 
428-432. 
The microprocessor 502 also communicates with the alphanumeric character 
display 510, the keypad 417 and indicators 421 and the memory card 
interface 138 via the bus 504. 
The keypad 417 and indicators 421 are coupled to the bus 504 via a 
connector 514 and a bus interface 515. As previously described, a memory 
card 140 can be coupled to the bus 504 by way of a conventional PCMCIA 
standard interface 138 and connector 520. 
Operational parameters, setpoints and special functions including metered 
parameters, log enables, log configuration data and local operator 
interfacing are accessed via the keypad 512. The keypad is preferably of 
the membrane type however any suitable switching device can be used. The 
keypad provides single keystroke access to regularly used functions, plus 
quick access (via a menu arrangement) to all of the remaining functions. 
The microprocessor 502 includes an SCI port 502awhich is connected to a 
communication port interface 522. 
The communication port interface 522 provides the SCI signals to the 
external local port 524 on the controller's front panel 416. An isolated 
power supply for the communication port interface 522 is provided by the 
high voltage interface 408 via high voltage signal interface connector 
526. 
The communication port interface 522 supports transfer of data in both 
directions, allowing the controller to be configured via a serial link, 
and also provides meter and status information to a connected device. In 
addition to supporting the configuration and data retrieval functions 
required for remote access, the communication port interface 522 supports 
uploading and/or downloading of the program code for the microprocessor 
502. 
The communication port interface 522 can be, for example, an RS-232 
compatible port. The local port connector 524 can be used for serial 
communication with other apparatus, for example a palmtop or other 
computer. The physical interface of the local port connectors 524 can be a 
conventional 9-pin D-type connector whose pin-out meets any suitable 
industry standard. 
The microprocessor 502 also includes a SPI port 502b which is connected to 
an expansion connector 528 by way of an SPI interface 530. The expansion 
connector brings the SPI bus 414 out to the I/O expansion chassis 412 via 
a cable. Other devices that reside on the SPI bus include the real time 
clock 532 and a serial EEPROM 534. The real time clock provides the time 
and date stamp data and the interval data for the log task 424. The serial 
EEPROM 534 stores operator programmed configuration data. The operator 
programmed configuration data is downloaded to the SRAM 532 by the 
microprocessor 502 when the processor section 406 is initialized. The SRAM 
copy is used, by the microprocessor, as the working copy of the 
configuration data. The real time clock 532 is programmed and read by the 
microprocessor 502. 
The high voltage signal interface connector 526 provides a mating 
connection with a connector on the high voltage interface 408. Scaled 
analog signals from the high voltage interface 408 are provided to an A/D 
converter port 502c by way of an analog sense signal interface 536. The 
analog sense signal interface 536 low pass filters the scaled analog input 
signals prior to their provision to the A/D converter port 502c. Digital 
signals from the high voltage interface 408 are provided to the bus 504 
via a digital sense signal interface 538. The digital sense signal 
interface 538 provides the proper timing, control and electrical signal 
levels for the data. 
Control signals from the microprocessor's general I/O port 502d are 
provided to the high voltage signal interface connector 526 by way of a 
relay control signal interface 540. The relay control signal interface 
converts the voltage levels of the I/O control signals to those used by 
the high voltage interface 408. A speaker driver 542 is connected to the 
GPT port 502e of the microprocessor 502. The processor section 406 also 
includes a power supply 544 which provides regulated power to each of the 
circuit elements of the processor board 406 as needed. The high voltage 
interface 408 provides an unregulated power supply and the main 5 volt 
power supply for the processor board 406. 
The microprocessor 502 recognizes that a memory card 140 has been plugged 
into the memory card interface 518 by monitoring the bus 504 for a signal 
so indicating. In response, the microprocessor 502 reads operator selected 
control parameters entered via the controller's keypad 417. Depending on 
the control parameters, the microprocessor either updates the programming 
code in its configuration EEPROM 506, executes the code from the memory 
card 140 while it is present but does not update its EEPROM 506, or dumps 
selected status information to the memory card 140 so that it can be 
analyzed at a different location. As an alternative embodiment, the 
processor section 406 can be programmed to default to the memory card 
program when the presence of a memory card is detected. In this case, upon 
detection, the program code from the memory card would be downloaded to 
the SRAM 508 and executed by the microprocessor from there. 
The I/O expansion chassis (rack) 412 includes a number (e.g. 6) of 
connectors 550 for receiving field installable, plug-in I/O modules 552. 
The connectors 550 are electrically connected to the SPI bus 414 via a 
common processor section interface connector 554 and couple the I/O 
module(s) 552 to the SPI bus 414 when they are plugged into the chassis. 
The processor section can communicate with the personality module 126 in a 
number of ways. For example, the microprocessor 502 can be provided with 
conventional RS-232 interface circuitry to the SCI bus or the data bus. A 
conventional RS-232 cable can then be used to connect this RS-232 
interface to an RS-232 interface on the personality module. Alternatively, 
an I/O module (SPI BUS R/T) in the I/O expansion chassis can provide the 
physical and electrical interface between the SPI bus 414 and a cable 
connected to the personality module. An SPI R/T can also be used to 
provide outside access to the data logs 422 and associated configuration 
parameters. 
Now that the invention has been described by way of the preferred 
embodiment, various modifications, enhancements and improvements which do 
not depart from the scope and spirit of the invention will become apparent 
to those of skill in the art. Thus, it should be understood that the 
preferred embodiment has been provided by way of example and not by way of 
limitation. The scope of the invention is defined by the appended claims.