DE19714353A1 - Method for self=testing computer mechanism of digital electrical power meter - Google Patents

Abstract

The method involves performing a self-check with respect to the correctness of an incremental counter state whilst fixed data patterns are entered using a predefined check plan. The result is compared with a stored number to distinguish between correct results and errors. The digital meter can be used for voltage and current detection. The validity of these values can be determined by comparison with previous values. All potential parameters can be output, including current and voltage, cos phi in four quadrants, effective, reactive and apparent power.

Description

There are known digital meters that the electrical energy in the execution of Capture network analyzers and test counters. Obviously, the end-to-end digital Therefore signal processing on electrical energy meters on the market is not used because both arithmetic and software for determining and Further processing of the effective values of current and voltage are too extensive and so that the digital version of the device is too complex.

With the plan for self-examination of the arithmetic unit of the digital electrical energy meter lies gives the electronics technician a detailed overview of how the counter works Based on IS and ES electrons. It is a device in which the electrical work is displayed without the reading of effective values in the memory must be done.

In addition to the general advantages of digital counters over static counters (there is a electronic counter is easily equated to a static counter, is still here be confirmed once that it is a real in the patent 195 39 547.6 digital counter) in particular the possibility of own or Self-check of the arithmetic unit of such a counter. A self-check can be done realize in several ways. So z. B. in that the check program in the counter memory is integrated, and this either on site, via remote access or by means of an internal Timer is started in order to read out the result of the meter check.

The self-check without the installation of an additional test facility offers the advantage that Electricity customers who have questions regarding their electricity consumption to their energy supplier have advised in a short time, in high quality and at the same time with little effort can be.

A counter is currently being checked by a representative of the Power supply the test item (meter to be tested) either with a test meter, certified test counter or network analyzer in series and according to the corresponding Test time receives the test result. The problem with this method is that the Test equipment is expensive, the workload is high and in most cases the test only is connected with the consequence of an energy interruption. The final statement is in that justifies that it is usually not possible to use the existing wiring Attach current transformer clamps so that auxiliary measures are required. After Realization of the outlined effort is here after the completion of the work in most Cases visible that consumers are present on the meter of the electricity customer, over the he either has no knowledge, or he has this knowledge over time has been lost.

If, according to the state of the art, a remote interrogation with the corresponding Realized customer, computer analysis can be done and it is a statement immediately possible. This statement can reliably relate to the statement of the check, whereby at the same time there will be a question of current and voltage, the Accuracy trend based on computer-aided consumption statistics (daily, weekly or monthly flow lines) is easy to manufacture.

How the check query works

The check project is carried out by data which are stored in a suitable manner in the meter's memory Are available, realized. In detail, the following procedure is followed at Processing the plan makes sense.  

For the sake of simplicity, the check is carried out in the active work area, ie the current and voltage input are switched off on the same date, which is provided by the corresponding analog-digital converter in normal operation. Furthermore, contrary to the main patent, this description uses a word width of 8 bits with 256 possible dual numerical values. The following numerical values are shown as a decimal number. B. the following known assignment exists:

The half-wave is thus described by 360 samples from maximum positive to maximum negative value in Figure 2. The sampling rate according to Figure 2 means that, based on the real-time conditions of the 50 Hz network, the current and voltage values would be queried every 55.71 µs. This corresponds approximately to a sampling frequency of 18 kHz. It can be seen from Figure 2 that this sampling rate is an optimum for the creation of different query words in the 8-bit analog-to-digital conversion.

The project implementation with regard to the sequence of numbers is based on calculated digital values described.

Before that, however, the variable and then the cost agreement is made with
x: word; i, u, period: integer;
p, ee, es, esue, esuez, esr, z, note: longint;
const
list array [0..359] of byte = (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 6, 6, 6, 7, 7, 7, 8, 8, 8, 9, 9, 10, 10, 11, 11, 11, 12, 12, 13, 13, 14, 14, 15, 15, 16, 17, 17, 18, 18, 19, 19, 20, 21, 21, 22, 22, 23, 24, 24, 25, 26, 26, 27, 28, 28, 29, 30, 31, 31, 32, 33, 33, 34, 35, 36, 37, 37, 38, 39, 40, 41, 41, 42, 43, 44, 45, 46, 46, 47, 48, 49, 50, 51, 52, 53, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 95, 96, 97, 98, 99, 100, 101, 102 103, 104, 105, 106, 108, 109, 110, 111, 112, 113, 114, 115 , 116, 117, 119, 120, 121, 122, 123, 124, 125, 126, 128, 129, 130, 131, 132, 133, 134, 135, 136, 138, 139, 140, 141, 142, 143 , 144, 145, 146, 147, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 162, 163, 164, 165, 166, 167, 168, 169, 170 , 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185 , 186, 187, 188, 189, 190, 191, 192, 193, 194, 195, 196, 197, 198, 199, 200, 201, 202, 202, 203, 204, 205, 206, 207, 208, 209 , 209, 210, 211, 212, 213, 214, 214, 215, 216, 217, 218, 218, 219, 220, 221, 222, 222, 223, 224, 224, 225, 226, 227, 227, 228 , 229, 229, 230, 231, 231, 232, 233, 233, 234, 234, 235, 236, 236, 237, 237, 238, 238, 239, 240, 240, 241, 241, 242, 242, 243 , 243, 244, 244, 244, 245, 245, 246, 246, 247, 247, 247, 248, 248, 248, 249, 249, 249, 250, 250, 250, 251, 251, 251, 251, 251 , 252, 252, 252, 252, 253, 253, 253, 253, 253, 254, 254, 254, 254, 254, 254, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255 , 255).

At this point, the sequential course of the plan can begin, taking care is that the register values for certain agreed variables are set to zero. It could otherwise happen that due to registers pre-assigned with numerical values the Bottom line becomes flawed.

The operation continues with two loop commands, which will be explained later. The sequential processing of the plan is carried out by first outputting the strobe signal high on the printer port to control the printer driver (74 LS 245) and latch (74LS 373), and then 8 byte data words.

port [890]: = 0;
port [888]: = list [x];

The word on the printer output can now be read in. In order to accomplish this task, an additional plug-in card with corresponding circuits according to Figure 1 was made and inserted into the slot socket of an IBM 286 computer. This arrangement was created so that real proof is provided in the form of a functional model of a digital meter.

The printer port is first read by reading the first byte [here byte 1 = 0]. From the printer output, the respective word is first picked up by the bus driver (INPUT) and stored by the latch until the next byte is set. The word is optionally read out of the latch by the bus driver i (current) and u (voltage), coupled to the bus of the processor and further processed there, each subtracting 127 in order to generate a bipolar current value i and u from the unipolar word.

i: = port [768] - 127,
u: = port [769] - 127;

The two are then multiplied to produce the power p.

p: = u.i;

Now the individual energy ee has to be declared. This is done by multiplying p by the sampling time, which is an integration and leads to electrical work. Since the sampling time is a constant, it is advisable to include further constants, e.g. B. the current and voltage transformer ratio, correction factors and the like. For these reasons, the value 1496 should be used as the global constant. The global constant k calculated somewhat more precisely was created as follows. A primary power of 4400 W should be taken as the basis. The maximum power p at the word level is 128.128 = 16384

Rounded up, k = 1496 was created to operate with a four-digit number. In order not to work with a floating point number, the two positions shifted to the right must later be shifted to the left again.

ee: = p.1496.

Now the individual energies can be summed up by adding them to the total energy as with a roller counter, which is achieved by the following step.

it: = ee + es;

So that the electronic roller counter counts in increments of 1 Ws each, it must be divided by 10 ⁶ (and = 10 ² because of the left shift ⁾ . This division creates a cycle with 1 WS as total energy transfer esue and the rest of this division should be referred to as esr (residual energy sum). The schedule for this function then looks like this:

In the following processing the clock with the output per Ws has to be generated. The summation of the respective ones is carried out as follows by forming the total energy count esuez.

esuez: = esue + esuez;

To ensure that only the new meter reading with an increase of one kWh is visible on the display, the count amount z must be formed and written on the display after the kWh cycle has been formed.

If you start according to the plan, you will find that nothing is displayed. This is because the plan initially only guarantees the expiry of a period. The following loop must therefore be implemented in the plan.

period: = period;

As already announced, the integration of the loop at the beginning of the plan must be integrated before the port commands. The number of repetitions is fixed. During the check run, the run variable should be 1000. If a counter is to be provided for practical use, then a loop with the number of digits of the counter must be installed for z, which, however, is not to be explained here because of the extensive topic. The loop line looks like this.

for period: = 0 to 1000 do begin

The processing of the plan is only complete when all lines of the table above are processed independently one after the other. If the plan is accomplished by assembly instructions, then e.g. B. such processing lines.

here are some routines to arrange

further routines and integrations.

According to the previous language, this problem could also be with the loop

for list [x]: = 0 to 359 begin

provided that the field is declared.

list: array [0..259] of byte = (0...) etc.

The check number comparison is by comparison operators z. B. of the BOOLEAN type to make.

The plan covered relates to circuit 80286 and compatible.

Claims (1)

Method for self-checking the arithmetic unit of the digital electrical energy meter according to file number 195 39 547.6, characterized in that

• a) the digital counter allows a self-check for the correctness of the counted amount.
  The number can be checked because fixed data patterns (bytes) are entered using a specified check plan and processed according to a specified number of loops. The result achieved is compared to a stored number and then the correct result or an error is recognized.
• b) the digital counter enables voltage and current queries and, by comparing them with previous values, allows a probability statement about the correctness of these values.
• c) with the integration of the functions according to c) and b) on-site and remote readings can be carried out with existing devices, so that time-consuming checks are omitted because in most cases the readout result creates clarity. In stubborn cases, comparative counts are required anyway, which are carried out anyway by an approved test center, usually by sending the meter to the test center by the energy supplier.
• d) that the analog-digital converter in digital counters all possible measured value outputs such as current, voltage cosϕ in four quadrants as well as active, reactive and apparent work can be generated in a spatially small device.
• e) that the digital electrical energy meter can be realized by assembled circuits or intelligent controllers with supplementary modules, Asics, processors offered on the market or processors specially manufactured for the purpose. If the software of a digital meter is approved by the test office, the hardware can then advantageously be put together.
• f) the digital electrical energy meter can be used wherever electrical energy is to be counted for customers or suppliers and prepared for billing.
• g) the meter reading of electrical energy meters can be read directly, can be coded, modulated or multiplexed for further processing, because after the formation of the individual energy ee a data word is available in every size ready for reading. The data words can of course also be read out in clock cycles in order to be compatible with current counter generations. The counters on the market currently output pulse sequences, so that, according to the prior art, the readout devices must advantageously generate data words or readout telegrams for remote readout (remote data transmission links) from the pulses in the vicinity of the counter.