DEH System SM-3 Step Voltage Regulator Control. Siemens Format B Group 1 and 2 Protocol Guide

Transcription

1 g DEH40281 System SM-3 Step Voltage Regulator Control Siemens Format B Group 1 and 2 Protocol Guide

2 Table of Contents Chapter 1 Introduction About the SM About this Guide...1 Chapter 2 Siemens Format B Group 1 and 2 Protocol Introduction...2 Basic Message Format from Master to Remote System...2 Basic Message Format from Remote to Master System...2 Processing of Master Packet at SM Chapter 3 Siemens Format B Group 1 Configuration...4 Chapter 4 Siemens Format B Group 2 Configuration...5 Copyright 2001 GE Company All Rights Reserved ii

3 Chapter 1 Introduction About the SM-3 The System Monitor 3 step voltage regulator control described in this manual is Model SM-3, shown in Figure 1. Its microprocessor-based design is a substantial departure from traditional analog-based controls. The SM-3 provides an advanced, user-friendly interface for programming setpoints and functions, and monitoring system parameters. SIEMENS Format B Group 1 or Group 2 communications are enabled. The SM-3 is connected to a communications network via its fiber optic ports. About this Guide This book describes the SM-3 s implementation of the Siemens Format B Group 1 and 2 communication protocols. This guide is not intended to be a tutorial on the protocols itself and it is assumed that the reader has previous experience with integrating communications-capable devices into Siemens Format B communications systems. Chapter 2 describes the Siemens Format B Group 1 and 2 protocols in relation to the SM-3. Chapter 3 provides the SM-3 register map for the Siemens Format B Group 1 protocol. Chapter 4 provides the SM-3 register map for the Siemens Format B Group 2 protocol. For information on using the Modbus RTU, 2179, or DNP communication protocols with the SM-3, refer to GEH-7293, GEH-7294, or DEH40280 respectively. Figure 1. SM-3 Step Voltage Control Regulator. The SM-3 s microprocessor monitors input parameters such as voltage and line current, and uses these parameters to make decisions controlling the tap changer drive motor. The data collected by the SM-3 and the setpoints programmed into the SM-3 are stored in the device s memory and may be accessed and/or changed via the SM-3 s communications capabilities. The SM-3 is equipped with a fiber-optic communications port, enabling it to be con nected to a communications network. Five industry-standard communications protocols are supported by the SM-3: Modbus RTU, 2179, DNP, Siemens Format B Group 1 and Siemens Format B Group 2 protocols. Any one of the above protocols may be used to monitor and control the device. The SM-3 offers three modes of operation: automatic, automatic + remote, or manual. In Manual mode, communications are disabled. There fore, Manual mode may be disregarded for the purpose of this manual. Automatic mode enables the SM-3 to exercise control over the regulator tap change motor based on user-defined setpoints. Remote users connected via a communications network can monitor the SM-3 s operation and read data, but cannot make changes to setpoints or operation. In Automatic + Remote mode, the SM-3 functions as in automatic mode, with the addition of remote control. You can make changes to setpoints and control the operation of the tap changer directly over the communications network. The following assumptions are made regarding the SM-3 s settings: The device is operating in automatic or automatic+remote mode. 1

4 Chapter 2 Siemens Format B Group 1 and 2 Protocol Introduction The System Monitor Control (SM-3) is required to maintain a selected output voltage, modified by line drop compensation, within a selected bandwidth. Any deviations from the selected output voltage are corrected by energizing a bi-directional motor which drives a tap change mechanism in the proper direction to bring the voltage level back into the bandwidth. This chapter elaborates on the usage of Siemens Format B Group 1 and 2 Protocol Interfaces between the SM-3 and a host System. It details the message formats for Format B Group 1 and Group 2. Basic Message Format from Master to Remote System The following description is the physical format for the transmission of data from the master to the remote system. This is same for both Format B Group 1 and Group 2. Formats from Master to Remote System 1 Character 1 Character 1 Character 1 Character Master Sync Remote Message Error Code Address Type Character Format Each character is transmitted in an asynchronous manner using one start bit, eight data bits, one stop bit and no parity. Master Sync The first character in the message packet is a master sync code. The master sync code signals the remote regulator controls that a master message packet is being transmitted. Each regulator control begins saving the data and processes it after the packet is complete. The total packet is always four bytes. If the packet is incomplete a time-out will occur and the control will revert to searching for a sync character. The master sync is (14H). Remote Address The second character in the message packet specifies the address of the destination Remote System. The remote address can vary from 0 to 255. Message Type A message type is a one-character code that defines a function to be performed. This is always 00 (00H) for both the Siemens format B Group 1 and Group 2. Error Code An error code is a one-character checksum, which is the one s complement of the sum of all the characters except the cync and error code. Basic Message Format from Remote to Master System This format is the same for both Siemens Format B Group 1 and Group 2 except that the data fields in the Group 1 are four whereas data fields in the Group 2 are ten. Character Formats Each character is transmitted in an asynchronous manner using one start bit, eight data bits, one stop bit and no parity. The character is transmitted/received low order bit first. If a word has two bytes, the lower byte is transmitted first, followed by the higher byte. Regulator Sync The first character in the message packet is a regulator sync code. The regulator sync code signals the master that a response message packet is being transmitted. The regulator sync is the same for both Siemens Format B Group 1 and Group 2. The Regulator Sync is (27H). Remote Address The second character of the message packet specifies the address of the responding remote system. This is same as the second character of the master message. Message Type A message type is a one-character code that defines a function to be performed. This is same as the third character in the master message. Message Length This length character gives the byte count of the data field. The message length is (08H) bytes for the Siemens Format B Group 1 protocol. The message length is (14H) bytes for the Siemens Format B Group 2 protocol. Formats from Remote to Master System 1 Character 1 Character 1 Character 1 Character 1 Character Regulator Remote Message Message Date Fields Error Code Sync Address Type Length Data Fields Error Code This contains variables as defined by specification. Each data field is two 8-bit bytes, least significant byte transmitted first. The Error Code is a one-character checksum, which is the one s complement of the sum of all the characters except the Sync and The Siemens Format B Group 1 protocol has four data fields. error code. The Siemens Format B Group 2 protocol has ten data fields. 2

5 Processing of Master Packet at SM-3 The master sync code signals the remote regulator controls that a master packet is being transmitted. Each regulator control begins saving the data and processes it after the packet is complete. The master packet is comprised of 4 characters in total. If the packet is incom plete a time-out will occur and the control will revert to searching for a sync pulse. After a complete packet is received, the data is analyzed as follows: If the received and computed error codes do not match, the packet is discarded and the control begins monitoring for another sync pulse. If the received and computed error codes match the control checks for the remote address. If this is not correct then the control begins monitoring for another sync pulse. If the address is correct, the control checks for the correct message type. The particular message type (00H) has been assigned to SM-3 control to define that the master control is asking for data. If the message type is not (00H), SM-3 will discard the data received and begin monitoring for another sync pulse. If the message type is (00H) then the control queues up the data for transmittal. The Siemens Format B Group 1 response has four data words and the Siemens Format B Group 2 response has ten data words. System Monitor 3 Chapter 2 Siemens Format B Group 1 and 2 Protocol 3

6 Chapter 3 Siemens Format B Group 1 Configuration Four variables are transmitted in the data fields. The table below gives the details of each of the data fields. Data Field # Description Conversion Factor Remarks 1 Load Volts 16 2 Load Amps 1 3 Power Factor 2 14 (+) = lagging (-) = leading 4 Integrated Amps 1 4

7 Chapter 4 Siemens Format B Group 2 Configuration Ten variables are transmitted in the data fields. The table below gives the details of each of the data fields. Data Field # Description Conversion Factor Remarks 1 Load Volts 16 2 Load Amps 1 3 Power Factor 2 14 (+) = lagging (-) = leading 4 Integrated Amps 1 5 Compensate line volts 16 6 Integrated minimum load voltage 16 7 Integrated maximum load voltage 16 8 Integrated maximum load current 1 9 Most leading power factor 2 14 (+) = lagging (-) = leading 10 Most lagging power factor 2 14 (+) = lagging (-) = leading 5

8 g GE Industrial Systems DEH40281 R General Electric Company 41 Woodford Ave., Plainville, CT General Electric Company