FILED OF THE INVENTION
The present invention relates to a centralised monitoring and control system for electrostatic precipitators (ESP) used for pollution control in thermal power plants, cement plants, glass plants and steel plants. More particularly the present invention relates to a multimaster server-client network for a PC based control and monitoring system for monitoring and user control of multiple units connected to the network.
BACKGROUND OF THE INVENTION
Electrostatic precipitators (ESP) are configured with a number of fields, which have collecting and emitting electrodes. A high electric field is generated between the electrodes to charge the dust particles and collect the charged particles on the collecting electrodes. Collected dust layer is dislodged using a rapping mechanism provided with hammers. High voltage is generated by means of a high voltage transformer-rectifier. Rapping motors are used for operating the hammers to remove the collected dust layer from the collecting electrodes.
Each field is provided with one high voltage transformer-rectifier and rapping motors for collecting and emitting electrode rapping. Both the transformer-rectifier and rapping motor are controlled and monitored by micro-controller based controllers, generally called ESP controller. The ESP controllers control and monitor various electrical parameters like feedback current, average, peak voltage and valley voltage, alarm conditions of the high voltage transformer-rectifier and rapping motor on/off feedback.

There is a PC based system which communicates with the ESP controllers in a cyclic manner and monitors all the electrical parameters, the rapping motor status, rapping frequencies etc. of the individual ESP fields, and the system displays in a user friendly Graphic user interface, the relevant parameters for later reference, communicates the status to the plant DCS. The system also communicates to the controllers the specific control commands from the user in an event-driven manner. This PC-based system is the master for communication purpose and the ESP controllers are acting as slaves. Being a single master system, this does not support having multiple such units for user monitoring and control of ESP parameters either for the purpose of redundancy or for the purpose of monitoring from different locations.
US patent No. US7,736,418 B2 dt: June 15, 2010 teaches a system in which the devices related to ESP for example, high voltage supply units and auxiliary functional units are set up as software modules in a server component. Multiple clients can be connected to this server to access these devices and permit user to control and monitor. This meets the need for control and monitoring from multiple locations. However, the software modules being existent only in one server component, the clients are not functional in absence of the server. Hence the aspect of redundancy is not addressed as per the prior art.
OBJECTS OF THE INVENTION
It is therefore an object of the present invention to propose a multimaster server-client network for a PC based control and monitoring system for monitoring and user control of multiple units connected to the network.

Anther object of the invention is to propose a multimaster server-client network for a PC based control and monitoring system for monitoring and user control of multiple units connected to the network, in which one-to-one redundancy or hot-stand by for the PC system is provided to allow in the event of failure by one PC, another PC to take over the remote control and monitoring functions seamlessly.
A further object of the invention is to propose a multimaster server-client network for a PC based control and monitoring system for monitoring and user control of multiple units connected to the network, which is easily adaptable for any configuration of the electrostatic precipitator irrespective of the number of fields, and current and voltage rating of the high voltage transformer-rectifier.
SUMMARY OF THE INVENTION
Accordingly, there is provided a multimaster server-client network for a PC based control and monitoring system for monitoring and user control of multiple units connected to the network. Thus, the present invention addresses the need for control and monitoring of the ESP parameters from multiple PCs. A server is linked to all the ESP controllers in a single master network so that it can continue the cyclic and event driven communication for status monitoring and control commands from the user respectively. The server is an embedded device which is capable of collecting the data associated with the current status of all the ESP fields in its memory buffer and push the status information to all its clients in a periodic manner.

The server is connected to a number of clients which are PC based systems with application programs to display the data for user monitoring as well as to enable user to give control commands to the ESP controllers. The client application has modules which act as software objects corresponding to the ESP as a whole, its constituent passes, fields, etc.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The invention can be described in detail with the help of the figures in accompanying drawings, where
Figure 1 shows a block diagram of the control and monitoring system with ESP controller network and PC side sever client network according to the invention
Figure 2 shows a schematic block diagram of the client application architecture running in the PC
Figure 3 shows a schematic block diagram illustrating the different object and subobjects of the ESP representation in the client application.
DETAILED DESCRIPTION OF THE INVENTION
As shown in figure-1, a server [3] that forms an interface between a server client PC [1] side network [2], and a master slave ESP controller network [6], is configured by a master implementation [5] and a server implementation [4]. The

master implementation [5] communicates to a plurality of ESP controllers [7] over the single master network [6] and loads the status information of the ESP parameters into its internal memory buffer. This memory buffer is read by the server implementation [4] to transmit the status information to the client [1] in a periodic manner. The clients [1] update the display for user monitoring based on this status information. This status information consists of the ESP field electrical parameters for example, operating and set values of current, average peak and valley voltages and spark rate. Any control commands sent from the client PC [1] are received by the server implementation [4] and are passed on to the master implementation [5] as an event and is communicated to the controller network [6] immediately.
A client program [8] is loaded on the client PCs [1] to establish connection with the server implementation [4] and included in the set of clients [1] that are linked to the server [3] over the server client network [2], The client program [8] has software modules distributed in various layers. The lowest layer being a client layer [12] that works as the communication interface of the server client network on the client PC [1]. A client layer [12] establishes a link with the server [3] with its unique ID and receives the packets transmitted from the server [3] on the server client network [2]. It maintains status buffers for ESP data and updates its upper layer [10] based on the server [4] information. This upper layer is the object layer [10] which contains all objects [11] and sub-objects [13,14,15,16 and 17] that represent the ESPs and its constituents objects associated with a boiler.

The object layer [10] has objects in the software representing various components or regions of the ESP. One of them is an ESP field object [14] which represents an ESP field which is the region in the ESP powered by one high voltage transformer-rectifier. This ESP field object [14] has two sub objects. One is an HVR object [15] that holds properties of the HVR for example, the ESP current and voltages. It also features methods to transmit the user commands for HVR control from its upper layer to the client layer. The second sub object is an auxiliary object [16] which holds properties for example, the rapping status, heater status, ash level, etc for the field. Another software object is an ESP pass object [13] that represents an ESP pass which is a set of ESP fields through which the flue gas passes before reaching the outlet. It is constituted by ESP field objects {14] and an auxiliary object [17] that holds properties for example, the GD rapping motor status that is specific to the pass. An ESP object [11] that may have one or two ESP pass objects [13] also has properties for example, the opacity meter reading which are specific to a physical.
ESP. The client layer [12] of the client program [8] updates the status properties of all the objects in the object layer [10].
The upper most layer or the user interface layer [9] hosts the forms and display modules that are used to present the status information to the user. User gives control commands to the ESP controllers through the user interface layer [9] and the commands are passed downwards to the client layer [12]. The performance optimization logic is also incorporated in this layer and when suitable mode is selected by the user in the client application [8], the algorithm monitors the status and gives commands using the same API as the user forms do.

The Client program [8] is developed such that it is easily configurable for any configuration of the ESP, with parameters for configuration being the number of fields, passes, current and voltage rating for the High voltage TR sets, etc. Configuration inputs are used to construct the objects in the object layer [10] and the display objects in the user interface layer [9] in the required number and combination at run-time. For example where a project has 32 fields with 4 passes, the relevant project configuration is taken as input to the software which generates 32 field objects and uses them as sub-objects for the 4 pass objects respectively and so on. These objects are then updated by the communication layer with the current status of the parameters communicated by the controllers. These objects' status is in-turn used to update the relevant user interface' objects which are also generated at run-time corresponding to the configuration input. The development and testing efforts are only one time since the same application program with a different set of configuration parameters will be used for different ESP configurations.
The server [3] has intelligence to identify if the optimization programs are switched ON in one client PC [1] and to not permit running the optimization programs from another client so as to avoid overlap and contradicting commands. In case the first client [1] fails, it permits the second client to run optimization programs, thus providing hot-standby for the monitoring system.

WE CLAIM
1. A centralized monitoring and control system for electrostatic precipitator (ESP) having a plurality of fields and ESP controllers, the system implementing cyclic and event driven communication for status monitoring and control commands respectively with the ESP controllers for HVR control and electrode rapping, wherein the ESP controllers are connected in a master slave configuration, wherein an interfacing server device with a master implementation and a server implementation disposed between a ESP controller network and a Client PC network, and wherein a client PC is detachably attachable to the server client network without affecting the other clients PCs, the server, the controller communication or the operation of the controllers.
2. The system as claimed in claim 1, wherein the system is enabled to control and monitor the ESP controllers from multiple locations and in a redundant manner.
3. The system as claimed in claim 1, wherein, the optimization algorithms for the ESP are incorporated in the client program and enabled to monitor the status of the fields including transmitting of commands for performance optimization.
4. The system as claimed in claim 3, wherein the server device is capable of permitting only one client program to run optimization programs at any time.

5. The system as claimed in claim 4, wherein the client program create during the run time software objects and display said objects corresponding to components or regions of the ESP for example, passes, fields, rapping system, opacity meter inputs.
6. The system as claimed in claim 5, wherein the number and combination of objects in an object layer and display objects in an user interface layer created by the Client application program is configurable corresponding to the configuration of the physical ESP.

ABSTRACT

A centralized monitoring and control system for electrostatic precipitator (ESP) having a plurality of fields and ESP controllers, the system implementing cyclic and event driven communication for status monitoring and control commands respectively with the ESP controllers for HVR control and electrode rapping, wherein the ESP controllers are connected in a master slave configuration, wherein an interfacing server device with a master implementation and a server implementation disposed between a ESP controller network and a Client PC network, and wherein a client PC is detachably attachable to the server client network without affecting the other clients PCs, the server, the controller communication or the operation of the controllers.