Design and Implementation of SIP System Simulation Based on LabVIEW

Design and Implementation of SIP System Simulation Based on LabVIEW

Introducing the concept of virtual instrument into the simulation of the SIP system of Daya Bay Nuclear Power Station and using computer simulation technology to participate in its system design can help shorten the design cycle, reduce design costs and improve design quality. Based on these advantages, LabVIEW was used to carry out the virtual simulation design of the SIP system, and the expected effect has been achieved. This paper mainly takes the RCP10 channel of the SIP system as an example to give a detailed introduction to the simulation design.

Keywords: SIP system; virtual instrument; system simulation

As part of the nuclear island system, the process instrumentation system (SIP system in French) receives analog signals (including pressure, water level, flow, temperature, speed, etc.) from on-site process measuring instruments, processes the on-site analog signals according to design requirements, and then sends them to related systems and equipment for display, recording and processing. In a sense, the SIP system is in a connecting position in the instrumentation and control system. The failure of the SIP system is hidden, but as an important part of the reactor general protection system, its failure will directly threaten the safety and normal operation of the nuclear power plant. In order to detect faults in time to ensure the availability of the SIP system, the SIP system must be tested regularly. However, the original periodic test device (SACMO test bench) has been aging and no spare parts are produced, which brings inconvenience to the test and maintenance work. Therefore, it is very urgent and critical to develop a new type of periodic test device.

Since the SIP system is in operation for a long time, it is impossible to provide environmental testing for the newly developed test device. In addition, since there are many system channels and required hardware boards, it is not suitable for hardware physical simulation of the SIP system. Therefore, computer simulation of the SIP system is finally adopted. This simulation method is often used in the system design stage and some occasions that are not suitable for physical simulation (including some failure modes). Its characteristics are good repeatability, high precision, great flexibility, easy use, low cost, and can be real-time or non-real-time. This makes it more convenient to develop a new type of periodic test device. The computer simulation environment uses the LabVIEW development environment. In order to verify the accuracy of the software simulation system finally developed, firstly, part of the hardware circuit of RCP10 in the SIP system was built, and then the SACMO test bench was used to inject signals into the newly developed SIP software system and hardware simulation system respectively, and the test results were compared. These provide a test basis for the development of a new type of periodic test device.

1 Introduction to LabVIEW

LabVIEW is a product of the American National Instruments Corporation. It is a fully functional software development environment and a powerful programming language ^[1] , which is mainly used in the fields of instrument control, data acquisition, data analysis and data display. LabVIEW uses a graphical programming language to generate program lines in the form of block diagrams. Compared with other simulation software, it is more intuitive, vivid, easy to use and convenient to modify. Based on the model, this project compiled a system simulation module. The simulation module mainly includes dynamic links of time parameters such as inertial links and lead-lag links, XU action output links, etc. By simply digitizing the transfer function of the dynamic link, the entire system can be simulated by computer.

2 SIP system simulation structure

The SIP simulation system has analog input and analog and digital output. The structure of this simulation system is shown in Figure 1. The system is mainly implemented by a computer and two NI boards, namely PCI6289 and 6733. PCI6733 has 8 AO channels, and the M series board PCI6289 has 32 AI channels and 48 DI channels. For each channel loop, there are at most 6 AI channels, 8 AO channels and 12 DI channels [2]. The computer simulation part only needs to simulate the processing and calculation modules in the loop channel, namely the dynamic modules (such as differential, lead, lag, filter and other time parameter modules) and threshold modules.

3 Partial circuit of RCP10 of SIP simulation system

The processing and calculation modules of the channels of the SIP system are basically similar. The dynamic parameter module is just different in time constant, and the XU threshold module is just different in action value and reset value. This paper takes the most complex RCP10 partial circuit as an example to carry out software simulation design, and uses the actual running board in the SIP system to build this circuit as a hardware simulation system to verify the correctness of the software simulation design. Figure 2 is a schematic diagram of a partial circuit of RCP10, where a block diagram represents a board used for a function.

In the figure, 458CC, 483CC, 448CC, 446CC, 495CC and 447CC are all input switch nodes of the RCP10 channel of the SIP system. FI and MT are both dynamic links with time parameters. AM, GD and ZO are static links, which are not related to time parameters but only to input quantities. This paper focuses on the detailed description of the simulation of dynamic links. PT and XU are both output nodes of the SIP simulation system. PT is analog output and XU is digital output. In system simulation, some dynamic links only know their transfer functions, while the values ​​collected by the system are discrete, that is, not continuous data, so they must be quantized into differential equations, which is convenient for simulation and program design.

(1) Filter FI module

The filter module transfer function is The differential equation is: The difference equation is: The output value of the FI link at this moment depends on the input and output values ​​at the previous moment.

When an initial value is injected, that is, X(t)=U(t), the y value will have a step response. The specific theoretical derivation is as follows: It can be seen that when t→∞, y(t)=U(t).

(2) Lead-lag MT module

The transfer function of the lead-lag module is The differential equation is: The difference equation is: The output value of the MT link at this moment depends on the input and output values ​​of the previous moment and the input at this moment.

When an initial value is injected, that is, X(t)=U(t), the y value will have a step response. The specific theoretical derivation is as follows: It can be seen that when t→∞, y(t)=U(t), so the system should be given some time to stabilize. After the system is stable, the next step of calculation can be carried out.

According to the established software simulation model of the partial loop of the RCP10 channel, some test steps in the SACMO test bench were used to inject signals into the SIP software simulation system and the hardware simulation system built with the original board. The test results are shown in Table 1.

These two-step tests indicate that 495CC, 483CC, and 446CC inject fixed value signals respectively, and 448CC injects an initial value signal. After waiting for a period of time for the MT link to stabilize, the ramp signal is then injected. The three columns of results in the table are the values ​​of the ramp signal at the moment of XU action, where the soft simulation results and the hard simulation results are the values ​​of multiple test results. As can be seen from Table 1, the error between the soft simulation results and the theoretical values ​​is within the range, proving that the NI board simulation meets the accuracy requirements; and the error between the soft simulation results and the hard simulation results is also within the required range, indicating that the mathematical formula of the soft simulation is completely correct. Therefore, it is feasible to use soft simulation to simulate the entire SIP system.

The characteristic of software simulation is that it is easy to implement and is not constrained by many external conditions. The characteristic of LabVIEW is its modular structure, so it is of great significance to the improvement of the program itself. Through the simulation results, preliminary analysis shows that LabVIEW is simple, intuitive and effective for system simulation and analysis. For these large systems in Daya Bay, the system construction is relatively complex and the conditions are not met, so it is feasible to simulate the system by computer, which has the advantages of simple implementation and easy operation. I believe that more computer simulation systems can be applied to actual platforms in the future.

References

[1] Yang Leping, Li Haitao, Zhao Yong. LabVIEW Advanced Programming. Beijing: Tsinghua University Press, 2003.

[2] National Instruments Corporation.PCI 6289 User Manual.2006.