Simulation-based integration testing for multiple PLCs in reactor protection system

Abstract

Programmable logic controllers (PLCs) have been widely used for developing safety-critical systems, such as Reactor Protection Systems (RPS), in nuclear power plants. Many PLC systems are composed of multiple PLCs and have many interfaces with other systems. Thus, integration testing for such systems is vital to evaluate their effectiveness. However, integration testing is costly to build a test bed, and it involves a lot of time to test the system manually. Simulation methods using PLC modeling or Open Platform Communications (OPC) standards can be an alternative to solving this problem. However, this procedure has a limitation because the simulation execution results may differ from the actual PLC program execution results. This study presents an integration testing approach using PLC synchronization techniques for multiple PLC programs. The study uses a MultiPLCTester to support the simulation and synchronization of multiple PLCs. MultiPLCTester can also be used to conduct integration testing with other systems using synchronized execution results. The primary objective is to conduct integrated testing to reduce the difference between simulation execution results and actual multiple PLC execution results. We performed experiments using real industrial cases to evaluate the effectiveness and efficiency of our approach. The test suite execution time of MultiPLCTester was significantly reduced compared with manual integration testing. When considering the cost of building a test bed, the proposed approach can provide a low-cost and effective integration testing approach for the PLC testers.