Research On The Method Of Testing Digital Substation Based On Electromagnetic Transient Simulation

With the development of power system and the increasing electricity consumption in industry and residents,the safe and stable operation of power grid becomes more and more important.As a key part of power system,it is particularly important to ensure the safe and stable operation of substation.At present,the technology of digital substation is widely used in power system.Compared with traditional substation,digital substation is more intelligent.Based on the smart primary equipment and the networked secondary equipment,the information exchange among the devices in substation can be more accurate and convenient.At the same time,the process of exchanging information in digital substation is very complex.As a result,higher requirements should be satisfied in the process of testing digital substation.At present,the methods of testing the secondary systems in power system is basically based on relay protection tester and other equipment.However,this method cannot completely test the whole substation.The Merge Units and other secondary equipment cannot be included into testing method,the function of those equipment is to transfer data in secondary system.This method will cause some serious safety risks.With the consideration of the deflects on the traditional test methods for the secondary system in digital substation,a cascade testing method for the secondary system is presented in this paper.This method incorporates the entire secondary system into the testing scope,and it can do the unified test for the information section of generation,distribution,and transmission in secondary system.As a result,the integrity of test to the greatest extent is ensured.At the same time,the testing system established by this method is described in this paper.According to the different type of transformer,the corresponding information transmission modes are designed and the system-level test in secondary system is put forward based on the closed-loop testing method.Then,the accuracy and stability of the proposed approach is verified by the comparison with other algorithms.Based on the implicit trapezoidal integration method,the transient model of components is established.By the simulation experiment,the circuit model established in this paper is compared with those established in PSCAD.The simulations results verify that the testing system proposed in this paper is correct,and it can realize the process of electromagnetic transient simulation.Because the admittance matrix is a sparse matrix in the process of simulation,if the sparse matrix is calculated directly,it will lead to a large amount of calculation and waste a lot of time.With the node reduction of new injection elements and the path tree of factor table,an improved algorithm of node numbering is proposed in this paper.By the strategy of readjusting the nodes sequence of the admittance matrix,the admittance matrix can be adjust to BBDF form and the simulation process can be accelerated by parallel computing method.Finally,the simulation experiments of several cases are used to verify the performance of the proposed method in sparse acceleration.The experimental results show that when the number of nodes is small,the performance of the method with parallel calculation is slightly worse than that of the conventional method in directly calculation.As the nodes number increases,the dimension and sparsity of the matrix both increases,the performance of parallel calculation is better.Therefore,the method with sparse matrix acceleration proposed in this paper is proved to be correct and excellent.