【正文】 ation and control system simulation front running front control system Front control system is a core part of the simulation system, which receives the data back control system, operation instructions to control the simulation. Received through the optical circuit to be tested device control mands and receiving simulation system circuit breakers, switch has a device such as the status of orders, according to the background of the various simulation control system digital signal through D / A transform analog waveform simulation system to send driven by test equipment to the power amplifier and control system operating under the mand back to plete a variety of simulation experiments. Power Amplifier Power amplifier control system receives from the front of the analog signal sent through the power amplifier output to be tested equipment and systems。 it must have good linearity, stability, and high frequency characteristics. Analog Circuit Breaker Analog circuit breaker must be able to simulate all the features of the actual circuit breaker, its main function of movement behaviors and circuit breakers to plete the realistic situation, it is under the operational mand simulation system or equipment and systems were tested under the action mand to achieve the open circuit division and, according to the state to change the location of circuit breaker simulation system topology.3 power system automation design process of digital simulation systems are generally In order to achieve the ultimate goal of simulation system, the need for simulation output waveform, switch identification signal, and the input data and proper handling of various signals. According to the simulation system used to plete the function module and a good manmachine interface to achieve, therefore, to get the best simulation system, the first step is to determine the system performance and signal processing requirements. The second step is carried out according to the system requirements of highlevel language for simulation, also known algorithm simulation, simulation of this algorithm is mainly verified the feasibility of the algorithm. The third step is to design realtime simulation system, realtime simulation system design, including hardware design and software design aspects. First of all, according to the system hardware design, the size of putation, the precision of the puting requirements, system cost and size constraints, power consumption asked to choose a suitable microprocessor chip and peripheral circuits. Software design and programming primarily selected according to system requirements and the preparation of the corresponding program microprocessor chip, the general background system uses highlevel language programming. Using this approach, can shorten the software development cycle and improve the readability and portability, the system can meet the requirements of realtime puting. The fourth step is the hardware and software debugging. Step five is the system integration. 4 fault waveform playback technology As the simulation system was developed primarily for engineering applications, notably the pletion of NARIRELAYS Electric power automation products factory test, This in order to save development resources, for some simulation system, there is no mathematical model to establish largescale, but with another more direct way, that dynamic simulation laboratory simulation system for the direct taking of the various waveforms, then back system for data interpolation, smoothing, and synchronous of data processing, realtime playback through the front, power amplifier and other reproduction of the original simulation system test environment. In order to ensure the simulated waveform with the waveform of the same dynamic model collection, so the handling of simulation data as possible to nonrealtime data required for data preprocessing to improve the system39。s realtime performance. Fault waveform playback of fault data, according to the characteristics of recorded wave data and conditions, sometimes subject to the synchronous of data for each channel to ensure the playback data of each channel39。s coherence time step, addition, according to Lu wave of data density and sampling rate during playback difference for the lower sampling rate of recorded data, the use of appropriate interpolation method to reduce the calculation of realtime playback of data requirements.5 Several New Power System Digital Simulation Automation System Introduction line realtime simulation system [9] Line realtime simulation system is accurate with a simplified model to replace the real number of physical prototypes, in the establishment of the system model, taking into account only need to detect line protection, Therefore, the two end models with different capacity generator threephase power instead of using the ideal turns ratio and the leakage resonance of the transformer is △ / Y wiring, neutral grounding。 threephase transmission line with lumped parameter description. This simulation system is the use of highspeed parallel processing system to calculate the equation by D / A digitalanalog converter to generate the load current and voltage and fault current and voltage. Transformer realtime simulation system [10] Transformer realtime simulation system is the direct taking of dynamic simulation laboratory simulation of various wave transformer required, then the data in the puter interpolation, smoothing processing, and then by the D / A transformation to generate voltage and current. The pany also pleted a bus protection, generator protection, transformer substation simulation system, these simulation systems to power system automation equipment of the pany39。s test, and achieved good results 6 Conclusion This paper described a simplified mathematical model of calculating and using waveform technology to achieve the corr