EMTP and HYPERSIM share the same user interface and network data format (*.ecf); thus, EMTP models can be open in HYPERSIM. However, the functionalities of the two software are not the same. Therefore, additional steps are required to simulate an EMTP model in HYPERSIM. 

This section presents two EMTP example models simulated in HYPERSIM. The first example, i.e., Simple Model, is a very simple passive model that is intended to show the basic steps required to simulate an EMTP model in HYPERSIM. The second example, i.e., the IEEE 39 Bus Benchmark, is a more complex model that integrates some of the blocks which present notable differences between the two software.

It is observed that after applying the proper changes to the models, EMTP and HYPERSIM simulation results match very well.

The steps in importing the example model from EMTP to HYPERSIM are following the ones which are mentioned as part of the workflow on EMTP | Overview.

Simple Model

EMTP model

The first example (simple.ecf), taken from the EMTP library, is shown in the following Figure. This example is a very simple model consisting of a passive circuit, a voltage source, and switch. The switch is closed in steady state and open at 4 ms. The example is intended to show the basic steps required to simulate an EMTP model in HYPERSIM. As opposed to EMTP, the end of a simulation in HYPERSIM is undefined. In HYPERSIM, the simulation is stopped manually by the user and the time is defined as absolutely or relatively. This example would help to show the notion of time and to better understand the difference between EMTP and HYPERSIM when modeling a switch.

HYPERSIM model

The following are the steps required to simulate the system of the previous Figure in HYPERSIM.

Step 1: Adding a POW

A point of wave (POW) must be included in all the HYPERSIM models, see Point-on-Wave Synchronization for details. It is remarked that the voltage source model from EMTP is based on a cosine function, while the HYPERSIM voltage source is based on a sine function. Thus, to maintain the same phase from the EMTP simulation, the POW is connected to an auxiliary HYPERSIM voltage source with the angle set as zero. The following Figure shows the final HYPERSIM model. 

Step 2: Replacing the switch

HYPERSIM needs to know the initial state (steady-state) of the circuit breaker and the definition of a sequence of at least two switching events. This is possible with the externally controlled EMTP circuit breaker or the one used to simulate a ground fault (initial state implicitly open, a first closing operation, and a second opening). However, EMTP switches must be replaced manually by the native circuit-breakers in HYPERSIM if they are not externally controlled, like the case of the switch of the circuit of this example.

The following Figure shows the simple example model after replacing the switch in HYPERSIM. The definition of T1 in CB1 is set accordingly to reproduce the switching events from EMTP, i.e., the breaker is initially closed and then open at 4 ms, see the following Figure. The user can find more details about the settings of the HYPERSIM breakers in Circuit Breaker, 1-Phase.

NOTE: For this example model, it was not needed to set voltage levels for buses and run the load flow and since there are no synchronous machines or exciters or else. There was no need to verify the compatibility of EMTP controllers either. Therefore, after step 2, it is time to run the simulation.

Simulation results

The following Figure shows the simulation results obtained in both HYPERSIM and EMTP. It is observed that results from both software are superimposed.

IEEE 39 Bus Benchmark

EMTP model

This example considers the network IEEE39_345kV_2018_02_05.ecf available in the example models of EMTP 4.1, see the following Figure. The model is a 345-kV system of 39 buses that includes synchronous machines, 3-phase loads, two-winding and three-winding transformers. Note that the names of buses 6 and 16, and the load 16 are remarked in red in the Figure.

The following figures show the subcircuit in the power plant 01 and the subcircuit of the control system of the synchronous machine. It is mentioned that the same control system is used in all power plants.

Modifications to the EMTP model

As a test example, a three-phase fault is applied at “LoadBus” in the load 16 block from 0.5 s to 0.7 s. Thus, a switch in series with resistance is added in the model to simulate the fault. The following Figure shows the subcircuit inside Load 16 where the three-phase fault is applied.

In the example model from EMTP, the constant value T_q0' of the synchronous machine (SM) from the Power_plant10 is equal to 0. However, this value is not supported in HYPERSIM. To address this issue, two data from SM10 are modified as shown in the following table.

HYPERSIM model

The following are the steps required to simulate the system of this example in HYPERSIM.

Step 1: Adding a POW

A point of wave (POW) must be included in all the HYPERSIM models, see Point-on-Wave Synchronization for details. The following Figure shows the POW block added to the slack bus, i.e., bus 6. It is mentioned that to maintain the same phase from the EMTP simulation in HYPERSIM, the detection level of the POW needs to be tuned to match the initial value shown in the EMTP waveform of reference. After a trial-and-error test, the detection level in this example has been set to 275 kV.

Step 2: Replacing the switch

The series-connected EMTP switch must be replaced manually by the circuit-breakers in HYPERSIM if they are not externally controlled. The following Figure shows the model of the subcircuit load 16 after replacing the switch in HYPERSIM. Note that the switching times in the CB2 breaker correspond to the ones from the EMTP model. The user can find more details about the settings of the HYPERSIM breakers in Circuit Breaker, 1-Phase or Circuit Breaker, 3-Phase.

Step 3a: Bus voltage level settings for load flow analysis

To simulate the model of this example in HYPERSIM, it is necessary to initialize the variable components properly. In HYPERSIM, the initial conditions are calculated from a load flow analysis. To execute the load flow successfully in HYPERSIM, we need to properly set the voltage levels in all the buses. There are multiple ways to do so, the procedure is detailed in (section 4) Quick Start | Load Flow.

The following Figure illustrates the settings of Bus 6 of the system of the IEEE 39 bus benchmark model as an example.

The following Table shows the results for the active power P and reactive power Q of the generators/power plants obtained from the load flow of the IEEE 39 bus system. It is observed that there is no significant difference between HYPERSIM and EMTP results.

Step 3b: Adding loop breakers in the machine controllers

A loop breaker block is added in the ST1 and IEEEG1 controllers present in all the power plants of the IEEE 39 bus model. The procedure to add a loop breaker is described in EMTP | Control.

Simulation results

Once the voltage level is entered correctly in all the buses, the model is ready to run in HYPERSIM. In the test shown in this example, a three-phase fault is applied at bus "LoadBus" located inside the load 16 block, from 0.5 s to 0.7 s, as mentioned before. The system is initialized from the load flow solution in both EMTP and HYPERSIM. The following figures show the simulation results obtained in both EMTP and HYPERSIM using a simulation time of 20 us. It is observed that EMTP and HYPERSIM results match very well.

Voltage waveforms at buses 6 (POW bus) and 16 (fault bus), and the fault current waveform during the fault.

Output results of the 10 machines. Similar results have been observed on the other machines.

Line model type selection

Note that in EMTP, the transmission line type model can be switch from CP to FD line models by changing the variable "oGlobalData.Linetype" as indicated on the text shown in the model.

Since this text exist in the EMTP model it is not removed when the model is imported to HYPERSIM. The global variable exists in EMTP to include/exclude FD or CP; however, this feature is not supported in HYPERSIM.

The example model in HYPERSIM is configured to work with CP models. However, the user can change the CP line models to FD models if needed. The EMTP FD line components need to be replaced by the native HYPERSIM FD line components manually. Note the line data (*.pun files) need to be generated and loaded for every line when using the FD line models, as the same way that is required in EMTP, see Frequency Dependent, 3-ph for details.

Example of changing the line type in Line_01_02