Keywords

1 Introduction

Virtual reality (VR) technologies routinely allow (for example) pilots, drivers and astronauts to experience realistic training, without risk of injury or equipment damage. On the other hand, it has to be recognized that the majority of uses of VR are for entertainment. However, lessons learned from entertainment systems could be useful for new non-entertainment applications: the present work reports development of a VR training system for power substation operators, who have to be aware of correct reactions to a wide range of both routine and fault or emergency situations.

Major issues that have to be handled include: (1) health and safety of substation operators, (2) operational integrity of substation equipment, (3) interruption of customers’ power supply as consequences of substation operators’ errors during switching. In addition, the Russian grid statistics show that 30–35% of faults and blackouts are due to errors during switching [1] and this indicates a need for substantial improvements in the training of substation operators.

The range of possible faults and of operator actions mean that VR training of substation operators could be a very beneficial and innovative technology.

2 Strengths and Shortcomings of Currently Used Simulators

There are many simulators currently used for training substation operators. They have some strengths, e.g.:

  • Control of simulated operation in routine and non-routine events.

  • Estimation and recording of the substation operators’ decisions made during routine and non-routine events.

  • Rapid evaluation of parameters of steady-state mode of network models.

At the same time, currently used simulators have shortcomings, such as:

  • Two-dimensional (2D) display of the main control room and substation equipment does not impart realistic scenarios to develop correct skills in substation operators.

  • Routine normal operations (verification actions, lockout-tagout, collective protection) tend to be perfunctory and without deep insight for the trainees.

  • Navigation around the substation is not a realistic representation of real time navigation.

Thus, it can be seen that the currently used simulators are imparting only a limited set of skills to substation operators. A VR simulator for substation operators has the potential to be vastly more meaningful and hence was developed to rectify the deficiencies of currently used simulators.

3 New Approaches to Training Substation Operators, Based on Virtual Reality

There are two main technologies of VR implementation: 3D CAVE [2] and 3D Helmet [3]. Both of them can be used for a simulator and both provide complete immersion in VR. The selection of the technology of VR implementation has to be made alongside consideration of the conditions of real use. If there is sufficient space both the CAVE technology and 3D Helmet may be used. However if the space is limited, only 3D Helmet technology is viable.

3.1 3D Model of Substation

Regardless of the chosen technology of VR implementation it is necessary to create a 3D model of the substation. The model must meet requirements such as: visual similarity, spatial analogues and functional similarity of the substation. Models should be implemented for a range of substations in order to justify the cost of the system.

The visual similarity of a substation 3D model leads the user (operator) to develop relevant skills of operation on a particular substation during the training. After finishing the training on a certain substation the operator does not need to adapt to the real substation because he or she has already interacted with it in VR. Spatial analogue representations of objects in a substation 3D model are also very important. Operators must know how long it takes to get from one point of the substation to another one. This could help in emergency cases when the speed of action is a decisive factor. The reactions to the user’s actions in the VR model must be the same as on the real substation. Otherwise, operational experience gained in VR will be of little use.

3.2 Scenarios of Training

The operation order of routine switching is highly critical. A training simulator must control the order of routine switching, comparing the user’s actions to the correct order of switching. The correct order of switching is contained in the programmed scenarios of training. The scenarios of training must include both regular and emergency cases. Scenarios of regular operations act to hone the skill of routine switching and understanding of the basic operation of the substation. Scenarios of emergency training start in the same way as regular training but suddenly an emergency appears. The user has to take correct decisions as fast as possible after the emergency moment [4]. The user can choose between training and test mode. If he or she chooses a training mode, they can select the type of scenario: emergency or regular training in selected specific scenarios. In test mode, the user does not know what type of training scenario he or she will encounter: it will be a random choice of the simulator. System estimate consist of comparation of right steps and user done steps. If user made some number of uncritical or one critical mistake it is not allowed to him work on real substation.

4 Implementation of Virtual Reality Simulator

In the Power Electrical Systems Department of MPEI (Russia) a 3D VR simulator for substation operators has been developed. The department receives ongoing research funding from the PJSC Interregional Distribution Grid Company of Central Russia to develop the simulator. As a prototype of the simulated substation a typical 110/35/10 kV substation in Russia was chosen. It contains: six 110 kV overhead line connections; six 35 kV overhead lines and one 35 kV cable line connection; thirty 10 kV cable line connections; outdoor switchgear for 110 kV; outdoor switchgear for 35 kV; indoor switchgear for 10 kV; three three-phase transformers. The area of the prototype is about 18000 m2. As can be appreciated, the prototype contains many kinds of equipment and hence many scenarios can be implemented on it.

As mentioned before, the choice of technology depends on the conditions of use. In the present case, there were significant constraints on space: to alleviate this, it was decided to include an “Omniroad” treadmill device in the project. Consequently, the 3D Helmet was chosen as the VR technology.

Creation of training scenarios is the last step of implementation of the virtual reality. As regular scenarios were chosen about taking out of/into service 110/35/10 kV: transformers, circuit-breakers, disconnectors, overhead and cable lines.

As emergency taking scenarios were chosen regular scenarios above with sudden powering off of transformer, emergency collapse of column insulation of disconnector, emergency SF6-gas depressurizing, emergency line-to-earth fault of 35 kV overhead line, emergency voltage transformer fuse failure, emergency current transformer explosion. These scenarios cover about 90% of the operations on the substation.

5 Brief Technical Description

The game engine part of the simulator is based on Unreal Engine 4. A mathematical model of a significant prototype has been written in the C language: this enabled the latency to be reduced to less than 0.01 s, which is essential for a convincing experience. The headset of the simulator uses an umbilical cable to link to the host computer because currently there is no single technology of wireless link that can transmit 2 channels of HD plus 3 channels of gyroscopic information and 1 usd-3 channel with acceptable latency. The mathematical modelling of the prototype and the 3D modelling took approximately 1200 person-hours in total, for six persons: one modeller (mesh creator), two programmers (mathematical model creators), one unifying programmer (connecting mathematical and 3D models) and two electrical power engineers.

6 Results

A mathematical model of a significant prototype has been completed with protection and automation. A 3D model of a 10 kV indoor switchgear group has been created (Fig. 1). Models of an outdoor 110 kV SF6 circuit-breaker and a disconnector are shown in Figs. 2 and 3 respectively. The interaction of operators with the 3D model is shown in Fig. 4. The system has been tested with a number of trainee operators and results have been successful, in the sense of perceived realism and relevance of the training. Work is now proceeding to implement other switchgear environments.

Fig. 1.
figure 1

3D model of 10 kV indoor switchgear group.

Full size image
Fig. 2.
figure 2

3D model of a 110 kV SF6 circuit-breaker.

Full size image
Fig. 3.
figure 3

3D model of a 110 kV disconnector.

Full size image
Fig. 4.
figure 4

Trainee operator interacting with a 3D model.

Full size image