Analysis of operation modes of shunting diesel locomotives when performing shunting work

on hydrogen energy sources, was carried out. The necessity to take into account the operating conditions of a shunting diesel locomotive when choosing an upgrade option is shown. The operation modes of shunting diesel locomotives during shunting operations at the Козятин-I freight station during three shifts were considered. By analyzing the data of the БІС-Р onboard system and processing the route sheets, the parameters of the operating modes were determined. Calculations of diesel engine power utilization indicators were performed, according to which it was determined that the full use of the installed diesel generator power is 7.5...8.4%, and the maximum diesel power recorded under the studied operating conditions is about 50%. The duration of work with traction loads is 49.5...68.8% of the shift time. The longest - 55...60% of the total duration of work under traction - are modes with a power of 0...50 kW. The duration of work without load is 18.1...36.9% of the duration of the shift. The shunting work performed is related to the formation and disassembly of trains, including the use of a sorting slide, as a result of which the traction power transmission operates with a low efficiency. In order to reduce the consumption of fuel and energy resources when performing shunting work, it is necessary to update the fleet of locomotives for shunting work, the characteristics of which are adapted to the operating modes.

(estimated at 870 diesel locomotives in 2033). Arguments for choosing this option are relatively small capital investments and the presence of a developed repair and technological base at all regional branches. At the same time, it is noted that during major repairs it is impossible to restore the passport characteristics of diesel locomotives, therefore significant costs for their current maintenance will remain, and due to the low quality of repairs, an increase in unplanned repairs is predicted. Alternative options for updating the fleet of shunting diesel locomotives, which are indicated in [1], are their complex modernization with remotorization (as well as the purchase of new diesel locomotives). The use of these options allows to improve the traction and energy characteristics of diesel locomotives, it is predicted that the cost of maintenance, repairs and fuel and lubricants will decrease, which will ultimately ensure a decrease in the cost of transportation. Taking into account the possibility of extending the service life of ЧME3 diesel locomotives for 10...15 years [2], it is considered urgent to work out options for comprehensive modernization of these diesel locomotives to improve their traction and energy characteristics.
Analysis of recent research and problem statement. In Ukraine, remotorization of ChМЕ3 diesel locomotives was carried out using the 4Д80Б diesel, in the CIS countries -using the 1-PD4B and 4-36DG diesel generators [3]. A deep complex modernization using a Caterpillar diesel engine, AC-DC power transmission (the traction motors were not changed), an electric drive for cooling fans and a compressor, and a microprocessor control system was carried out in Ukraine at Poltava Tractor Repare Plant, where diesel locomotives were modernized according to the designs of the ZOS company Zvolen (Fig. 1a) and CZ LOCO (Fig. 1b) [4]. The latter company's project was also used in the modernization of ЧME3 diesel locomotives in the CIS and Baltic countries. a) b) Fig.1

. Modernized ChМЕ3 diesel locomotives
The paper [5] analyzed the fuel consumption of serial diesel locomotives ChМЕ3 and modernized diesel locomotive ChМЕ3P-№1744. It was established that the modernized diesel locomotive, despite the use of a more powerful diesel engine with a capacity of 1455 kW, consumes 29.4% less fuel than a serial diesel locomotive. Similar results were obtained during the operation of TEM2 diesel locomotives, which are modernized according to the same concept as ChМЕ3П. Compared to the TEM TMХ diesel locomotive with a 970 kW diesel engine, which was created using the crew part of the TEM18DM diesel locomotive and the equipment of modernized ChМЕ3 diesel locomotives, the fuel consumption during shunting was 37.5%. In both cases, it is noted that fuel economy depends on the type of maneuvering. The greatest savings of 40...45% are observed when modernized diesel locomotives are used in export work. The smallest one is at hill work. It is worth noting that during the modernization, the traction characteristics of the diesel locomotive at the positions of the driver's controller and the applied electric drive of the motor cooling fans were changed. This also had an effect on reducing fuel consumption, but this is difficult to assess.
An alternative way to update shunting diesel locomotives is to create a hybrid locomotive. The paper [6] substantiates the feasibility of creating a hybrid locomotive based on the ChМЕ3 diesel locomotive and the technical parameters of such a diesel locomotive for Ukrainian railways. In [7], a study was conducted on the use of combined storage units as part of the power plant of a shunting diesel locomotive. In [8], the application of a traction electric drive based on valve-inductor electric motors in the traction system of a hybrid shunting locomotive was investigated. [9] shows the expediency of using traction asynchronous electric motors in the modernization of diesel locomotives of ChМЕ3 type.
Hybrid shunting locomotives are becoming increasingly common in commercial operation [10,11]. New locomotives Prima H3 (Fig. 2a) [12], Prima H4 (Fig. 2b) [13] and modernized locomotives of the BR203H series (Fig. 2c)  Diesel locomotives with several diesel power plants are also used. For example, the diesel locomotive MDD5 (Fig. 3a) [22] manufactured by Express Service uses two diesel generator sets, the diesel locomotives 3GS21B (Fig. 3b) [23] from National Railway Equipment and RP20BD (Fig. 3c) [24] from Railpower Technologiesthree diesel generators. At the same time, the RP20BD diesel locomotive has a modification where one diesel generator is replaced by an energy accumulator. In TEM2-UGMK diesel locomotive (Fig. 3d) [25] an auxiliary diesel engine is used, which is included in operation during long-term downtimes of the diesel locomotive. The main diesel generator set is not working at this moment.

Fig.2. Hybrid shunting diesel locomotives
At present, extensive research has gained application on locomotives of alternative primary sources of energy -fuel cells, gas engines or exclusively battery cells [26]. Also implemented are projects for retrofitting diesel locomotives to run on natural gas (LNG, LPG, compressed gas) or biogas (TEM2 diesel locomotives in the Baltic countries and Kazakhstan, the OptiFuel project), use of biodiesel (WDM7 locomotive of the Indian Railways on biodiesel), a mixture of gas and hydrogen in the piston engine (Freightliner Class 66).
It is worth noting that in the CIS countries, samples of hybrid diesel locomotives, two-diesel, with gas engines and biofuels have been created.
It is also worth emphasizing that the locomotives of foreign companies can be equipped with a power plant of any configuration in order to adapt to real operating conditions. In particular, locomotives can be powered by a contact network [34].
Thus, various technologies can be used in the modernization and creation of new shunting locomotives. Classic deep modernization with the use of a modern diesel engine is proven and it ensures a reduction in operating costs. An alternative to it is a hybrid shunting locomotive or electric shunting locomotive, as well as multi-diesel diesel locomotives. The use of fuel cells is considered to be extremely promising for rolling stock, but this technology is actually at a research stage. In addition, today the spread of hydrogen technologies is "impeded" by the high cost of hydrogen. The situation is similar with biofuel, the use of which for locomotives is at the experimental stage. Pure battery locomotives are used for a certain class of shunting operations, which is primarily related to the characteristics of battery cells. Therefore, according to the authors, the acceptable ways to modernize ChМЕ3, in addition to the "classical" modernization with the use of a modern diesel engine, are the creation of hybrid shunting diesel locomotives and contact-battery shunting electric locomotives.

. Traction generator power diagrams according to BІС-Р system data
In fig. 6 shows the distribution of working time in a certain range of power depending on the total working time in traction mode. It should be noted that the BІС-Р registers the average power for 2 minutes of operation, and therefore the actual power cannot be determined from them. The analysis of the mass of trains and groups of wagons shows that they varied from 300 t to 4100 t, and the mass of a significant part belongs to the range of 1000...2000 t. A comparison of the data on power and the type of shunting operation shows that when rearranging wagons, the diesel locomotive works with greater power, than in other types of work. This can be explained by the need to maintain a certain speed of movement, for which it is necessary to spend energy to overcome movement resistance. The operations of formation and de-formation are carried out at speeds close to zero by the method of "shocks", and therefore the energy consumption is related to displacements of the composition from its place and its acceleration. For this case, the position of the driver's controller is selected from the condition of realizing a certain traction force. Table 7 shows the quantitative indicators characterizing the modes of operation of the diesel locomotive during the investigated shifts, as the following values are used.
The coefficient that determines the full use of the installed capacity of the diesel engine for powering the traction electric drive [35,36] where EFthe actual energy that is transmitted to the traction electric motors, ENtheoretical value of the energy that can be given under the condition of operation of a diesel generator with nominal power. The actual energy supplied to the traction electric motors is determined by the expression where Δtthe time interval over which the power is averaged, Pipower at the i-th reading, Nthe number of intervals at which traction electric motors are powered. Accordingly, the theoretical energy value is calculated by the expression where PNpower at the generator terminals at the nominal speed of the diesel engine is 890 kW. The coefficient that determines the full use of the maximum available traction power (for powering the traction electric drive) where Pmaxthe highest average power per shift. Also, from the input data, we determine the duration of shunting operations with wagons, reserve movement, operation of the diesel generator without load (hot idle and coasting) and cold idle. The results are shown in Table 7.  Figure 7 shows the duration of work modes during the shift. From Table 7 and Fig. 7 it follows that the duration of traction modes when moving with wagons is 49.5...68.8% of the shift duration, the duration of traction when moving with a reserve is 7.2...11.4%. The duration of operation of the diesel engine without a traction load is 18.1...36.9% of the duration of the shift, and falls on both "preparatory" operations, which are necessary for performing maneuvers, and simple "inside" maneuvering operations. From 1.7 to 6.4% of the shift duration, the diesel does not work on the diesel locomotive. Table 7 shows that the Kp coefficient does not exceed 10%, and the maximum value of the Kм coefficient does not significantly exceed 50%, which indicates that for the studied operating conditions, the full power of the diesel engine is not used.
In general, for the studied case of operation of the ChМЕ3 diesel locomotive in shunting work, it is established: its power is redundant, more than 50% of the time, the traction electric drive consumes power up to 50 kW, the most demanded power reaches 200 kW, which corresponds to positions 1...4 of the driver's controller, peak power is 460 kW; -when the weight of the composition increases, work is carried out with higher power values. Thus, the above information testifies the possibility and expediency of using a less powerful diesel engine on a locomotive in cases of its use, similar to the one under study. An important direction of improving the traction and energy characteristics of the locomotive for shunting work is the use of energy-efficient traction electric motors and optimization of their control. Traction motors TE006 are used in ЧME3 diesel locomotive, in accordance with the recommendations [37]. The calculation of their efficiency taking into account the parameters of the external characteristics of the generator at the positions of the driver's controller [38] shows that the efficiency of the electric motors varies from 27% to 50% at high current values, that flow through the traction electric motors, when the locomotive moves and moves at low speeds. And it is precisely these modes of operation that prevail during the "disassembly" of trains on the sorting slide or maneuvers with "shocks". Since such modes of operation are the most common, it is advisable to use traction electric motors that have significantly higher energy efficiency indicators in such modes. The paper [9] proposed the use of asynchronous traction electric motors simultaneously with the replacement of axial gearboxes. In [8], the use of valve-inductor motors is proposed. When creating the HD300 diesel locomotive, synchronous electric motors with excitation from permanent magnets were used [39]. In [40], the structure of the traction system of a hybrid shunting diesel locomotive was investigated.
The wide range of changes in the mass of the train also draws attention, and therefore the possibility of optimizing the number of working traction motors depending on the mass of the trains: it is advisable to turn off part of the traction motors when working with trains of small mass, because this reduces losses in the traction electric drive.
An important aspect of energy saving is the optimization of locomotive auxiliary systems, which can account for up to 20% of total energy consumption. Reduction of energy consumption is provided both by the use of energy-efficient equipment and by controlling its operating modes. Since energy accumulators can be used on locomotives, in order to reduce operating costs, it is advisable to provide for the possibility of charging the on-board energy accumulator from an external source with a low energy cost [41][42][43][44].
Thus, the analysis of the parameters of the operational modes of the ЧME3 diesel locomotive when performing shunting work shows the inconsistency of its characteristics for this work. To improve a diesel locomotive, and even more so when creating a new one, it is necessary to take into account the operating conditions and the application of modern energy-saving technologies.
Conclusions. Modern trends in the modernization and creation of shunting locomotives are considered. Currently, the most common for old diesel locomotives is remotorization with the renewal of traction electrical equipment. When creating new locomotives, hybridization of their power plants is used.
The operating parameters of the shunting diesel locomotive at the Kozyatyn-I station were analyzed. Based on the results of the analysis, it was established that for the studied case of shunting operation, the power of the diesel locomotive is excessive, and its traction electric drive operates with low efficiency. The use of the ChМЕ3 diesel locomotive in such conditions leads to increased consumption of fuel and energy resources for shunting operations.
For the investigated case of shunting work, it is advisable to use a locomotive with a power of about 500 kW. The type and structure of the power plant and traction electric drive must be optimized for lowspeed operating conditions.