System with pulse-wise high energy-consuming components and a power supply from the grid of an energy supplier, as well as a system for the conductive heating of curved metallic workpieces, such as stabilizers for motor vehicles.

Abstract

A system for carrying out processes, with one or more system components as consumers of electrical power, with a power supply from the grid of an energy supplier, wherein at least one system component is supplied with electrical power varying in pulses between a maximum and zero during the execution of the process, with standby times without power for the system component between the repeating pulses, and with the further features that an energy storage device is integrated into the circuit for the power supply, such that during the duration of the pulse the power supplied to the system component is formed as the sum of a power component that can be drawn from the grid and a power component that can be drawn from the energy storage device, and that in the standby time following the pulse the energy storage device is charged with grid power.

Description

[0001] The invention relates to systems for carrying out processes in which the system has at least one system component to which a high electrical power is supplied in pulsed operation for the execution of the process.

[0002] Such a system can be used, for example, for the heat treatment of curved metallic workpieces, such as stabilizers for motor vehicles. The workpiece, clamped in a conduction unit, is heated to the hardening temperature with electricity in just a few seconds. It is then removed from the conduction unit via an automated workpiece changer and processed further in the system. The current in the conduction unit is applied in pulsed on / off mode. Operating such a system requires a very high electrical power supply, e.g., 100 kVA.

[0003] If several such systems are used, e.g., 2, 3, 4, or 5 identical systems, the total available capacity then amounts to 200, 300, 400, or 500 kVA. This high connected load must be continuously available, regardless of whether all, some, or only one of the systems is operating at full load, partial load, or standstill. The grid operator's costs for providing such high capacities are enormous.

[0004] The object of the invention is therefore to design systems of the type described above in such a way that they can be operated more cost-effectively with regard to the supply of electrical energy.

[0005] This problem is solved according to the invention with the features specified in claim 1, namely by a

[0006] Power supply from an energy supplier's grid for a plant for Execution of processes with one or more plant components as consumers of electrical power, wherein at least one plant component is supplied with electrical power that varies pulse-wise between a maximum and zero during the execution of the process, with ... for the system component, standby times without power between the repeating pulses, and with the further features that an energy storage system is integrated into the power supply, such that during the duration of the pulse the power supplied to the system component is formed as the sum of a power component available from the grid and a power component available from the energy storage system, and that in the standby time following the pulse the energy storage system is charged with grid power.

[0007] In an advantageous further development of the power supply according to the invention, the energy storage device is formed with a device comprising at least one battery.

[0008] The invention also relates to a system for the conductive heating of curved metallic workpieces, such as stabilizers for motor vehicles, with a power supply according to claim 1 or 2.

[0009] The advantages of such a power supply system are considerable: If the ratio between the time for the current pulse and the standby time were, for example, 1:1, the connected load for a system would be reduced by about half - for example, from 100 kVA for a power supply without support from an energy storage system to approximately 50 kVA for the same system, but with a power supply supported by an energy storage system.

[0010] Assuming longer standby times between power pulses, the required grid power could be reduced even further.

[0011] It goes without saying that if the energy storage system is designed as a device comprising at least one battery, the battery's capacity and high-current capability must be adapted accordingly.

[0012] If an operator has several systems in operation and their utilization rates are known, it would be possible to enable communication between the systems. With five 100 kVA systems as described above (without energy storage, 5 x 100 kVA = 500 kVA; with energy storage and a pulse duration to standby time ratio of 1:1, only 5 x 50 kVA = 250 kVA total power is required), the connected load could be reduced even further. The more systems are in operation, the more systems are idle, undergoing maintenance, being upgraded, or operating at partial load. By properly sizing the energy storage system, the connected load can therefore be reduced even further.

[0013] The advantages of the solution according to the invention are obvious. The installed grid capacity relative to the peak power output of the systems can be drastically reduced. By retrofitting energy storage, the system operator can run more systems on existing power supplies / transformers without further expansion. The enormous provisioning costs are minimized or even eliminated. The peak power outputs to the grid operator, which are significantly higher without energy storage, are correspondingly reduced. In industry, exceeding or extending a peak load is very costly.

[0014] The invention is explained in more detail below using an exemplary embodiment and with reference to the drawing:

[0015] The invention can be used in processes requiring high energy levels in pulses. An exemplary embodiment is a non-continuous heating process in which short heating cycles alternate with standby phases during which no energy is supplied. Such a process can, for example, take place in an induction heating system where individual workpieces are heated to high temperatures using an inductor, followed by a changeover of the parts. The energy required for heating is supplied by an inverter. Fig. Figure 1 shows a schematic representation of the time sequence of power transmission, starting from the power grid and the energy storage device - in this embodiment a battery - as well as the state of charge of the battery. Fig. Figure 2 shows a circuit diagram for the power supply using the battery integrated in the circuit as an energy storage device (battery storage).

[0016] In Fig. Figure 1 schematically illustrates the process flow when using the battery storage system. The diagram shows power (y) and the battery's state of charge (z) over time (x). The inverter power [number 1 in the legend shown in the figure] is drawn during the heating phases (A). During the intervening standby periods (B), there are process steps in which the inverter does not supply power, for example, when changing workpieces. In the example shown, the ratio of heating time to standby time is 1:2. The power drawn from the grid [2 in the legend] during heating is 0.5 times lower than the required inverter power. This inverter power during heating consists of grid power and battery power [3 in the legend]. The battery charge [4 in the legend] decreases during the heating phase (C). During the standby period, the battery is recharged with a specific grid power supply (D).

[0017] Fig. Figure 2 shows the circuit diagram for an inverter with battery storage. (a) marks the three-phase connection to the power grid with conductors 1-3 (L1-L3). The battery E (G: DC voltage source) is connected between rectifier A and intermediate circuit B. The inverter C consists of four transistors (T1-T4), to which the resonant circuit D is connected. The arrows indicate the charging [number 2 of the legend shown in the figure] and discharging processes [1 in the legend]. Inductances are labeled L, capacitances C, and resistances R. The connected grid power at (a) is 50 kW in this example, and the maximum power drawn at (b) is 100 kW.

[0018] Without the battery support according to the invention, a much higher electrical connection power would be required to operate the system. However, this higher power is only actually needed for a fraction of the time in pulsed operation.

[0019] The battery support according to the invention offers the advantage that part of the power used can be drawn not from the mains, but from the battery, which recharges itself with mains power during standby times.

[0020] This allows the system to be operated cost-effectively with a lower available power supply. Energy supply costs are minimized. With an existing connection, the number of devices can be increased by using inverters with battery backup. Short-term power peaks are avoided.

[0021] If multiple systems are in operation with known utilization rates, they can be networked, further reducing the required power supply. During maintenance, upgrades, or partial load operation, full power does not need to be provided for each individual system. Properly sizing the battery backup capacity minimizes the overall power requirement.

[0022] Exceedances or extensions of peak loads, which are very costly in industry, are reduced by the use of energy storage according to the invention.

Claims

[1] A system for carrying out processes, with one or more system components as consumers of electrical power, with a power supply from the network of an energy supplier, wherein at least one system component is supplied with electrical power varying in pulses between a maximum and zero during the execution of the process, with standby times without current for the system component between the repeating pulses, and with the further features that an energy storage device is integrated into the circuit for the power supply, such that during the duration of the pulse the power supplied to the system component is formed as the sum of a power component available from the network and a power component available from the energy storage device, and that in the standby time following the pulse the energy storage device is charged with network current. [2] System according to claim 1, wherein the energy storage device is formed with a device comprising at least one battery. [3] Device for the conductive heating of curved metallic workpieces, such as stabilizers for motor vehicles, with a power supply as in the devices according to claim 1 or 2.

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