Method for commissioning installation for electrical power conversion and installation for electrical power conversion

Abstract

The application relates to an installation (10) for electrical power conversion and a method for commissioning an installation (10) for electrical power conversion. The plant (10) has at least one power converter (16) with an intermediate circuit and a bridge circuit, the plant (10) is connected on a DC side (32) to at least one DC unit, in particular a DC generator (12), and on an AC side (34) to an AC network (14), the at least one power converter (16) can be connected on the DC side to the DC side (32) by means of at least one DC switch (18) and on the AC side to the AC side (34) by means of at least one AC switch (20). The method comprises a first phase (A) comprising establishing an auxiliary network (36) for powering components of the installation (10), a second phase (B) having a temporarily connected AC power grid (14) without connecting to at least one DC unit, a third phase (C) having a connected AC power grid (14) and at least one connected DC unit. The facility is configured to perform the method.

Description

Technical Field

[0001] This application relates to a method for commissioning (Inbetriebnahme) of a facility for power conversion, particularly for large-scale power facilities, such as those starting from about 1 MW. This application also relates to a facility for power conversion, particularly for large-scale power facilities, such as those starting from about 1 MW. Background Technology

[0002] Commissioning of a power converter facility for electrical power conversion, having at least one power electronic bridge circuit, may include, for example, turning on the facility in normal mode. Turning on in normal mode specifically results in the facility operating at its rated power when available. In the case of a photovoltaic generator (PV generator) serving as the facility's energy source, the facility may be configured in normal mode to maximize the power of the PV generator. In the case of a load (e.g., an electrolyzer serving as a DC unit on the power converter), the facility may be configured in normal mode to supply power to the electrolyzer at its rated power.

[0003] When operating power converters in a facility, failures can occur, leading to converter malfunction and / or damage to individual components. For power converters in facilities of approximately 1 MW or larger, failures of the power converter and / or its components can result in costs of tens of thousands of euros per failure case.

[0004] Failure analysis of the faulty components revealed that some power converter component failures occurred during or shortly after commissioning. While the power converter is theoretically repairable, repairs for severe faults (such as failures in the power electronic bridge circuitry of the power converter) may not be possible at the installation site. Therefore, transporting the power converter and / or other parts of the facility incurs higher costs and a greater workload. This is particularly true in large facilities, where the corresponding maintenance workload is especially high due to the physical size of the power converters. Summary of the Invention

[0005] This application is based on the objective of providing a method and facility with improved commissioning, thereby preventing damage to the facility power converter during subsequent normal operation.

[0006] This task is accomplished by a method having the features of claim 1 and a facility having the features of claim 16. Embodiments are given in the dependent claims.

[0007] A device for electrical power conversion includes at least one power converter with an intermediate loop and a bridge circuit. This power converter may, in particular, be a converter capable of converting electrical power from AC (Alternating Current) to DC (Direct Current) and / or vice versa. The device is connected to at least one DC unit (especially a DC generator) on the DC side and to an AC grid on the AC side, wherein the at least one power converter can be connected to the DC side via at least one DC switch and to the AC side via at least one AC switch.

[0008] Methods for commissioning such facilities include: A) The first phase includes establishing an auxiliary network to power the components of the facility. B) The second stage has a temporarily connected AC power grid and does not have a connection to the at least one DC unit. C) The third stage has a connected AC power grid and at least one connected DC unit.

[0009] Phase A) of the method may, for example, also include receiving input from a facility operator. Such input may, for example, trigger the initiation of the method. Alternatively, the method may also be initiated automatically. The operator's input may, for example, also confirm the end of phase A) and thus trigger the start of phase B).

[0010] DC units may include, for example, photovoltaic generators, batteries, and / or electrolyzers.

[0011] The auxiliary network can be, in particular, a DC auxiliary network with a voltage of, for example, 12 volts, 15 volts, or 24 volts. The DC auxiliary network can be powered, for example, from the AC grid through the facility's rectifier. The DC auxiliary network can also be powered by an external power source, either alternatively or additionally.

[0012] Phases A), B), and C of this method can also be referred to as the commissioning or testing phases. In these phases, different states of the facility are specifically established so that the functionality of the facility components can be prepared and / or tested independently of each other as part of the commissioning process. This ensures the functionality of the facility in normal operating mode after commissioning and may also aid in troubleshooting.

[0013] The commissioning method involves phases that operate at least partially automatically and are used to slowly start up the facility to avoid or limit severe and / or costly damage, particularly to the facility's power converters. The selection of these phases ensures that only the minimum damage is incurred in the event of any failure. This has particular advantages: the slow startup of the bridge circuitry of the power converter (e.g., including power modules with semiconductor power switches, especially IGBT modules) through this method avoids early failures in the bridge circuitry and / or allows for their immediate identification. When a failure occurs in the power path of the facility, slow startup can keep costly secondary damage low or avoid it as much as possible.

[0014] Furthermore, a step-by-step debugging process allows for better localization of any faults in terms of time and / or space, because the activities of individual steps performed during debugging and their resulting effects are known. This allows for tracing back what was checked and what happened.

[0015] The facility for electrical power conversion has a control unit configured and set to perform the steps of the various stages of the method. The control unit may, for example, be located in the power converter of the facility and simultaneously perform the task of controlling the power switches of the power converter's bridge circuit.

[0016] In one embodiment of this method, the power converter of the facility can be placed into a commissioning mode at the end of production, so that the power converter starts directly and only in commissioning mode upon first power-on. This could, for example, mean that the control unit of the power converter automatically executes the commissioning method upon the first power converter startup.

[0017] The controlled, step-by-step commissioning process can significantly reduce secondary damage to the facility. By gradually starting up the at least one power converter, damage to power components (e.g., power semiconductor switches in a bridge circuit) can be detected early. This prevents short-circuit currents (e.g., on the DC side of the power converter and its connected DC units, such as batteries) from triggering DC fuses, necessitating their replacement. Furthermore, it prevents a fault in one of multiple parallel bridges in a bridge circuit from propagating to adjacent bridges and causing subsequent damage there, for example, through unwanted circulating currents.

[0018] Therefore, this commissioning method can particularly protect the hardware components of at least one power converter in the facility and reduce or prevent secondary failures. This reduces the costs associated with secondary failures. The method can operate automatically or at least partially automatically. Personnel responsible for commissioning, such as facility operators, can be supported during commissioning through automated or semi-automatic processes. By suspending the method in the event of a failure, guided troubleshooting can be provided to the operator in such situations.

[0019] In one implementation of the method, stage A) includes: An auxiliary network is established to supply power from the AC grid to the facility's components via facility rectifiers, particularly for the operation of AC switches, DC switches, and sinusoidal filter capacitor contactors (Sinusfilterkondensator-Schütz). Close the AC switch. Connect the capacitor of the AC-side sinusoidal filter to the AC power grid, especially through the sinusoidal filter capacitor contactor. Check the power supply through the auxiliary network, then turn on the AC switch, and If the power supply through the auxiliary network is within a predefined limit, the method continues; otherwise, if the power supply through the auxiliary network exceeds a predefined limit, the method is terminated.

[0020] Additionally, optionally, one or all steps of Phase A may be confirmed by the facility operator via input.

[0021] Predefined limits for power supply via an auxiliary network can be, for example, permissible limits for the safe operation of the facility. These limits can be predefined, for example, by the facility's control unit, or by the facility operator.

[0022] By establishing the auxiliary network in stage A), components powered by the auxiliary network, such as the switching devices of the facility, can be checked step by step. Furthermore, the stability of the auxiliary network during pre-charging processes (e.g., pre-charging of a sinusoidal filter capacitor) can be examined, for example.

[0023] In one embodiment of the method, stage B) includes: The DC intermediate circuit is pre-charged through a pre-charge circuit. Perform a self-test on the bridge circuit of the power converter. If the self-test is successful: connect to the AC power grid by closing at least one of the AC switches.

[0024] This allows for early detection of faults in the power electronics of the bridge circuit and prevents subsequent failures. In particular, it enables testing of the basic switching function and withstand voltage of the bridge circuit switches with virtually no current. The AC power grid is then connected only after this point. Therefore, the AC power grid is only temporarily connected to the bridge circuit during phase B).

[0025] In one embodiment of the method, stage B) includes: When connected to the AC grid: the bridge circuit of the at least one power converter is clock-controlled to exchange reactive power, especially inductive reactive power, between the intermediate loop and the AC grid.

[0026] By exchanging reactive power, the at least one power converter can be heated, in particular. The facility, especially the at least one power converter, can reach its designed operating temperature range for subsequent operation at this stage. This, in particular, allows the semiconductor elements of the at least one power converter to be brought into a temperature range corresponding to the operating temperature of the power converter during normal operation, within which the semiconductor switches can operate efficiently and for a long lifespan.

[0027] In one embodiment of the method, the temperature in the power converter (especially in the bridge circuit of the power converter) is detected, and the temperature is increased by matching the fans of the reactive power exchange and / or control facilities until the temperature in the power converter exceeds a pre-defined lower threshold and / or reaches a pre-defined upper threshold. In particular, the temperature increase is performed until the temperature in the power converter is within a pre-defined range, which may be, for example, between the lower threshold and the upper threshold.

[0028] In one embodiment of the method, the lower and upper thresholds have a temperature difference of at least 40 Kelvin, preferably at least 60 Kelvin. The temperature in the power converter (especially in the bridge circuit of the power converter) is changed by controlling reactive power exchange and / or manipulating the fan, such that the lower and upper thresholds are repeatedly and alternately reached.

[0029] By setting up these temperature increases, the temperature effect of repeated heating and cooling can be used to prepare for subsequent operation.

[0030] In one embodiment of the method, stage C) includes: In the case of a connected AC power grid and at least one connected DC unit: Power is exchanged between the AC and DC sides, the exchanged AC power and exchanged DC power of the at least one power converter are detected, and the reasonableness of the detected power is checked. Power exchange can be performed, especially at low power levels, particularly between 5% and 20% of the rated power of the at least one power converter.

[0031] In one embodiment of the method, stage C) includes: In the case of a connected AC power grid and multiple DC units connected in parallel on the DC side: The current of the DC unit in a parallel circuit is detected, and the symmetry of the detected current is checked. In particular, the current of each DC unit in a parallel circuit can be detected, and the symmetry of the detected current can be checked.

[0032] Optionally, voltage can be additionally detected. Using the detected voltage and current, by comparing them with pre-defined comparison values, it can be determined whether the DC unit (e.g., photovoltaic generator, battery, or load such as an electrolyzer) connected to the facility is operating as expected. The pre-defined comparison values ​​can be, for example, stored in the facility's control unit and / or input by the operator via an interface.

[0033] The detection of various currents can be performed, especially at low power levels in the DC unit, such as at minimum power levels in the electrolytic cell. At low power levels, or even precisely at low power levels, functional malfunctions of the facility can be identified by detecting current and / or voltage.

[0034] In one embodiment of the method, stage C) further includes: Check the facility's fans and / or other sensors.

[0035] In one embodiment of the method, stage C) further includes: In the case of a connected AC power grid and at least one connected DC unit: Power is exchanged between the AC and DC sides, with the power exchange increasing in multiple stages.

[0036] This allows for the gradual startup of the at least one power converter and the gradual increase of its load. If any fault occurs, the method can be stopped, and the load level at the time of the fault may indicate the cause of the fault.

[0037] Power exchange between the AC and DC sides can be increased, in particular, by approximately 10% to approximately 60% of the facility's rated power over several stages. When a facility has exactly one power converter, the facility's rated power corresponds to the rated power of that power converter. If the facility includes multiple power converters, the facility's rated power can correspond to the sum of the rated power of the multiple power converters.

[0038] In one embodiment of the method, stage C) further includes: When at least one pre-defined temperature of the at least one power converter is reached for a pre-defined duration: the commissioning method ends and normal operation of the facility is initiated.

[0039] In one embodiment, the facility includes a sinusoidal filter capacitor contactor for switching on or connecting the sinusoidal filter capacitor to the AC power grid. The sinusoidal filter capacitor contactor, for example, has an electrical operating device and is powered by an auxiliary network. This allows the function of the contactor to be tested and evaluated in method phase A).

[0040] In one embodiment, the facility has an auxiliary network with an auxiliary network disconnect switch for connecting the auxiliary network to the AC power grid, wherein a sinusoidal filter capacitor contactor may be functionally coupled to the auxiliary network disconnect switch.

[0041] This can be particularly useful for reducing any backlash to the auxiliary network when establishing connections between the sinusoidal filter capacitor and the AC grid, and especially for preventing overvoltages in the auxiliary network. This allows for the safe and secure supply of power to facility components via the auxiliary network even when there is a temporary large current flowing between the sinusoidal filter capacitor and the AC grid.

[0042] In one embodiment, the auxiliary network of the facility has a rectifier that provides a DC auxiliary voltage, wherein the functional coupling between the sinusoidal filter capacitor contactor and the auxiliary network disconnect switch is configured to maintain the DC auxiliary voltage with a pre-defined quality when the sinusoidal filter capacitor contactor is operated. This could, for example, mean keeping the voltage of the auxiliary network within a tolerance range, for example, 24 V of its rated voltage. This can thus protect components powered by the auxiliary grid from fluctuations in the auxiliary network voltage.

[0043] The impact of connecting the sinusoidal filter capacitor to the AC grid and exchanging power on the auxiliary network can also be tested and evaluated in phase A). Here, the functional coupling between the sinusoidal filter capacitor contactor and the auxiliary network disconnector can be examined in phase A). This is particularly relevant during the electrical pre-charging of the sinusoidal filter capacitor through the AC grid. Attached Figure Description

[0044] The present application will now be further elaborated and described based on the embodiments shown in the accompanying drawings.

[0045] Figure 1 A schematic flow of the method is shown.

[0046] Figure 2 A schematic diagram of a facility used for electrical power conversion is shown.

[0047] Figure 3 The diagram illustrates the effects of temperature in facilities used for electrical power conversion. Detailed Implementation

[0048] Figure 1 A schematic flow diagram of the method with stages A), B), and C) is shown. In stages A), B), and C) (also referred to as levels), the states of facility 10 are established in a targeted manner, through which the functionality of individual components of the facility can be checked and / or prepared. The sequence of states and the selection of components involved ensure that any possible failure has the least possible subsequent impact, and in particular, results in as few or no subsequent failures as possible.

[0049] In Phase A), an auxiliary network 36 (specifically a DC auxiliary network) is established to power the components of facility 10. The other steps of Phase A) are performed after the auxiliary network 36 has been established.

[0050] The auxiliary network 36 can, in particular, supply power to electrically operated switching devices (such as switches and contactors). Therefore, in stage A), the functionality of the switches, especially the AC switch 20, the DC switch 18, and the sinusoidal filter capacitor contactor 30, can be tested.

[0051] Step B) of Phase 2 is performed by temporarily connecting facility 10 to the AC power grid 14. During step B), the connection to the DC unit of facility 10 is disconnected.

[0052] In phase B), the DC intermediate loop of the power converter 16 of facility 10 can first be precharged via the precharge circuit 22. Subsequently, a self-test of the power converter 16 can be performed with the AC grid 14 disconnected. After a successful self-test, the semiconductor switches of the individual bridge circuits of the power converter 16 can be preheated by exchanging reactive power with the AC grid; that is, their temperature can be brought to a predefined range, preferably corresponding to a temperature range common in normal operation and / or within which the semiconductor switches exhibit good efficiency and / or long durability.

[0053] The steps of stage C) are performed with the AC grid 14 connected and at least one connected DC unit (e.g., a connected DC generator 12).

[0054] In stage C), facility 10, particularly power converter 16, can be tested during power exchange between the AC and DC sides. In particular, current and / or voltage can be detected and their suitability checked by comparing them with pre-given values.

[0055] Phase D) is used for commissioning of facility 10 with both AC and DC power, where the power is increased in stages. For this purpose, a cycle and power ramp-up (Leistungshübe) are set up.

[0056] Figure 2One embodiment of a facility 10 for electrical power conversion is shown. Facility 10 includes power converters 16 connected to a DC bus via a DC switch 18. The power converters 16 are connected to the DC side 32 of facility 10 via the DC bus. DC units, such as a DC generator 12 as a power source and / or a battery (not shown) and / or a load (not shown) such as an electrolytic cell, can be connected to the DC side 32 of facility 10. On the AC side, the power converters 16 are connected to the AC side 34 of facility 10 via an AC switch 20. On the AC side 34, facility 10 can be connected to an AC power grid 14 via a first transformer T1.

[0057] The auxiliary network 36 can be connected to the AC side of facility 10 via the auxiliary network disconnect switch 38 and the second transformer T2, thereby drawing power from the AC power grid 14. The auxiliary network 36 can supply power to components of facility 10, such as fan 24, heater, and / or switching devices of facility 10.

[0058] based on Figure 2 This further elaborates on a possible procedure for the commissioning of facility 10.

[0059] Phase A) is particularly used for commissioning and testing of facility 10, which is powered independently via auxiliary network 36. Auxiliary network 36 may also be referred to as an on-board network, and particularly includes DC networks, such as 24V DC networks.

[0060] The auxiliary network 36 of facility 10 can be powered by AC grid 14, with the power section of power converter 16 connected to AC grid 14 on the AC side. Alternatively or additionally, the auxiliary network 36 can be powered by an external power source independent of AC grid 14, such as a separate low-voltage network constructed independently of AC grid 14. In both cases, the AC voltage is converted to DC voltage by rectifier 40 to power the auxiliary network 36.

[0061] In phase A), it should be ensured that both the external DC unit and the external AC power grid 14 are disconnected from the power converter 16. This can be done, for example, by a professional, such as the operator or service technician of facility 10.

[0062] In subsequent steps of phase A), the switching devices of facility 10, such as DC switch 18, AC switch 20 and / or sine filter capacitor contactor 30, can be gradually put into operation and tested.

[0063] To do this, first, the DC switches 18 are switched on and off multiple times. Each DC switch 18 is switched individually. After all the DC switches 18 have been switched once, the switching process for each DC switch 18 is repeated twice. Approximately 2 minutes should be allowed between each switching process. These switching processes can be performed automatically or manually.

[0064] Since the DC switches 18 are switched individually, it can be identified (e.g., by an operator) whether certain switches are not switched. Alternatively or additionally, the at least one DC switch 18 may include a self-diagnostic function and automatically issue a corresponding message. If a fault is detected at this stage, the method is aborted to avoid further damage to facility 10.

[0065] In the next step after stage A), AC switch 20 is switched on and off twice. Approximately 2 minutes should be allowed between each switching process. These switching processes can be performed automatically or manually.

[0066] In the next step after stage A), the sinusoidal filter capacitor contactor 30 is switched on and off twice. These switching processes can be performed automatically or manually. Optionally, the sinusoidal filter capacitor 26 can be pre-charged by a suitable pre-charge circuit.

[0067] When the sinusoidal filter capacitor contactor 30 is turned on when AC switch 20 is closed (i.e., connected to AC grid 14), a considerable balancing current may be generated to balance the voltage between the sinusoidal filter capacitor 26 and AC grid 14 due to the potential voltage difference between the sinusoidal filter capacitor 26 and the grid voltage. This can cause significant fluctuations in the input voltage of auxiliary network 36, leading to a failure of auxiliary network 36, and in particular, causing rectifier 40 to shut down. Therefore, the sinusoidal filter capacitor contactor 30 and auxiliary network disconnect switch 38 are coupled such that turning on the voltage of the sinusoidal filter capacitor contactor 30 causes the auxiliary network disconnect switch 38 to briefly open. This means that when the sinusoidal filter capacitor contactor 30 is operated, the auxiliary network 36 is temporarily disconnected from the AC side 34 of facility 10 by opening the auxiliary network disconnect switch 38. Thus, voltage fluctuations that may be caused by the balancing current flowing to the sinusoidal filter capacitor 26 are isolated from the auxiliary network 36. The auxiliary network 36 itself can briefly overcome such interruptions (approximately a few seconds, especially about one second), and the 24 V DC network can be maintained by a buffer capacitor. A 24 V DC network can be used in particular for the switching devices of the operating facility 10, such as DC switch 18, AC switch 20 and / or sine filter capacitor contactor 30.

[0068] Therefore, by test-switching the sinusoidal filter capacitor contactor 30, it is possible to check whether the power supply to the auxiliary network (e.g., its 24 V DC power supply) is securely protected from the switching operation. Maintaining the target voltage (e.g., 24 V) can be used as an acceptance criterion.

[0069] After completing this self-powered check, facility 10 can automatically switch to phase B, or shut down and enter a safe state in case of a fault.

[0070] In phase A), there may be someone on site, such as a service technician. Phase A) can be observed with the assistance of this person, and / or some switching devices can be operated manually. Phase A) can be confirmed, for example, through input from this person. If the test is interrupted, the point at which the interruption occurred can be displayed, for example. After appropriate maintenance, the method can be restarted from phase A).

[0071] Phase B) is used for commissioning of facility 10 in the case where AC power is provided at least in part by AC grid 14.

[0072] First, in stage B), self-tests are performed on each bridge circuit (so-called stack) of the power converter 16. The AC pre-charge circuit 22 pre-charges each DC intermediate circuit of the power converter 16. After pre-charging, self-tests on each bridge circuit of the power converter 16 can be performed without the AC grid 14 and without the DC unit.

[0073] A self-test can be performed, for example, once. If the self-test passes, the AC power grid 14 can be connected by closing AC switch 20.

[0074] In the next step of phase B), the power converter 16 of facility 10 can operate in the so-called Q@night mode, in which reactive power exchange, especially pure reactive power exchange, is performed with the AC grid 14 when the DC switch 18 is open.

[0075] Power converters 16 are started in so-called Q@night mode. Each power converter 16, controlled by an appropriate clock of its bridge circuit, exchanges reactive power between the AC grid 14 and its intermediate loop capacitor to heat the semiconductor power switches (e.g., performing as IGBT modules). During this process, the DC voltage can be kept low, especially to safely remove any moisture that may remain in the IGBT modules. For example, the DC voltage can be set at a level slightly higher than the rectified AC voltage value, minimizing the load on the IGBT modules regarding potential fault current during the drying process.

[0076] Furthermore, heating, especially cyclic heating, can trigger a settling mechanism and eliminate mechanical stresses that may arise from the storage and transportation of the facility 10.

[0077] Furthermore, through stage B), the distribution of thermal paste within the power converter 16 can be facilitated, particularly between the IGBT modules and their respective heat sinks in the bridge circuit. The thermal paste distribution may not be complete during commissioning. If this is the case, the IGBT modules are not yet fully operational. For example, there may be undefined gaps on the IGBT modules on the baseplate that should be filled with thermal paste. Thermal risers are beneficial in this regard, acting like a pumping process to move the individual IGBT modules and thus direct the thermal paste to the correct locations. Since the power converter 16 is designed with rated power and the maximum power loss generated during this process in mind, assuming defined heat dissipation during operation, this process facilitates optimal thermal paste distribution, thereby achieving the desired heat dissipation.

[0078] Advantageously, at least five cycles with temperature rise are run to optimize the distribution of thermal paste on the heatsink (e.g., the heatsink of an IGBT module). Following this process, better heat transfer is achieved. This improvement in heat transfer can be achieved through the thermally stepped startup of the power converter 16.

[0079] Figure 3 Exemplary curves of the reactive power Q exchanged on the bridge circuits of each power converter 16 are shown. The upper graph shows the reactive power Q expressed as a fraction of the rated apparent power S_Nenn of each power converter 16. The lower graph shows the resulting temperature curves, with the temperature TM (larger value) measured at the IGBT modules of the bridge circuit and the temperature TB (smaller value) measured at the base plate. Energy input and thermal cycling steadily increase, achieving multiple temperature cycles with a temperature difference from approximately 30 Kelvin initially to over 60 Kelvin in the final cycle. Particularly advantageous are temperature cycles with a temperature difference of approximately 60-70 Kelvin, which can be achieved by correspondingly extending the individual cycles and / or increasing the reactive power during the heating phase and / or increasing the cooling performance during the cooling phase via fan 14.

[0080] Therefore, the reactive power pre-setting and fan 24 control can be "temperature-regulated". If the individual power converters are connected to the AC grid 14, which is constructed as a medium-voltage grid, via corresponding medium-voltage cables, then the preferred inductive reactive power Q may be advantageous.

[0081] Phase B) may last longer than Phase A. It may, for example, run automatically at night. Phase B) may run without personnel present at Facility 10. Once Phase B) is complete, the method can automatically transition to Phase C.

[0082] If the test is aborted, the point at which the abort occurred can be displayed, for example. After any necessary repairs, the method can be restarted from either stage A or stage B. It is preferable to restart the method from stage A.

[0083] Phase C) is used for commissioning of facility 10 in the presence of both AC and DC power (i.e., connected AC grid 14 and connected DC unit).

[0084] In the first step of phase C), a plausibility check is performed on different aspects of facility 10. This plausibility check can be performed, in particular, by taking measured values ​​(e.g., current and voltage) and comparing them to pre-given test values. These test values ​​can be stored in the control unit of facility 10 and / or entered by the operator.

[0085] First, check the efficiency of each power converter 16. To do this, determine and check the ratio of measured AC power to measured DC power at low power. This check includes comparison with a pre-defined test value having a tolerance bandwidth. If the measured AC power to DC power ratio exceeds the tolerance range, a fault condition has occurred. This could be due to incorrect parameter settings on the individual power converters or damage to the measuring instrument (e.g., a measuring sensor). The goal of this test is specifically to check whether the parameter settings are correct and / or whether the measuring instrument is functioning properly. Checking the efficiency itself is not necessarily performed in this step.

[0086] In the next step after stage C), the DC current symmetry between multiple parallel DC input terminals (DC units, especially DC generators connected here) can be checked.

[0087] For parallel-connected and identical DC generators 12, such as photovoltaic (PV) generators, if the DC generator 12 produces DC power, the DC current at the parallel DC input terminals can be automatically determined using a measuring tool. For example, if a power converter 16 is a PV converter with multiple parallel DC generators 12 configured as PV strings, and the asymmetry of its input current (e.g., series current) exceeds 4%, there may be a defect in the connection distribution (e.g., the structure of the PV strings). This can then be corrected. This process can be performed, for example, with a minimum power (e.g., about 20%) between 10% and 30% of the rated power of each power converter 16. Within the smaller power range, measurement inaccuracies may distort the comparison of measured values.

[0088] In a further step, the rationality of the thermal management of facility 10 can be checked. For example, it can be checked whether the fans are operating at the set values ​​and / or whether all temperature and humidity sensors are displaying reasonable values.

[0089] Subsequently, optional self-testing of each DC unit (e.g., PV, battery, electrolyzer) can be performed.

[0090] Phase C) can, for example, run automatically. Phase C) may run without personnel at the facility 10 site. Once Phase C) is complete, the method can automatically transition to Phase D).

[0091] If the test is aborted, the point at which the abort occurred can be displayed, for example. After any necessary repairs, the method can be restarted from stage A), stage B), or stage C). It is preferable to restart the method from stage A).

[0092] Phase D) is used for commissioning of facility 10 with both AC and DC power, where the power is increased in stages. Cycles and power ramps are set up for this purpose.

[0093] First, in the first step of stage D), the power converter 16 is started with power limitation and its power is gradually increased. Alternatively, or in addition to stage B), reactive power heating is used, while stage D can be used to heat the power converter 16 by exchanging active power.

[0094] In cases where, for example, a PV generator is used as a DC unit, the power is naturally limited by the irradiance, so it cannot be guaranteed that there is enough power available for heating in this stage D); therefore, in this case, it is preferable to use reactive power for heating as in stage B).

[0095] However, in cases where, for example, a battery or electrolytic cell is used as the DC unit, targeted heating can be achieved in principle by setting an adjustable active power between 0 and the rated power of each power converter 16 in this stage D), thus eliminating the need for reactive power heating as in stage B).

[0096] Specifically, for heating in stage D), especially for batteries that function as DC units, the following timeframes can be considered: - First 8 hours: 10-60% of the rated power of each power converter (16).

[0097] - Second 8 hours: 10-80% of the rated power of each power converter 16. During this process, a forced stop can be performed after about 4 hours to obtain additional hot-cold cycles.

[0098] - The test can be completed after 16 hours; if possible, the time can be reduced, for example, to be completed within one day / one daylight cycle.

[0099] Phase D) may, for example, operate automatically. Phase D) may operate without personnel present at Facility 10. Once Phase D) is complete, the method may end, and Facility 10 may, for example, automatically return to normal operation.

[0100] If the test is aborted, the point at which the abort occurred can be displayed, for example. After any necessary repairs, the method can be restarted from stage A), stage B), stage C), or stage D). It is preferable to restart the method from stage A).

[0101] In this step, the operation management parameters are also set so that the facility can operate in normal mode when it is subsequently restarted.

[0102] All four phases of this method can be documented in one or more protocol files and can be identified as individual phases. Once the method aborts, the point at which the abort occurred can be shown. This can also be identified in the protocol file (or protocol document).

[0103] List of reference numerals 10 facilities 12 DC generator 14 AC power grid 16 Power Converter 18 DC switches 20 AC switch 22 Pre-charge circuit 24 fans 26 Sine wave filter capacitor 30 Sine wave filter capacitor contactor 32 DC side 34 AC side 36. Auxiliary Networks 38 Auxiliary network isolation switch 40 Rectifier A), B), C) Stages of the method Transformers T1 and T2

Claims

1. A method for commissioning a facility (10) for electrical power conversion, said facility having at least one power converter (16) with an intermediate loop and a bridge circuit, wherein, The facility (10) is connected to at least one DC unit, particularly a DC generator (12), on the DC side (32) and to an AC grid (14) on the AC side (34), wherein the at least one power converter (16) is connected to the DC side (32) via at least one DC switch (18) and to the AC side (34) via at least one AC switch (20), wherein the method has: Phase 1 (A), which includes establishing an auxiliary network (36) for powering the components of facility (10), The second stage (B) has a temporarily connected AC power grid (14) and does not have a connection to the at least one DC unit. The third stage (C) has a connected AC power grid (14) and at least one connected DC unit.

2. The method according to claim 1, wherein, The first stage (A) includes: - Establish an auxiliary network (36) for supplying power to the components of the facility (10) from the AC grid (14) via the rectifier (40) of the facility (10), particularly for supplying power to the operation of the AC switch (20), the at least one DC switch (18), and the sinusoidal filter capacitor contactor (30). - Close the AC switch (20). - Connect the capacitor (26) of the AC-side sinusoidal filter to the AC power grid (14). - Check the power supply through the auxiliary network (36), and then turn on the AC switch (20), and - If the power supply through the auxiliary network (36) is within a pre-given limit, the method continues; or if the power supply through the auxiliary network (36) exceeds a pre-given limit, the method is terminated.

3. The method according to claim 1 or 2, wherein, The second phase (B) includes: - The DC intermediate circuit is precharged by the pre-charge circuit (22). - Perform a self-test on the bridge circuit of the at least one power converter (16), - In the case of a successful self-test: connect to the AC grid (14) by closing at least one AC switch (20).

4. The method according to any one of claims 1 to 3, wherein, The second phase (B) includes: In the case of a connected AC grid (14): the bridge circuit of the at least one power converter (16) is clocked to exchange reactive power, especially inductive reactive power, between the intermediate loop and the AC grid (14).

5. The method according to claim 4, wherein, The temperature in the power converter (16), especially the temperature in the bridge circuit of the power converter (16), is detected and the temperature is increased by matching reactive power exchange and / or manipulating the fan (24) of the facility (10) until the temperature in the power converter exceeds a pre-given lower threshold and / or reaches a pre-given upper threshold.

6. The method according to claim 5, wherein, The lower and upper thresholds have a temperature difference of at least 40 Kelvin, preferably at least 60 Kelvin, and are achieved by repeatedly alternating reactive power exchange.

7. The method according to any one of the preceding claims, wherein, The third stage (C) includes: In the case of a connected AC power grid (14) and at least one connected DC unit: Power is exchanged between the AC side (34) and the DC side (32), the exchanged AC power and exchanged DC power of the at least one power converter (16) are detected, and the reasonableness of the detected power is checked.

8. The method according to claim 7, wherein, The power exchange is performed at low power, particularly between 5% and 20% of the rated power of the at least one power converter (16).

9. The method according to any one of the preceding claims, wherein, The third stage (C) includes: In the case where there is a connected AC power grid (14) and multiple DC units connected in parallel circuits on the DC side (32): The current of the DC unit in the parallel circuit is detected, and the symmetry of the detected current is checked.

10. The method according to claim 9, wherein, Current detection is performed when the DC unit is at low power, especially when the DC unit is at minimum power.

11. The method according to any one of the preceding claims, wherein, The third stage (C) includes: Inspect the fan (24) and / or other sensors of the facility (10).

12. The method according to any one of the preceding claims, wherein, The third stage (C) includes: In the case of a connected AC power grid (14) and at least one connected DC unit: Power is exchanged between the AC side (32) and the DC side (34), wherein the power exchange is increased in multiple stages.

13. The method according to claim 12, wherein, The power exchange increases in several stages between approximately 10% and approximately 60% of the rated power.

14. The method according to claim 12 or 13, wherein, The power exchange increases in several stages between approximately 10% and approximately 80% of the rated power.

15. The method according to any one of claims 12 to 14, wherein, include: If at least one pre-given temperature of the at least one power converter (16) is reached for a pre-given duration: the commissioning method is terminated and the facility (10) is put into normal operation.

16. A device (10) for electrical power conversion, said device having at least one power converter (16) with an intermediate loop and a bridge circuit, wherein, The facility (10) is connectable to at least one DC generator (12) on the DC side (32) and to an AC grid (14) on the AC side (34), wherein the at least one power converter (16) is connectable to the DC side (32) via at least one DC switch (18) and to the AC side (34) via at least one AC switch (20), wherein the facility (10) has a control unit configured and set to perform the method according to any one of the preceding claims.

17. The facility (10) according to claim 16, wherein, The facility (10) has a sinusoidal filter capacitor contactor (30) and an auxiliary network with an auxiliary network disconnector (38) for connecting the auxiliary network (36) to the AC power grid (14), wherein the sinusoidal filter capacitor contactor (30) is functionally coupled to the auxiliary network disconnector (38).

18. The facility (10) according to claim 16 or 17, wherein, The auxiliary network (36) has a rectifier (40) that provides a DC auxiliary voltage, wherein the functional coupling between the sinusoidal filter capacitor contactor (30) and the auxiliary network disconnect switch (38) is configured to maintain the DC auxiliary voltage with a pre-given quality when the sinusoidal filter capacitor contactor (30) is manipulated.

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