Automatic grid-connected control system of three-in-one of commercial power, diesel generator and photovoltaic

Abstract

The utility model provides a municipal power, diesel generator and photovoltaic three electric one's automatic parallel operation control system, municipal power line is connected to parallel operation 10KV bus through 120KV / 10KV transformer, incoming line circuit breaker, photovoltaic power generation circuit contains many parallel branches, and each branch connects photovoltaic board, inverter, step -up transformer in turn, and is connected to bus through first parallel operation cabinet, and part branch also contains energy storage module and PCS bidirectional current transformer, and diesel generator power generation circuit also contains many parallel branches, and each branch connects diesel generator, first 8610 controller, second parallel operation cabinet in turn, and is connected to bus through second 8610 controller, third parallel operation cabinet, and parallel operation 10KV bus is connected user power line through feeder cabinet. System gathers each power parameter through EMS, adjusts voltage, frequency, phase of photovoltaic and diesel generator system, realizes undisturbed switching, improves power supply continuity, safety and energy utilization efficiency, reduces operating cost.

Description

Technical Field

[0001] This utility model relates to the field of power distribution network technology, specifically to an automatic grid-connected control system that integrates mains power, diesel generator, and photovoltaic power. Background Technology

[0002] Globally, many regions face the problem of unstable power supply, with the reliability of external power grids frequently threatened. Power rationing and outages are common occurrences, disrupting normal production and causing significant economic losses. To address this issue, businesses typically employ dual power sources, generally combining local grid power (municipal power) with their own diesel generator sets.

[0003] This traditional model has significant limitations: during normal operation, the enterprise's internal power grid remains connected to the mains power. When the mains power fails, the diesel generator starts as a backup power source, only able to maintain the enterprise's minimum isolated grid operation, and cannot operate simultaneously with the mains power. The main reason is that if the diesel generator operates in parallel with the mains power, a power grid failure can easily cause significant load fluctuations in the self-provided diesel generator set, potentially damaging the generator.

[0004] Meanwhile, the model of connecting the grid power and the photovoltaic system separately also has its drawbacks. Because photovoltaic power generation is significantly affected by natural conditions, the photovoltaic system cannot supply power to the site during periods of insufficient sunlight, such as cloudy days or nighttime. If the grid power fails at this time, the enterprise will face a production interruption and suffer losses.

[0005] While existing research on multi-power grid connection has touched upon some key aspects, such as photovoltaic system structural design and inverter grid connection performance optimization, reflecting the trend of grid-connected systems towards intelligent, safe, and high-quality power output, shortcomings remain in the coordinated operation of multiple power sources. For example, it is difficult to achieve stable grid connection and seamless switching between diesel generators, mains power, and photovoltaic systems, and it is difficult to rationally allocate the output of each power source according to load demand, resulting in low energy utilization efficiency, high operating costs, and disturbances during power switching, affecting power supply stability and failing to meet the needs of continuous production for enterprises.

[0006] Therefore, how to achieve efficient and coordinated grid connection of mains power, diesel generators, and photovoltaic systems, solve power switching disturbances, improve energy utilization efficiency, and ensure power supply continuity has become an urgent problem to be solved in the field of power system control. Utility Model Content

[0007] The technical problem to be solved by this utility model is to provide an automatic grid-connected control system that integrates mains power, diesel generator and photovoltaic power, so as to solve the problems in the existing technology that cannot achieve stable coordinated grid connection of mains power, diesel generator and photovoltaic system, are prone to disturbance during power switching, have low energy utilization efficiency and are difficult to guarantee power supply continuity.

[0008] To solve the above-mentioned technical problems, the embodiments of this utility model provide the following technical solutions: An automatic grid-connected control system integrating mains power, diesel generator, and photovoltaic power, comprising mains power lines, photovoltaic power generation lines, and diesel generator power generation lines; The mains power line includes a 120KV / 10KV transformer and an incoming circuit breaker. The output terminal of the 120KV / 10KV transformer is connected to the incoming circuit breaker, and the incoming circuit breaker is connected to the grid-connected 10KV bus. The photovoltaic power generation line includes multiple parallel branch photovoltaic power generation lines. Each branch photovoltaic power generation line includes photovoltaic panels, inverters, and step-up transformers connected in sequence. The step-up transformer is connected to the grid-connected 10KV busbar through the first grid-connected cabinet. The diesel generator power generation line includes multiple parallel branch diesel generator lines. Each branch diesel generator line includes a diesel generator, a first 8610 controller, and a second grid-connected cabinet connected in sequence. The branch diesel generator lines are connected to the grid-connected 10KV busbar in sequence through the second 8610 controller and the third grid-connected cabinet. The grid-connected 10KV busbar is connected to multiple user power lines via feeder cabinets.

[0009] Optionally, the branch photovoltaic power generation line also includes an energy storage module, a PCS bidirectional converter, and a step-up transformer connected in sequence, and the step-up transformer is connected to the grid-connected 10KV busbar through the first grid-connected cabinet.

[0010] Optionally, the inverter includes a DSP processor, an FPGA processor, a voltage and current detection module, an external switch module, a switch quantity control module, a power supply module, a communication interface circuit, a drive circuit, and an inverter main circuit. The DSP processor is electrically connected to the FPGA processor, the voltage and current detection module, the external switch module, the switch quantity control module, the power supply module, and the communication interface circuit. The FPGA processor is connected to the inverter main circuit through the drive circuit.

[0011] Optionally, the DSP processor is a TMS320F28335.

[0012] Optionally, the FPGA processor model is EP2C35F672C6N.

[0013] Optionally, the voltage and current detection module is connected to the DSP processor via a signal conditioning circuit.

[0014] Optionally, the signal conditioning circuit employs an amplifier circuit based on the operational amplifier OP284EPZ.

[0015] Optionally, the driving circuit uses a 2SD106AI module.

[0016] The beneficial effects of the above-mentioned technical solution of this utility model are as follows: 1. This utility model constructs an automatic grid-connected control system integrating mains power, diesel generator, and photovoltaic power, achieving coordinated operation and seamless switching of multiple power sources, significantly improving power supply continuity. The system utilizes an EMS to collect parameters of each power source in real time, precisely adjusting the voltage, frequency, and phase of the photovoltaic and diesel generator systems to ensure parameter matching during grid connection and avoid equipment failures caused by parameter inconsistencies. When mains power is restricted or interrupted, the photovoltaic system can be quickly connected, combined with an energy storage module to ensure load supply. When photovoltaic power is insufficient, it automatically switches to the diesel generator system, completely solving the production interruption problem caused by power outages in traditional single-power or dual-power modes, and greatly improving the stability of enterprise production.

[0017] 2. This utility model adopts a non-disruptive switching technology. During the switching process between mains power and photovoltaic power, and between photovoltaic power and diesel power, the coordinated control of the 8610 and 8660 controllers and EMS ensures a smooth transition of parameters such as voltage and frequency, avoiding current surges and load fluctuations during switching. Attached Figure Description

[0018] Figure 1 This is a block diagram illustrating the principle of the automatic grid-connected control system integrating mains power, diesel generator, and photovoltaic power in this utility model. Figure 2 This is a block diagram of the inverter principle of the automatic grid-connected control system integrating mains power, diesel generator and photovoltaic power of this utility model; Figure 3 This is a schematic diagram of the inverter main circuit control principle of the automatic grid-connected control system integrating mains power, diesel generator and photovoltaic power. Figure 4 This is a schematic diagram of the signal conditioning circuit of the automatic grid-connected control system that integrates mains power, diesel generator, and photovoltaic power. Detailed Implementation

[0019] To make the technical problems, technical solutions and advantages of this utility model clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0020] like Figure 1As shown, this utility model provides an automatic grid-connected control system that integrates mains power, diesel generator, and photovoltaic power, including mains power lines, photovoltaic power generation lines, and diesel generator power generation lines.

[0021] The municipal power line includes a 120KV / 10KV transformer 15 and an incoming circuit breaker 14. The output terminal of the 120KV / 10KV transformer 15 is connected to the incoming circuit breaker 14, and the incoming circuit breaker 14 is connected to the grid-connected 10KV bus.

[0022] The photovoltaic power generation line includes multiple parallel branch photovoltaic power generation lines. Each branch photovoltaic power generation line includes a photovoltaic panel 1, an inverter 2, and a step-up transformer 3 connected in sequence. The step-up transformer 3 is connected to the 10KV busbar through the first grid-connected cabinet 4. In addition, the branch photovoltaic power generation line also includes an energy storage module 5, a PCS bidirectional converter 6, and a step-up transformer 3 connected in sequence. The step-up transformer 3 is connected to the 10KV busbar through the first grid-connected cabinet 4.

[0023] The diesel generator power generation line includes multiple parallel branch diesel generator lines. Each branch diesel generator line includes a diesel generator 7, a first 8610 controller 8, and a second grid-connected cabinet 9 connected in sequence. The branch diesel generator lines are connected to the grid-connected 10KV busbar in sequence through the second 8610 controller 10 and the third grid-connected cabinet 11.

[0024] The grid-connected 10KV busbar is connected to multiple user power lines 13 via feeder cabinet 12.

[0025] like Figure 2 As shown, the inverter 2 includes a DSP processor 21, an FPGA processor 22, a voltage and current detection module 23, an external switch module 24, a switch quantity control module 25, a power supply module 26, a communication interface circuit 27, a drive circuit 28, and an inverter main circuit 29. The DSP processor 21 is electrically connected to the FPGA processor 22, the voltage and current detection module 23, the external switch module 24, the switch quantity control module 25, the power supply module 26, and the communication interface circuit 27. The FPGA processor 22 is connected to the inverter main circuit 29 through the drive circuit 28.

[0026] Among them, the DSP processor 21 is model TMS320F28335, and the FPGA processor 22 is model EP2C35F672C6N.

[0027] Voltage and current detection module 23 is connected to DSP processor 21 through signal conditioning circuit. The signal conditioning circuit adopts an amplifier circuit based on operational amplifier OP284EPZ, such as... Figure 4As shown. The voltage and current detection module 23 mainly includes sampling of DC side voltage and current signals, bus side voltage and current signals, and three-phase grid side voltage and current signals. The main function of the signal conditioning circuit is to amplify and limit the collected signals before transmitting them to the DSP.

[0028] The drive circuit 28 uses a 2SD106AI module. Since the power of the PWM signal generated in the FPGA is small, it is insufficient to drive the IGBT switching transistor of the main circuit 29 of the lower inverter. Therefore, the PWM signal needs to be amplified by a power amplifier circuit.

[0029] This invention utilizes a photovoltaic panel to generate electricity. A grid-connected inverter converts DC to AC, and a step-up transformer boosts the voltage to 10kV before supplying it to the 10kV busbar. Excess electricity generated by the photovoltaic panel is stored in a battery for nighttime and peak-shaving use. The grid-connected inverter monitors the voltage, frequency, and phase angle parameters of the entire DC busbar and executes grid connection.

[0030] The diesel generator is controlled by a single 8610 controller, which directly outputs 10kV voltage. The 8660 coordinating controller controls the generator's voltage, frequency, and phase parameters for grid connection. The generator control system uses a DSE8660 data processing module with signal input / output functions, remote load start, mains power closing output, and busbar circuit breaker closing output. It also uses a DSE8610 data acquisition module to detect signals including generator voltage, generator current, busbar voltage, mains voltage, mains current, generator circuit breaker closing feedback, busbar circuit breaker closing feedback, and mains circuit breaker closing feedback.

[0031] The 120kV mains power is introduced to the No. 1 main transformer and converted to 10kV voltage on a section of the busbar. The diesel generator system and photovoltaic system adjust their respective system parameters by collecting mains voltage, frequency, and phase angle parameters for grid connection.

[0032] like Figure 3 As shown, the DSP processor of this invention integrates a phase-locked loop (PLL) circuit. The function of the PLL is to ensure that the signals generated and obtained inside the system maintain the same frequency and phase as the reference signal, and to eliminate the steady-state error in the PLL angle estimation. Figure 3 The signal flow is as follows: reference voltage → voltage outer loop adjustment → current reference signal → coordinate transformation → current inner loop adjustment → PWM drive signal → IGBT switching transistor, while ensuring synchronization with the power grid through a phase-locked loop. IGBT switching transistor ( , , , , , The six IGBT power switches, corresponding to the three-phase full-bridge inverter circuit, constitute the main circuit of the DC / AC inverter. By controlling their on and off states, the DC voltage is inverted into a three-phase AC voltage.

[0033] Reference voltage ( The target reference value for the DC bus voltage is used to ensure stable input DC-side voltage (such as the DC output of photovoltaic or energy storage modules). The outer voltage loop is controlled by the DSP processor, which compares the actual DC bus voltage with the reference voltage. The PI controller outputs a d-axis reference current (Idref) to achieve stable regulation of the DC voltage and provide a reference for the inner current loop.

[0034] Then, current reference and coordinate transformation (dq / abc) are performed. To achieve unity power factor grid connection, Idref is usually set to 0 (reactive current is 0). Idref is determined by the voltage outer loop output (active current reference).

[0035] The dq / abc transformation includes "abc→dq" (Park transformation) and "dq→abc" (Park inverse transformation). The former converts the three-phase AC current (abc coordinate system) into a two-phase rotating coordinate system (dq), simplifying control; the latter converts the adjusted dq-axis current back into the abc coordinate system for generating three-phase PWM drive signals.

[0036] The process involves a phase-locked loop (PLL) and phase synchronization (θ). The core function of the PLL is to ensure that the inverter output signal is completely synchronized with the grid signal in terms of frequency and phase. By detecting the grid voltage and eliminating phase errors through PI regulation, the output phase angle θ is used for synchronization during coordinate transformation (ensuring that the dq coordinate system rotates synchronously with the grid). θ is the real-time phase angle output by the PLL, providing a reference for coordinate transformation, ensuring phase matching between the inverter output and the grid, and avoiding phase conflicts during grid connection.

[0037] The DSP and FPGA work together, with the DSP responsible for high-precision calculations such as "voltage outer loop control", "data acquisition (voltage and current)", "phase-locked loop operation", and "coordinate transformation", and transmitting the current reference signal to the FPGA.

[0038] The FPGA is responsible for "current inner loop control" and "PWM signal generation" to drive the IGBT switching transistors.

[0039] The two communicate via SPI to ensure synchronized control timing. The PWM modulator, implemented by an FPGA, generates six PWM pulses (corresponding to six IGBTs) based on the output signal of the inner current loop, controlling the on / off time of the switching transistors and adjusting the amplitude and frequency of the inverter output voltage.

[0040] Through a three-layer control system consisting of "voltage outer loop stabilizing DC side voltage, current inner loop tracking active / reactive current reference, and PLL ensuring synchronization with the grid," combined with the efficient collaboration of DSP and FPGA, the inverter output AC power is ultimately perfectly matched with the grid voltage, frequency, and phase, meeting the requirements for disturbance-free grid connection.

[0041] Meanwhile, this invention primarily uses EMS to collect parameters from the photovoltaic-storage system, diesel generator system, and external mains power system. Based on the mains power, it adjusts the grid connection parameters of the photovoltaic-storage system and diesel generator system—voltage, frequency, and phase—ensuring that the phase, frequency, and voltage of the photovoltaic-storage system and diesel generator system are within a controllable range during grid connection. This avoids accidents caused by inconsistencies in voltage, frequency, and phase when the three energy systems (photovoltaic-storage system, diesel generator system, and external mains power system) are connected to the grid, thus improving the safety of grid connection between the photovoltaic-storage system, diesel generator system, and external mains power system.

[0042] The Energy Management System (EMS) of this utility model is one of the core subsystems of the battery energy storage system. It is responsible for collecting data from the entire station, including actual power generation, output power, battery capacity, battery status, line status, current, active power, reactive power, PCS status, and all BMS information. The EMS system includes an energy storage monitoring and power control system, an energy storage coordination controller, a remote control unit, and other network equipment. It realizes comprehensive data acquisition and control of all battery cells, battery clusters, battery stacks, PCS energy storage converters, and transformer substations within the energy storage system. After receiving and scheduling data from the remote control unit, the EMS performs power allocation based on the collected PCS and BMS information, achieving the specified power output while ensuring the safe operation of the energy storage system, and controlling the charging and discharging power of the energy storage converters.

[0043] The above description is the preferred embodiment of this utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this utility model, and these improvements and modifications should also be considered within the protection scope of this utility model.

Claims

1. An automatic grid-connected control system integrating mains power, diesel generator, and photovoltaic power, comprising mains power lines, photovoltaic power generation lines, and diesel generator power generation lines; The mains power line includes a 120KV / 10KV transformer and an incoming circuit breaker. The output terminal of the 120KV / 10KV transformer is connected to the incoming circuit breaker, and the incoming circuit breaker is connected to the grid-connected 10KV bus. The photovoltaic power generation line includes multiple parallel branch photovoltaic power generation lines. Each branch photovoltaic power generation line includes photovoltaic panels, inverters, and step-up transformers connected in sequence. The step-up transformer is connected to the grid-connected 10KV busbar through the first grid-connected cabinet. The diesel generator power generation line includes multiple parallel branch diesel generator lines. Each branch diesel generator line includes a diesel generator, a first 8610 controller, and a second grid-connected cabinet connected in sequence. The branch diesel generator lines are connected to the grid-connected 10KV busbar in sequence through the second 8610 controller and the third grid-connected cabinet. The grid-connected 10KV busbar is connected to multiple user power lines via feeder cabinets.

2. The automatic grid-connected control system integrating mains power, diesel generator, and photovoltaic power as described in claim 1, characterized in that, The branch photovoltaic power generation line also includes an energy storage module, a PCS bidirectional converter, and a step-up transformer connected in sequence. The step-up transformer is connected to the grid-connected 10KV busbar through the first grid-connected cabinet.

3. The automatic grid-connected control system integrating mains power, diesel generator, and photovoltaic power as described in claim 1, characterized in that, The inverter includes a DSP processor, an FPGA processor, a voltage and current detection module, an external switch module, a switch quantity control module, a power supply module, a communication interface circuit, a drive circuit, and an inverter main circuit. The DSP processor is electrically connected to the FPGA processor, the voltage and current detection module, the external switch module, the switch quantity control module, the power supply module, and the communication interface circuit. The FPGA processor is connected to the inverter main circuit through the drive circuit.

4. The automatic grid-connected control system integrating mains power, diesel generator, and photovoltaic power as described in claim 3, characterized in that, The DSP processor is a TMS320F28335.

5. The automatic grid-connected control system integrating mains power, diesel generator, and photovoltaic power as described in claim 3, characterized in that, The FPGA processor model is EP2C35F672C6N.

6. The automatic grid-connected control system integrating mains power, diesel generator, and photovoltaic power as described in claim 3, characterized in that, The voltage and current detection module is connected to the DSP processor via a signal conditioning circuit.

7. The automatic grid-connected control system integrating mains power, diesel generator, and photovoltaic power as described in claim 6, characterized in that, The signal conditioning circuit uses an amplifier circuit based on the operational amplifier OP284EPZ.

8. The automatic grid-connected control system integrating mains power, diesel generator, and photovoltaic power as described in claim 3, characterized in that, The driving circuit uses a 2SD106AI module.

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