Reverse power protection system and power grid system for triple co-generation distributed power plant
The reverse power protection device connected by optical fiber monitors and controls the reverse power of the combined heat and power (CHP) system in real time, solving the problem of reverse power backfeeding and improving the economy and grid security of the CHP system.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- CHINA IPPR INT ENG CO LTD
- Filing Date
- 2025-04-24
- Publication Date
- 2026-05-26
AI Technical Summary
After being connected to the grid, combined heat and power (CHP) systems may cause reverse power transmission, resulting in economic losses and reduced grid security.
The reverse power protection device, which uses optical fiber connection, collects signals through current and voltage detection devices, transmits signals using photoelectric converters, and calculates the off-grid power by combining logic modules, calculation modules, and judgment modules. It identifies reverse power and controls the generator's power generation and circuit breaker protection.
It effectively avoids reverse power backfeeding, improves the economy of generator rooms and the safety of the power grid, reduces power loss, and enhances the safety and flexibility of the protection system.
Smart Images
Figure CN224289288U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of reverse power protection technology, and in particular to a reverse power protection system for a combined heat and power (CHP) distributed power plant and a power grid system. Background Technology
[0002] Gas-fired combined cooling, heating, and power (CCHP) is a type of distributed energy source with comprehensive benefits including energy conservation, environmental improvement, and increased power supply. CCHP power generation systems enable comprehensive cascade utilization of energy, offering numerous advantages over conventional power generation systems. Furthermore, CCHP systems fully utilize the thermal energy of natural gas, achieving an overall energy utilization efficiency of approximately 90%. Simultaneously, as a novel distributed energy system, CCHP is clean and environmentally friendly, effectively reducing emissions of harmful gases such as carbon dioxide and sulfur dioxide.
[0003] Existing combined heat and power (CHP) systems generally adopt a "self-consumption" model, which avoids peak electricity demand, alleviates grid supply pressure, and achieves peak shaving and valley filling. However, these CHP systems are usually implemented in existing main distribution networks, where grid load changes irregularly, leading to uncertainty in the local absorption of generated power. Therefore, the integration of distributed generation systems changes the original power flow direction, from a unidirectional flow from the grid to the load to a bidirectional flow between the load and the grid. This allows the generated power of the CHP distributed generation system to be entirely absorbed locally, reducing the impact on the grid. However, it also introduces the problem of backfeeding power from the CHP system to the grid via power transformers, resulting in economic losses and reduced grid security. Summary of the Invention
[0004] To address the aforementioned problems, this utility model provides a reverse power protection system for a combined heat and power (CHP) distributed power plant and a power grid system. By setting up a reverse power protection device based on optical cable connection, it overcomes the defect of the CHP power generation system feeding back power to the grid.
[0005] To achieve the above objectives, this utility model provides a reverse power protection system for a combined heat and power (CHP) distributed power plant, comprising a CHP distributed generator room and a power user distribution room connected by a dedicated line, wherein the power user distribution room is connected to the power grid via a transformer. The power user distribution room includes: a current detection device connected between the transformer and the power grid, used to collect current signals from the power grid, the current signals including the direction and magnitude of the current; a signal acquisition device connected to the current detection device, used to convert the analog signals detected by the current detection device into digital signals; and a first photoelectric converter connected to the signal acquisition device, used to convert electrical signals into optical signals. The CHP distributed generator room includes: a second photoelectric converter connected to the first photoelectric converter via an optical cable, used to convert optical signals into electrical signals; an execution protection device connected to the transformer, used for adjusting power generation and circuit breaking protection; and a reverse power protection device, with its two ends connected to the second photoelectric converter and the execution protection device respectively, the reverse power protection device used to control the execution protection device to adjust power generation and break the circuit.
[0006] The power user distribution room also includes a voltage detection device, which connects the transformer and the power grid and the first photoelectric converter, for collecting the voltage signal of the power grid.
[0007] The reverse power protection device includes a logic module, a calculation module, and a judgment module. The calculation module calculates the amount of electricity flowing from the power grid to the power user's distribution room based on the voltage and current signals transmitted by the second photoelectric converter. The judgment module identifies the current direction and compares the amount of electricity flowing from the power grid to a preset power threshold. When the amount of electricity flowing from the power grid is lower than the preset power threshold, the judgment module sends a warning signal to the logic module. When the current direction is negative, it determines that reverse power has occurred, indicating that current is flowing from the power user's distribution room to the power grid. The logic module receives the warning signal and sends a signal to the execution protection device to reduce power generation. When the judgment module determines that reverse power has occurred, it sends a circuit breaker signal to the execution protection device.
[0008] The protection device includes a generator and a generator output circuit breaker, which are respectively connected to the reverse power protection device.
[0009] The protection device includes a generator and a generator output circuit breaker, which are respectively connected to the logic module. When the reverse power disappears, the logic module sends a closing signal to the generator output circuit breaker and sends an increase power generation signal to the generator when the warning signal disappears.
[0010] There are multiple reverse power protection devices, generators, and generator output circuit breakers. The number of reverse power protection devices is equal to or less than the number of generators and generator output circuit breakers. The number of generators is the same as the number of generator output circuit breakers.
[0011] The reverse power protection device also includes an alarm module, which is connected to the judgment module and is used to issue an alarm signal when reverse power occurs.
[0012] The current detection device includes an integrated current transformer and a Hall effect sensor.
[0013] The voltage detection device is a voltage transformer.
[0014] On the other hand, this utility model also provides a power grid system, including the aforementioned reverse power protection system for a combined heat and power distributed generation plant.
[0015] As can be seen from the above solutions, the advantages of this utility model are:
[0016] This invention, by setting up a reverse power protection device, helps to prevent the distributed generator room of the combined heat and power system from feeding back power to the grid through the transformer, thereby improving the economy of the distributed generator room of the combined heat and power system and enhancing the safety of the grid. By connecting the first photoelectric converter in the power user's distribution room and the second photoelectric converter in the distributed generator room of the combined heat and power system with an optical cable, it solves the problem of electrical signal transmission attenuation caused by the long distance between the power user's distribution room and the distributed generator room of the combined heat and power system, thus improving the efficiency of reverse power protection.
[0017] This invention first determines the difference between the grid power and a preset power threshold. When the grid power is lower than the preset power threshold, it indicates that reverse power is about to occur, thus issuing a warning signal and reducing the generator's power output. Then, when the current direction changes from positive to negative, it is determined that reverse power has occurred, and circuit protection is then performed. This not only helps operators take action in advance, but also enhances the safety of the entire protection system while reducing power loss. Attached Figure Description
[0018] Figure 1 This is a circuit diagram of the reverse power protection system for a combined heat and power (CHP) distributed power plant according to this utility model.
[0019] Figure 2 This is a schematic diagram of the reverse power protection device of this utility model;
[0020] In the attached figures, the following labels are used:
[0021] 100 - Power user distribution room;
[0022] 101-Combined Generator Distributed Generator Room;
[0023] 1-Transformer;
[0024] 2-Voltage detection device;
[0025] 3-Current detection device;
[0026] 4-Signal acquisition device;
[0027] 5 - First photoelectric converter;
[0028] 6-Reverse power protection device;
[0029] 60 - Logic Module;
[0030] 61-Calculation Module;
[0031] 62-Judgment Module;
[0032] 63-Alarm module;
[0033] 7- Optical fiber cable;
[0034] 8-Gas generator;
[0035] 9-Generator outlet circuit breaker;
[0036] 10, 11 - Signal lines;
[0037] 12-Power Grid;
[0038] 13 - Second photoelectric converter;
[0039] 14 - Load side;
[0040] 15-Dedicated Line. Detailed Implementation
[0041] The technical solution of this utility model will be described in detail below with reference to the accompanying drawings and specific embodiments to further understand the purpose, solution and effect of this utility model, but it is not intended to limit the scope of protection of the appended claims of this utility model.
[0042] References to "embodiment," "another embodiment," "this embodiment," etc., in the specification refer to embodiments that may include specific features, structures, or characteristics, but not every embodiment must include these specific features, structures, or characteristics. Furthermore, such expressions do not refer to the same embodiment. Moreover, when describing specific features, structures, or characteristics in conjunction with embodiments, whether or not explicitly described, it is indicated that incorporating such features, structures, or characteristics into other embodiments is within the knowledge of those skilled in the art.
[0043] The specification and subsequent claims use certain terms to refer to specific components or parts. Those skilled in the art will understand that users or manufacturers may use different names or terms to refer to the same component or part. This specification and claims do not distinguish components or parts by differences in name, but rather by differences in function. The terms "comprising" and "including" used throughout the specification and claims are open-ended and should be interpreted as "including but not limited to". Furthermore, the term "connection" here includes any direct and indirect electrical connection means. Indirect electrical connection means include connections via other means.
[0044] Figure 1 This is a circuit diagram of a reverse power protection system for a combined heat and power (CHP) distributed power plant according to an embodiment of the present invention. The CHP distributed power plant reverse power protection system includes a CHP distributed generator room 101 and a power user distribution room 100 connected by a dedicated line 15. The power user distribution room 100 is connected to the power grid 12 through a transformer 1.
[0045] The power user's distribution room 100 includes: a current detection device 2, a voltage detection device 3, a signal acquisition device 4, and a first photoelectric converter 5. The current detection device 2 and the voltage detection device 3 are connected between the transformer 1 and the power grid 12, and are used to acquire current and voltage signals from the power grid 12, respectively. The current signal includes the direction and magnitude of the current. One end of the signal acquisition device 4 is connected to the current detection device 2 and the voltage detection device 3, and the other end is connected to the first photoelectric converter 5. The signal acquisition device 4 is used to convert the analog signals detected by the current detection device 2 and the voltage detection device 3 into digital signals. The first photoelectric converter 5 is connected to the signal acquisition device 4 and is used to convert electrical signals into optical signals.
[0046] Specifically, the electrical signals collected by the voltage detection device 2 and the current detection device 3 are transmitted to the signal acquisition device 4 via signal lines. The signal acquisition device 4 converts the analog signals into digital signals using its internal A / D conversion module, and then transmits the signals to the first photoelectric converter 5. The first photoelectric converter 5 converts the received electrical signals (i.e., digital signals) into optical signals. For example, the voltage detection device 2 is a voltage transformer, and the current detection device 3 is an integrated current transformer and Hall effect sensor. The Hall effect sensor can identify the direction of current based on changes in the magnetic field.
[0047] The combined cooling, power, and power (CCHP) distributed generator room 101 includes: a second photoelectric converter 13, an execution protection device, and a reverse power protection device 6. The second photoelectric converter 13 is connected to the first photoelectric converter 5 via an optical cable 7, and is used to convert the optical signal transmitted by the first photoelectric converter 5 into an electrical signal. The execution protection device is connected to the load side 14 of the power user's distribution room 100 and is used for regulating power generation and circuit breaker protection. The reverse power protection device 6 is connected to the second photoelectric converter 13 and the execution protection device at its two ends, respectively. When the reverse power generation is detected to be lower than a preset power threshold, the reverse power protection device 6 controls the execution protection device to reduce the power generation, and when reverse power is detected, it controls the execution protection device to perform circuit breaker protection. The optical cable 7 has strong anti-electromagnetic interference capability and can solve the attenuation problem of long-distance electrical signal transmission.
[0048] Specifically, the second photoelectric converter 13 receives the optical signal from the first photoelectric converter 5 and restores the optical signal to an electrical signal (i.e., a digital signal), which is then transmitted to the reverse power protection device 6. The reverse power protection device 6 includes a logic module 60, a calculation module 61, a judgment module 62, and an alarm module 63, wherein:
[0049] The calculation module 61 is connected to the second photoelectric converter 13 and calculates the grid-connected power and grid-disconnected power based on the voltage and current signals transmitted by the second photoelectric converter 13. The grid-disconnected power is the power flowing from the power grid 12 to the power user's distribution room 100, and the grid-connected power is the power flowing from the power user's distribution room 100 to the power grid 12. The power can be obtained, for example, by integrating the instantaneous power over time using an integration method. The instantaneous power is obtained by multiplying the voltage and current.
[0050] The judgment module 62 is used to identify the current direction and compare the downstream power supply with a preset power threshold. When the downstream power supply is lower than the preset power threshold, it indicates that reverse power is about to occur. At this time, the judgment module 62 first sends a warning signal to the logic module 60. When the current direction is negative, that is, the current flows from the power user's distribution room 100 to the power grid 12, it is determined that reverse power has occurred. The judgment module 62 sets the preset power threshold. Normally, the current direction should be from the power grid 12 to the power user's distribution room 10 (e.g., ...). Figure 1 (The arrow direction shown indicates that the current direction is positive.) When reverse power occurs, the generated energy from the combined cycle power (CCHP) distributed generator room 101 flows to the power grid 12 through the power user distribution room 100.
[0051] The logic module 60 receives the warning signal and sends a signal to the gas generator 8 of the protection device to reduce its power generation. When the judgment module 62 determines that reverse power has occurred, it sends a circuit breaker signal to the generator outlet circuit breaker 9 of the protection device. The protection device includes the gas generator 8 and the generator outlet circuit breaker 9. Each gas generator 8 outlet is equipped with a generator outlet circuit breaker 9.
[0052] When the judgment module 62 determines that the power output is lower than the preset power threshold, the reverse power protection device 6 performs D / A conversion (digital signal to analog signal) and sends a power adjustment signal (i.e., a power reduction signal) to the gas generator 8 through signal line 10, reducing the power output of the gas generator 8 and achieving the power adjustment function. When the judgment module 62 determines that reverse power has occurred, the alarm module 63 issues an alarm signal (e.g., light or voice reminder), and simultaneously, after the reverse power protection device 6 performs D / A conversion (digital signal to analog signal), the logic module 60 controls the generator output circuit breaker 9 to disconnect through signal line 11. In this way, the generated power from the combined cooling, heating, and power (CCHP) distributed generator room 101 can be prevented from being fed back to the power grid 12 through transformer 1.
[0053] When reverse power disappears (i.e., the current direction is positive), logic module 60 controls the generator output circuit breaker 9 to close, restoring its connection with the gas generator 8. When the downstream power supply exceeds a preset power threshold, logic module 60 sends a signal to increase the power generation of the gas generator 8, thereby increasing the power generation of the gas generator 8 and achieving power regulation. Alternatively, when reverse power disappears and the downstream power supply exceeds a preset power threshold, logic module 60 controls the generator output circuit breaker 9 to close, restoring its connection with the gas generator 8.
[0054] In other embodiments, multiple reverse power protection devices 6, gas generators 8, and generator outlet circuit breakers 9 may be provided. The number of reverse power protection devices 6 is equal to or less than the number of gas generators 8 and generator outlet circuit breakers 9, and the number of gas generators 8 and generator outlet circuit breakers 9 are the same.
[0055] Specifically, such as Figure 1 As shown, one reverse power protection device 6 corresponds to four gas generators 8 and four generator output circuit breakers 9. In other embodiments, for example, if a project has six generators, then there are six gas generators 8 and six generator output circuit breakers 9. The reverse power protection device 6 can have six sets of output signals to the corresponding gas generators 8 and generator output circuit breakers 9, or each set of gas generators 8 and generator output circuit breakers 9 corresponds to one reverse power protection device 6. This improves the flexibility and adaptability of this invention.
[0056] Another embodiment of this utility model provides a power grid system equipped with the aforementioned reverse power protection system for combined heat and power (CHP) distributed power plants.
[0057] In summary, this utility model, by incorporating a reverse power protection device, helps prevent the distributed generator room of the combined cooling, heating, and power (CCHP) system from feeding power back to the grid via a transformer, thus improving the economic efficiency of the CCHP distributed generator room, enhancing grid security, preventing the distributed generator room from impacting the upstream grid, and ensuring that all the energy generated by the CCHP distributed generator room is consumed locally, thereby improving the project's economic benefits. Connecting the second photoelectric converter in the power user's distribution room and the first photoelectric converter in the CCHP distributed generator room via optical cable solves the problem of signal transmission attenuation caused by the long distance between the power user's distribution room and the distributed generator room, improving the efficiency of reverse power protection. Before reverse power occurs, by comparing the downstream power supply with a preset power threshold, an early warning of impending reverse power can be issued, helping operators take action in advance and enhancing the safety of the entire protection system while reducing power loss.
[0058] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims, and all of these forms fall within the protection scope of the present invention.
Claims
1. A reverse power protection system for a combined heat and power (CHP) distributed power plant, comprising a CHP distributed generator room and a power user distribution room connected by a dedicated line, wherein the power user distribution room is connected to the power grid via a transformer, characterized in that, The power user distribution room includes: A current detection device is connected between the transformer and the power grid to collect the current signal of the power grid, the current signal including the direction and magnitude of the current; A signal acquisition device, connected to the current detection device, is used to convert the analog signal detected by the current detection device into a digital signal; The first photoelectric converter, connected to the signal acquisition device, is used to convert electrical signals into optical signals; The combined heat and power (CHP) distributed generator room includes: The second photoelectric converter is connected to the first photoelectric converter via an optical cable and is used to convert optical signals into electrical signals; The protection device is connected to the load side of the power user's distribution room and is used to regulate power generation and provide circuit breaker protection. The reverse power protection device is connected at both ends to the second photoelectric converter and the execution protection device, respectively.
2. The reverse power protection system for a combined heat and power (CHP) distributed power plant according to claim 1, characterized in that, The power user distribution room also includes a voltage detection device, one end of which is connected between the transformer and the power grid, and the other end is connected to the signal acquisition device for collecting the voltage signal of the power grid; the signal acquisition device is also used to convert the analog signal collected by the voltage detection device into a digital signal.
3. The reverse power protection system for a combined heat and power (CHP) distributed power plant according to claim 1, characterized in that, The protection device includes a generator and a generator output circuit breaker, which are respectively connected to the reverse power protection device.
4. The reverse power protection system for a combined heat and power (CHP) distributed power plant according to claim 3, characterized in that, There are multiple reverse power protection devices, generators, and generator output circuit breakers. The number of reverse power protection devices is equal to or less than the number of generators and generator output circuit breakers. The number of generators and the number of generator output circuit breakers are the same.
5. The reverse power protection system for a combined heat and power (CHP) distributed power plant according to claim 1, characterized in that, The current detection device includes an integrated current transformer and a Hall effect sensor.
6. The reverse power protection system for a combined heat and power (CHP) distributed power plant according to claim 2, characterized in that, The voltage detection device is a voltage transformer.
7. A power grid system, characterized in that, The reverse power protection system for a combined heat and power (CHP) distributed power plant, as described in any one of claims 1 to 6.