Operating system of power system transient state compensated renewable power plant

Abstract

The present invention relates to an operating system of a power system transient state compensated renewable power plant. The operating system comprises: a renewable power plant; a smart converter coupled to the renewable power plant; a point common coupling (PCC) power monitoring sensor installed at a PCC to collect state information about a power system; and a compensation command generation device for adjusting an output of the smart converter by transmitting a control command to the smart converter, determining a transient state of the power system by receiving the state information about the PCC power monitoring sensor, and adding a compensation command to the smart converter in real time when the transient state of the power system occurs and resolving the transient state, wherein when the transient state of the power system occurs, an output of the smart converter is automatically controlled and compensated. According to the present invention, it is advantageous to provide an operating system of a power system transient state compensated renewable power plant, the power system rapidly adjusting an output to stabilize a system frequency when a transient state of the power system occurs, contributing to maintaining a voltage, supplying reactive power to maintain a system voltage, improving power quality, providing inertia like a rotary generator to improve stability of the system, and integrally managing a plurality of distributed energy resources to improve system stability.

Description

Power grid transient compensation type renewable energy complex operation system

[0001] The present invention relates to a power system transient compensation type renewable energy complex operation system, and more specifically, to a system that reduces the variability of a renewable energy complex by automatically controlling the inertia coefficient of the smart converter when a transient state occurs in the power system.

[0002] Renewable energy is an essential energy source for a sustainable future, but its stable connection to the power grid is a major challenge due to its high variability and difficulty in prediction.

[0003] Therefore, when connecting renewable energy to the power grid, it must be considered in advance that the amount of renewable energy generated, such as solar and wind power, can fluctuate significantly depending on weather conditions, which can destabilize the grid frequency, and that the amount of generation fluctuates irregularly due to changes in sunrise, sunset, and wind speed, making prediction difficult, and that the large-scale introduction of renewable energy can affect grid stability and that sufficient grid connection capacity must be secured for renewable energy power complexes.

[0004] Considering this, efficiently connecting new and renewable energy to the power grid can yield various benefits, such as reduced carbon emissions, improved energy independence, and strengthened energy security.

[0005] When connecting renewable energy to the power grid, grid stability must be maintained through frequency regulation and reactive power compensation, and the efficiency of grid operation must be improved through accurate power generation forecasting. Additionally, energy must be stored and released using ESS to respond to fluctuations in power generation, and a smart grid capable of enabling bidirectional energy flow must be established.

[0006] Meanwhile, if transient conditions occur in the power system, the stability of the system can be significantly degraded. In particular, as the proportion of new and renewable energy sources increases, system variability grows and the likelihood of transient conditions increases; therefore, it is very important for new and renewable energy sources to respond effectively to transient conditions.

[0007] A transient state of a power system refers to a situation in which the operating state of the system deviates from a normal state and becomes temporarily unstable due to external events such as short circuits, switch operations, or load fluctuations, or internal faults. When a transient state occurs, the voltage, frequency, and power flow of the system fluctuate rapidly, and in severe cases, it can lead to the collapse of the system.

[0008] The most common cause of transient conditions is short-circuit faults occurring in transmission lines, transformers, etc., but instantaneous current changes that occur when operating circuit breakers or switches in substations can also cause transient conditions, and the shutdown or restart of large-scale factories or load fluctuations due to weather conditions can also cause transient conditions.

[0009] In addition, a failure in the generator can cause system frequency fluctuations, leading to transient conditions.

[0010] When a transient condition occurs, power equipment may be damaged due to excessive current or voltage, and severe transient conditions may cause system collapse leading to a large-scale power outage, and protective relays may malfunction and shut off more equipment than necessary.

[0011] In addition, power quality may deteriorate due to voltage fluctuations, frequency fluctuations, etc., potentially causing damage to power consumers.

[0012] For transient conditions, it is necessary to establish a protective relay system that predicts the dynamic behavior of the system through transient analysis, evaluates stability, rapidly isolates the fault section when a transient occurs, and stabilizes the system.

[0013] To this end, FACTS (Flexible AC Transmission Systems) can be used to regulate the voltage and reactive power of the system to suppress transient conditions, and the output of the renewable energy power plant in the renewable energy interconnection system can be regulated to improve system stability.

[0014] However, in the case of renewable energy complexes using conventional technology, particularly wind power complexes, a centralized control system is mainly adopted.

[0015] The centralized control method operates by having the power plant's operating system transmit each set-point to the generators within the power plant through communication. For example, when the power plant's operating system receives a set-point of 100 from the grid operator, it distributes the set-point to each power source within the renewable energy power plant according to an internal algorithm.

[0016] This centralized control method is difficult to respond quickly to real-time changes in system conditions due to communication delays occurring in the process of transmitting commands from the central system to each generator, and it is difficult to respond flexibly to the characteristics of each generator or changes in system conditions, which can impair system stability when transients occur.

[0017] In addition, if a problem occurs in the central system, it can disrupt the operation of the entire power plant and is vulnerable to system fluctuations such as voltage and frequency variations, which can exacerbate system instability. Therefore, there are technical problems that make it difficult to respond effectively when transient conditions occur in the power system.

[0018] The present invention aims to solve the aforementioned technical problems by providing a power system transient compensation type renewable energy complex operation system that rapidly adjusts output when a power system transient occurs to stabilize the system frequency and contributes to maintaining the voltage, supplies reactive power to maintain the system voltage and improve power quality, provides inertia like a rotary generator to improve system stability, and integrates and manages multiple distributed energy resources to improve system stability.

[0019] To achieve the above objective, the present invention provides a renewable energy complex operation system for efficient operation of a renewable energy complex by transmitting control commands to a smart converter connected to the renewable energy complex to adjust the output of the renewable energy complex, and further comprises: a PCC power monitoring sensor installed at a power grid connection point (PCC) to collect status information of the power grid; and a compensation command generating device that receives status information from the PCC power monitoring sensor, determines a transient state of the power grid, and, when a transient state of the power grid occurs, adds a compensation command in real time to the smart converter to compensate for output fluctuations caused by the transient state to resolve the transient state, thereby reducing the output variability of the renewable energy complex by compensating and controlling the smart converter when a transient state of the power grid occurs.

[0020] In the present invention, the compensation command is an inertia coefficient of the smart converter, and it is preferable that the power system transient state compensation type renewable energy complex operation system be characterized by compensating for the inertia of the smart converter when a transient state occurs and responding in real time.

[0021] In addition, it is desirable to have a power system transient compensation type renewable energy complex operation system characterized by the above-mentioned inertia coefficient being selected as a value that mitigates the output variability of the renewable energy complex when a transient state occurs.

[0022] In addition, it is desirable that the above compensation command be a frequency, voltage, or functional curve coefficient value of the smart converter, and be a power system transient compensation type renewable energy complex operation system characterized by varying the output of the smart converter to improve power quality when a transient state occurs.

[0023] In addition, it is desirable that the above compensation command be a power system transient state compensation type renewable energy complex operation system characterized by compensating the output power of the smart converter in real time when a transient state occurs, as the active power and reactive power control amount of the smart converter.

[0024] In addition, it is preferable that the smart converter be formed with n unit converter modules that transmit and receive information while having a unique ID with the compensation command generating device, thereby improving system scalability and maintainability, and become a power system transient state compensation type renewable energy complex operation system.

[0025] In addition, it is preferable that the above compensation command generating device be a power system transient state compensation type renewable energy complex operating system characterized by receiving the output of each unit converter module, transmitting an independent compensation command to each unit converter module, and independently adjusting the output variability of the renewable energy complex connected to each unit converter module.

[0026] According to the present invention described above, there is an advantage in providing a power system transient compensation type renewable energy complex operation system that rapidly adjusts output when a power system transient occurs to stabilize the system frequency and contributes to maintaining the voltage, supplies reactive power to maintain the system voltage and improve power quality, provides inertia like a rotary generator to improve the stability of the system, and integrates and manages multiple distributed energy resources to improve the stability of the system.

[0027] FIG. 1 is a configuration diagram of the present invention

[0028] The present invention will be examined below with reference to the drawings. In describing the present invention, if it is determined that a detailed description of related known technologies or configurations may unnecessarily obscure the essence of the invention, such detailed description will be omitted.

[0029] Furthermore, the terms described below are defined in consideration of their functions in the present invention; since these may vary depending on the intentions or practices of the user or operator, their definitions should be based on the content throughout this specification describing the present invention.

[0030]

[0031] As illustrated in FIG. 1, the present invention relates to a renewable energy complex operation system with power system transient state compensation, comprising a renewable energy complex (10), a smart converter (200), and a power system connection point (PCC), and further comprising a PCC power monitoring sensor (20) and a compensation command generating device (51).

[0032]

[0033] The renewable energy complex (10) of the present invention refers to a place where facilities that produce electricity using natural energy such as solar, wind, and hydroelectric power are gathered in one place. Various renewable energy generation facilities are gathered together like a factory to produce electricity, and this electricity is connected to the power grid to supply it as electricity for us to use.

[0034] The renewable energy complex (10) includes solar power complexes, wind power complexes, hydroelectric power complexes, geothermal power complexes, and biomass power complexes, depending on the energy source mainly used.

[0035] The renewable energy produced at the renewable energy complex (10) has the advantage of having low carbon emissions, contributing to the solution of climate change problems and enabling a sustainable energy supply.

[0036]

[0037] The smart converter (200) of the present invention is a device connected to a renewable energy power generation complex to stably connect and efficiently operate a power grid with a renewable energy generation system with high variability, such as solar power and wind power.

[0038] The smart converter (200) goes beyond the conventional simple power conversion function and performs the role of increasing grid stability and maximizing energy efficiency through an intelligent algorithm.

[0039]

[0040] A Point of Common Coupling (PCC) refers to a point where two or more power systems are connected, where the flow of power is regulated and system stability is maintained.

[0041] In the present invention, the PCC specifically refers to the connection point between the power produced by a renewable energy complex and the power grid.

[0042] The renewable energy complex operation system (50) is a system that adjusts the output of the renewable energy complex by transmitting control commands to a smart converter (200) connected to the renewable energy complex.

[0043] The above-mentioned renewable energy complex operating system (50) performs the function of maintaining grid stability by adjusting frequency and compensating for reactive power when connecting renewable energy to the power grid according to the instructions of the grid operator (40), improving the efficiency of grid operation through accurate power generation forecasting, and storing and releasing energy by utilizing an ESS to respond to fluctuations in power generation.

[0044] The above PCC plays an important role in maintaining the stability of the system, and in the event of a transient state, the stability of the system can be ensured by monitoring and controlling voltage and frequency fluctuations in the PCC.

[0045] In addition, the PCC monitors and controls power quality to supply high-quality power to power consumers.

[0046] The protection device installed in the PCC quickly shuts off the system in the event of abnormal situations, such as short circuits, to minimize damage to the system.

[0047] In the present invention, the PCC is a point that connects a renewable energy generation system to the power grid, enabling the efficient utilization of renewable energy while maintaining grid stability.

[0048] In the conventional technology method, the operation system of a renewable energy complex is operated using a centralized control method in which the grid operator transmits each smart converter operation command value (set-point) to the operation system of the complex. According to this centralized control method, when the operation system of the complex receives a command value of 100 from the grid operator, it distributes the command value to each power source within the renewable energy complex through an internal algorithm.

[0049] However, this centralized control method is vulnerable to voltage fluctuations and frequency fluctuations in the power system, which can exacerbate system instability, and thus has technical problems that make it difficult to respond effectively when transient conditions occur in the power system.

[0050] To solve such technical problems, the present invention is configured to further include a PCC power monitoring sensor (20) and a compensation command generating device (51) in the renewable energy complex operating system.

[0051] The above PCC power monitoring sensor (20) is a device installed at the above power system connection point (PCC) to collect status information of the power system.

[0052] The above PCC power monitoring sensor (20) monitors the voltage and frequency in the PCC and quickly collects and transmits status information when an abnormal situation in the power system, such as a short circuit, occurs.

[0053]

[0054] In the present invention, the compensation command generating device (51) is a device that can be installed within the renewable energy complex operating system (50) and is a device that transmits a control command to the smart converter (200) to adjust the output of the smart converter.

[0055] The above compensation command generating device (51) receives status information from the PCC power monitoring sensor (20), determines the transient state of the power system, and when the transient state of the power system occurs, adds a compensation command to the smart converter in real time so that the transient state is resolved through output compensation of the smart converter.

[0056]

[0057] The compensation command produced by the compensation command generating device (51) is an inertia coefficient of the smart converter, and can respond in real time by compensating for the inertia of the smart converter (200) when a transient state occurs.

[0058] The inertia factor is one of the important indicators for evaluating the stability of a power system. Just as a spinning top tends to maintain its rotation even after a sudden shock, a power system tends to maintain a constant frequency in the event of sudden load fluctuations or faults.

[0059] This property is called inertia, and the numerical value representing the magnitude of inertia is the coefficient of inertia.

[0060] While power generation systems centered on rotating machinery, such as conventional thermal power plants, possess high inertia and contribute to maintaining the grid's frequency stably, new and renewable energy complexes, such as solar and wind power plants, are characterized by having almost no inertia because they are mostly connected to the grid through inverters.

[0061] If the inertia of the power system decreases, the system's frequency fluctuates rapidly, which can cause major problems such as power outages. As the proportion of new and renewable energy generation increases, the system's inertia decreases, raising concerns about grid stability and potentially consequently acting as a constraint on the expansion of renewable energy.

[0062]

[0063] Since the smart converter (200) is a device that links the renewable energy complex (10) and the power grid (30), the inertia coefficient of the smart converter (200) produced by the compensation command generating device (51) compensates for the inertia of the smart converter (200) when a transient state occurs, thereby mitigating the variability of the renewable energy and ensuring grid stability.

[0064] The inertia coefficient transmitted to the smart converter (200) controls the output current of the smart converter, causing it to operate like a generator with a rotating mass.

[0065] Inertia adjustment using such inertia coefficients can be implemented using only software without additional hardware and has a fast response speed.

[0066] In the power system (30), inertia acts as a force that resists changes in system frequency, thereby maintaining the stability of the system.

[0067] If we examine the difference between conventional thermal power generation and new and renewable energy, conventional thermal power generation has a massive rotating body and thus possesses great inertia, allowing it to stably maintain the system frequency even if a fault occurs in the power grid.

[0068] However, in the case of new and renewable energy, it is primarily connected to the grid through inverters, and since there are no rotating bodies, the inertia is very small or almost non-existent.

[0069] Therefore, there is a problem in that the inertia of the power system decreases, and system frequency fluctuations may increase when transient conditions occur.

[0070] The reason for adding inertia to the smart converter (200) is that as the amount of renewable energy generated increases, the inertia of the system decreases, which can lower the system stability. Therefore, adding inertia to the smart converter (200) can reinforce the inertia of the system and improve system stability.

[0071] In addition, since the system frequency may fluctuate significantly when a transient state occurs, the inertia function of the smart converter (200) suppresses frequency fluctuations to ensure stable operation of the system.

[0072] A method for adding inertia to the smart converter (200) is a virtual inertia control method that simulates inertia as if there were a real rotating body through the control algorithm of the smart converter (200).

[0073] In addition, there is a grid forming control method that detects changes in the grid frequency, increases the output to provide inertia when the frequency decreases, and decreases the output when the frequency increases, or operates the smart converter (200) as a voltage source to supply voltage to the grid and stabilize the grid frequency.

[0074] Accordingly, the above inertia coefficient can be used in a method of controlling the output current according to changes in grid frequency by forming a frequency-based virtual inertia, and in a method of controlling the output current based on real-time power deviation by forming a power deviation-based virtual inertia.

[0075] In addition, by regulating grid frequency through the storage and release of energy in conjunction with surrounding energy storage systems (ESS), it is possible to provide significant inertia and increase energy efficiency.

[0076] In this way, the present invention generates virtual inertia by selecting and transmitting an inertia coefficient equal to the amount of transient compensation to the smart converter when a power system transient occurs, thereby contributing to stably maintaining the system frequency.

[0077] Therefore, if the above inertia coefficient is selected as a value that mitigates the output variability of the renewable energy complex (10) when a transient state occurs, the smart converter responds quickly to the power system (30) when a transient state occurs due to sudden load fluctuations or failures, thereby improving system stability.

[0078]

[0079] In addition, the above compensation command is a frequency, voltage, or function curve coefficient value of the smart converter (200), and can improve power quality by varying the output of the smart converter (200) when a transient state occurs.

[0080] The frequency of the smart converter (200) is used as a switching frequency, resonance frequency, etc., to determine the operating characteristics of the smart converter (200).

[0081] In a PWM (Pulse Width Modulation) type smart converter (200), it refers to the on / off frequency of the switching element, which affects switching loss and noise, and in an LLC resonant type converter, it refers to the natural frequency of the resonant circuit, which affects power conversion efficiency.

[0082] When the frequency of the power system (30) drops, the smart converter (200) supplies more power, causing the frequency to rise. This is because the power system operates like a giant rotating body, so supplying more power increases the rotational speed and raises the frequency.

[0083] More specifically, the frequency of the power system (30) is directly related to the rotational speed of the generator, so that if the generator rotates faster, the frequency increases, and if it rotates slower, the frequency decreases.

[0084] When the load on the power system (30) increases, the generator has to do more work, so the rotational speed slows down and the frequency decreases. Conversely, when the load decreases, the burden on the generator decreases, so the rotational speed increases and the frequency increases.

[0085] The smart converter (200) plays a role in balancing this system. Since a decrease in frequency means an increase in the load on the system, if the smart converter (200) supplies more power, it produces an effect similar to an additional generator operating, thereby increasing the rotational speed of the entire system and raising the frequency again.

[0086] As such, frequency is an indicator of the rotational speed of the power system, and when the smart converter (200) supplies more power, it increases the rotational speed of the system as if adding power to an engine, thereby increasing the frequency, which maintains the stability of the power system and prevents sudden frequency fluctuations.

[0087]

[0088] Voltage is used as input voltage, output voltage, control voltage, etc., to control the operation of the smart converter.

[0089] In addition, the gain, which represents the ratio of the output signal to the input signal, also represents the amplification characteristics of the smart converter (200) and can be used importantly as a compensation command.

[0090] Additionally, power quality can be controlled using phase, bandwidth, and distortion as compensation commands.

[0091] The above function curve coefficients represent values ​​such as the slope and intercept of a curve representing a specific function of the smart converter (200), and are used to mathematically express and analyze the operational characteristics of the smart converter (200).

[0092] For example, it can be used for power system stability control as a voltage-frequency curve or a PQ curve (a curve representing the relationship between active power and reactive power).

[0093] Accordingly, the above compensation command is an active power and reactive power control amount of the smart converter (200), and when a transient state occurs, it compensates the output power of the smart converter (200) to enable real-time response.

[0094] As such, the compensation commands of the present invention are elements that determine the performance and characteristics of the smart converter (200), such as frequency, voltage, and gain of the smart converter (200), and are effective for efficient smart converter system control.

[0095]

[0096] Meanwhile, for the efficient operation of the renewable energy complex (10), the smart converter (200) connected to the renewable energy complex (10) may be formed with n unit converter modules (200-1, 2,...n) that have a unique ID and transmit and receive information with the compensation command generating device.

[0097] When manufactured with such unit converter modules (200-1, 2,...n), system scalability and maintainability can be improved.

[0098] When formed with n unit converter modules (200-1, 2,...n), the compensation command generating device (51) receives the output of each unit converter module and transmits an independent compensation command to each unit converter module to independently adjust the output variability of the renewable energy complex connected to each unit converter module.

[0099] The above compensation command generating device (51) is a system that uses a plurality of unit converter modules in a renewable energy power generation complex to independently control the output of each power generation complex. The compensation command generating device receives real-time output information from each unit converter module (200-1, 2,...n) and gives a customized compensation command to each module, thereby individually controlling the output fluctuation of each renewable energy power generation complex.

[0100] Each unit converter module (200-1, 2,...n) transmits its output information in real time to a compensation command generating device, and the compensation command generating device calculates an optimal compensation command for each module based on the collected information, and the calculated compensation command is transmitted to each unit converter module, and each unit converter module (200-1, 2,...n) adjusts the output according to this command.

[0101] According to this system, each unit converter module (200-1, 2,...n) can be controlled independently, thereby improving the flexibility of the entire system and enabling optimal control tailored to the characteristics of each unit converter module, which can increase the efficiency of the entire system and ensure the stability of the entire system by preventing other modules from being affected when a problem occurs in each unit converter module.

[0102]

[0103] The drawings illustrated above for the purpose of explaining the present invention are one embodiment in which the present invention is embodied, and it can be seen that various combinations are possible to realize the gist of the present invention as illustrated in the drawings.

[0104] Therefore, the present invention is not limited to the embodiments described above, and the technical spirit of the present invention extends to the scope in which various modifications can be made by anyone with ordinary knowledge in the field to which the invention belongs, without departing from the essence of the invention as claimed in the following patent claims.

Claims

1. In a renewable energy plant operation system that adjusts the output of a renewable energy plant by transmitting control commands to a smart converter connected to the renewable energy plant for the efficient operation of the renewable energy plant, A PCC power monitoring sensor installed at a power system interconnection point (PCC) to collect status information of the power system; and A compensation command generating device that receives status information from the above-mentioned PCC power monitoring sensor, determines a transient state of the power system, and resolves the transient state by adding a compensation command in real time to the above-mentioned smart converter to compensate for output fluctuations caused by the transient state when a transient state of the power system occurs; It is configured to include more A power system transient compensation type renewable energy complex operation system characterized by compensating and controlling the smart converter when a transient state occurs in the power system to reduce the output variability of the renewable energy complex.

2. In Paragraph 1, the above compensation order is A power system transient state compensation type renewable energy complex operation system characterized by compensating for the inertia of the smart converter in the event of a transient state, as an inertia coefficient of the smart converter above, and responding in real time.

3. In paragraph 2, the above coefficient of inertia is A power system transient compensation type renewable energy complex operation system characterized by being selected as a value that mitigates output variability of the renewable energy complex when a transient state occurs.

4. In Paragraph 1, the above compensation order is A power system transient compensation type renewable energy complex operation system characterized by improving power quality by varying the output of the smart converter when a transient state occurs, using the frequency, voltage, or functional curve coefficient value of the smart converter.

5. In Paragraph 1, the above compensation order is As the active power and reactive power control amounts of the smart converter above, A power system transient compensation type renewable energy complex operation system characterized by compensating the output power of a smart converter to respond in real time when a transient state occurs.

6. In Paragraph 1 A power system transient state compensation type renewable energy complex operation system characterized by the above-described smart converter being formed with n unit converter modules that transmit and receive information while having a unique ID and the above-described compensation command generating device, thereby improving system scalability and maintainability.

7. In Paragraph 6 The above compensation command generating device is Receive the output of each unit converter module and transmit independent compensation commands to each unit converter module A power grid transient compensation type renewable energy complex operation system characterized by independently adjusting the output variability of the renewable energy complex connected to each unit converter module.

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