Large-load fluctuation electric power isolated network scheduling and stability control equipment and use method thereof

Abstract

The invention relates to the field of power generation, and discloses a large-load fluctuation electric power isolated network dispatching and stability control device and a use method thereof.The large-load fluctuation electric power isolated network dispatching and stability control device comprises a generator set, an electric load balancing device, electric equipment and a safety and stability control dispatching device; the safety and stability control dispatching device is electrically connected with the generator set, the electric load balancing device and the electric equipment, and controls the generator set, the electric load balancing device and the electric equipment; the generator set generates electric energy, and the electric equipment and the electric load balancing device use the electric energy; the electric load balancing devices are arranged in multiple groups, and the safety and stability control dispatching device balances the generator set and the electric equipment by controlling the multiple groups of electric load balancing devices to start and stop. The large-load fluctuation electric power isolated network scheduling and stability control equipment can effectively regulate and control the power balance of the isolated network.

Description

Technical Field

[0001] The present invention relates to the field of power generation, and in particular to a large-load fluctuation power isolated grid dispatching and stabilization control device and a use method thereof. Background Art

[0002] Due to the lack of grid support, offshore islands need to build their own power plants. The electricity consumption projects and self-provided power plants on the islands belong to isolated grids. The power supply of isolated grids depends on the power generation equipment and energy storage systems in the area. The stability and reliability of the operation of isolated grids completely depend on the power generation equipment and energy storage equipment within the isolated grid.

[0003] When operating in an isolated grid, there may be frequency and voltage instability problems. Due to the lack of support from the main grid, any slight load change may cause system instability. Therefore, when operating in an isolated grid, the balance of power supply and demand is very important. The control system needs to monitor and adjust in real time to avoid power overload or shortage.

[0004] In normal production processes, electricity demand is generally within the range of ±15% of the target value, while the load shock that the generator set can withstand is ±5%, which cannot meet the ±15% fluctuation requirement of electricity demand. Therefore, how to balance the fluctuation of electricity demand with the maximum load shock range of the generator set has become a problem that needs to be solved urgently. Summary of the invention

[0005] In order to overcome the problem in the prior art that the fluctuation range of electric energy demand exceeds the maximum load impact range of the generator set, the present invention provides a large-load fluctuation electric power isolated network dispatching and stabilization control device and a method of using the same, which can effectively regulate the power balance of the isolated network.

[0006] In order to achieve the above-mentioned object, the present invention provides a large-load fluctuation power isolated grid dispatching and stabilization control device, the large-load fluctuation power isolated grid dispatching and stabilization control device comprises a generator set, an electric load balancing device, an electric device and a safe and stable dispatching device, the safe and stable dispatching device is electrically connected to the generator set, the electric load balancing device and the electric device, and controls the generator set, the electric load balancing device and the electric device;

[0007] The generator set generates electric energy, and the electric equipment and the electric load balancing device use the electric energy;

[0008] The electric load balancing device is provided in multiple groups, and the safety and stability control dispatching device starts and stops balancing the generator set and the electrical equipment by controlling the multiple groups of electric load balancing devices.

[0009] Preferably, the electric load balancing device comprises a boiler and a heating rod, the heating rod is arranged in the boiler for heating water in the boiler, and the safety and stability scheduling device controls the opening and closing of the heating rod.

[0010] The present invention also provides a method for using the large-load fluctuation power isolated grid dispatching and stabilization control device, the method comprising:

[0011] Step 1: During normal production, the electric energy generated by the generator set is balanced with the electric energy required by the electric equipment by starting and stopping the electric load balancing device, and the safety and stability control dispatching device controls the start and stop of the electric load balancing device;

[0012] Step 2: When the electric energy required by the electric equipment suddenly decreases, the safety and stability control dispatching device starts the electric load balancing device, and then the safety and stability control dispatching device simultaneously reduces the power generation of the generator set and the usage of the standby electric load balancing device;

[0013] Step three: when the power generation of the generator set suddenly decreases, the safety and stability control scheduling device cuts off the power supply to the electrical equipment according to the reduction in power generation.

[0014] Preferably, the generator set is provided with a load meter, the busbar of the electrical equipment is provided with a current transformer and a voltage transformer, the load meter measures the power P1 of the generator set, and the current transformer and the voltage transformer measure the power P2 of the electrical equipment;

[0015] The safety and stability control dispatching device is electrically connected to the load meter, the current transformer and the voltage transformer. The safety and stability control dispatching device compares the fluctuation △P of the power P1 of the generator set and the power P2 of the electrical equipment in real time, △P=(P2-P1).

[0016] Preferably, in step 1, if -5%≤ΔP / P1≤5%, the electric load balancing device is not started.

[0017] Preferably, in step 2, if ΔP / P1<-15%, the safety and stability control scheduling device controls the electric load balancing device to start.

[0018] Preferably, in step 1, the safety and stability control scheduling device records the power P2 and current I2 of the electrical equipment, and the safety and stability control scheduling device is also provided with a monitoring period T;

[0019] The power at any time t is P2t, and the current is I2t. At time t+T after one monitoring cycle, the power is P2(t+T), and the current is I2(t+T). The safety and stability scheduling device calculates the power fluctuation P2(t+T)-P2t and the current fluctuation I2(t+T)-I2t, and compares them with the power fluctuation design value △Ps and the current fluctuation design value △Is.

[0020] Preferably, in step one, the electrical equipment is configured to be able to propose a load increase plan to the safety and stability control scheduling device, and the load increase plan at least includes: execution time and planned power increase P3.

[0021] The safety and stability control dispatching device shown starts the electric load balancing device equivalent to P3 in advance according to the specific value of P3, and increases the power generation of the generator set at the same time. After the start-up is successful, the electric load balancing device is turned off and the load increase plan is executed at the same time. (Note the execution time)

[0022] Preferably, there are multiple electrical devices. In step three, the safety and stability control scheduling device determines the list of electrical devices that need to be powered off according to the value of ΔP, and performs the power-off operation on the electrical devices at the same time.

[0023] Preferably, the plurality of electrical devices are rated according to their importance, and the more important the electrical device is, the higher its importance level;

[0024] In step three, when powering off the electrical equipment, priority is given to powering off the electrical equipment with a low importance level.

[0025] According to the above technical solution, the generator set is provided with a sensor for detecting the implemented power, and the sensor outputs a signal to the safety and stability control scheduling device. The safety and stability control scheduling device collects the electric power signal of the generator set for comparison with the power used by the electrical equipment. If the generated power is balanced with the used power, the safety and stability control scheduling device will not adjust the system. If the comparison finds that the power on the power generation side is not equal to the power on the power consumption side, the safety and stability control scheduling device needs to regulate the system.

[0026] In one embodiment, the safety and stability control scheduling device compares the difference rate between the power on the power consumption side and the power on the power generation side. If the difference between the power on the power consumption side and the power on the power generation side does not exceed ±5% of the power on the power generation side, the safety and stability control scheduling device believes that the load fluctuation is not large, and the parameters of the generator set can be adjusted so that the function of the power generation side can match the power on the power consumption side.

[0027] The engine unit itself has a certain power regulation function. In one embodiment, the engine unit is set as a steam generator. The real-time power of the generator unit can be controlled by adjusting the steam pressure and flow of the steam turbine, but the adjustment range is only ±5%. Therefore, when the electric power fluctuation range on the power consumption side is within the range of ±5%, the safe and stable control scheduling device can achieve electric load balance by controlling the control parameters of the generator itself.

[0028] However, if the difference between the power on the power consumption side and the power on the power generation side exceeds ±5% of the power on the power generation side, the generator cannot adapt to the fluctuation of the power load, and the safety and stability control dispatching device needs to take other control measures. Specifically: if the power on the power consumption side is greater than the power on the power generation side, the safety and stability control dispatching device needs to immediately remove the load on the power consumption side to maintain the power load balance of the isolated grid. If the power on the power generation side is greater than the power on the power consumption side, the power on the power generation side and the power consumption side is balanced by starting the load balancing device.

[0029] Multiple groups of electric load balancing devices are arranged. During actual use, the safety and stability control dispatching device determines the number of electric load balancing devices that need to be started according to the difference between the power on the power consumption side and the power on the power generation side, and starts the electric load balancing device immediately to quickly respond to the electric load fluctuation of the isolated grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is an internal connection relationship between large load fluctuation power isolated grid dispatching and stabilization control equipment;

[0031] Figure 2 It is a working principle diagram of a safe and stable dispatching device;

[0032] Figure 3 It is a diagram of the offline decision-making mode of a safe and stable dispatching device;

[0033] Figure 4 It is an online decision-making method diagram of a safe and stable dispatching device;

[0034] Figure 5 It is a schematic diagram for judging power and current mutation. DETAILED DESCRIPTION

[0035] In the present invention, unless otherwise stated, directional words such as "away from, up, down, sideways, both ends" generally refer to the orientation of the term in normal use, or are common names understood by those skilled in the art, and should not be regarded as limitations on the term.

[0036] See also Figure 1The large-load fluctuation power isolated grid dispatching and stabilization control equipment includes a generator set, an electric load balancing device, electric equipment and a safe and stable dispatching device, the safe and stable dispatching device is electrically connected to the generator set, the electric load balancing device and the electric equipment, and controls the start and stop of the generator set, the electric load balancing device and the electric equipment;

[0037] The generator sets generate electrical energy, and the electrical equipment and electrical load balancing devices use the electrical energy;

[0038] Multiple groups of electric load balancing devices are arranged, and the safety and stability control dispatching device starts and stops balancing the generating sets and the electrical equipment by controlling the multiple groups of electric load balancing devices.

[0039] Through the implementation of the above technical solution, the generator set is provided with a sensor for detecting the implemented power, and the sensor outputs a signal to the safety and stability control scheduling device. The safety and stability control scheduling device collects the electric power signal of the generator set for comparison with the power used by the electrical equipment. If the generated power is balanced with the used power, the safety and stability control scheduling device will not adjust the system. If the comparison finds that the power on the power generation side is not equal to the power on the power consumption side, the safety and stability control scheduling device needs to regulate the system.

[0040] In one embodiment, the safety and stability control scheduling device compares the difference rate between the power on the power consumption side and the power on the power generation side. If the difference between the power on the power consumption side and the power on the power generation side does not exceed ±5% of the power on the power generation side, the safety and stability control scheduling device believes that the load fluctuation is not large, and the parameters of the generator set can be adjusted so that the function of the power generation side can match the power on the power consumption side.

[0041] The engine unit itself has a certain power regulation function. In one embodiment, the engine unit is set as a steam generator. The real-time power of the generator unit can be controlled by adjusting the steam pressure and flow of the steam turbine, but the adjustment range is only ±5%. Therefore, when the electric power fluctuation range on the power consumption side is within the range of ±5%, the safe and stable control scheduling device can achieve electric load balance by controlling the control parameters of the generator itself.

[0042] However, if the difference between the power on the power consumption side and the power on the power generation side exceeds ±5% of the power on the power generation side, the generator cannot adapt to the fluctuation of the power load, and the safety and stability control dispatching device needs to take other control measures. Specifically: if the power on the power consumption side is greater than the power on the power generation side, the safety and stability control dispatching device needs to immediately remove the load on the power consumption side to maintain the power load balance of the isolated grid. If the power on the power generation side is greater than the power on the power consumption side, the power on the power generation side and the power consumption side is balanced by starting the load balancing device.

[0043] Multiple groups of electric load balancing devices are arranged. During actual use, the safety and stability control dispatching device determines the number of electric load balancing devices that need to be started according to the difference between the power on the power consumption side and the power on the power generation side, and starts the electric load balancing device immediately to quickly respond to the electric load fluctuation of the isolated grid.

[0044] In this embodiment, preferably, the electric load balancing device includes a boiler and a heating rod, the heating rod is arranged in the boiler for heating water in the boiler, and the safety and stability scheduling device controls the opening and closing of the heating rod.

[0045] The boiler is filled with a large amount of water, and the heating rod is set in the boiler. When the heating rod is powered on, it will generate heat to heat the water in the boiler, thereby realizing the operation of converting electrical energy into thermal energy. In this process, the electric load balancing device consumes electrical energy together with the electrical equipment. When the electrical load returns to balance, the electric load balancing device will also be turned off, the heated water will gradually lose temperature, and the heat will overflow into the environment. Therefore, the use of the electric load balancing device will cause a certain degree of electrical energy waste.

[0046] The electric load balancing device is only provided with a heating rod, which together with the electrical equipment generates the power on the power-consuming side for balancing the power on the power-generating side. Only when the power on the power-consuming side of the isolated grid is suddenly greater than the power on the power-generating side, and the excess power value is greater than 5% of the power on the power-generating side, the safety and stability control and dispatching device will control the heating rod to be turned on.

[0047] A method for using a large load fluctuation power isolated grid dispatching and stabilization control device, the method comprising:

[0048] Step 1: During normal production, the electric energy generated by the generator set is balanced with the electric energy required by the electrical equipment by starting and stopping the electric load balancing device, and the safety and stability control dispatching device controls the start and stop of the electric load balancing device;

[0049] Step 2: When the electric energy required by the electric equipment is suddenly reduced, the safety and stability control dispatching device starts the electric load balancing device, and then the safety and stability control dispatching device simultaneously reduces the power generation of the generator set and the usage of the standby electric load balancing device;

[0050] Step 3: When the power generation of the generator set suddenly decreases, the safety and stability control dispatching device cuts off the power supply to the electrical equipment according to the reduction in power generation.

[0051] When the power fluctuation on the power consumption side is not greater than ±5%, that is, the difference between the power consumption side and the power generation side does not exceed ±5% of the power generation side, the system can be considered to be in normal operation. At this time, the safe and stable control dispatching device can adapt to the power fluctuation on the power consumption side by adjusting the control parameters of the generator set.

[0052] When the power on the power consumption side is reduced, and the power reduction is greater than 5% and less than 15%, the safety and stability control dispatching device can start the electric load balancing device of the corresponding power value to balance the excess power on the power generation side. Preferably, the electric load balancing device equivalent to the power reduction value can be started, so that when the power fluctuation of the power consumption equipment returns to a normal state, the electric load balancing device can be directly turned off, and the isolated grid system can still return to a balanced state.

[0053] When the power of electrical equipment decreases suddenly and the power reduction is greater than 15%, the safety and stability control dispatching device needs to quickly start the electric load balancing device of the corresponding power value, and reduce the load on the power consumption side and the power generation side as soon as possible after the electric load of the isolated grid is balanced.

[0054] Specifically, when the electric load of the isolated grid is balanced, the safety and stability control dispatching device shuts down the electric load balancing device with a certain power value, and correspondingly shuts down the generator set with the same power value, and performs real-time detection of the power on the power generation and power consumption sides of the isolated grid, and adjusts in real time according to the detection results.

[0055] Preferably, in order to avoid large fluctuations in the power of the isolated grid due to excessive load being removed at one time, a safety and stability control dispatching device can be set to perform load unloading operations in multiple times according to the actual load conditions. Specifically, after the first load removal, the power of the power generation side and the power consumption side is detected. After the load of the isolated grid is balanced, the safety and stability control dispatching device will again close the electric load balancing device with a certain power value, and correspondingly close the generator set with the same power value. Subsequently, the power of the power generation side and the power consumption side of the isolated grid will be tested. After the power balance between the power generation side and the power consumption side is detected, the next load removal operation can be performed. Until all the electric load balancing devices.

[0056] If a generator set fails, causing its power generation to suddenly decrease, the power on the power consumption side will be significantly higher than the power on the power generation side. At this time, the safety and stability control dispatching device quickly cuts off some equipment on the power consumption side so that the power on the power consumption side can be quickly matched with the power on the power generation side, and the isolated grid load can quickly return to a balanced state.

[0057] In this embodiment, preferably, the generator set is provided with a load meter, the busbar of the electrical equipment is provided with a current transformer and a voltage transformer, the load meter measures the power P1 of the generator set, and the current transformer and the voltage transformer measure the power P2 of the electrical equipment;

[0058] The safety and stability control dispatching device is electrically connected to the load meter, current transformer and voltage transformer. The safety and stability control dispatching device compares the fluctuation △P of the power P1 of the generator set and the power P2 of the electrical equipment in real time, △P=(P2-P1).

[0059] In order to protect the generator set as much as possible, the safety and stability control dispatching device needs to monitor the values ​​of P1 and P2 in real time, and adjust the power on the power consumption side or the power generation side according to the value of △P.

[0060] In this embodiment, preferably, in step 1, if -5%≤ΔP / P1≤5%, the electric load balancing device is not started.

[0061] If -5%≤△P / P1≤5%, the safety and stability control dispatching device can adjust the control parameters of the generator set to meet the requirements of electrical load balance.

[0062] In step 1, if -5%>△P / P1≥-15%, the safety and stability control dispatching device controls the electric load balancing device to start.

[0063] When the power reduction of the electrical equipment in the isolated grid exceeds 5%, the generator set cannot achieve automatic load balance. At this time, the safety and stability control dispatching device will start the load balancing device. According to the actual power reduction value, the load balancing device with the corresponding power value can quickly respond to the power fluctuation of the isolated grid, so as to achieve a balance between the power on the power side and the power on the power generation side.

[0064] Since system fluctuations always exist, after the electric load balancing device is started, the safety and stability control dispatching device will meet the control requirements for the isolated grid electric load balance by adjusting the input current and usage of the electric load balancing device according to actual conditions.

[0065] Since the electric load balancing device is a power-consuming device, it will cause energy waste. Therefore, it is necessary to control the use time of the electric load balancing device. Preferably, the use time of the electric load balancing device is up to 1 hour, that is, within 1 hour, according to the actual production situation, the safety and stability control dispatching device stops using the electric load balancing device in use by removing the power from the power generation side.

[0066] In this embodiment, preferably, in step 2, if ΔP / P1<-15%, the safety and stability control dispatching device controls the electric load balancing device to start.

[0067] When the power of electrical equipment decreases suddenly and the power reduction is greater than 15%, the safety and stability control dispatching device needs to quickly start the electric load balancing device of the corresponding power value, and reduce the load on the power consumption side and the power generation side as soon as possible after the electric load of the isolated grid is balanced.

[0068] Since the electric load balancing device is a device that consumes electric energy and will cause energy waste, when it is needed to use the electric load balancing device to balance the electric load of the isolated grid, the use of the electric load balancing device should be reduced or avoided as much as possible after the electric load is balanced in order to achieve the purpose of saving energy.

[0069] Specifically, when the electric load of the isolated grid is balanced, the safety and stability control dispatching device shuts down the electric load balancing device with a certain power value, and correspondingly shuts down the generator set with the same power value, and performs real-time detection of the power on the power generation and power consumption sides of the isolated grid, and adjusts in real time according to the detection results until the electric load of the isolated grid is balanced.

[0070] Preferably, in order to avoid large fluctuations in the power of the isolated grid due to excessive load being removed at one time, a safety and stability control dispatching device can be set to perform load unloading operations in multiple times according to the actual load conditions. Specifically, after the first load removal, the power of the power generation side and the power consumption side is detected. After the load of the isolated grid is balanced, the safety and stability control dispatching device will again close the electric load balancing device with a certain power value, and correspondingly close the generator set with the same power value. Subsequently, the power of the power generation side and the power consumption side of the isolated grid will be tested. After the power balance between the power generation side and the power consumption side is detected, the next load removal operation can be performed. Until all the electric load balancing devices.

[0071] In this implementation, preferably, in step 1, the safety and stability control scheduling device records the power P2 and current I2 of the electrical equipment, and the safety and stability control scheduling device is also provided with a monitoring period T;

[0072] The power at any time t is P2t, and the current is I2t. At time t+T after one monitoring cycle, the power is P2(t+T), and the current is I2(t+T). The safety and stability scheduling device calculates the power fluctuation P2(t+T)-P2t and the current fluctuation I2(t+T)-I2t, and compares them with the power fluctuation design value △Ps and the current fluctuation design value △Is.

[0073] In addition to real-time monitoring of the power of electrical equipment and generators to achieve power regulation of the isolated grid, power regulation of the isolated grid can also be achieved by detecting power fluctuations on the power consumption side.

[0074] Since the generator set has a response time to the power fluctuation of the electrical equipment, some sudden fluctuations of a short duration, although with a large amplitude, will not affect the generator set due to their short duration. Based on this characteristic, a monitoring period T is set in the safety and stability control dispatching device. The monitoring period T is less than the response time of the system, so that the control sensitivity of the safety and stability control dispatching device is more sensitive than the generator set, and thus it can effectively block the impact of power fluctuations on the generator set. Therefore, this method can avoid the problem of the safety and stability control dispatching device frequently needing to control the isolated grid system, and can effectively reduce the control complexity of the safety and stability control dispatching device while ensuring safety and effectiveness.

[0075] Usually the response time of a generator set is not less than 1 second, therefore, the monitoring period T needs to be less than 1 second, preferably, T is less than 500 ms, taking T=200 ms as an example.

[0076] At the beginning and end of a monitoring cycle, the power change is P2(t+T)-P2t. If the power change does not exceed the power fluctuation design value △Ps, the power fluctuation design value △Ps is 0.05P2t. At this time, the safe and stable control dispatching device achieves the power balance of the isolated grid system by adjusting the control parameters of the generator set.

[0077] If the power change exceeds △Ps, the safe and stable control dispatching device needs to start the electric load balancing device, and the control method is the same as the control principle for implementing the control.

[0078] In addition to setting the monitoring period T to reduce the control complexity of the safety and stability control dispatching device, the signal collection period of the safety and stability control dispatching device can also be controlled. The signal collection period can be less than the monitoring period T. A higher signal collection frequency can improve the reliability of monitoring, and a lower signal collection frequency can effectively reduce the control complexity of the safety and stability control dispatching device. Therefore, by setting a suitable signal collection frequency and monitoring period T in the safety and stability control dispatching device, the two generator sets can be effectively coordinated and more conveniently adapted to various usage environments.

[0079] Preferably, it is also possible to determine whether it is necessary to start the safety and stability control scheduling device to perform power regulation by judging the sudden change amount of current and the sudden change amount of power.

[0080] Figure 5 The schematic diagram of judging the sudden change of current and power when T=200ms, where P i Indicates the current active power value, P i-200ms is the active power value 200ms ago, i i Indicates the instantaneous value of the current, i i-200ms It indicates the instantaneous value of current 200ms ago. △Ps and △Is respectively indicate the sudden change range of power and current set by the system.

[0081] |Pt-0.2s|≥Ps1 (Ps1 power setting value before the accident)

[0082] |Pt|<Ps2 (Ps2 power setting value after the accident)

[0083] There are two-phase currents I≤Is1

[0084] |△I|=|Ik-Ik-0.02s|≥△Is

[0085] The time to meet the above conditions is greater than Ts1

[0086] After the device is started, if 1, 2, 3, 4, 5, 6, and 7 are met at the same time, it will be judged as tripping.

[0087] The load shock that a single generator can normally withstand is ±5%, which cannot meet the requirements of large load shocks. Combined with the energy management and control platform, new power system management and control functions are added: by adding real-time automatic power generation control functions, multiple generator sets can synchronously bear large load shocks; adding real-time automatic voltage control functions, the voltage of the power grid bus is controlled and responded in time. At the same time, voltage compensation is performed. When the voltage enables the generator set to obtain ±10% of the ability to resist load shocks, multiple generator sets can bear large load shocks in the range of +18% to -100% of the power grid capacity. This function is a subsystem of the machine network dispatching and stabilization control. Therefore, the study believes that the use of the machine network dispatching and stabilization control system can control the large load shocks of multiple generator sets.

[0088] The following measures can be taken to prevent large-scale load tripping from affecting the stability of the power grid:

[0089] 1) The tripping of large power consumption side loads ensures the stability of voltage and frequency of the power grid through automatic power generation, automatic voltage control and voltage compensation functions.

[0090] 2) Larger-scale load tripping may affect the frequency and voltage of the power grid; the stable combustion of the boiler may be affected because the load of the generator set is too low. Through the automatic power generation control function, the load of each generator is monitored to ensure the combustion stability of other boilers.

[0091] 3) Due to the particularity of self-provided power generation being connected to the grid but not connected to the grid, its monitoring and feedback requirements are higher than those of the large grid, and the comprehensive protection requirements are quite different. The machine-grid dispatching and stabilization control system is essentially a dispatching and stabilization control integrated system implemented in accordance with the requirements of the power grid, in order to maintain the stability of the entire power system while ensuring the output of the generator and the safety of the equipment. This function integrates various functions of the power grid dispatching and comprehensive automation protection. Combined with the actual situation of metallurgical enterprises: the functional needs of stabilization dispatching, emergency automatic control and real-time protection of "multiple units and high impact load power grids" require the configuration of a machine-grid dispatching and stabilization control system for substation power.

[0092] Based on the above technical analysis, the following is concluded: The machine-grid dispatching and stabilization control system is the dispatching and control center of the power grid operation of the steel enterprise. It realizes the safe and stable operation of the power grid through the comprehensive coordinated management of the generator sets and the power load. If the machine-grid dispatching and stabilization control system is not adopted, some functions can be realized by combining the dispatching, stabilization and other general products of the large power grid. The performance indicators of similar products in the large grid are low, the functions are incomplete, and the technical reliability is lacking, which cannot guarantee the safe and reliable operation of the power grid of the metallurgical enterprise.

[0093] In this embodiment, preferably, in step one, the electrical equipment is configured to be able to propose a load increase plan to the safety and stability control scheduling device, and the load increase plan at least includes: execution time and planned increase in power P3.

[0094] The safety and stability control dispatching device shown starts the electric load balancing device equivalent to P3 in advance according to the specific value of P3, and increases the power generation of the generator set at the same time. After the start-up is successful, the electric load balancing device is turned off and the load increase plan is executed at the same time.

[0095] When electrical equipment needs to be put into use according to a planned method according to the production plan, the power generation frequency of the generator set can be increased in advance to a level that matches the needs of the electrical equipment according to the plan for the equipment to be put into use. After that, the electric load balancing device can be switched to the electrical equipment to achieve a smooth start-up of the electrical equipment.

[0096] Preferably, in order to ensure the smooth operation of the isolated grid system, the electrical equipment may be started in batches, and certain load balancing devices may be correspondingly turned off until all load balancing devices are turned off and the system enters the normal use stage.

[0097] The safe and stable control dispatching device also needs to consider the time when the use plan of the electrical equipment begins to be implemented, so as to avoid wasting electricity by long-term operation of the electric load balancing device.

[0098] In this embodiment, preferably, a plurality of electrical equipment are provided, and in step three, the safety and stability control scheduling device determines a list of electrical equipment that needs to be powered off according to the value of ΔP, and simultaneously performs a power-off operation on the electrical equipment.

[0099] When a generator set fails, causing the power on the power generation side to decrease, or when other power consumption sides suddenly increase, the power on the power consumption side is greater than the power on the power generation side. When △P / P1>5%, the sub-main regulation of the generator cannot achieve power balance. At this time, the safety and stability control dispatching device needs to immediately unload the load on the power consumption side, that is, shut down the power consumption equipment on the power consumption side to reduce the power on the power consumption side.

[0100] The safe and stable control dispatching device reduces the power on the power consumption side according to the value of △P, and makes the reduced power on the power consumption side match the current power generation power, so that the power of the isolated grid can reach a balanced state again.

[0101] In this embodiment, preferably, the plurality of electrical devices are rated according to their importance, and the more important electrical devices have a higher importance level;

[0102] In step three, when power is cut off to electrical equipment, priority is given to electrical equipment with a low importance level.

[0103] After rating the importance of electrical equipment and combining it with the power value of the electrical equipment, when it is necessary to cut off the power to the electrical equipment, the safety and stability control scheduling device can quickly form a list of electrical equipment that needs to be cut off, thereby achieving the purpose of a rapid response system.

[0104] like Figure 1 As shown in the figure, the network dispatching and stabilization control system includes three parts: unit-level control interface, load control terminal and control center:

[0105] 1) The unit-level control interface communicates with the generator set DCS, oil motor and external excitation device in an all-round way, comprehensively monitors the real-time operation status of the generator for data collection, and monitors and controls instructions in real time through the dispatching platform.

[0106] 2) The large load stabilization device is a special controllable load, and the machine network dispatching stabilization control can quickly control the switching of the large load stabilization device.

[0107] 3) The control center completes data collection, automatic power generation, automatic voltage control, power angle / power factor leveling, turbine life optimization, load management, and stable control scheduling of the machine network dispatching and stabilization control system.

[0108] The safety and stability control dispatching device mainly consists of five parts, such as Figure 2 shown.

[0109] Input part (analog quantity, switch quantity): component electrical quantity input; component tripping signal, position signal and other strong current switch quantity input (for example: protection A, B, C tripping signal, TWJ signal, etc.); weak current input signal such as function pressure plate.

[0110] Logical processing unit: component fault judgment; collect and process key component information of each power grid plant and station, judge the power grid mode, and decide on measures after power grid failure.

[0111] Output part (analog quantity, switch quantity): component tripping output contact output; various alarm center signals of the device.

[0112] Human-machine interface: interface operation; monitoring protocol interface with energy management and control platform

[0113] Communication module part: data exchange between plants and stations, including power grid information, component information, various commands in emergency situations, etc.

[0114] The safety and stability control dispatching device is the carrier for the implementation of various control measures. The implementation of its decision-making strategy usually includes "offline decision-making method" and "online pre-decision-making method".

[0115] like Figure 3 Shown is the offline decision method

[0116] like Figure 4 Shown is the online decision-making approach.

[0117] Safety and stability control dispatching devices have different control methods and can be divided into three categories according to the control range:

[0118] 1) Local stability control: It is installed separately in each secondary substation area. There is no information exchange and communication between them. It solves the stability problems that occur when important power equipment in the station fails.

[0119] 2) Regional power grid stability control: Stability control devices installed in multiple secondary stations within a fixed range are connected together using communication equipment in integrated automation to form a stability control system.

[0120] 3) Regional interconnected power grid stability control: According to the substation level and zoning, the interconnected power grid stability control completes the emergency control related to the interconnection line and transmits important information within the relevant regional power grid when necessary.

[0121] The safety and stability dispatching device takes pre-defined control measures according to the frequency and voltage values, change trends and rates. Usually, it cuts the load at low frequency and low voltage, and cuts the machine at over frequency and over voltage. In some cases, it also has the functions of low frequency and low voltage disconnection and over frequency and over voltage disconnection. An important measure to prevent frequency collapse is to install low frequency load shedding devices in appropriate quantities and locations.

[0122] Measures for emergency frequency control: automatic low-frequency load reduction when the grid frequency drops; automatic over-frequency machine cutting when the frequency rises; low-frequency disconnection of the interconnecting lines.

[0123] Criteria for frequency emergency control: judged by real-time frequency value, frequency change rate and action delay. The accuracy of frequency measurement and the authenticity of load feedback in the system during the transient process are extremely important and may cause false operation.

[0124] When the system power shortage is too large (for example, the shortage reaches 20%), a tie line tripping or large unit tripping should be installed to cut the load, which can effectively prevent a sharp drop in frequency.

[0125] The safe and stable control dispatching device can also perform automatic low-frequency load reduction operations. When there is a sudden shortage of active power in the power system, the low-frequency automatic load reduction device can be used to cut off the corresponding number of loads to maintain the balance between the power generation load and the power consumption load, so as to keep the system running safely and stably and ensure stable power supply to the first and second level loads.

[0126] The setting principle of low frequency load reduction:

[0127] 1) Cooperate with low-frequency protection of generator set

[0128] 2) Coordination with low-frequency disconnection of the tie line

[0129] 3) Greater than the low-frequency protection setting value of the power plant cooling medium pump (> 0.3 - 0.5 Hz)

[0130] 4) The time when the system frequency is restricted below 47 Hz should not exceed 0.5 seconds

[0131] 5) When over-cutting occurs, the frequency value cannot exceed 51 Hz to avoid mis-tripping of large units

[0132] Low-frequency and low-voltage load shedding: Low-frequency and low-voltage load shedding is a function of cutting loads based on the deviations of frequency and voltage. There is a centralized low-frequency and low-voltage load shedding function in the unit-network dispatching and stability control. Generally, there is a low-frequency and low-voltage load shedding function in electrical comprehensive protection devices. It is required that this function be available in the system, and in actual applications, it is determined according to the configuration of electrical comprehensive protection devices. The discrimination element of the low-frequency function is the bus voltage. The low-frequency load shedding using a combination of multiple basic rounds and special rounds can cover the low-frequency load shedding scheme for calculation reports

[0133] The low-voltage load shedding criterion (the low-frequency function pressure plate needs to be input) is as follows

[0134]

[0135] Note: When the frequency decreases, if the rate of frequency change 0 < -df / dt < d(f / t)1, it is considered that the frequency drops slowly, and then the low-frequency rounds 1 - 5 are output in sequence, that is, the judgment of the next low-frequency round must be after the previous low-frequency action

[0136] If the rate of frequency change d(f / t)1 ≤ -df / dt < d(f / t)2 and the duration is Tfld1, it is considered that the frequency drops rapidly, and the low-frequency rounds 1 and 2 act simultaneously to stop the frequency drop as early as possible, and then the 3rd round acts

[0137] If the rate of frequency change d(f / t)2 ≤ -df / dt < d(f / t)b1 and the duration is Tfld2, it is considered that the frequency drops very fast, and the low-frequency rounds 1, 2, and 3 act simultaneously to stop the frequency drop as early as possible

[0138] The 6th, 7th, and 8th rounds are special rounds, independent of other rounds. As long as the frequency drops to the setting value of the corresponding round level and lasts for the corresponding delay, this round can act

[0139] If the rate of frequency change -df / dt ≥ d(f / t)b1, it is considered that due to reasons such as load feedback, high-order harmonics, and poor contact in the voltage circuit, the frequency change is abnormal, and the low-frequency function is blocked

[0140] After the low-frequency action, calculate the load capacity to be cut according to the percentage of the capacity to be cut, select the loads to be cut according to the load priority, and execute according to the principle of minimum over-cut

[0141] Measures to prevent voltage collapse

[0142] Dynamic reactive power source: Reactive power compensation is carried out by switching capacitors to ensure the stability margin. Control the network voltage and the reactive power output of the generator, coordinate protection and control, and achieve distribution voltage control by controlling the transformer tap regulator.

[0143] Voltage emergency control: After a disturbance occurs in the power system, the voltage drop may fluctuate to an unacceptable value, resulting in voltage instability. Emergency control measures for automatically limiting voltage fluctuations should be set.

[0144] The discrimination element for the low-voltage function is the bus voltage.

[0145] If all buses are normal, a low voltage in the system is considered only when multiple sections of buses experience a low voltage simultaneously; if one section of the bus is abnormal (voltage disappears or zero-sequence voltage is abnormal), the low voltage is judged based on a normal section of the bus; if two sections of the bus are abnormal (voltage disappears or zero-sequence voltage is abnormal), the low-voltage function is blocked.

[0146] The low-voltage load shedding with a total of 8 rounds including 5 basic rounds and 3 special rounds can cover the low-voltage load shedding scheme in the calculation report. In the following description, the recommended setting values for each round of low-voltage load shedding will be given.

[0147] The criterion (the low-voltage function pressure plate needs to be input) is as follows:

[0148]

[0149]

[0150] When the voltage drops, if the voltage change rate 0 < -du / dt < d(u / t)1, it is considered that the voltage drops slowly, and the low-voltage rounds 1 to 5 operate in sequence, that is, the judgment of the next round of low voltage must be after the previous round of low voltage operates; if the voltage change rate d(u / t)1 ≤ -du / dt < d(u / t)2 and the duration is Tvld1, it is considered that the voltage drops quickly, and the low-voltage rounds 1 and 2 operate simultaneously to stop the voltage drop as soon as possible, and then round 3 operates; if the voltage change rate d(u / t)2 ≤ -du / dt < d(u / t)b1 and the duration is Tvld2, it is considered that the voltage drops very quickly, and the low-voltage rounds 1, 2, and 3 operate simultaneously to stop the voltage drop as soon as possible.

[0151] Rounds 6, 7, and 8 are special rounds, independent of other rounds. As long as the voltage drops to the setting value of the corresponding round and lasts for the corresponding delay, this round can operate.

[0152] If the voltage change rate du / dt ≥ d(u / t)b1, it is considered that the voltage change is abnormal due to reasons such as load feedback, short-circuit fault, and poor contact in the voltage circuit, and the low-voltage function is blocked.

[0153] After the low-voltage action, the load cutting capacity to be cut is calculated according to the percentage of the required cutting capacity, and the load is cut according to the load priority, and it is executed according to the principle of minimum over-cutting.

[0154] The dispatching and stabilization control system has the following functions:

[0155] 1) Automatic power generation control: Communicate with the generator control system to quickly and reasonably distribute active power and maintain the power frequency of 50Hz.

[0156] 2) Automatic voltage control: Through real-time monitoring of the automatic control of the brushless excitation system of other machines, the reactive power is distributed in time and the voltage is stabilized at the rated value.

[0157] 3) Power angle measurement and adjustment, coordinate reactive power compensation and the active and reactive loads of the unit, adjust the power angle / power factor balance, and maintain the maximum transient stability margin.

[0158] 4) Stability control, monitoring of grid faults.

[0159] 5) Optimize the life of the generator set, manage the power generation and power load in a unified manner, reduce the frequency of generator set adjustment, and reduce life loss. Through overall coordination, reduce the ineffective power consumption of large load stabilization devices.

[0160] 6) Provide optimized dispatching plans for power dispatchers, and combine the entire energy management and control platform as the overall dispatching platform for the entire production area.

[0161] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0162] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0163] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A large load fluctuation power isolated grid dispatching and stabilization control device, characterized in that: The large load fluctuation power isolated grid dispatching and stabilization control equipment includes a generator set, an electric load balancing device, an electric device and a safe and stable dispatching device, wherein the safe and stable dispatching device is electrically connected to the generator set, the electric load balancing device and the electric device, and controls the generator set, the electric load balancing device and the electric device; The generator set generates electric energy, and the electric equipment and the electric load balancing device use the electric energy; The electric load balancing device is provided in multiple groups, and the safety and stability control dispatching device starts and stops balancing the generator set and the electrical equipment by controlling the multiple groups of electric load balancing devices.

2. The large load fluctuation power isolated grid dispatching and stabilization control equipment according to claim 1 is characterized in that: The electric load balancing device includes a boiler and a heating rod. The heating rod is arranged in the boiler to heat the water in the boiler. The safety and stability scheduling device controls the opening and closing of the heating rod.

3. A method for using the large load fluctuation power isolated grid dispatching and stabilization control device according to any one of claims 1-2, characterized in that: The method of use includes: Step 1: During normal production, the electric energy generated by the generator set is balanced with the electric energy required by the electric equipment by starting and stopping the electric load balancing device, and the safety and stability control dispatching device controls the start and stop of the electric load balancing device; Step 2: When the electric energy required by the electric equipment suddenly decreases, the safety and stability control dispatching device starts the electric load balancing device, and then the safety and stability control dispatching device simultaneously reduces the power generation of the generator set and the usage of the standby electric load balancing device; Step three: when the power generation of the generator set suddenly decreases, the safety and stability control scheduling device cuts off the power supply to the electrical equipment according to the reduction in power generation.

4. The method of use according to claim 3, characterized in that: The generator set is provided with a load meter, and the busbar of the electrical equipment is provided with a current transformer and a voltage transformer, the load meter measures the power P1 of the generator set, and the current transformer and the voltage transformer measure the power P2 of the electrical equipment; The safety and stability control dispatching device is electrically connected to the load meter, the current transformer and the voltage transformer. The safety and stability control dispatching device compares the fluctuation △P of the power P1 of the generator set and the power P2 of the electrical equipment in real time, △P=(P2-P1).

5. The method of use according to claim 4, characterized in that: In step 1, if -5%≤ΔP / P1≤5%, the electric load balancing device is not started.

6. The method of use according to claim 4, characterized in that: In step 2, if ΔP / P1<-15%, the safety and stability control dispatching device controls the electric load balancing device to start.

7. The method of use according to claim 4, characterized in that: In step 1, the safety and stability control scheduling device records the power P2 and current I2 of the electrical equipment, and the safety and stability control scheduling device is also provided with a monitoring period T; The power at any time t is P2t, and the current is I2t. At time t+T after one monitoring cycle, the power is P2(t+T), and the current is I2(t+T). The safety and stability scheduling device calculates the power fluctuation P2(t+T)-P2t and the current fluctuation I2(t+T)-I2t, and compares them with the power fluctuation design value △Ps and the current fluctuation design value △Is.

8. The method of use according to claim 4, characterized in that: In step 1, the electrical equipment is configured to be able to propose a load increase plan to the safety and stability control scheduling device, and the load increase plan at least includes: execution time and planned increase in power P3; The safety and stability control scheduling device shown starts the electric load balancing device equivalent to P3 in advance according to the specific value of P3, and increases the power generation of the generator set at the same time. After the start-up is successful, the electric load balancing device is turned off and the load increase plan is executed at the same time.

9. The method of use according to claim 4, characterized in that: There are multiple electrical equipments. In step three, the safety and stability control scheduling device determines the list of electrical equipments that need to be powered off according to the value of △P, and performs the power-off operation on the electrical equipments at the same time.

10. The method of use according to claim 9, characterized in that: The plurality of electrical devices are rated according to their importance, and the more important the electrical device is, the higher its importance level; In step three, when powering off the electrical equipment, priority is given to powering off the electrical equipment with a low importance level.

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