Introduction: The scope and functions of dispatch automation systems have continuously expanded since their inception, differing significantly from traditional automation systems (formerly known as remote control systems). Ensuring the stable, reliable, and normal operation of the entire dispatch automation system requires a large amount of fast and reliable plant and substation basic information. Digital transparent transmission technology can transmit automation information quickly and stably, offering advantages such as low error rate, high stability, and high transmission speed. Information Transmission Methods in Automation Systems: Currently, dispatch automation systems primarily use two methods for information transmission: network transmission and dedicated remote control channels. Network transmission is a highly effective method, offering advantages such as large data capacity, speed, and reliability. When installing new plants and substations, the master station does not require additional hardware, and the debugging workload is relatively small.
1. Improve the reliability of accident alarms
Improving the switch fault alarm signal loop enhances the reliability of fault alarms in the power grid monitoring system. The substation "general fault signal" is a crucial signal in the power grid dispatch automation system and the centralized control center monitoring system. Currently, the system employs multiple fault alarm methods, including the general protection action signal, switch-related protection actions, and "close-and-go" with switch tethering, all of which have operational flaws, causing inconvenience for operation and maintenance. Constructing a complete substation switch fault signal loop is key to solving this problem. Building a new general fault loop is challenging; therefore, in the monitoring system database, a switch fault trip alarm is issued by using the protection action signal associated with each switch, or by using the switch action signal associated with one of the most important signals in the centralized control center monitoring system—the switch that tripped. The main SCADA system then determines the switch fault trip, pushes the fault display, and initiates/stops the alarm. A drawback is that a switch tripping without warning may not trigger an alarm. This also serves as the basis for triggering the fault sound. Missed or false general fault signals can affect the normal operation of the dispatch automation system and power grid monitoring. In recent years, integrated automated substations, especially 110kV and above substations, have strengthened their handling of power grid faults. For voltage-level switch fault signals, the "close-and-connect" contact on the protection panel or monitoring and control panel (mainly the protection panel) and the switch's individual position auxiliary substation fault total signal are used to form the fault alarm signal for a single switch. For all substations and unmanned substations undergoing upgrades, the switch fault alarm signals are combined to form the overall station fault system. The main operational drawback is that during local switch operation, the "close-and-connect" contact affects the currently operating power grid dispatch automation system and centralized control, causing the switch to trip without triggering a fault alarm signal. Furthermore, in new substation systems, there are various forms of fault total signals and fault alarm methods based on different periods, technical concepts, and ideas for perfecting switch fault alarm signal circuits, all of which have certain operational defects, causing inconvenience to operation and maintenance. Currently, to avoid the aforementioned application defects of the fault total signal, it is necessary to standardize the application forms of fault alarms in the operating system. These can be summarized into three main types: using interval fault alarm signal circuits to construct complete fault alarm signals. The transmission and reset circuits, constructing signal circuit anomaly monitoring and signal test 1.1 protection action total signal verification circuit, first ensure the reliability of fault remote signal acquisition to ensure fault reporting by the power grid dispatch automation system and centralized control center monitoring system (mainly used in 110kV and below substations). In the project, the substation switch fault alarm signal circuit is the key to solving the problem. When remotely resetting, a dedicated fault signal reset remote control circuit should be used (occupying one remote control object) to avoid the risk of misoperation that may be caused by open/closed switches. Use the copy of the relevant switch open position remote signal as the real-time data information connection point of the signal reset button. Connect the closed output of the reset remote control to the "composite terminal" of the locker relay, and connect the open output of the reset remote control to the "open/closed terminal" of the locker relay. According to the conventional remote control definition of the monitoring system, when the reset button information is that the switch is in the open state, perform remote opening operation, triggering the "open after closing" contact of the locker relay to close and the "close after closing" contact to open. If a switch fault alarm signal is activated, remote "fault signal" reset can be performed.
2. Data is unambiguous
In a well-designed power dispatch automation system, electrical connectors, connecting wires, and interfaces are represented by different colors. Data on the control screen also uses different colors to distinguish different information, different blocks to divide different information, different locations to display different information, and different methods to present information to ensure the unambiguity of power data. In this way, dispatchers operating the power dispatch automation system can understand grid operation information as quickly as possible, improving work efficiency.
3. Database functionality expansion
One significant advantage of databases is their scalability. From the data of a small business to the massive amounts of data of an entire corporation, large database systems can handle them with ease. This scalability also makes it possible to add practical functions to the power dispatching system's automated master station and to further develop and expand its functionality. Correlation analysis can be performed based on the information in the database to uncover relevant factors needed in our daily work, helping power companies solve complex problems.
Information on the main transformer tap changers of some primary and secondary substations within the regional power grid can be transmitted online in real time. However, information on the main transformer tap changers of some primary and secondary substations cannot yet be uploaded to the regional power dispatch master station and centralized control station. Based on the relatively stable and predictable nature of this information, the "manual data setting" function provided by the EMS database was utilized to set up offline corrections for power dispatch personnel on the substation wiring diagram of the regional dispatch automation master station, enhancing the service functions of the automation system.
4. Closed-loop defect handling
The closed-loop management process for identified equipment defects typically involves several steps: from discovery to reporting, from instructing relevant departments to implement the solution to submitting a maintenance application plan, from approving the maintenance plan to issuing a maintenance notice, from completion of maintenance to recording the defect elimination time, the person responsible for elimination, and the elimination conclusion, culminating in the acceptance personnel's signature. While there may be some special steps involved, regardless of the method, if any step is not performed properly, the loop will never be closed.
5. Ensure accurate and complete measurements, aesthetically pleasing images, and reduce eye strain.
Accurate information provided to power dispatchers by the power dispatch automation system is a fundamental requirement. Therefore, from the outset of system application, power dispatchers should conduct on-site measurements using instruments and compare these measurements with the system readings. The results of calculations must also be verified to ensure their correctness. This includes ensuring the accuracy of P, Q, and I values of the main transformer, bus voltage (including line and phase voltages), outgoing line currents, main transformer temperature, and all switch, disconnector, and transformer tap positions. Changes in outgoing line names and CT ratios should be promptly updated. The P, Q, and I values on the primary and secondary sides of the transformer should conform to power balance and current conversion relationships. When the power factor of each distribution line load is roughly the same, the sum of the secondary current of the main transformer and the outgoing line current should essentially satisfy Kirchhoff's Current Law. The voltage curves, current curves, bus voltage bar charts, and daily dispatch reports for each substation should be correctly linked to the database.
While ensuring comprehensive and accurate automated information, paying attention to the aesthetic design of the visuals is crucial. Font size and spacing should be determined based on the specific content to guarantee horizontal and vertical alignment of data. Values in dispatch reports should retain appropriate decimal places based on their magnitude. In voltage and load curves, appropriate values should be selected for the horizontal and vertical axes according to the different CT and PT ratios of the equipment, resulting in harmonious curve proportions. A reasonable combination of background and foreground colors in graphics can reduce visual fatigue for dispatchers, thereby protecting their eye health.
6. Conclusion: With the rapid development of the national economy, modern power grids are becoming increasingly large-scale and complex. Traditional power grid operation and management models are no longer suitable for the safe operation requirements of modern power grids. The development of dispatch automation systems is an inevitable trend in the development of modern power grids, and the practical application of dispatch automation system master stations is a crucial link in ensuring their healthy, stable, and continuous operation.
