CN100386642C - Generator real-time power angle monitoring device - Google Patents

Abstract

The present invention discloses a monitoring device of a real-time power angle of a generator, which comprises a CPU module, a GPS module, a rotor pulse sampling and optoelectronic isolation circuit, a hardware clock and signal collecting circuit, a keyboard and display module, a power supply module, etc. Firstly, a global positioning system (GPS) sends clock information and obtains current accurate time, and meanwhile, pulse signals emitted by a photoelectric sensor on a rotor of the generator are collected by utilizing a rotor pulse collection circuit and a signal collection circuit so as to monitor the position of the rotor of the generator in real time and to obtain inner electric potential phase of the generator; voltage phase on the end of the generator is obtained through data communication; finally, the power angle is obtained by calculating phase difference between the inner electric potential phase of the generator and the voltage phase on the end of the generator. The present invention has the characteristics of high measurement precision, fast response, low cost, small volume.

Description

Generator real-time power angle monitoring device

technical field

The invention relates to a device for directly measuring the rotor position and power angle of a generator in real time.

Background technique

With the development of the economy and society, the scale of the power system is expanding day by day, and more stringent requirements are put forward for the monitoring and control of the safe and stable operation of the power system. The power angle in the power system is the most direct physical quantity that reflects the stable state of the system. However, due to the lack of a high-precision synchronous clock, the power system has not been able to directly obtain the voltage phasor and power angle of each node in the system at the same time for a long time. As the United States opened its Global Positioning System, or GPS, to civilian use, electric power systems got a new means of time synchronization. In recent years, a GPS-based phasor measurement unit (Phase Measurement Unit, PMU for short) has been successfully developed and put into practical application in the United States, France and other countries. Some units in our country have also carried out the development and application of PMU.

In the power system, the bus voltage phasor, including its amplitude and phase angle, can be easily measured using the existing PMU. But in a power plant, it is also necessary to measure the potential phase of the generator, and the measurement methods include indirect method and direct method. Among them, the indirect method is to use the measured generator terminal voltage and current, as well as the known generator parameters to calculate the internal potential phase of the generator; the direct method is to use the position sensor installed on the generator to measure the power generation by detecting the rotor position. Internal potential phase. The direct method is not affected by the generator model and parameters, and has higher measurement accuracy than the indirect method when the system is in a transient process, so it has greater advantages.

At present, my country's power system is carrying out research and construction of a wide-area dynamic safety and stability monitoring system. Needs for safety evaluation, prevention and emergency control. Although the existing PMU device can also be used for generator measurement, it calculates the internal potential phase and power angle of the generator through the indirect method, which is affected by factors such as the generator model and transient process, and its accuracy is not as good as the direct method. Therefore, it is very necessary to develop a high-precision generator rotor position and power angle monitoring device using the current GPS system and position sensors on the generator (such as photoelectric sensors, etc.).

Contents of the invention

Aiming at the deficiencies of the prior art, the invention provides a generator real-time power angle monitoring device with high detection precision, fast response speed and low cost.

The present invention adopts following technical scheme to realize:

The generator real-time power angle monitoring device includes CPU module, GPS module, rotor pulse acquisition and photoelectric isolation circuit, hardware clock and signal acquisition circuit, keyboard and display module, and power supply module:

CPU module: connected with GPS module, rotor pulse acquisition and photoelectric isolation circuit, hardware clock and signal acquisition circuit, keyboard and display module, used for rotor position signal acquisition, forming GPS time scale, performing data communication and completing angular calculation data processing and analysis tasks;

GPS module: connected to the CPU module, when receiving the GPS signal, send time information to the CPU module through the serial communication port, and provide a second pulse signal at the same time;

Rotor pulse acquisition and photoelectric isolation circuit: connected with the CPU module and hardware clock and signal acquisition circuit, the pulse electrical signal generated by the rotor position sensor when the generator rotor rotates is detected and collected by the CPU after photoelectric isolation and filtering, and at the same time Under the control of the CPU, it cooperates with the hardware clock and the signal acquisition circuit to determine the precise moment when the pulse electrical signal appears, thereby determining the rotor position and the electric potential phase in the generator;

Hardware clock and signal acquisition circuit: connected with the CPU module and photoelectric isolation circuit, the hardware clock circuit is used to provide microsecond-level time, and the timing pulse signal with a unit of less than 1 microsecond is generated by a high-precision clock source, and the signal is sent to the counter circuit Carry out cumulative counting for the CPU to read; the signal acquisition circuit is used to read the microsecond-level time provided by the hardware clock circuit under the control of the CPU when the rotor pulse signal arrives, so as to combine with the time information provided by GPS to form a microsecond-level The GPS time scale can accurately determine the moment when the rotor position pulse arrives.

Keyboard and display module: connected to the CPU module, detect the status of each key under the control of the CPU, execute the corresponding command when a key is pressed, and send information to the LCD in the display module through the data bus to display the GPS receiving status, Monitoring function, communication status, etc.

Power module: Provides stable power for the entire system.

The invention utilizes the position sensor (such as photoelectric sensor) on the generator and the clock signal of GPS to directly detect the rotor position and internal potential phase of the generator, and then calculates the power angle. First, receive the clock information sent by GPS to obtain the current precise time; at the same time, use the rotor pulse acquisition circuit and signal acquisition circuit to collect the pulse signal sent by the photoelectric sensor on the generator rotor to monitor the position of the generator rotor; It directly determines the internal potential phase of the generator, so it also obtains the internal potential phase of the generator at the same time. Then it obtains the generator terminal voltage phase through data communication, and finally calculates the phase difference between the internal potential phase of the generator and the generator terminal voltage phase to obtain the power angle. Using this device to cooperate with the existing phasor measurement unit (PMU), under the unified GPS clock reference, the power angle monitoring of generators and buses at different locations can be realized in a wide area, thereby forming a power system power angle Monitoring system to realize wide-area stability monitoring and control of power system.

The invention has the characteristics of high measurement precision, fast response speed, low cost and small volume. Among them, the high measurement accuracy is the main advantage of the present invention, which is guaranteed by the following technical measures. First of all, in terms of working principle, the present invention adopts the direct method for measurement, which is not affected by the generator model, and can accurately measure various types of generators. Secondly, the present invention can measure the rotation speed of the generator in real time, so even if the rotation speed of the generator changes, the measurement result can be corrected by software, so as to calculate the accurate power angle. Finally, due to the use of GPS clock (with an error of 1 microsecond) and a specially designed microsecond-level hardware clock circuit, the total measurement error is less than 5 microseconds (corresponding to a phase angle of about 0.09 degrees), which can fully meet the needs of power system stability monitoring . In addition, due to the strategy of sending immediately after collection, the sending interval of the data frame depends on the rotational speed of the rotor, which is about 20ms. The invention adopts a general-purpose single-chip microcomputer (Intel 80C196 CPU), reasonably arranges each functional module, and constitutes a data acquisition device with low cost and reasonable function configuration, and the assembled device has a small volume.

Description of drawings:

Fig. 1 is a block diagram of the working principle of the present invention.

Fig. 2 is the circuit principle diagram of CPU module and GPS module of the present invention

Fig. 3 is a schematic diagram of the rotor pulse acquisition and photoelectric isolation circuit, and the hardware clock and signal acquisition circuit of the present invention.

Fig. 4 is a schematic circuit diagram of the keyboard and display module of the present invention.

Among them: 1. CPU microprocessor, 2. Latch, 3. Program memory, 4. Data memory, 5. Decoder, 6. External communication interface, 7. GPS module, 8. Rotor position sensor, 9. Photoelectric isolation circuit, 10, clock source, 11, counter, 12, latch, 13, programmable logic device, 14, liquid crystal display, 15, keyboard, 16, bus input interface chip, 17, programmable logic device

Detailed ways

Example:

Fig. 1 has provided the working principle block diagram of the present invention. The generator real-time power angle monitoring device mainly includes a CPU module, a GPS module, a rotor pulse acquisition and photoelectric isolation circuit, a hardware clock and signal acquisition circuit, a keyboard and a display module, and a power supply module.

CPU module: connected with GPS module, rotor pulse acquisition and photoelectric isolation circuit, hardware clock and signal acquisition circuit, keyboard and display module, used to complete the acquisition of rotor position signal, form GPS time scale, perform data communication, complete angle Computing and other tasks. As shown in FIG. 2 , the CPU module includes a CPU microprocessor 1 , a latch 2 , a program memory 3 , a data memory 4 , a decoder 5 , and an external communication interface 6 . Among them, CPU microprocessor 1 adopts 16-bit 80C196 single-chip microcomputer, which has 256 bytes of on-chip RAM and special registers, and the addressable space outside the chip is 64K bytes. Since the 80C196 does not contain a program memory, the program memory 3 and data memory 4 are expanded externally, and the lower 8-bit address and data are separated by the latch 2, and the address space is allocated by the decoder 5. 80C196 CPU has rich I/O interfaces, including high-speed input ports, high-speed output ports, A/D conversion interfaces, timer interfaces, interrupt interfaces, serial communication interfaces, etc., suitable for industrial sites to complete various monitoring and control Task. Utilize the high-speed output port HSO3 of 80C196 and the high-speed input port HSI3 to construct the software serial port among the present invention, realize the sending and receiving of serial data by software programming, be used for communicating with GPS module 7, obtain GPS time information; GPS The second pulse signal (1PPS) output by the module is directly sent to the high-speed input port HSI0 of the CPU; the original RXD and TXD serial interfaces of the CPU are used to communicate with external devices (such as PMU) to obtain the voltage phase of the generator terminal, thereby Realize the calculation of power angle. In order to connect to other peripheral modules, the CPU module also uses 8-bit data bus (DataBus), lower 8-bit address bus (AddrBus), upper 8-bit address decoding output (PA5), read enable signal (/RD), write enable signal (/WR), high-speed output port (HSI0 and HSI1), and high-speed input port (HSI1) and other signal lines lead out, manage and control the peripheral rotor pulse acquisition and photoelectric isolation circuit, hardware clock and signal acquisition circuit, keyboard and display module .

GPS module: connected with the GPS antenna and the CPU module, the circuit wiring diagram of the GPS module 7 and the CPU microprocessor 1 is shown in Fig. 2 . This device selects GPS (Global Positioning System) as the system clock. In order to obtain GPS time information, the GPS module of this device uses a timing GPS receiver, which has the characteristics of small size and easy installation. The GPS module requires an external GPS antenna, and the GPS antenna is usually installed outdoors at a higher position to obtain better GPS signal reception performance. After receiving the GPS signal, the GPS module can provide the CPU with year, month, day, hour, minute, second and other time information through the serial port (that is, its RXD and TXD pins), and also output a second pulse signal (1PPS ).

Rotor pulse acquisition and photoelectric isolation circuit: connected with CPU module, and hardware clock and signal acquisition circuit, the circuit schematic diagram is shown in Figure 3. The rotor position sensor 8 (such as a photoelectric sensor) installed on the generator can generate a pulse electrical signal when the generator rotor rotates, and the pulse electrical signal is detected and collected by the high-speed input port HSI1 of the CPU after being processed by the photoelectric isolation circuit 9 and filtering , and provide the hardware clock and signal acquisition circuit at the same time. Since the pulse electric signal corresponds to the rotor position, the rotor position and the potential phase in the generator can be determined by detecting the precise moment (microsecond level) when the pulse electric signal appears. In order to ensure the measurement accuracy, when the device collects the rotor pulse signal, the photoelectric isolation circuit 9 is designed by using a photoelectric isolation device (TLP521-4) that can withstand thousands of volts of high voltage, and cooperates with capacitor filtering and software filtering to effectively filter out interference signal, and protect the safety of the internal circuit of the device.

Hardware clock and signal acquisition circuit: It is connected with CPU module and photoelectric isolation circuit. The schematic diagram of the circuit is shown in Figure 3. The circuit includes two parts: hardware clock circuit and signal acquisition circuit. The hardware clock circuit includes a 2MHz clock source 10 and two counters 11, and the signal acquisition circuit includes three latches 12, which are all completed by a programmable logic device (GAL16V8) 13 for address decoding and logic control. Since the minimum time unit of the clock signal sent by the GPS module is seconds, it cannot meet the accuracy requirements of the power system when calculating the power angle. Therefore, the present invention specially designs a hardware clock circuit to generate a microsecond-level time scale. Compared with using the software clock in the CPU, the advantage of using the hardware clock circuit is that it will not be affected by factors such as CPU task busyness and interrupt response time, and has higher timing accuracy. The hardware clock circuit uses a high-precision clock source with a frequency of 2MHz to generate a timing signal with a unit of 0.5 microseconds. The timing signal is sent to the counter circuit 11 for cumulative counting for the CPU to read, so as to provide the arrival of the rotor pulse signal microsecond time. The RST (reset) pins of the two counters CD4040 are connected to the output of GAL16V8, and are logically controlled by the high-speed output port HSO0 of the CPU, so that the CPU can reset and clear the counters as needed. When the rotor pulse signal arrives, the signal acquisition circuit 12 firstly provides latch signals to the CLK pins of the two latches 12 under the control of HSO1 and GAL16V8, and memorizes the count value of the counter 11 at that time; then uses GAL16V8 to decode sequentially Output the read data signal to the OE (output enable) pin of the latch 12, and provide the microsecond-level time information stored in the three latches to the CPU through the data bus (DataBus) in three times. In this way, the CPU comprehensively utilizes the GPS time information (in seconds) obtained from the GPS module and the microsecond-level time provided by the hardware clock circuit to form a microsecond-level GPS time scale, thereby accurately determining the moment when the rotor position pulse arrives.

Keyboard and display module: connected to the CPU module. Figure 4 shows its circuit schematic diagram, which includes liquid crystal display (LCD) 14, keyboard (KEY1～KEY7) 15, bus input interface chip (74LS244) 16, and programmable logic Device (GAL16V8)17. This device has a good man-machine connection function, equipped with a membrane keyboard and a liquid crystal display, and can control and display the GPS receiving status, monitoring function, communication status, etc. of the device through the buttons on the panel. When reading the keyboard information, first the CPU controls the output address signal (A2~A4 and PA5) and the read signal (/RD) to GAL16V8, and after GAL16V8 completes the address decoding, it outputs the read permission signal to the 1st and 19th pins of 74LS244 , and then the data bus (DataBus) can read the state of each button through the bus input interface chip 74LS244. When it is detected that a key is pressed, the CPU executes the corresponding command. When displaying information, the CPU first outputs address signals (A0~A5 and PA5) and write signals (/WR) to GAL16V8, GAL16V8 performs address decoding and then strobes the liquid crystal display (LCD), and then the CPU passes the data bus (DataBus) Send information to the liquid crystal display (LCD) in the display module to display GPS receiving status, monitoring function, communication status, etc.

Power supply module: It adopts general switching power supply to provide stable power supply for the whole system.

The present invention has the following characteristics:

1. High measurement accuracy

First of all, in terms of working principle, this device uses the direct method to measure the generator, which is not affected by the generator model, and can accurately measure various types of generators. Secondly, this device can measure the rotation speed of the generator in real time, so even when the rotation speed of the generator changes, the measurement result can be corrected by software, so as to calculate the accurate power angle. In addition, due to the use of GPS clock (with an error of 1 microsecond) and a specially designed microsecond-level hardware clock circuit, the total measurement error is less than 5 microseconds (corresponding to a phase angle of about 0.09 degrees), which can fully meet the needs of power system stability monitoring .

2. Fast response

Since the direct method is used for measurement, the time interval for the device to output rotor position and power angle information mainly depends on the rotational speed of the generator rotor, which is basically constant at 20 milliseconds.

3. Low cost

The general-purpose single-chip microcomputer 80C196 of INTEL Company is adopted to form a data acquisition device with low cost and reasonable functions.

4. Small size

By rationally dividing functional modules, the device makes each circuit into several parts such as CPU board, signal acquisition board, display and keyboard board, power supply module, etc. The volume of the device after assembly is very small.

Claims (1)

1. monitoring device of power generator real time power angle. comprise CPU module, GPS module, rotor pulse collection and photoelectric isolating circuit, keyboard and display module, and power module:

CPU module: be connected with display module with photoelectric isolating circuit, keyboard with GPS module, rotor pulse collection, be used for the collection of rotor-position signal, form the GPS markers, carry out data communication, finish data processing and analysis task such as merit angle calculating;

GPS module: be connected with the CPU module, after receiving gps signal, send temporal information to the CPU module, a pps pulse per second signal is provided simultaneously by serial communication interface;

Rotor pulse collection and photoelectric isolating circuit: be connected with signal acquisition circuit with CPU module and hardware clock, the pulse electrical signal that generates by rotor-position sensor when generator amature rotates, through detecting and gather by CPU after photoelectricity isolation and the Filtering Processing, under the control of CPU, cooperate with signal acquisition circuit simultaneously with hardware clock, determine the accurate moment that this pulse electrical signal occurs, thereby determine rotor-position and generator built-in potential phase place;

Keyboard and display module: be connected with the CPU module, under CPU control, detect the state of each button, when key is pressed, carry out corresponding order, and send information, show GPS accepting state, monitoring function, communication state etc. by the LCD of data bus in display module;

Power module: adopt Universal Switching Power Supply, for whole device provides stable power.

It is characterized in that: also comprise

Hardware clock and signal acquisition circuit: be connected with CPU module and photoelectric isolating circuit, hardware clock circuit is used to provide the time of microsecond level; Signal acquisition circuit is used for when the rotor pulse signal arrives, under CPU control, read the microsecond level time that hardware clock circuit provides, thereby combining with temporal information that GPS provides forms the GPS markers of microsecond level, accurately determines the moment that the rotor-position pulse arrives.

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