Arrangement and signal generator module for price-based load release with analog output for a PLC analog input

Abstract

Arrangement for load- or cost-optimized release of an electrical load, comprising (a) a signal transmitter module with (a1) an interface for receiving a time series of an external control variable from the group: energy price, cost index, CO2 intensity, grid frequency deviation or power forecast, (a2) a memory for buffering the time series, (a3) ​​a processing unit that determines a continuous load release index from the time series, and (a4) an output stage that provides the load release index as an analog output signal that can be detected by a PLC analog input; and (b) a PLC with analog input that scales the analog output signal and, by means of a PLC program with hysteresis, minimum on time and minimum off time as well as time windows / calendar, generates a switching variable for controlling an actuator; wherein, in the event of invalidity of the analog output signal, a failsafe reaction defined in the PLC is triggered.

Description

Technical field

[0001] The invention relates to the energy- and cost-optimized control of electrical loads using programmable logic controllers (PLCs). In particular, it relates to a signal generator module with an analog output (e.g., 4-20 mA or 0-10 V) and an arrangement comprising such a signal generator module and a PLC with an analog input for load- and cost-optimized switching of actuators. State of the art

[0002] In current technology, loads are often switched based on rigid schedules or local thresholds. Solutions that consider external control variables (e.g., energy price, CO2 intensity, or grid signals) typically output digital enable signals to PLC digital inputs. Continuous analog signals suitable for PLC analog inputs with clearly coded error states are rarely described, especially not in combination with PLC-side decision logic featuring hysteresis, minimum on / off times, and calendar / time windows. Task

[0003] The aim is to provide a complete solution that takes external control variables into account, delivers a PLC-compatible analog signal, robustly codes errors and implements the actual switching decision in the PLC, in order to easily retrofit and parameterize existing controllers. Summary of the invention

[0004] The task is solved by (i) a signal generator module with a communication interface for receiving a time series of a reference variable (e.g., energy price, cost index, CO2 intensity, grid frequency deviation), a buffer memory, and a processing unit that generates a continuous load release index from this data and provides it as an analog output (4-20 mA and / or 0-10 V), whereby fault conditions are encoded by parameters outside the measurement range; and (ii) an arrangement consisting of such a signal generator module and a PLC with an analog input that scales the analog value and, using a PLC program with hysteresis, minimum on and off times, and time windows / calendar, creates a switching signal for an actuator (contactor / SSR). In the event of an invalid analog signal, the PLC enforces a defined failsafe response (e.g., OFF or Hold). 1. Signal transmitter module (hardware / software)

[0005] The module includes a communication interface (e.g., Ethernet, cellular, WLAN, LPWAN, or fieldbus), a microcontroller with memory for receiving, buffering, and preprocessing a time series of a reference variable. A mapping function converts the reference variable to a continuous index (e.g., 0...100%). An analog output driver provides the index as 4-20 mA (active or loop-fed) and / or 0-10 V.

[0006] For error coding, the module outputs values ​​outside the normal range in the event of communication, sensor, or internal errors (e.g., < 3.6 mA or > 20.5 mA, or < -0.2 V or > 10.2 V). The module can be configured with or without galvanic isolation of the analog output. Parameterization (scaling, inversion, filter time) is performed locally and / or via the web. 2. PLC page

[0007] The PLC has at least one analog input (AI) that scales the analog signal to the index. A PLC function block (library FB) implements: hysteresis (separate on / off thresholds), minimum on and off times, time windows / calendars (e.g., blackout periods, tariff windows), and failsafe in case of an invalid AI (e.g., OFF or holding the last valid state). The resulting Boolean output controls an actuator (contactor, relay, SSR) via a PLC DO module. Parameters can be changed online and saved via recipes. 3. Variants • Dual analog output (simultaneously 4-20 mA and 0-10 V). • Multi-channel module (multiple independent indices / load groups). • Extended indexing (e.g., prediction models, PV surplus, grid signals). • Watchdog monitoring; time base via RTC / NTP. • IEC-compliant input / output characteristics (e.g., IEC 61131-2 analog). 4. Advantages • Easy retrofitting of existing PLC systems via analog input. • Robust error handling through clearly interpretable error values. • Flexible parameterization of the switching logic in the PLC without firmware modifications to the module.

Claims

[1] Arrangement for load- or cost-optimized release of an electrical load, comprising (a) a signaling module with (a1) an interface for receiving a time series of an external control variable from the group: energy price, cost index, CO2 intensity, grid frequency deviation or power forecast, (a2) a memory for buffering the time series, (a3) ​​a processing unit that determines a continuous load release index from the time series, and (a4) an output stage that provides the load release index as an analog output signal that can be detected by a PLC analog input; and (b) a PLC with analog input that scales the analog output signal and, by means of a PLC program with hysteresis, minimum on time and minimum off time as well as time windows / calendar, generates a switching variable for controlling an actuator; wherein, in the event of invalidity of the analog output signal, a failsafe reaction defined in the PLC is triggered. [2] Arrangement according to claim 1, wherein the analog output signal is a current signal 4-20 mA and fault conditions are encoded by characteristic currents outside 4-20 mA. [3] Arrangement according to claim 1 or 2, wherein the analog output signal is a voltage 0-10 V and fault conditions are encoded by characteristic voltages outside 0-10 V. [4] Arrangement according to one of claims 1-3, wherein the signal generator module simultaneously provides a 4-20 mA and a 0-10 V signal. [5] Arrangement according to one of the preceding claims, wherein the PLC failsafe response comprises OFF or holding the last valid switching state. [6] Arrangement according to one of the preceding claims, wherein the processing unit provides filtering / smoothing of the received time series and / or parameterization of the scaling (offset, gain, inversion). [7] Arrangement according to one of the preceding claims, wherein the output stage is designed without galvanic isolation or with galvanic isolation from the PLC. [8] Arrangement according to one of the preceding claims, wherein the PLC program is provided as a parameterizable function block with interfaces for threshold values, minimum times and calendar entries. [9] Arrangement according to one of the preceding claims, wherein the signal generator module additionally derives a multi-stage operating mode index from the time series and encodes it in defined analog value windows. [10] Signal transmitter module for providing a PLC-detectable analog output signal for load- or cost-optimized switching, with an interface for receiving and a memory for buffering a time series of an external control variable, a processing unit for determining a continuous load release index from the time series and an output stage that provides the index as a 4-20 mA and / or 0-10 V analog signal, wherein fault conditions are coded by parameters outside the respective measuring range. [11] Signal transmitter module according to claim 10, with dual output (4-20 mA and 0-10 V) and configurable characteristic shape (linear, stepped, inverted). [12] Signal transmitter module according to claim 10 or 11, with communication interface selected from Ethernet, mobile network, WLAN, LPWAN or fieldbus, and time base via RTC and / or NTP. [13] Signal transmitter module according to one of claims 10-12, wherein the output stage provides NAMUR-like fault ranges (undercurrent / overcurrent or undervoltage / overvoltage) and includes monitoring. [14] Arrangement according to one of claims 1-9 comprising an actuator from the group: contactor, relay, solid-state relay or power semiconductor switch, controlled by a PLC digital output resulting from the PLC program.