Phase 1 — Core Simulation & Energy Architecture

Siemens Smart Solar Plant
SCADA System

A modular industrial renewable energy simulation platform engineered in Siemens TIA Portal V19 on an S7-1500 PLC architecture — implementing real-time environmental simulation, layered energy management, battery storage logic, and smart grid balancing within a fully virtualised PLCSIM commissioning environment.

Project Overview

This project constructs a virtualised renewable energy microgrid simulation using Siemens' industrial automation stack. Designed from the ground up as a scalable, SCADA-ready system, it models the behaviour of a modern solar utility installation — from environmental input processing through to grid export decisions — entirely within a software-defined PLC runtime.

The architecture enforces strict separation of concerns across simulation, energy generation, storage, and control layers. Each subsystem is implemented as an independent Function Block with dedicated instance Data Blocks, following professional Siemens object-oriented PLC engineering methodology.

Software Environment

ComponentTechnology
PLC PlatformSiemens S7-1500 (CPU 1511-1 PN)
Engineering EnvironmentTIA Portal V19
Simulation EnvironmentSiemens PLCSIM V19
Programming LanguageSCL (Structured Control Language)
HMI / SCADA TargetWinCC Unified (Phase 2)

System Architecture

The project follows a strict top-down layered industrial architecture. Each layer consumes outputs from the layer above it, maintaining clean data flow and enabling independent testing of every subsystem.

WEATHER SIMULATION LAYER
↓
SOLAR ENERGY GENERATION LAYER
↓
BATTERY ENERGY STORAGE LAYER
↓
GRID MANAGEMENT LAYER
↓
SCADA / OPERATOR VISUALISATION LAYER

PLC Project Structure

The program block organisation mirrors professional Siemens industrial project conventions, with dedicated folders segregating simulation, energy, control, alarms, utilities, data types, and testing logic: 

00_Main        — Execution entry point (OB1)
01_Simulation  — Environmental simulation FBs
02_Energy      — Solar array + battery FBs
03_Control     — Grid management control logic
04_Alarms      — Alarm handling (Phase 3)
05_Utilities   — Shared utility functions
06_DataTypes   — UDT definitions
07_Testing     — Watch tables and commissioning tools

Data Architecture

All process data is structured using User Defined Types (UDTs), providing strongly-typed, scalable data models consistent with industrial SCADA engineering standards. Global Data Blocks act as shared memory accessible across all Function Blocks.

UDT_Weather — Environmental simulation state
  • Irradiance — Simulated solar irradiance (W/m²)
  • CloudFactor — Dynamic cloud attenuation coefficient
  • AmbientTemp — Ambient temperature (°C)
  • TimeOfDay — Simulated 24-hour clock value
  • DayCycleSpeed — Accelerated time progression scalar
UDT_Power — Energy generation and grid values
  • Generated_kW, Efficiency, Voltage, Current, Frequency
  • GridImport_kW, GridExport_kW
UDT_Battery — Battery Energy Storage System state
  • SOC — State of charge (%)
  • ChargeRate, DischargeRate, BatteryTemp, Mode
UDT_PlantState — Plant-wide operating state enum — UDT_Alarm reserved for Phase 3 fault handling.

Function Block Architecture

FB_WeatherEngine [FB1] — Weather Simulation Engine

Simulates a complete 24-hour environmental cycle using SCL. Computes irradiance via a piecewise daylight curve, applies cloud attenuation, and drives ambient temperature — all at an accelerated simulation rate for rapid commissioning validation.

  • Simulated 24h cycle with day/night transitions and automatic reset
  • Piecewise irradiance model: (SimTime - 6.0) × 100.0 during solar hours, clamped to 1,000 W/m²
  • Dynamic cloud factor modulates effective irradiance in real time
  • Outputs: IrradianceOut, CloudOut, TempOut, TimeOut → written to DB_Weather.WeatherData

FB_SolarArray [FB2] — Solar Generation Engine

Calculates dynamic solar power production from live weather inputs. Models panel efficiency degradation under cloud cover and derives simulated electrical output parameters consistent with a grid-tied inverter model.

  • Inputs: IrradianceIn, CloudFactorIn from DB_Weather
  • Outputs: Generated_kW, Efficiency, Voltage, Current, Frequency → DB_Energy.PowerData

FB_BatterySystem [FB3] — Battery Energy Storage System

Implements charge/discharge logic with full state-of-charge tracking and thermal simulation. Battery mode switches dynamically based on available solar generation — charging under surplus, discharging under deficit.

  • Input: GeneratedPowerIn from solar generation layer
  • Outputs: SOC_Out, ChargeRateOut, BatteryTempOut, ModeOut → DB_Energy.BatteryData

FB_GridManager [FB4] — Smart Grid Management System

Implements microgrid energy balancing logic. Evaluates real-time solar generation and battery SOC to determine optimal grid interaction mode — exporting surplus capacity, importing when generation is insufficient, or operating autonomously in balanced state.

  • Inputs: SolarPowerIn (Generated_kW), BatterySOC_In
  • Outputs: GridImportOut, GridExportOut, GridModeOut → DB_Energy.PowerData
  • Excess solar: exports surplus to utility grid
  • Low generation + low SOC: imports from utility grid
  • Balanced state: operates autonomously without import/export

Project Screenshots

All screenshots captured from live PLCSIM runtime session — project in RUN state with active watch table monitoring.

Main [OB1] — Network 1: FB_WeatherEngine instantiated with DB_WeatherEngine [DB6]
Main [OB1] — Network 1: FB_WeatherEngine (FB1) instantiated with DB_WeatherEngine [DB6] as its instance DB. Outputs wired directly to DB_Weather.WeatherData structured fields (Irradiance, CloudFactor, AmbientTemp, TimeOfDay).
FB_WeatherEngine [FB1] — SCL implementation of the 24-hour time progression loop
FB_WeatherEngine [FB1] — SCL implementation of the 24-hour time progression loop and piecewise irradiance curve. SimTime advances by 0.05 per scan cycle and resets at 24.0. Solar hours (06:00–18:00) drive the irradiance model with a 1,000 W/m² ceiling clamp.
UDT_Weather — Structured data type definition
UDT_Weather — Structured data type definition showing all five Real-typed fields: Irradiance, CloudFactor, AmbientTemp, TimeOfDay, DayCycleSpeed. All fields marked Accessible, Writable, and Visible for full SCADA tag exposure.
Extended Download to Device — PLCSIM virtual commissioning workflow
Extended Download to Device — PLCSIM virtual commissioning workflow. CPU-1500 Simulator detected at 192.168.0.1 via PN/IE interface. Scan confirmed 1 compatible device; compile passed with 0 errors. Project loaded successfully to virtual PLC runtime.
Main [OB1] — Network 2: FB_SolarArray (FB2)
Main [OB1] — Network 2: FB_SolarArray (FB2) with instance DB_SolarArray [DB7]. Weather inputs consumed from DB_Weather.WeatherData; power outputs written to DB_Energy.PowerData (Generated_kW, Efficiency, Voltage, Current, Frequency).
Main [OB1] — Network 3: FB_BatterySystem (FB3)
Main [OB1] — Network 3: FB_BatterySystem (FB3) with instance DB_BatterySystem [DB8]. Solar generation feeds GeneratedPowerIn; SOC, ChargeRate, BatteryTemp, and Mode written back to DB_Energy.BatteryData.
Main [OB1] — Network 4: FB_GridManager (FB4)
Main [OB1] — Network 4: FB_GridManager (FB4) with instance FB_GridManager_DB [DB9]. Consumes solar generation and battery SOC; drives GridImport_kW, GridExport_kW, and GridModeOut into DB_Energy.PowerData. Loading completed with 0 errors.
WT_Main Watch Table — live runtime monitoring during PLCSIM execution
WT_Main Watch Table — live runtime monitoring during PLCSIM execution. PLC_1 confirmed RUN state. Live values visible: DB_Weather Irradiance ~40.0, TimeOfDay 6.0, DB_Energy Generated_kW ~34.59, BatteryData SOC 0.0, PlantState 0. All data blocks show green online status.

Virtual Commissioning & Runtime Validation

The complete system was deployed to a Siemens PLCSIM virtual PLC instance via TIA Portal's Extended Download workflow. The CPU 1511-1 PN simulator was configured at 192.168.0.1 via PN/IE interface. All program blocks compiled to zero errors; the PLC entered RUN state with all Data Blocks online and green-flagged.

WT_Main — Centralised Commissioning Watch Table
  • Live irradiance and time-of-day monitoring from DB_Weather.WeatherData
  • Real-time solar generation readout from DB_Energy.PowerData.Generated_kW
  • Battery SOC live tracking from DB_Energy.BatteryData.SOC
  • Plant state enum monitoring via DB_Global.PlantState
  • Grid import/export values visible for real-time energy balance validation
● PLC STATUS: RUN
● COMPILE: 0 ERRORS / 0 WARNINGS
● INTERFACE: PLCSIM PN/IE 192.168.0.1
● RUNTIME: VIRTUAL COMMISSIONING ACTIVE

Current System Capabilities

Development Roadmap

✅ Phase 1 — Core Simulation

Weather engine, solar generation, BESS, grid manager. Full PLCSIM virtual commissioning. Complete.

➡ Phase 2 — WinCC Unified SCADA

Operator overview screens, animated power flow diagrams, battery indicators, solar dashboards, trend visualisation.

Phase 3 — Alarm & Fault Handling

Inverter faults, overtemperature alarms, grid instability simulation, alarm acknowledgment workflows.

Phase 4 — Historical Trends

Energy historian, 24h accelerated playback, trend logging and reporting.

Phase 5 — Hybrid Microgrid

Wind turbine simulation, diesel generator backup, automatic transfer switching logic.

Phase 6 — Advanced Control

Plant state machines, PID thermal control, predictive optimisation, operational recipes.

Siemens Smart Solar Plant SCADA System — Phase 1: Core Simulation & Energy Architecture
Developed in TIA Portal V19 · S7-1500 · SCL · PLCSIM Virtual Commissioning