Phase 2 — Advanced Energy Management & SCADA Visualisation

Siemens Smart Solar Plant
SCADA System

Phase 2 extends the virtualised renewable energy platform into a fully operational intelligent energy management system — integrating dynamic load demand modelling, adaptive energy routing, battery dispatch logic, real-time KPI computation, and a live WinCC Advanced HMI dashboard. All subsystems are orchestrated through structured SCL function blocks executing on a virtualised S7-1500 runtime under Siemens TIA Portal V19.

Phase Objective

Phase 1 established the core simulation and energy generation architecture. Phase 2 transforms that static monitoring foundation into a responsive, decision-making system capable of dynamic energy routing — evaluating real-time solar generation, plant load demand, battery state of charge, and grid availability to autonomously determine the optimal energy distribution strategy on every PLC scan cycle.

The primary deliverable is a fully operational SCADA HMI screen running in WinCC Advanced Runtime, displaying live plant telemetry, animated energy flow indicators, renewable contribution tracking, and industrial-grade KPI metrics — consistent with the visualisation layer of a real solar utility installation.

Software Environment

ComponentTechnology
PLC PlatformSiemens S7-1500 (CPU 1511-1 PN)
Engineering EnvironmentTIA Portal V19
Simulation RuntimeSiemens PLCSIM V19
Programming LanguageSCL (Structured Control Language)
HMI / SCADA PlatformWinCC Advanced Runtime (V19)
HMI Hardware TargetTP700 Comfort Panel (virtualised)

Expanded System Architecture

Phase 2 introduces three new functional layers above the Phase 1 energy core. Dynamic load demand feeds the energy router, which in turn drives real-time grid command resolution before efficiency metrics are computed — enforcing strict data dependency ordering within the PLC scan cycle.

WEATHER SIMULATION LAYER [FB1]
↓
SOLAR ENERGY GENERATION LAYER [FB2]
↓
BATTERY ENERGY STORAGE LAYER [FB3]
↓
★ DYNAMIC LOAD DEMAND LAYER [FB5] — Phase 2
↓
★ INTELLIGENT ENERGY ROUTING LAYER [FB6] — Phase 2
↓
★ GRID COMMAND RESOLUTION [Network 6 SCL] — Phase 2
↓
★ EFFICIENCY METRICS ENGINE [FB7] — Phase 2
↓
★ WINCC ADVANCED SCADA HMI — Phase 2

Phase 2 Program Block Structure

Three new function blocks and one inline SCL network were added to the Main [OB1] execution sequence. Block ordering is critical — energy routing must resolve grid commands before the efficiency metrics block executes to avoid zero-value outputs caused by stale data. 

Network 1  — FB_WeatherEngine   [FB1 / DB6]  — Phase 1
Network 2  — FB_SolarArray      [FB2 / DB7]  — Phase 1
Network 3  — FB_BatterySystem   [FB3 / DB8]  — Phase 1
Network 4  — FB_LoadDemand      [FB5 / DB12] — Phase 2 ★
Network 5  — FB_EnergyRouter    [FB6 / DB13] — Phase 2 ★
Network 6  — Grid SCL Resolution             — Phase 2 ★
Network 7  — FB_EfficiencyMetrics [FB7/DB14] — Phase 2 ★

New Function Block Architecture — Phase 2

FB_LoadDemand [FB5 / DB12] — Dynamic Plant Load Simulation

Simulates a variable plant consumption profile keyed to the simulated time-of-day, replicating realistic industrial load curves including peak demand periods. The block consumes DB_Weather.WeatherData.TimeOfDay and outputs a continuously varying Demand_kW value alongside a boolean PeakMode flag — allowing downstream routing logic to apply peak-demand prioritisation strategies.

  • Input: TimeOfDay_In — sourced from DB_Weather.WeatherData.TimeOfDay
  • Output: Demand_kW_Out → DB_Load.LoadData.Demand_kW
  • Output: PeakMode_Out → DB_Load.LoadData.PeakMode
  • Instance DB: DB_Load_Demand [DB12]

FB_EnergyRouter [FB6 / DB13] — Intelligent Energy Distribution Engine

The central decision-making block of the Phase 2 system. On every PLC scan, the router evaluates four live inputs — solar generation, plant demand, battery SOC, and peak mode status — and resolves the optimal energy routing strategy, issuing boolean command outputs that drive grid import, grid export, battery charge, and battery discharge operations. This single block replaces and supersedes the legacy FB_GridManager, consolidating all energy distribution authority into one deterministic control source.

  • Input: Solar_kW_In — from DB_Energy.PowerData.Generated_kW
  • Input: Demand_kW_In — from DB_Load.LoadData.Demand_kW
  • Input: BatterySOC_In — from DB_Energy.BatteryData.SOC
  • Input: PeakMode_In — from DB_Load.LoadData.PeakMode
  • Output: ChargeCmd_Out → DB_Energy.PowerData.ChargeCommand
  • Output: DischargeCmd_Out → DB_Energy.PowerData.DischargeCommand
  • Output: GridImportCmd_Out → DB_Energy.PowerData.GridImportCommand
  • Output: GridExportCmd_Out → DB_Energy.PowerData.GridExportCommand

Network 6 — Inline Grid Command Resolution [SCL]

Translates the boolean command outputs from FB_EnergyRouter into quantified power flow values. This inline SCL block reads the active grid commands and computes actual kilowatt values — import as the deficit between demand and generation, export as the surplus above demand. Executed immediately after the router and before the metrics block to guarantee that resolved values are available for efficiency calculations within the same scan cycle.

IF "DB_Energy".PowerData.GridImportCommand THEN
    "DB_Energy".PowerData.GridImport_kW :=
    "DB_Load".LoadData.Demand_kW -
    "DB_Energy".PowerData.Generated_kW;
ELSE
    "DB_Energy".PowerData.GridImport_kW := 0.0;
END_IF;

IF "DB_Energy".PowerData.GridExportCommand THEN
    "DB_Energy".PowerData.GridExport_kW :=
    "DB_Energy".PowerData.Generated_kW -
    "DB_Load".LoadData.Demand_kW;
ELSE
    "DB_Energy".PowerData.GridExport_kW := 0.0;
END_IF;

FB_EfficiencyMetrics [FB7 / DB14] — Real-Time KPI Computation Engine

Computes four plant-wide performance indicators on every scan cycle, sourcing resolved power flow values from upstream blocks. Outputs are written to a dedicated DB_Metrics data block and bound directly to WinCC HMI display fields, providing operators with live renewable contribution percentages and grid dependency ratios consistent with industrial SCADA energy dashboards.

  • Input: Solar_kW_In — from DB_Energy.PowerData.Generated_kW
  • Input: Demand_kW_In — from DB_Load.LoadData.Demand_kW
  • Input: GridImport_kW_In — from DB_Energy.PowerData.GridImport_kW
  • Output: RenewablePercent_Out → DB_Metrics.RenewablePercent
  • Output: GridDependency_Out → DB_Metrics.GridDependency
  • Output: SelfSufficiency_Out → DB_Metrics.SelfSufficiency
  • Output: PlantEfficiency_Out → DB_Metrics.PlantEfficiency

WinCC Advanced SCADA HMI

A full operator overview screen was designed and deployed in WinCC Advanced Runtime, bound via HMI tag connections to the live PLC data blocks. The screen aggregates all critical plant parameters into a single operator view, modelled after industrial solar SCADA conventions.

HMI Panel Layout — SMART SOLAR PLANT SCADA
  • Battery Panel — SOC gauge (0–100%) with live numeric readout, colour-coded by charge state
  • Solar Panel — Live Generated_kW numeric display with dynamic background colour indicating generation intensity
  • Grid Panel — Separate import and export kW readouts with live values from GridImport_kW and GridExport_kW
  • Weather Panel — Live irradiance (W/m²) and cloud factor percentage sourced from DB_Weather.WeatherData
  • Energy Flow Overview — Animated topology diagram: Solar Array → Power Bus → Battery Storage / Grid Connection, with colour-changing flow lines and status indicator circles
  • System Status Bar — Four live KPI fields: Renewable %, Grid Dependency %, Self Sufficiency %, Plant Efficiency %; sourced from DB_Metrics
  • Plant Consumption (LOAD) — Live demand readout from DB_Load.LoadData.Demand_kW
HMI Tag Architecture
  • All HMI tags bound directly to DB-level variables — no intermediate memory tags
  • Animation properties configured using range-based value mapping (0 / 1) for boolean state visualisation
  • Flow line colours change dynamically based on active routing commands
  • SOC gauge needle driven by DB_Energy.BatteryData.SOC with 0–100 scale mapping

PLC Program Block Screenshots

Live TIA Portal screenshots captured from the active PLCSIM runtime session with all Phase 2 networks compiled and loaded. All blocks confirmed green-online with zero compile errors.

Main OB1 Network 1 — FB_WeatherEngine
Main [OB1] Network 1 — FB_WeatherEngine [FB1 / DB6]. Weather simulation outputs (Irradiance, CloudFactor, AmbientTemp, TimeOfDay) wired to DB_Weather.WeatherData. HMI_1 TP700 Comfort device visible in project tree — Phase 2 WinCC integration active.
Main OB1 Network 2 — FB_SolarArray
Main [OB1] Network 2 — FB_SolarArray [FB2 / DB7]. Weather inputs consumed from DB_Weather.WeatherData; five power outputs (Generated_kW, Efficiency, Voltage, Current, Frequency) written to DB_Energy.PowerData. Source of Solar_kW_In for all downstream Phase 2 blocks.
Main OB1 Network 1 closeup — FB_WeatherEngine wiring
Main [OB1] Network 1 (isolated view) — Full FB_WeatherEngine output wiring: IrradianceOut, CloudOut, TempOut, TimeOut resolved to DB_Weather.WeatherData structured fields. TimeOfDay feeds directly into FB_LoadDemand in Network 4.
Main OB1 Network 3 — FB_BatterySystem
Main [OB1] Network 3 — FB_BatterySystem [FB3 / DB8]. Generated_kW consumed from PowerData; SOC, ChargeRate, BatteryTemp, and Mode written back to DB_Energy.BatteryData. BatteryData.SOC sourced as BatterySOC_In by the Phase 2 energy router.
Main OB1 Network 4 — FB_LoadDemand Phase 2
Main [OB1] Network 4 — FB_LoadDemand [FB5 / DB12]. Phase 2 addition. TimeOfDay_In consumed from DB_Weather; Demand_kW_Out and PeakMode_Out written to DB_Load.LoadData. Dynamic load profile drives energy routing decisions in Network 5.
Main OB1 Network 5 — FB_EnergyRouter Phase 2
Main [OB1] Network 5 — FB_EnergyRouter [FB6 / DB13]. Phase 2 central routing engine. Four inputs (Solar_kW, Demand_kW, BatterySOC, PeakMode) resolved into four boolean command outputs: ChargeCommand, DischargeCommand, GridImportCommand, GridExportCommand — written to DB_Energy.PowerData.
Main OB1 Network 6 — Inline SCL Grid Command Resolution
Main [OB1] Network 6 — Inline SCL grid command resolution. Translates GridImportCommand and GridExportCommand boolean flags into quantified kW values. GridImport_kW computed as Demand − Generation; GridExport_kW as Generation − Demand. Executed before FB_EfficiencyMetrics to guarantee scan-order data availability.
Main OB1 Network 7 — FB_EfficiencyMetrics Phase 2
Main [OB1] Network 7 — FB_EfficiencyMetrics [FB7 / DB14]. Phase 2 KPI computation block. Consumes resolved Solar_kW, Demand_kW, and GridImport_kW; outputs RenewablePercent, GridDependency, SelfSufficiency, and PlantEfficiency to DB_Metrics — HMI tag-bound for live WinCC display.

WinCC Advanced Runtime — Live HMI Screenshots

Three operational states captured from the live WinCC Advanced Runtime session during PLCSIM execution. Each state demonstrates a distinct energy routing condition as the simulated day cycle progresses and solar irradiance varies.

WinCC HMI — High Solar Generation State
WinCC HMI Runtime — High Solar Generation State. Solar output: 616.4 kW at 1,000 W/m² irradiance. Renewable contribution: 88.06%, Grid Dependency: 11.94%, Self Sufficiency: 88.06%, Plant Efficiency: 87.93%. Grid import active at 83.6 kW to supplement 700 kW plant demand. Battery SOC: 2.6%. Energy flow line Solar → Power Bus shown green (high-generation active).
WinCC HMI — Heavy Cloud / Grid-Dominant State
WinCC HMI Runtime — Heavy Cloud / Grid-Dominant State. Solar output reduced to 60.7 kW at 660 W/m² with 90% cloud factor. Grid import surges to 639.3 kW to cover 700 kW demand. Renewable contribution collapses to 8.67%, Grid Dependency climbs to 91.33%. Solar panel background changes to muted blue, indicating low-generation mode. Battery SOC: 0.0% — discharge unavailable.
WinCC HMI — Partial Solar / Mixed Routing State
WinCC HMI Runtime — Partial Solar / Mixed Routing State. Solar output: 205.4 kW at 385 W/m² irradiance with 42% cloud cover. Grid import: 494.6 kW to meet 700 kW demand. Renewable: 29.35%, Grid Dependency: 70.65%, Self Sufficiency: 29.35%, Efficiency: 29.31%. Energy flow line colour changes to yellow — partial generation mid-state. All four KPI fields updating live from DB_Metrics via HMI tag bindings.

Virtual Commissioning & Runtime Status

All eight program blocks compiled to zero errors under TIA Portal V19 and loaded to the PLCSIM CPU 1511-1 PN virtual runtime. The WinCC Advanced HMI project was synchronised via the integrated HMI connection and launched in Runtime Advanced. All DB tag bindings confirmed active with live value updates visible across every HMI field during simulation.

● PLC STATUS: RUN
● COMPILE: 0 ERRORS / 0 WARNINGS
● INTERFACE: PLCSIM PN/IE 192.168.0.1
● HMI RUNTIME: WINCC ADVANCED — ACTIVE
● HMI DEVICE: TP700 COMFORT [VIRTUALISED]

Integration Issues & Resolutions

Several non-trivial engineering challenges were encountered and systematically diagnosed during Phase 2 implementation.

⚠ Issue 1 — WinCC Bit Animation Incompatibility

Single-bit animation mode was unavailable for certain WinCC object types, preventing direct boolean-driven colour changes on the energy flow diagram.

Resolution: Animation properties reconfigured to range-based value mapping — values 0 and 1 used as discrete range boundaries, replicating bit-driven behaviour within WinCC's supported animation framework.

⚠ Issue 2 — Zero-Value Efficiency Metrics (Scan Order Dependency)

All four efficiency KPI outputs remained fixed at 0.0 during initial commissioning. Root cause: the inline grid command resolution SCL (Network 6) had been placed after FB_EfficiencyMetrics in the OB1 execution sequence. The metrics block was reading stale, unresolved grid import values from the previous scan cycle.

Resolution: Network ordering restructured — grid SCL resolution moved above FB_EfficiencyMetrics. This enforced correct data dependency sequencing within the PLC scan, ensuring all upstream values were fully resolved before KPI computation executed.

⚠ Issue 3 — Conflicting Grid Control Authority (Dual Source Conflict)

The legacy FB_GridManager [FB4] from Phase 1 continued to write GridImport_kW and GridExport_kW concurrently with the new FB_EnergyRouter routing commands, producing indeterminate and oscillating SCADA values as two independent control sources competed for the same process variables.

Resolution: FB_GridManager removed from the OB1 execution sequence entirely. FB_EnergyRouter designated as the sole authoritative control source for all grid interaction variables, restoring deterministic and consistent energy routing behaviour.

⚠ Issue 4 — HMI Tag Binding Failures

Multiple WinCC HMI tags failed to resolve at runtime. Causes included incorrect DB variable path references, PLC-to-HMI tag name mismatches, and UDT structure path errors in some tag definitions.

Resolution: Affected tags rebuilt manually — HMI tags rebound directly to DB-level variables with fully qualified path syntax. Tag connections validated in the WinCC tag editor and confirmed live in Runtime Advanced before commissioning sign-off.

⚠ Issue 5 — WinCC Runtime System Screen Compilation Errors

WinCC generated compilation errors during Runtime launch related to invalid event handler references on auto-generated system screens.

Resolution: Invalid event references removed from the affected system screens. WinCC runtime compiled cleanly on subsequent build with no residual errors.

Engineering Lessons — Phase 2

✔ PLC Scan Order Is a First-Class Engineering Concern

The zero-value metrics issue demonstrated that data dependency sequencing in OB1 is as architecturally significant as the function block logic itself. In any system where calculated values feed subsequent calculations within the same scan, block execution order must be explicitly designed — not assumed.

✔ Single Ownership of Process Variables Is Non-Negotiable

Allowing two control blocks to write the same process variable simultaneously produces non-deterministic, unstable SCADA behaviour. Industrial automation systems must enforce strict single-source ownership for every controlled variable — particularly for grid interaction and power flow values where conflicting commands have real operational consequences.

✔ Modular FB Architecture Dramatically Reduces Debugging Scope

Each Phase 2 issue was isolated to a specific network or block within minutes, rather than requiring full-system analysis. The strict separation of concerns across weather, generation, storage, demand, routing, and metrics layers meant that each diagnosis affected one block — not a monolithic control program.

✔ HMI Tag Architecture Requires the Same Rigour as PLC Data Models

Multiple commissioning hours were consumed by incorrect HMI tag references rather than PLC logic errors. WinCC tag binding must be treated as a structured engineering activity — fully qualified DB paths, validated against the PLC data model, and tested independently of animation and screen logic.

✔ Industrial SCADA Systems Are Built in Disciplined Layers

This phase reinforced the architectural progression from monitoring → simulation → intelligent routing → metrics and diagnostics → operator visualisation. Each layer consumed verified outputs from the layer below it. That discipline is what allowed the system to scale from a static energy monitor into a responsive, decision-making plant management platform across two development phases.

Phase 2 System Capabilities

Development Roadmap

✅ Phase 1 — Core Simulation

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

✅ Phase 2 — Advanced Energy Management

Dynamic load demand, intelligent energy routing, efficiency KPIs, WinCC Advanced SCADA HMI. Complete.

🚨 Phase 3 — Alarm & Fault System

Inverter fault simulation, overtemperature alarms, grid instability events, alarm acknowledgment workflows, UDT_Alarm integration.

Phase 4 — Historical Trends

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

Phase 5 — Hybrid Microgrid

Wind turbine simulation, diesel generator backup logic, automatic transfer switching and source priority management.

Phase 6 — Advanced Control

Full plant state machines, PID thermal regulation, predictive energy optimisation, operational recipes.

Siemens Smart Solar Plant SCADA System — Phase 2: Advanced Energy Management & SCADA Visualisation
Developed in TIA Portal V19 · S7-1500 · SCL · PLCSIM · WinCC Advanced Runtime